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Measurable residual disease (MRD) is a powerful prognostic factor in acute myeloid leukemia (AML). However, pre-treatment molecular predictors of immunophenotypic MRD clearance remain unclear. We analyzed a dataset of 211 patients with pre-treatment next-generation sequencing who received induction chemotherapy and had MRD assessed by serial immunophenotypic monitoring after induction, subsequent therapy, and allogeneic stem cell transplant (allo-SCT). Induction chemotherapy led to MRD- remission, MRD+ remission, and persistent disease in 35%, 27%, and 38% of patients, respectively. With subsequent therapy, 34% of patients with MRD+ and 26% of patients with persistent disease converted to MRD-. Mutations in CEBPA, NRAS, KRAS, and NPM1 predicted high rates of MRD- remission, while mutations in TP53, SF3B1, ASXL1, and RUNX1 and karyotypic abnormalities including inv (3), monosomy 5 or 7 predicted low rates of MRD- remission. Patients with fewer individual clones were more likely to achieve MRD- remission. Among 132 patients who underwent allo-SCT, outcomes were favorable whether patients achieved early MRD- after induction or later MRD- after subsequent therapy prior to allo-SCT. As MRD conversion with chemotherapy prior to allo-SCT is rarely achieved in patients with specific baseline mutational patterns and high clone numbers, upfront inclusion of these patients into clinical trials should be considered.

We present a case of a patient with multiply relapsed, refractory myeloma whose clinical course showed evidence of a synergistic abscopal-like response to chimeric antigen receptor (CAR) T-cell therapy and localized radiotherapy (XRT). Shortly after receiving B-cell maturation antigen (BCMA)–targeted CAR T-cell therapy, the patient required urgent high-dose steroids and XRT for spinal cord compression. Despite the steroids, the patient had a durable systemic response that could not be attributed to XRT alone. Post-XRT findings included a second wave of fever and increased CRP and IL6, beginning 21 days after CAR T cells, which is late for cytokine-release syndrome from CAR T-cell therapy alone on this trial. Given this response, which resembled cytokine-release syndrome, immediately following XRT, we investigated changes in the patient's T-cell receptor (TCR) repertoire over 10 serial time points. Comparing T-cell diversity via Morisita's overlap indices (CD), we discovered that, although the diversity was initially stable after CAR T-cell therapy compared with baseline (CD = 0.89–0.97, baseline vs. 4 time points after CAR T cells), T-cell diversity changed after the conclusion of XRT, with >30% newly expanded TCRs (CD = 0.56–0.69, baseline vs. 4 time points after XRT). These findings suggest potential synergy between radiation and CAR T-cell therapies resulting in an abscopal-like response.

Supplementary Data Combined

Aims Chimeric antigen receptor T-cell therapy (CAR-T) harnesses a patient’s immune system to target cancer. There are sparse existing data characterizing death outcomes after CAR-T-related cardiotoxicity. This study examines the association between CAR-T-related severe cardiovascular events (SCE) and mortality. Methods and results From a multi-centre registry of 202 patients receiving anti-CD19 CAR-T, covariates including standard baseline cardiovascular and cancer parameters and biomarkers were collected. Severe cardiovascular events were defined as a composite of heart failure, cardiogenic shock, or myocardial infarction. Thirty-three patients experienced SCE, and 108 patients died during a median follow-up of 297 (interquartile range 104–647) days. Those that did and did not die after CAR-T were similar in age, sex, and prior anthracycline use. Those who died had higher peak interleukin (IL)-6 and ferritin levels after CAR-T infusion, and those who experienced SCE had higher peak IL-6, C-reactive protein (CRP), ferritin, and troponin levels. The day-100 and 1-year Kaplan–Meier overall mortality estimates were 18% and 43%, respectively, while the non-relapse mortality (NRM) cumulative incidence rates were 3.5% and 6.7%, respectively. In a Cox model, SCE occurrence following CAR-T was independently associated with increased overall mortality risk [hazard ratio (HR) 2.8, 95% confidence interval (CI) 1.6–4.7] after adjusting for age, cancer type and burden, anthracycline use, cytokine release syndrome grade ≥ 2, pre-existing heart failure, hypertension, and African American ancestry; SCEs were independently associated with increased NRM (HR 3.5, 95% CI 1.4–8.8) after adjusting for cancer burden. Conclusion Chimeric antigen receptor T-cell therapy recipients who experience SCE have higher overall mortality and NRM and higher peak levels of IL-6, CRP, ferritin, and troponin.

Accurate classification and risk stratification is critical for clinical decision making in AML patients. In the newly proposed World Health Organization (WHO) and International Consensus classifications (ICC) of hematolymphoid neoplasms, the presence of myelodysplasia-related (MR) gene mutations is included as one of the diagnostic criteria of AML, myelodysplasia-related (AML-MR), largely based on the assumption that these mutations are specific for AML with an antecedent myelodysplastic syndrome. ICC also prioritizes MR gene mutations over ontogeny (as defined by clinical history). Furthermore, European LeukemiaNet (ELN) 2022 stratifies these MR gene mutations to the adverse-risk group. By thoroughly annotating a cohort of 344 newly diagnosed AML patients treated at Memorial Sloan Kettering Cancer Center (MSKCC), we show that ontogeny assignment based on database registry lacks accuracy. MR gene mutations are frequently seen inde novoAML. Among MR gene mutations, onlyEZH2andSF3B1were associated with an inferior outcome in a univariate analysis. In a multivariate analysis, AML ontogeny had independent prognostic values even after adjusting for age, treatment, allo-transplant and genomic classes or ELN risks. Ontogeny also stratified the outcome of AML with MR gene mutations. Finally,de novoAML with MR gene mutations did not show an adverse outcome. In summary, our study emphasizes the importance of accurate ontogeny designation in clinical studies, demonstrates the independent prognostic value of AML ontogeny and questions the current classification and risk stratification of AML with MR gene mutations.Key pointsBoth ontogeny and genomics show independent prognostic values in AML.The newly proposed myelodysplasia-related gene mutations are neither specific to AML-MRCWHO2016nor predictive for adverse outcomes.Ontogeny stratifies the outcome of AML with myelodysplasia-related gene mutations.

Patients with hematological malignancies are at risk for poor outcomes when diagnosed with Coronavirus Disease 2019 (COVID-19). It remains unclear whether cytopenias and specific leukemia subtypes play a role in the clinical course of COVID-19 infection. Here we report outcomes and their clinical/laboratory predictors for 65 patients with acute and chronic leukemias diagnosed with COVID-19 between March 8, 2020 and May 19, 2020 at Memorial Sloan Kettering Cancer Center in New York City. Most patients had CLL (48%) or AML (26%). A total of 14 (22%) patients required high flow nasal cannula or were intubated for mechanical ventilation and 11 patients (17%) died. A diagnosis of AML (OR 4.7, p=0.028), active treatment within the last 3 months (OR 5.22, p=0.047), neutropenia within seven days prior and up to 28 days after SARS-CoV-2 diagnosis (11.75, p=0.001) and ≥ 3 comorbidities (OR 6.55, p=0.019) were associated with increased odds of death.

CD19-targeted chimeric antigen receptor (CAR) T-cell therapy has become a breakthrough treatment of patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, despite the high initial response rate, the majority of adult patients with B-ALL progress after CD19 CAR T-cell therapy. Data on the natural history, management, and outcome of adult B-ALL progressing after CD19 CAR T cells have not been described in detail. Herein, we report comprehensive data of 38 adult patients with B-ALL who progressed after CD19 CAR T therapy at our institution. The median time to progression after CAR T-cell therapy was 5.5 months. Median survival after post–CAR T progression was 7.5 months. A high disease burden at the time of CAR T-cell infusion was significantly associated with risk of post–CAR T progression. Thirty patients (79%) received salvage treatment of post–CAR T disease progression, and 13 patients (43%) achieved complete remission (CR), but remission duration was short. Notably, 7 (58.3%) of 12 patients achieved CR after blinatumomab and/or inotuzumab administered following post–CAR T failure. Multivariate analysis revealed that a longer remission duration from CAR T cells was associated with superior survival after progression following CAR T-cell therapy. In summary, overall prognosis of adult B-ALL patients progressing after CD19 CAR T cells was poor, although a subset of patients achieved sustained remissions to salvage treatments, including blinatumomab, inotuzumab, and reinfusion of CAR T cells. Novel therapeutic strategies are needed to reduce risk of progression after CAR T-cell therapy and improve outcomes of these patients.

Hematopoietic growth factors, including erythrocyte stimulating agents (ESAs), granulocyte colony-stimulating factors, and thrombopoietin mimetics, can mitigate anemia, neutropenia, and thrombocytopenia resulting from chemotherapy for the treatment of cancer. In the context of pandemic SARS-CoV-2 infection, patients with cancer have been identified as a group at high risk of morbidity and mortality from this infection. Our subcommittee of the NCCN Hematopoietic Growth Factors Panel convened a voluntary group to review the potential value of expanded use of such growth factors in the current high-risk environment. Although recommendations are available on the NCCN website in the COVID-19 Resources Section (https://www.nccn.org/covid-19/), these suggestions are provided without substantial context or reference. Herein we review the rationale and data underlying the suggested alterations to the use of hematopoietic growth factors for patients with cancer in the COVID-19 era.

Administration of pediatric-inspired chemotherapy to adults up to age 60 with acute lymphoblastic leukemia (ALL) is challenging in part due to toxicities of asparaginase as well as myelosuppression. We conducted a multi-center phase II clinical trial (clinicaltrials gov. Identifier: NCT01920737) investigating a pediatric-inspired regimen, based on the augmented arm of the Children’s Cancer Group 1882 protocol, incorporating six doses of pegaspargase 2,000 IU/m2, rationally synchronized to avoid overlapping toxicity with other agents. We treated 39 adults aged 20-60 years (median age 38 years) with newly-diagnosed ALL (n=31) or lymphoblastic lymphoma (n=8). Grade 3-4 hyperbilirubinemia occurred frequently and at higher rates in patients aged 40-60 years (n=18) versus 18-39 years (n=21) (44% vs. 10%, P=0.025). However, eight of nine patients rechallenged with pegaspargase did not experience recurrent grade 3-4 hyperbilirubinemia. Grade 3-4 hypertriglyceridemia and hypofibrinogenemia were common (each 59%). Asparaginase activity at 7 days post-infusion reflected levels associated with adequate asparagine depletion, even among those with antibodies to pegaspargase. Complete response (CR)/CR with incomplete hematologic recovery was observed post-induction in 38 of 39 (97%) patients. Among patients with ALL, rates of minimal residual disease negativity by multi-parameter flow cytometry were 33% and 83% following induction phase I and phase II, respectively. Event-free and overall survival at 3 years (67.8% and 76.4%) compare favorably to outcomes observed in other series. These results demonstrate pegaspargase can be administered in the context of intensive multi-agent chemotherapy to adults aged ≤60 years with manageable toxicity. This regimen may serve as an effective backbone into which novel agents may be incorporated in future frontline studies. Trial registration: https://clinicaltrials. gov/ct2/show/NCT01920737

Hypofibrinogenemia (HF) in acute leukemia has largely been attributed to hyperfibrinolysis and disseminated intravascular coagulation (DIC). Pathological alterations in hemostasis through various m...

Novel monoclonal antibody (mAb)-based therapies targeting CD19 and CD22 (blinatumomab and inotuzumab) have shown high rates of complete remission (CR) and been used as a bridging treatment to potentially curative allogeneic hematopoietic stem cell transplantation (alloHSCT) in adults with relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). However, limited data exist on the outcome of patients resistant to both mAbs as well as responses to each agent when progressed after the alternate antigen-targeted mAb. Herein, we report outcomes of 29 patients with R/R B-ALL previously treated with both blinatumomab and inotuzumab. Twenty-five patients (86.2%) received blinatumomab as first mAb (mAb1), and CD19-negative/dim relapses were observed in 44% of the patients. Inotuzumab induced CR in 68% of the patients for post-blinatumomab relapse regardless of CD19 expression status. The median time between mAb1 and mAb2 was 99 days. Twelve (63.2%) of 19 patients who achieved remission after mAb2 underwent alloHSCT. The median time from mAb2 to alloHSCT was 37.5 days. Acute graft-versus-host disease and nonrelapse mortality were observed in 58.3% (grade 3 or higher, 25%) and 41.7%, respectively. With a median follow-up of 16.8 months after mAb2, 19 patients (65.5%) relapsed, and 21 patients (72.4%) have died. Overall survival was not different between alloHSCT and non-alloHSCT patients. In conclusion, patients with B-ALL who relapsed after blinatumomab could be successfully rescued by inotuzumab as a bridge to alloHSCT but represent an ultra-high-risk group with poor overall survival. Further studies, including novel consolidation and treatment sequence, may improve outcomes of these patients.

Signaling through JAK1 and/or JAK2 is common among tumor and nontumor cells within peripheral T-cell lymphoma (PTCL). No oral therapies are approved for PTCL, and better treatments for relapsed/refractory disease are urgently needed. We conducted a phase 2 study of the JAK1/2 inhibitor ruxolitinib for patients with relapsed/refractory PTCL (n = 45) or mycosis fungoides (MF) (n = 7). Patients enrolled onto 1 of 3 biomarker-defined cohorts: (1) activating JAK and/or STAT mutations, (2) ≥30% pSTAT3 expression among tumor cells by immunohistochemistry, or (3) neither or insufficient tissue to assess. Patients received ruxolitinib 20 mg PO twice daily until progression and were assessed for response after cycles 2 and 5 and every 3 cycles thereafter. The primary endpoint was clinical benefit rate (CBR), defined as the combination of complete response, partial response (PR), and stable disease lasting at least 6 months. Only 1 of 7 patients with MF had CBR (ongoing PR > 18 months). CBR among the PTCL cases (n = 45) in cohorts 1, 2, and 3 were 53%, 45%, and 13% (cohorts 1 & 2 vs 3, P = .02), respectively. Eight patients had CBR > 12 months (5 ongoing), including 4 of 5 patients with T-cell large granular lymphocytic leukemia. In an exploratory analysis using multiplex immunofluorescence, expression of phosphorylated S6, a marker of PI3 kinase or mitogen-activated protein kinase activation, in

Background: Measurable residual disease (MRD) is a powerful prognostic factor in AML, including in prediction of outcomes post allogeneic stem cell transplant (alloSCT). However, genomic predictors of successful MRD eradication with chemotherapy prior to alloSCT are unclear. Objectives: Here we provide an integrated analysis of 233 patients (pts) who underwent induction chemotherapy with baseline next-generation sequencing (NGS) followed by serial immunophenotypic monitoring for MRD while patients received additional therapy and alloSCT. Methods: All pts who received anthracycline + cytarabine, +/- investigational agents at Memorial Sloan Kettering Cancer Center starting in April 2014 were retrospectively studied (A). 142 out of 233 pts subsequently underwent alloSCT after induction or additional therapy (A). Immunophenotypic MRD was identified in bone marrow aspirates (BMA) by multiparameter flow cytometry. Any level of residual disease was considered MRD+. Molecular analysis was obtained from pre-induction BMA by NGS using 28 or 49 or 400 gene panels. Results: Patient and treatment characteristics for all pts are detailed in panel (B). Induction chemotherapy resulted in an MRD-CR/CRi and MRD+CR/CRi in 29% and 23% of all pts, respectively (C). Additional therapy included consolidation (n=51), intensive re-induction/salvage (n=47) and non-intensive therapy (n=9). Of 83 AML pts with persistent AML and 58 pts with MRD+CR/CRi after induction (R1), 38/141 (27%) were able to be converted to MRD-CR/CRi. While 33/38 of pts went on to alloSCT after conversion to MRD-CR/CRi, 22 and 36 pts went to alloSCT with persistent AML and MRD+CR/CRi AML, respectively. We focused on pre-induction molecular predictors for achieving an MRD-CR/CRi response prior to transplant for the 142 pts who underwent alloSCT (D). Pts with a NPM1 (79%, Odds ratio [OR] 3.7, p=0.01), IDH1 (92%, OR 3.9, p=0.01) and KRAS (100%, OR 5.0, p=0.03) mutations achieved high rates of MRD-CR/CRi prior to alloSCT. In contrast, RUNX1 (28%, OR 0.2, p=0.01), TP53 (12%, OR 0.1, p=0.02) and SF3B1 (14%, OR 0.1, p=0.04) mutations predicted decreased odds of achieving MRD-CR/CRi prior to alloSCT despite induction and post-induction therapy. AlloSCT resulted in high rates of conversion from MRD+ and persistent disease to MRD negativity. Most pts who entered transplant with CR/CRi MRD+ (28/36, 76%) or persistent AML (14/22, 64%) cleared MRD by the first post-transplant BMA at a median of 32 days (E). Post-alloSCT follow-up indicated value in converting MRD+ to MRD- prior to alloSCT. There was no significant difference in post-transplant cumulative incidence of relapse (F) and OS (G) between early MRD-CR/CRi immediately following induction versus later conversion to MRD-CR/CRi with additional therapy prior to alloSCT. Despite initial post-transplant MRD clearance, pts who entered alloSCT with persistent AML or MRD+ had higher incidence of relapse (p=0.00037, F) and poorer post-transplant OS (p=0.013, G) compared to pts who entered alloSCT with MRD-. Pts with persistent disease prior to alloSCT had shorter duration of MRD- induced by alloSCT compared to pts with MRD-CR/CRi after induction or converted MRD-CR/CRi prior to alloSCT (p=0.0042, H). Importantly, duration of MRD negativity after alloSCT for patients who achieved MRD- prior to alloSCT was not affected by whether patients received induction +/- consolidation (I: treatment type 1-3 from B) vs. induction and salvage treatment for refractory AML (I: treatment type 4-6 from B). Conclusion: We show that transplanted AML pts with specific molecular mutations (RUNX1, SF3B1, and TP53) are unlikely to achieve MRD-CR/CRi after induction, consolidation or salvage therapy, while other mutations (NPM1, IDH1, KRAS) predict high rates of MRD- prior to alloSCT. Additional post-induction therapy may be advantageous for some MRD+ pts to achieve MRD- prior to alloSCT. Post-transplant OS is improved in pts who are MRD- at time of transplant, regardless of whether they required additional therapy beyond induction to achieve this state. AlloSCT is highly effective at eradicating MRD, but post-transplant MRD- is more durable in pts who are MRD- pre-alloSCT. Our results suggest that development of MRD-eradicating therapies has the potential to improve post-transplant outcomes and argues for innovative trials for pts with adverse molecular features currently unlikely to achieve MRD- pre alloSCT. Figure Disclosures Cai: Imago Biosciences, Inc.: Consultancy, Current equity holder in private company; DAVA Oncology: Honoraria. Geyer:Amgen: Research Funding. Glass:Gerson Lehman Group: Consultancy. Stein:Syros: Membership on an entity's Board of Directors or advisory committees; PTC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biotheryx: Consultancy; Bayer: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Research Funding; Seattle Genetics: Consultancy; Abbvie: Consultancy; Amgen: Consultancy; Celgene Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Levine:Gilead: Honoraria; Isoplexis: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Qiagen: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy; Lilly: Consultancy, Honoraria; Imago: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy; Novartis: Consultancy; Prelude Therapeutics: Research Funding; Loxo: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Morphosys: Consultancy; Roche: Consultancy, Honoraria, Research Funding. Gyurkocza:Actinium: Research Funding. Perales:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Nektar Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; MolMed: Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Medigene: Membership on an entity's Board of Directors or advisory committees, Other; Servier: Membership on an entity's Board of Directors or advisory committees, Other; Omeros: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Consultancy, Honoraria; NexImmune: Membership on an entity's Board of Directors or advisory committees; Cidara Therapeutics: Other; Miltenyi Biotec: Research Funding; Kite/Gilead: Honoraria, Research Funding; Incyte Corporation: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria; Bellicum: Honoraria, Membership on an entity's Board of Directors or advisory committees. Abdel-Wahab:H3 Biomedicine Inc.: Consultancy, Research Funding; Janssen: Consultancy; Envisagenics Inc.: Current equity holder in private company; Merck: Consultancy. Papaemmanuil:Kyowa Hakko Kirin: Consultancy, Honoraria; Isabl: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; MSKCC: Patents & Royalties; Novartis: Consultancy, Honoraria; Illumina: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Prime Oncology: Consultancy, Honoraria. Giralt:KITE: Consultancy; NOVARTIS: Consultancy, Honoraria, Research Funding; OMEROS: Consultancy, Honoraria; AMGEN: Consultancy, Research Funding; TAKEDA: Research Funding; ACTINUUM: Consultancy, Research Funding; MILTENYI: Consultancy, Research Funding; CELGENE: Consultancy, Honoraria, Research Funding; JAZZ: Consultancy, Honoraria. Tallman:Glycomimetics: Research Funding; Rafael: Research Funding; Amgen: Research Funding; Bioline rx: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees; KAHR: Membership on an entity's Board of Directors or advisory committees; UpToDate: Patents & Royalties; Rigel: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Membership on an entity's Board of Directors or advisory committees; Oncolyze: Membership on an entity's Board of Directors or advisory committees; Delta Fly Pharma: Membership on an entity's Board of Directors or advisory committees; BioSight: Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Research Funding; Orsenix: Research Funding; Cellerant: Research Funding; Abbvie: Research Funding. Goldberg:AROG: Research Funding; Aprea: Research Funding; ADC Therapeutics: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy; Aptose: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Dava Oncology: Honoraria; Pfizer: Research Funding; Celularity: Research Funding.

INTRODUCTION Hairy cell leukemia (HCL) is a rare, chronic B-cell lymphoproliferative disorder characterized by distinctive morphologic features and an indolent clinical course. The discovery of a recurrent activating mutation in BRAF (BRAF V600E) as a disease-defining genetic event in HCL has substantial diagnostic and therapeutic implications. Areas covered: Herein the authors review the role of BRAF V600E and RAF-MEK-ERK signaling in the pathogenesis of HCL, anecdotal clinical reports of BRAF inhibitor monotherapy in management of relapsed or refractory HCL, larger phase 2 trials investigating efficacy of BRAF inhibitor therapy for HCL, adverse effects commonly associated with BRAF inhibitor therapy, including cutaneous toxicity, and mechanisms of therapeutic resistance. Expert opinion: Ongoing and planned studies will help to optimize the use of BRAF inhibitor therapy for HCL by determining the efficacy of BRAF inhibition in combination with other antigen targeted or molecularly targeted therapies, and more broadly, to determine how hematologists can best utilize and sequence emerging diagnostic and therapeutic modalities in the care of patients with newly diagnosed and relapsed or refractory HCL.

With the US Food and Drug Administration (FDA) approval of four CD19- and one BCMA-targeted chimeric antigen receptor (CAR) therapy for B cell malignancies, CAR T cell therapy has finally reached the status of a medicinal product. The successful manufacturing of autologous CAR T cell products is a key requirement for this promising treatment modality. By analyzing the composition of 214 apheresis products from 210 subjects across eight disease indications, we found that high CD14+ cell content poses a challenge for manufacturing CAR T cells, especially in patients with non-Hodgkin’s lymphoma and multiple myeloma caused by the non-specific phagocytosis of the magnetic beads used to activate CD3+ T cells. We demonstrated that monocyte depletion via rapid plastic surface adhesion significantly reduces the CD14+ monocyte content in the apheresis products and simultaneously boosts the CD3+ content. We established a 40% CD14+ threshold for the stratification of apheresis products across nine clinical trials and demonstrated the effectiveness of this procedure by comparing manufacturing runs in two phase 1 clinical trials. Our study suggests that CD14+ content should be monitored in apheresis products, and that the manufacturing of CAR T cells should incorporate a step that lessens the CD14+ cell content in apheresis products containing more than 40% to maximize the production success., Graphical abstract, By analyzing 214 apheresis products and CAR T cell manufacturing runs across multiple disease indications, IR and colleagues have established a threshold of 40% CD14+ cell content as the trigger for the introduction of a rapid plastic adherence monocyte depletion step to enable a 97% manufacturing success rate.

Pegaspargase is a modified version of asparaginase with prolonged asparagine depletion. It appears to be safe in adults40 years old, but has a unique spectrum of toxicities, the risks of which appear to increase with age. The primary objective of this study was to evaluate pegaspargase tolerability and toxicity as assessed by evaluation of incidence and severity of adverse events. Secondary objectives included characterization of the reasons underlying pegaspargase discontinuation, when applicable. Grade 3/4 asparaginase-related toxicities with ≥10% incidence included: hyperbilirubinemia, hyperglycemia, hypertriglyceridemia, hypoalbuminemia, hypofibrinogenemia, and transaminitis. 63% of patients (38 of 60) received all intended doses of pegaspargase, with the most common reasons for discontinuation noted as hypersensitivity (12%), hyperbilirubinemia/transaminitis (8%), and hematopoietic transplantation in complete remission (10%). This study suggests that while hepatotoxicity and other known adverse effects are common, with careful monitoring, pegaspargase can safely be administered to adults with ALL age ≥40 years old.

There is a Blood Commentary on this article in this issue., Key Points Both watch-and-wait and treated CLL patients have high mortality rates when admitted for COVID-19. Receiving a BTKi for CLL at COVID-19 diagnosis severe enough to require hospitalization did not influence case fatality rate in this study., Given advanced age, comorbidities, and immune dysfunction, chronic lymphocytic leukemia (CLL) patients may be at particularly high risk of infection and poor outcomes related to coronavirus disease 2019 (COVID-19). Robust analysis of outcomes for CLL patients, particularly examining effects of baseline characteristics and CLL-directed therapy, is critical to optimally manage CLL patients through this evolving pandemic. CLL patients diagnosed with symptomatic COVID-19 across 43 international centers (n = 198) were included. Hospital admission occurred in 90%. Median age at COVID-19 diagnosis was 70.5 years. Median Cumulative Illness Rating Scale score was 8 (range, 4-32). Thirty-nine percent were treatment naive (“watch and wait”), while 61% had received ≥1 CLL-directed therapy (median, 2; range, 1-8). Ninety patients (45%) were receiving active CLL therapy at COVID-19 diagnosis, most commonly Bruton tyrosine kinase inhibitors (BTKi’s; n = 68/90 [76%]). At a median follow-up of 16 days, the overall case fatality rate was 33%, though 25% remain admitted. Watch-and-wait and treated cohorts had similar rates of admission (89% vs 90%), intensive care unit admission (35% vs 36%), intubation (33% vs 25%), and mortality (37% vs 32%). CLL-directed treatment with BTKi’s at COVID-19 diagnosis did not impact survival (case fatality rate, 34% vs 35%), though the BTKi was held during the COVID-19 course for most patients. These data suggest that the subgroup of CLL patients admitted with COVID-19, regardless of disease phase or treatment status, are at high risk of death. Future epidemiologic studies are needed to assess severe acute respiratory syndrome coronavirus 2 infection risk, these data should be validated independently, and randomized studies of BTKi’s in COVID-19 are needed to provide definitive evidence of benefit., Visual Abstract

Although novel agents (NAs) have improved outcomes for patients with chronic lymphocytic leukemia (CLL), a subset will progress through all available NAs. Understanding outcomes for potentially curative modalities including allogeneic hematopoietic stem cell transplantation (alloHCT) following NA therapy is critical while devising treatment sequences aimed at long-term disease control. In this multicenter, retrospective cohort study, we examined 65 patients with CLL who underwent alloHCT following exposure to ≥1 NA, including baseline disease and transplant characteristics, treatment preceding alloHCT, transplant outcomes, treatment following alloHCT, and survival outcomes. Univariable and multivariable analyses evaluated associations between pre-alloHCT factors and progression-free survival (PFS). Twenty-four-month PFS, overall survival (OS), nonrelapse mortality, and relapse incidence were 63%, 81%, 13%, and 27% among patients transplanted for CLL. Day +100 cumulative incidence of grade III-IV acute graft-vs-host disease (GVHD) was 24%; moderate-severe GVHD developed in 27%. Poor-risk disease characteristics, prior NA exposure, complete vs partial remission, and transplant characteristics were not independently associated with PFS. Hematopoietic cell transplantation–specific comorbidity index independently predicts PFS. PFS and OS were not impacted by having received NAs vs both NAs and chemoimmunotherapy, 1 vs ≥2 NAs, or ibrutinib vs venetoclax as the line of therapy immediately pre-alloHCT. AlloHCT remains a viable long-term disease control strategy that overcomes adverse CLL characteristics. Prior NAs do not appear to impact the safety of alloHCT, and survival outcomes are similar regardless of number of NAs received, prior chemoimmunotherapy exposure, or NA immediately preceding alloHCT. Decisions about proceeding to alloHCT should consider comorbidities and anticipated response to remaining therapeutic options.

Background: Autologous CD19-targeted chimeric antigen receptor-modified (CAR) T-cell therapy leads to complete responses (CR) in patients (pts) with (w/) relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL, >80% CR rate) and diffuse large B-cell lymphoma (DLBCL, ~40-55% CR rate). However, following fludarabine/cyclophosphamide (Flu/Cy) conditioning and CAR T-cell therapy w/ a CD28 costimulatory domain (e.g. 19-28z CAR T-cells), rates of grade ≥3 ICANS and grade ≥3 cytokine release syndrome (CRS) in pts w/ R/R DLBCL and morphologic R/R B-ALL exceed 30%. CRS and ICANS are associated w/ considerable morbidity, including increased length of hospitalization, and may be fatal. Host monocytes appear to be the major reservoir of cytokines driving CRS and ICANS post-CAR T-cell therapy (Giavradis et al. and Norelli et al., Nature Medicine, 2018). Circulating monocytic myeloid-derived suppressor cells (MDSCs) may also blunt efficacy of 19-28z CAR T-cells in R/R DLBCL (Jain et al., Blood, 2021). The CD45-targeted antibody radioconjugate (ARC) 131-I apamistamab is being investigated at myeloablative doses as conditioning prior to hematopoietic cell transplantation in pts w/ R/R acute myeloid leukemia. However, even at low doses (4-20 mCi), transient lymphocyte and blast reduction are observed. Preclinical studies in C57BL/6 mice demonstrate low-dose anti CD45 radioimmunotherapy (100 microCi) transiently depletes >90% lymphocytes, including CD4/CD8 T-cells, B-cells, NK cells, and T-regs, as well as splenocytes and MDSCs, w/ negligible effect on bone marrow (BM) hematopoietic stem cells (Dawicki et al., Oncotarget, 2020). We hypothesized a higher, yet nonmyeloablative dose of 131-I apamistamab may achieve more sustained, but reversible depletion of lymphocytes and other CD45 + immune cells, including monocytes thought to drive CRS/ICANS. We additionally hypothesized this approach (vs Flu/Cy) prior to CAR T-cell therapy would promote CAR T-cell expansion while reducing CSF levels of monocyte-derived cytokines (e.g. IL-1, IL-6, and IL-10), thus lowering the risk of severe ICANS (Fig 1A). Study design and methods: We are conducting a single-institution pilot study of 131-I apamistamab in lieu of Flu/Cy prior to 19-28z CAR T-cells in adults w/ R/R BALL or DLBCL (NCT04512716; Iomab-ACT); accrual is ongoing. Pts are eligible for leukapheresis if they are ≥18 years-old w/ R/R DLBCL (de novo or transformed) following ≥2 chemoimmunotherapy regimens w/ ≥1 FDG-avid measurable lesion or B-ALL following ≥1 line of multi-agent chemotherapy (R/R following induction/consolidation; prior 2 nd/3 rd gen TKI required for pts w/ Ph+ ALL) w/ ≥5% BM involvement and/or FDG-avid extramedullary disease, ECOG performance status 0-2, and w/ appropriate organ function. Active or prior CNS disease is not exclusionary. Pts previously treated w/ CD19-targeted CAR T-cell therapy are eligible as long as CD19 expression is retained. See Fig 1B/C: Post-leukapheresis, 19-28z CAR T-cells are manufactured as previously described (Park et al., NEJM, 2018). Bridging therapy is permitted at investigator discretion. Thyroid blocking is started ≥48h pre-ARC. 131-I apamistamab 75 mCi is administered 5-7 days pre-CAR T-cell infusion to achieve total absorbed marrow dose ~200 cGy w/ remaining absorbed dose The primary objective is to determine safety/tolerability of 131-I apamistamab 75 mCi given prior to 19-28z CAR T-cells in pts w/ R/R B-ALL/DLBCL. Secondary objectives include determining incidence/severity of ICANS and CRS, anti-tumor efficacy, and 19-28z CAR T-cell expansion/persistence. Key exploratory objectives include describing the cellular microenvironment following ARC and 19-28z CAR T-cell infusion using spectral cytometry, as well as cytokine levels in peripheral blood and CRS. The trial utilizes a 3+3 design in a single cohort. If dose-limiting toxicity (severe infusion-related reactions, treatment-resistant severe CRS/ICANS, persistent regimen-related cytopenias, among others defined in protocol) is seen in 0-1 of the first 3 pts treated, then up to 6 total (up to 3 additional) pts will be treated. We have designed this study to provide preliminary data to support further investigation of CD45-targeted ARCs prior to adoptive cellular therapy. Figure 1 Figure 1. Disclosures Geyer: Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Actinium Pharmaceuticals, Inc: Research Funding; Amgen: Research Funding. Geoghegan: Actinium Pharmaceuticals, Inc: Current Employment. Reddy: Actinium Pharmaceuticals: Current Employment, Current holder of stock options in a privately-held company. Berger: Actinium Pharmaceuticals, Inc: Current Employment. Ludwig: Actinium Pharmaceuticals, Inc: Current Employment. Pandit-Taskar: Bristol Myers Squibb: Research Funding; Bayer: Research Funding; Clarity Pharma: Research Funding; Illumina: Consultancy, Honoraria; ImaginAb: Consultancy, Honoraria, Research Funding; Ymabs: Research Funding; Progenics: Consultancy, Honoraria; Medimmune/Astrazeneca: Consultancy, Honoraria; Actinium Pharmaceuticals, Inc: Consultancy, Honoraria; Janssen: Research Funding; Regeneron: Research Funding. Sauter: Genmab: Consultancy; Celgene: Consultancy, Research Funding; Precision Biosciences: Consultancy; Kite/Gilead: Consultancy; Bristol-Myers Squibb: Research Funding; GSK: Consultancy; Gamida Cell: Consultancy; Novartis: Consultancy; Spectrum Pharmaceuticals: Consultancy; Juno Therapeutics: Consultancy, Research Funding; Sanofi-Genzyme: Consultancy, Research Funding. OffLabel Disclosure: 131-I apamistamab and 19-28z CAR T-cells are investigational agents in treatment of ALL and DLBCL

Background: Gilteritinib monotherapy provides a CR/CRh rate of 34% and a median event-free survival of 2.3 months in relapsed FLT3 mutant AML. Many AML patients (pts) who relapse after gilteritinib still express mutant FLT3 receptor and could potentially respond to FLT3 inhibition. Crenolanib is a type I, pan-FLT3 inhibitor which can be given as monotherapy or combined at full doses with standard salvage chemotherapy. Methods: We here report our experience with 7 consecutive pts who received crenolanib on compassionate basis after progressing on gilteritinib. IRB/local ethics approval was obtained prior to treatment for each pt and all pts signed informed consent forms. Results: Prior Treatment history: From Sep 2019 to July 2020, 7 consecutive pts with multiply relapsed FLT3-mutant AML who received compassionate use crenolanib after progressing on gilteritinib were identified. Four pts had relapsed after allogeneic HSCT (one pt had undergone two HSCT) and the other 3 were primary refractory despite multiple prior lines of therapy (range 2-5, median 4). Clinical presentation: At the time of treatment all pts had bone-marrow infiltration or greater than 20% circulating blasts. 1 pt did not undergo BM assessment prior to salvage chemotherapy and crenolanib but had 87% circulating blasts in the peripheral blood. One pt had cranial nerve palsy due to leukemic meningitis, another pt had extramedullary relapse in spleen and lymph nodes. Five pts had FLT3-ITD (1 of whom also had the gate-keeper FLT3-F691L mutations); 1 had FLT3-D835 and 1 had both FLT3-ITD and TKD. Crenolanib treatment: Crenolanib at 100mg TID was administered with intensive salvage therapy in 3 pts (FLAG-IDA in 2, HiDAC in 1). In the other 4 pts crenolanib was given with a palliative intent (with decitabine in 2, with azacytidine in 1 and as monotherapy in 1). Tolerability of crenolanib: Crenolanib has been clinically well tolerated, with mild nausea and vomiting reported in 3 pts which was controlled by antiemetics without causing any drug interruptions. Two pts had elevated transaminases (which resolved as concomitant medications were discontinued). There were no cardiac toxicities, pericardial effusion, fluid retention or weight gain. Response to crenolanib: At the time of this abstract, 5 of the 7 pts remain on crenolanib from a period of 18-160 days. Six of 7 pts reported clinical benefit with crenolanib. Of the 3 pts being treated with curative intent, the pt with extramedullary disease in the spleen and lymph nodes had complete resolution of her AML by PET scan. She also had exhibited clearance of bone-marrow blasts with full count recovery and became FLT3 negative. The pt with FLT3-F691 mutation and cranial nerve palsy due to CNS leukemia had clearance of CNS blasts and improvement in cranial nerve function after HIDAC, crenolanib, and intrathecal cytarabine; this patient achieved morphologic leukemia free state and FLT3 negativity in the BM. A 22-year-old pt treated with FLAG-IDA has only received 18 days of crenolanib at time of data cutoff. All pts treated with curative intent continue on crenolanib. Of the 4 pts treated with palliative intent, the pt with mutant TP53 had no benefit following crenolanib and azacytidine and died within two months. One patient, who had had two prior HSCTs, had 90% reduction in circulating blasts with azacytidine + crenolanib, but chose to discontinue treatment after 9 days. The other 2 pts continue on crenolanib 2 and 5 months after starting treatment. Conclusion: With the widespread availability of gilteritinib, more pts are now in need of treatment options after gilteritinib refractoriness or treatment failure. These pts often have resistant clones due to either acquisition of the gate-keeper FLT3-F691 mutation or RAS mutant clones. In this consecutive case series of 7 post-gilteritinib pts, treated in US and Europe, crenolanib can be given at full doses in combination with intensive salvage chemotherapy or decitabine/azacitidine. The individual-patient-level experience suggests crenolanib could effectively clear FLT3-ITD and variant FLT3-TKD mutations in pts progressing from multiple lines of treatment including gilteritinib. Clinical trials combining crenolanib with salvage chemotherapy in relapsed and refractory AML with FLT3 mutations are ongoing. More information about crenolanib compassionate use program is available by emailing compassionate@arogpharma.com. Disclosures Goldberg: Celgene: Consultancy; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Aptose: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Research Funding; Aprea: Research Funding; AROG: Research Funding; Celularity: Research Funding; Dava Oncology: Honoraria; Pfizer: Research Funding. Geyer:Amgen: Research Funding. Pardee:Rafael Pharmaceuticals: Consultancy; AbbVie: Consultancy; Genentech, Inc.: Consultancy; BMS: Consultancy, Honoraria, Speakers Bureau; Karyopharm: Research Funding; Rafael: Research Funding; Celgene: Consultancy, Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Pharmacyclics: Speakers Bureau. Grunwald:Cardinal Health: Consultancy; Amgen: Consultancy; Amgen: Consultancy; Agios: Consultancy; Merck: Consultancy; Merck: Consultancy; Abbvie: Consultancy; Agios: Consultancy; Daiichi Sankyo: Consultancy; Agios: Consultancy; Abbvie: Consultancy; Abbvie: Consultancy; Trovagene: Consultancy; Daiichi Sankyo: Consultancy; Incyte: Consultancy, Research Funding; Celgene: Consultancy; Incyte: Consultancy, Research Funding; Astellas: Consultancy; Astellas: Consultancy; Astellas: Consultancy; Genentech/Roche: Research Funding; Premier: Consultancy; Premier: Consultancy; Janssen: Research Funding; Genentech/Roche: Research Funding; Genentech/Roche: Research Funding; Forma Therapeutics: Research Funding; Merck: Research Funding; Janssen: Research Funding; Forma Therapeutics: Research Funding; Forma Therapeutics: Research Funding; Trovagene: Consultancy; Premier: Consultancy; Merck: Consultancy; Daiichi Sankyo: Consultancy; Trovagene: Consultancy; Incyte: Consultancy, Research Funding; Pfizer: Consultancy; Celgene: Consultancy; Celgene: Consultancy; Cardinal Health: Consultancy; Pfizer: Consultancy; Amgen: Consultancy; Pfizer: Consultancy; Cardinal Health: Consultancy. Wang:Arog Pharmaceuticals: Current Employment. Pathan:Arog Pharmaceuticals: Current Employment. Messahel:AROG Pharmaceuticals: Current Employment.

BACKGROUND: Subgroups of patients with relapsed or refractory (R/R) chronic lymphocytic leukemia (CLL) exhibit suboptimal outcomes after standard therapies, including oral kinase inhibitors. We and others have previously reported on the safety and efficacy of autologous CD19-targeted CAR T cells for these patients. Here, we report safety and long-term follow-up of CAR T cell therapy with or without conditioning chemotherapy for patients with R/R CLL and indolent B cell non-Hodgkin lymphoma (B-NHL). METHODS: We conducted a phase I clinical trial investigating CD19-targeted CAR T cells incorporating a CD28 costimulatory domain (19–28z). Seventeen of twenty patients received conditioning chemotherapy prior to CAR T cell infusion. Five patients with CLL received ibrutinib at the time of autologous T cell collection and/or CAR T cell administration. RESULTS: This analysis included 16 patients with R/R CLL and 4 patients with R/R indolent B-NHL. Cytokine release syndrome (CRS) was observed in all 20 patients, but grade 3 and 4 CRS and neurological events were uncommon (10% for each). Ex vivo expansion of T cells and proportions of CAR T cells with the CD62L(+)CD127(+) immunophenotype were significantly greater (P = 0.047; CD8 subset, P = 0.0061, CD4 subset) in patients on ibrutinib at leukapheresis. Three of twelve evaluable CLL patients receiving conditioning chemotherapy achieved complete response (CR) (2 had minimal residual disease–negative CR). All patients achieving CR remained progression free at median follow-up of 53 months. CONCLUSION: Conditioning chemotherapy and 19–28z CAR T cells were acceptably tolerated across investigated dose levels in heavily pretreated patients with R/R CLL and indolent B-NHL, and a subgroup of patients achieved durable CR. Ibrutinib therapy may modulate autologous T cell phenotype. TRIAL REGISTRATION: ClinicalTrials.gov NCT00466531. FUNDING: Juno Therapeutics and NIH/National Cancer Institute Cancer Center Support Grant (P30-CA08748).

Introduction: Incorporation of ABL-targeted oral tyrosine kinase inhibitors (TKIs) to conventional chemotherapy regimens has improved outcomes for adult patients (pts) with (w/) Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). However, the addition of chemotherapy to TKIs may increase rates of infectious complications, organ toxicity, hospitalization, and mortality. As a result, we and others have investigated novel chemotherapy-sparing approaches for pts w/ Ph+ ALL. The CD3/CD19-targeted bispecific T-cell engager blinatumomab (BLIN) has demonstrated single-agent activity in pts w/ B-ALL w/ minimal residual disease (MRD) or relapsed/refractory (R/R) ALL, including R/R Ph+ ALL (Martinelli et al., J Clin Oncol, 2017). In an effort to deepen responses, we have used BLIN concomitantly w/ commercially available TKIs as consolidation and re-induction therapy. Reported experience w/ BLIN+TKI is limited. Herein we describe the observed safety and efficacy of BLIN+TKI in pts w/ Ph+ ALL w/ varying disease burden at our institution. Methods: We reviewed electronic medical records of pts ≥ 18 years (yrs) old w/ previously treated Ph+ ALL receiving BLIN w/ concomitant, FDA-approved TKIs at Memorial Sloan Kettering Cancer Center (MSKCC) who began BLIN+TKI between March 2017 and April 2018. The primary objectives were to characterize the safety/toxicity profile and rates of MRD negativity by flow cytometry (FACS) and/or quantitative real-time PCR for BCR-ABL1 transcripts following consolidation (n=9) or re-induction (n=2) w/ BLIN+TKI. Results: Eleven pts (6F, 5M) were identified (Table 1). Median age at start of BLIN+TKI was 61.2 yrs (range, 27.7-76.9). Three pts had undergone prior allogeneic hematopoietic cell transplantation (alloHCT). No pt had baseline hepatic dysfunction, central nervous system (CNS) or extramedullary (EM) disease prior to BLIN+TKI. All pts had documented CD19 expression on blasts prior to treatment. Ponatinib (PON) was the most commonly used TKI (n=7) followed by dasatinib (DAS, n=3), and nilotinib (NIL, n=1); one pt taking BLIN+PON briefly received BLIN+DAS during cycle 1. All pts were admitted for initiation of BLIN+TKI. BLIN was started at 9 mcg/day IVCI w/ escalation to 28 mcg/day IVCI on day 8 (per recommended dosing for pts w/ R/R ALL) in 10 pts and at 28 mcg/day IVCI in one pt (per flat dosing schedule described by Gökbuget et al., Blood, 2018). All 7 pts w/ MRD by FACS (n=5) and/or BCR-ABL1 PCR (n=7) prior to BLIN+TKI exhibited MRD negativity by FACS following 1 cycle of BLIN+TKI; 6 of these 7 pts achieved complete molecular response (CMR) by PCR following 1 cycle (n=5) or 2 cycles (n=1) of BLIN+TKI. All 6 remain in ongoing CMR at 1.8-15.1 months after initial achievement of CMR. Neither of the 2 pts w/ morphologic disease responded to BLIN+TKI and ultimately succumbed to their disease. The 2 pts who began BLIN+TKI in CMR have both maintained continuous CMR. Three pts have proceeded to 1st (n=2) or 2nd (n=1) alloHCT post-BLIN+TKI, without documented, relevant toxicities attributable to prior blinatumomab exposure. Median event-free and overall survival were not reached in this small group of pts, w/ median follow-up of 7.7 months among survivors (range, 3.2-16.0 months). Three pts developed grade 1 cytokine release syndrome (CRS). Notably, 2 of these pts had morphologic ALL at time of BLIN+TKI; none of these events warranted interruption of therapy or corticosteroids. No pts developed neurologic toxicity. Five pts exhibited transient transaminitis during BLIN+TKI; none reached recommended parameters to discontinue BLIN. Of these 5 pts, 4 were on concurrent PON. One pt required dose attenuation of PON; hepatic enzymes otherwise normalized w/o intervention. Conclusions: Our small series suggests that BLIN+TKI may be a safe and effective consolidation strategy for pts w/ MRD+ Ph+ ALL to achieve or sustain CMR, creating a platform for alloHCT or other post-remission therapy. Observed rates of CRS were higher and neurologic toxicity appeared lower (none documented) than in other studies of BLIN in pts w/ MRD (Gökbuget et al., Blood, 2018). Higher risk of transaminitis was noted in pts receiving BLIN+PON and warrants further observation, particularly as 28 mcg/day IVCI flat dosing is increasingly used for pts w/ MRD. Earlier incorporation of BLIN+TKI into treatment paradigms for Ph+ ALL may limit toxicity while deepening response and maintaining CMR. Disclosures King: Genentech: Other: Advisory Board . Tallman:Daiichi-Sankyo: Other: Advisory board; Orsenix: Other: Advisory board; Cellerant: Research Funding; ADC Therapeutics: Research Funding; AbbVie: Research Funding; AROG: Research Funding; BioSight: Other: Advisory board. Park:Pfizer: Consultancy; Juno Therapeutics: Consultancy, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy; Novartis: Consultancy; Kite Pharma: Consultancy; Adaptive Biotechnologies: Consultancy; Shire: Consultancy. Geyer:Dava Oncology: Honoraria.

The past several years have been marked by extraordinary advances in clinical applications of immunotherapy. In particular, adoptive cellular therapy utilizing chimeric antigen receptor (CAR) modified T cells targeted to CD19 has demonstrated substantial clinical efficacy in children and adults with relapsed or refractory B cell acute lymphoblastic leukemia (B-ALL), and durable clinical benefit in a smaller subset of patients with relapsed or refractory chronic lymphocytic leukemia (CLL) or B cell non-Hodgkin lymphoma (B-NHL). Early phase clinical trials are presently assessing CAR T cell safety and efficacy in additional malignancies. Herein, we discuss clinical results from the largest series to date investigating CD19-targeted CAR T cells in B-ALL, CLL, and B-NHL, including discussion of differences in CAR T cell design and production and treatment approach, as well as clinical efficacy, nature of severe cytokine release syndrome and neurologic toxicities, and CAR T cell expansion and persistence. We additionally review the current and forthcoming use of CAR T cells in multiple myeloma and several solid tumors, and highlight challenges and opportunities afforded by the current state of CAR T cell therapies, including strategies to overcome inhibitory aspects of the tumor microenvironment and enhance antitumor efficacy.

Adoptive transfer of T cells genetically modified to express chimeric antigen receptors (CARs) targeting CD19 has produced impressive results in treating patients with B-cell malignancies. Although these CAR-modified T cells target the same antigen, the designs of CARs vary as well as several key aspects of the clinical trials in which these CARs have been studied. It is unclear whether these differences have any impact on clinical outcome and treatment-related toxicities. Herein, we review clinical results reflecting the investigational use of CD19-targeted CAR T-cell therapeutics in patients with B-cell hematologic malignancies, in light of differences in CAR design and production, and outline the limitations inherent in comparing outcomes between studies.

Background: Combining oral ABL-targeted tyrosine kinase inhibitors (TKIs) with (w/) multi-agent chemotherapy has improved the long-term disease-free survival of adults w/ Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). However, Ph+ ALL occurs more commonly in older adults, and toxicities of multi-agent chemotherapy, including sequelae of prolonged myelosuppression, are amplified in this population. Others have previously reported rates of morphologic complete response (mCR) approaching 100% among adults w/ Ph+ ALL treated w/ corticosteroids (CS) and dasatinib (DAS) alone as induction therapy, but w/ low rates of minimal residual disease (MRD) negativity by flow cytometry (FACS) and BCR-ABL1 PCR (complete molecular response, CMR) and high rates of relapse in the absence of further consolidation. The bispecific T-cell engager blinatumomab (BLIN) has considerable efficacy in clearing MRD in patients (pts) w/ Ph- B-cell ALL. We have previously reported our institutional experience combining ABL TKIs w/ BLIN in pts w/ Ph+ ALL and MRD, including encouraging safety data and high rates of MRD eradication (King/Geyer et al., Leuk Res, 2019). The ongoing D-ALBA study (GIMEMA LAL2116) is also investigating BLIN + DAS consolidation following 12 weeks of induction (prednisone + DAS followed by DAS), w/out protocol-specified maintenance, and has demonstrated preliminary evidence of efficacy (Chiaretti et al., ASH Meeting, 2019). As such, we designed a phase II study of BLIN as part of a chemotherapy sparing strategy in pts w/ Ph+ ALL (BLISSPHALL), introducing BLIN as early as 6 weeks into treatment for pts in morphologic CR, w/ aim of enhancing early MRD negativity and suppressing resistant clones early in disease course. Study design and methods: Our institution is leading a phase II trial of TKI + BLIN consolidation and maintenance in adults w/ newly-diagnosed Ph+ ALL, w/ potential multicenter expansion (NCT04329325). Pts are eligible if they are ≥18 years-old w/ Ph+ ALL confirmed by cytogenetic or molecular studies, ECOG performance status 0-2, w/out prior therapy for ALL beyond CS, hydroxyurea, or intrathecal chemotherapy, w/out known active extramedullary disease and/or CNS-3 disease, and w/ appropriate organ function. See Figure 1: pts will receive a CS pre-phase (days [d] -6 - 0) followed by modified GIMEMA LAL1205 induction (dexamethasone [DEX] 10 mg/m2 [max 24 mg/d], d1-24, tapered off d25-32) + DAS 140 mg/d (dose adjustments or TKI change permitted per protocol) w/ intrathecal methotrexate (IT MTX) d22, 43 and bone marrow (BM) assessments including FACS and BCR-ABL1 PCR. Pts in mCR on d43 (or optional reassessment ≤ 3 weeks later) will be eligible to proceed to consolidation w/ 3 cycles (C) BLIN 28 mcg/d IVCI, d1-28, concurrent w/ TKI, w/ 14d off BLIN between cycles and BM MRD assessment/IT MTX after each cycle. C1 BLIN + TKI is required to begin inpatient x72 hours. TKI is given continuously including between BLIN cycles. Pts in CMR after consolidation may proceed to maintenance (C4-7 BLIN + TKI, 28d off between cycles). Pts may come off study to proceed to hematopoietic cell transplant (HCT) at any point, though it is recommended such pts receive ≥2C of BLIN + TKI. The primary objective is to determine the proportion of evaluable pts achieving CMR by the end of consolidation (≤ 3C BLIN + TKI). Secondary objectives include safety/toxicity of BLIN + DAS, duration of CMR, incidence of relapse, event-free/overall survival. Exploratory objectives include safety/toxicity of non-DAS TKIs + BLIN, defining patterns/mechanisms of resistance to BLIN+TKI (including ABL kinase mutations), and outcomes among pts not undergoing HCT. The trial utilizes a Simon's minimax two-stage design; 20% CMR rate is considered not promising, a 50% CMR rate is considered promising, and probabilities of type I/II error are set at 0.10/0.10. If ≥ 3 of the first 10 pts achieve CMR we will continue enrollment to max 17 pts. If ≥ 6 pts achieve CMR, then BLIN + TKI will be considered promising for further investigation. The investigators are hopeful this study will add to the currently limited prospective data supporting TKI + BLIN consolidation/maintenance for pts w/ Ph+ ALL and efforts to develop chemotherapy-sparing and immunotherapeutic strategies for older pts w/ ALL. Disclosures Geyer: Amgen: Research Funding. King:Abbvie: Other: advisory board. Park:Novartis: Consultancy; Genentech/Roche: Research Funding; Intellia: Consultancy; Artiva: Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics: Research Funding; Takeda: Consultancy, Research Funding; Servier: Consultancy, Research Funding; AstraZeneca: Consultancy; Allogene: Consultancy; Incyte: Consultancy, Research Funding; Kite: Consultancy, Research Funding; Juno Therapeutics: Research Funding; GSK: Consultancy; Autolus: Consultancy, Research Funding; Minverva: Consultancy; Amgen: Consultancy, Research Funding. OffLabel Disclosure: Blinatumomab is not approved to be given in combination with ABL tyrosine kinase inhibitors for treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia.

Introduction: Peripheral and cutaneous T cell lymphomas (TCL) are highly heterogeneous diseases that in the relapsed/refractory (R/R) stage have poor outcome. JAK/STAT, Pi3K/AKT and MAP kinase signaling are commonly involved in the pathogenesis of these lymphomas, and the efficacy of small molecule inhibitors targeting these pathways is being assessed in phase II trials. However, biomarkers to define patients most likely to benefit from specific inhibitors are lacking and mechanisms of acquired resistance in TCLs have not been reported. Methods: We are conducting two early phase trials in R/R TCL: 1) NCT02974647 targets JAK1/JAK2 with ruxolitinib (RUX, a JAK 1-2 inhibitor) and has enrolled 53 patients and 2) NCT02783625 targets Pi3K/AKT with duvelisib (DUV, a Pi3K gamma-delta inhibitor) in combination with either romidepsin or bortezomib and has enrolled 92 patients. We analyzed pre-, on and post- treatment biopsies with multiplex immunofluorescence (mIF) using the Vectra platform, and analyzed images for marker expression and cellular location using HALO software. We designed multiple mIF panels with 6 markers per slide, 3 identifying TCL cells based on disease-specific phenotypes (e.g. CD4+PD1+CD8- for angioimmunoblastic TCL), pSTAT3,5, pS6, and a macrophage marker (CD68). Areas of TCL involvement within biopsy slides were manually defined during image analysis based on mIF and comparison to clinical immunohistochemistry. Differences in marker expressions were analyzed with the Wilcoxon test using the program R. Results: We analyzed 53 biopsies from 39 patients with high-quality mIF images, of which 17 were from lymph nodes and 36 were from extranodal sites. Of 39 patients, 13 were treated with RUX (9 biopsies pre-, 7 on, 4 post- treatment) and 26 with DUV (20 biopsies pre-, 6 on, 10 post- treatment). Median number of total TCL cells in pre-treatment biopsies was 1041 (range, 97-6463) and median TCL cell fraction within involved areas was 27.86% (range, 5.12-88.02%). Median macrophage fraction within involved areas was 5.92% (range, 2.89-11.88%). For either agent, response to treatment was not associated with: 1) quantity of macrophages (p=0.1 for responders vs non-responders to DUV, p=0.53 for RUX), 2) average distance between TCL cells and closest macrophage, 3) TCL cell fraction within involved areas, or 4) fraction of TCL cells expressing pSTAT3/5 (Figure). In contrast, pS6 expression in Conclusions: mIF is a feasible platform for biomarker discovery and translation in TCL, a set of lymphomas with heterogeneous immunophenotypes. pS6 expression in Citation Format: Paola Ghione, Alison Moskowitz, Priadarshini Kumar, Andrea Knezevic, Venkatraman Seshan, Eric Jacobsen, Jia Ruan, Johnathan Schatz, Sarah Noor, Patricia Myskowski, Helen Hancock, Theresa Davey, Obadi Obadi, Carlissa Onwasigwe, Nivetha Ganesan, Lauren Pomerantz, Christine Jarjies, Allison Sigler, Mark Geyer, Ariela Noy, David Straus, Natasha Galasso, Giorgio Inghirami, Steven Horwitz, David Weinstock, Travis Hollmann, Ahmet Dogan. Multispectral immunofluorescence identifies pS6 as a biomarker of intrinsic resistance to ruxolitinib in patients with relapsed/refractory T-cell lymphomas [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4248.

Within the past several years, renewed interest in immunotherapy has been observed in multiple fields of oncology, including antibody-based therapeutics (e.g., checkpoint blockade) and adoptive cellular therapies. In the field of adult leukemias, such interest has been driven by the limitations of presently available therapies to induce durable remissions reliably in patients with relapsed and refractory leukemia. The adoptive transfer of genetically modified autologous T-cells aims to rapidly establish specific antitumor activity. This strategy requires targeting of autologous T-cells by means of a transgene-encoded antigen receptor, consisting of a chimeric antigen receptor (CAR), as will be discussed herein, or T-cell receptor (TCR) chains. CD19 is nearly universally expressed by B-ALL, CLL, and hairy cell leukemia, while not expressed on normal tissues other than B-cells, including multipotent hematopoietic progenitor cells. Multiple generations of CARs have been developed and investigated in clinical studies and will be discussed in this review. In this chapter, we review clinical outcomes of adults with leukemia treated with CAR T-cells, toxicities associated with CAR T-cell administration, present challenges limiting therapeutic efficacy, and future directions, including novel targets and enhancements to improve antileukemic activity.

Measurable residual disease is associated with inferior outcomes in patients with acute myeloid leukemia (AML). Measurable residual disease monitoring enhances risk stratification and may guide therapeutic intervention. The European LeukemiaNet working party recently came to a consensus recommendation incorporating leukemia associated immunophenotype-based different from normal approach by multi-color flow cytometry for measurable residual disease evaluation. However, the analytical approach is highly expertise-dependent and difficult to standardize. Here we demonstrate that loss of plasmacytoid dendritic cell differentiation after 7+3 induction in AML is highly specific for measurable residual disease positivity (specificity 97.4%) in a uniformly treated patient cohort. Moreover, loss of plasmacytoid dendritic cell differentiation as determined by a blast-to-plasmacytoid dendritic cell ratio >10 was strongly associated with inferior overall and relapse-free survival (RFS) [Hazard ratio 2.79, 95% confidence interval (95%CI): 0.98-7.97; P=0.077) and 3.83 (95%CI: 1.51-9.74; P=0.007), respectively), which is similar in magnitude to measurable residual disease positivity. Importantly, measurable residual disease positive patients who reconstituted plasmacytoid dendritic cell differentiation (blast/ plasmacytoid dendritic cell ratio

Background We aimed to characterize institutional resources utilized (other than T cell collection and CAR T cell manufacturing and infusion) peri-chimeric antigen receptor-modified (CAR) T cells administration. Methods Adult patients treated on selected investigator-initiated clinical trials of CAR T cell therapy at Memorial Sloan Kettering Cancer Center were identified from the institutional database. Utilization data was collected from the start of admission for CAR T cell infusion through the end of the initial admission for infusion or through 30 days following initial CAR T cell infusion, whichever was longer. Descriptive statistics were used to analyze the data. Results Between 6/2007 to 4/2018, 106 pts (56 pts (53%) B-cell acute lymphoblastic leukemia (ALL), 37 (35%) chronic lymphocytic leukemia (CLL), B-cell non-Hodgkin lymphoma (NHL), and 13 (12%) multiple myeloma (MM)) on 4 clinical trials receiving inpatient CAR T cell infusions. The median age was 53 yrs (range 22-77) with 65% male. The median length of stay for the admission during which CAR T cells was given was 23 days (range 4 -133), with ALL patients admitted longer (Figure 1). 43 (41%) spent at least one day in the intensive care unit (ICU), with a range of 0-43 days. Outpatient clinic visits through day 30 post CAR T cell infusion occurred in 57 (53%) patients. A total of 62,953 laboratory panels and 1,190 radiology studies done during the study time frame. Fourteen percent of the labs were complete blood counts, basic or comprehensive metabolic panels, or liver function tests. For the total population, ALL, CLL/NHL, MM, there were a median of 63.5 (range 13-368), 91.5 (21-368), 47 (13-167), and 51 (range 38-113) of these panels done per patient during the time frame, respectively. Among the radiology studies, 25% were CT scans, 10% MRIs, 7% PET scans, 5% ultrasounds, and 53% x-rays, with differences in patterns of use by disease type (Figure 2). Chemotherapy accounted for 328 units (0.8%) of the 41,331 units of medications given in this time frame. The median medication units per patient was 255 (range 35-2091), 423 (range 35-2091), 200 (range 41-1190), and 207 (range 90-666) for the total population, and the ALL, CLL/NHL, and MM pts, respectively. Thirty-two doses of tocilizumab were given to 25 patients (24%), with ALL pts receiving 23 of those doses (72%). Conclusion CAR T cell therapy utilizes many resources and can create challenges in institutional resource capacity. Identifying these resources will allow for better allocation and care delivery. Further refinement of CAR T cell products and improvements in CAR T cell-related toxicity management may permit safer delivery of this therapy and reduce costs per patient. Comparison with alternative therapies and analysis of resource utilization for the commercial CAR T cell products is warranted.

Acute leukemias in children with CR3, refractory relapse, or induction failure (IF) have a poor prognosis. Clofarabine has single agent activity in relapsed leukemia and synergy with cytarabine. We sought to determine the safety and overall survival in a Phase I/II trial of conditioning with clofarabine (doses 40 - 52 mg/m2), cytarabine 1000 mg/m2, and 1200 cGy TBI followed by alloSCT in children, adolescents, and young adults with poor-risk leukemia. Thirty-seven patients; Age 12 years (1-22 years); ALL/AML: 34:3 (18 IF, 10 CR3, 13 refractory relapse); 15 related, 22 unrelated donors. Probabilities of neutrophil, platelet engraftment, acute GvHD, and chronic GvHD were 94%, 84%, 49%, and 30%, respectively. Probability of day 100 TRM was 8.1%. 2-year EFS (event free survival) and OS (overall survival) were 38.6% (CI95: 23-54%), and 41.3% (CI95: 25-57%). Multivariate analysis demonstrated overt disease at time of transplant (relative risk (RR) 3.65, CI95: 1.35-9.89, P = 0.011) and umbilical cord blood source (RR 2.17, CI95: 1.33-4.15, P = 0.019) to be predictors of worse EFS/OS. This novel myeloablative conditioning regimen followed by alloSCT is safe and well tolerated in CAYA with very poor-risk ALL or AML. Further investigation in CAYA with better risk ALL and AML undergoing alloSCT is warranted.

Background Impairments in T-cell and macrophage-mediated host defense lead to increased infection-related morbidity and mortality in neonates, partly because of immaturity in T helper (Th)1 function. Listeria monocytogenes (Lm) is an intracellular pathogen disproportionately causing severe disease among neonates and the immunocompromised. Intact macrophage and Th1-mediated immune responses are critical for Lm clearance. We and others have previously demonstrated downregulation of Th1 and macrophage immunoregulatory cytokines in cord blood versus adult peripheral blood. We sought to determine whether therapeutic or prophylactic single agent or combination recombinant murine interleukin (rmIL)-12, rmIL-18, recombinant murine macrophage-colony stimulating factor (rmM-CSF), recombinant murine granulocyte macrophage-colony stimulating factor (rmGM-CSF) and recombinant murine interferon (rmIFN)-γ would enhance survival during experimental neonatal Lm sepsis. Methods A 90% lethal dose (LD90) of Lm was established in C57/BL/6 neonatal mice. rmIL-12, rmIL-18, rmM-CSF, rmGM-CSF and rmIFN-γ were administered singly or sequentially, before or after LD90 Lm inoculation; ampicillin was administered 24 hours after inoculation. Results Therapeutic doses of rmIL-12, rmIL-18, rmM-CSF, rmGM-CSF and rmIFN-γ as single agents and sequential therapy with rmM-CSF + (rmIL-12 and/or rmIL-18) + rmIFN-γ in addition to ampicillin were not associated with increased survival. However, prophylactic single doses of rmIL-12, rmIL-18, rmM-CSF and rmIFN-γ and prophylactic sequential doses of rmM-CSF + (rmIL-12 and/or rmIL-18) + rmIFN-γ in addition to ampicillin were associated with significantly enhanced survival compared with ampicillin alone. Conclusions These data suggest prophylactic administration of macrophage and Th1 immunoregulatory cytokines can potentially overcome deficits in neonatal immunity to protect against Lm.

Bronchoalveolar lavage (BAL) has been a useful initial diagnostic tool in the evaluation of pulmonary complications after hematopoietic stem cell transplantation (HSCT); however, the diagnostic sensitivity, prevalence, and outcome after BAL versus lung biopsy (LB) in pediatric HSCT patients remains to be determined. We reviewed 193 pediatric HSCT recipients who underwent a total of 235 HSCTs. Sixty-five patients (34%) underwent a total of 101 BALs for fever, respiratory distress, and/or pulmonary infiltrates on chest radiograph and/or computed tomography scan. The 1-year probability of undergoing BAL was 43.0% after allogeneic stem cell transplantation (alloSCT) and 8.5% after autologous stem cell transplantation (autoSCT) (P = .001). Sixteen of the 193 patients (8%) patients underwent 19 LBs. The probability of undergoing LB at 1 year after HSCT was 9.3%. No grade III or IV adverse events related to either procedure were observed. Of the 101 BALs performed, 40% (n = 40) were diagnostic, with a majority revealing a bacterial pathogen. Among the 19 LBs performed, 94% identified an etiology. In multivariate analysis, myeloablative conditioning alloSCT conferred the highest risk of requiring a BAL (hazard ratio [HR],8.5; P = .0002). The probability of 2-year overall survival was 20.2% in patients who underwent BAL, 17.5% for patients who underwent biopsy, and 67.4% for patients who had neither procedure. In multivariate analysis, only the requirement of a BAL was independently associated with an increased risk of mortality (HR, 2.96; P

BU and CY (BU/CY; 200 mg/kg) before HLA-matched sibling allo-SCT in children with sickle cell disease (SCD) is associated with ~85% EFS but is limited by the acute and late effects of BU/CY myeloablative conditioning. Alternatives include reduced toxicity but more immunosuppressive conditioning. We investigated in a prospective single institutional study, the safety and efficacy of a reduced-toxicity conditioning (RTC) regimen of BU 12.8-16 mg/kg, fludarabine 180 mg/m(2), alemtuzumab 54 mg/m(2) (BFA) before HLA-matched sibling donor transplantation in pediatric recipients with symptomatic SCD. Eighteen patients, median age 8.9 years (2.3-20.2), M/F 15/3, 15 sibling BM and 3 sibling cord blood (CB) were transplanted. Mean whole blood and erythroid donor chimerism was 91% and 88%, at days +100 and +365, respectively. Probability of grade II-IV acute GVHD was 17%. Two-year EFS and OS were both 100%. Neurological, pulmonary and cardiovascular function were stable or improved at 2 years. BFA RTC and HLA-matched sibling BM and CB allo-SCT in pediatric recipients result in excellent EFS, long-term donor chimerism, low incidence of GVHD and stable/improved organ function.

Introduction: Adults with (w/) B-cell acute lymphoblastic leukemia (B-ALL) exhibit high rates of complete response (CR) to induction chemotherapy, but relapse is common. Inotuzumab ozogamicin (IO), an antibody-drug conjugate targeting CD22, achieves high rates of CR in patients (pts) w/ relapsed/refractory (R/R) B-ALL and is FDA-approved for R/R B-ALL in adults. It remains unknown whether cytogenetic and molecular features associated w/ decreased response rate and poor prognosis following conventional chemotherapy are associated w/ response to IO. As such, we investigated the relationship between several high-risk genetic alterations and outcome following IO treatment in pts w/ R/R B-ALL. Methods: We reviewed electronic medical records of pts of all ages w/ R/R B-ALL or chronic myeloid leukemia in lymphoid blast phase (CML-LBP) receiving IO at Memorial Sloan Kettering Cancer Center (MSK) between January 2011 and April 2019. The primary objective was to assess whether recurrent cytogenetic or molecular features were associated w/ achievement of CR or CR w/ incomplete hematologic recovery (CRi), w/ or w/o measurable residual disease (MRD), and disease-free (DFS) and overall survival (OS) following IO. Secondary objectives included association of baseline clinical features, including central nervous system (CNS) or other extramedullary (EM) disease, w/ outcomes post-IO. MRD was defined as any unequivocal evidence of B-ALL detectable by RT-PCR (Ph+ ALL) or flow cytometry (FACS). Genomic alterations were defined by MSK IMPACT-Heme (Cheng, J Mol Diagn, 2015), FoundationOne Heme, or similar platforms. A set of selected high-risk (HR) features in Philadelphia chromosome-negative (Ph-) B-ALL was defined prior to the analysis (HR: mutations/loss of TP53, IKZF1/3, CDKN2A, CREBBP; activating RAS mutations; "Ph-like" profile). DFS and OS were computed using Kaplan-Meier methods and compared between groups using log-tank tests. Results: 32 pts (13F, 19M) w/ R/R B-ALL (n=31) or CML-LBP (n=1) treated w/ IO were identified. IO was given as monotherapy in 27 pts and w/ other systemic therapy in 5 pts (mini-hyper-CVD-like regimen, n=4; ponatinib, n=1). Median age at start of IO was 45 years (range 3-78). 10 pts had undergone prior allogeneic hematopoietic cell transplantation (alloHCT). Seven and 15 pts had a history of CNS disease or other EM involvement by B-ALL, respectively, including 3 and 6 pts immediately prior to IO, respectively. Pts received a median 3 lines of salvage prior to IO, including prior CD19-targeted immunotherapy (blinatumomab and/or CAR-T cells) in 24 pts(Table 1). Among 27 pts w/ Ph- B-ALL, 12 had the selected HR features (Table 2). Five pts had Ph+ ALL (n=4) or CML-LBP (n=1) and 5/5 harbored ABL1 kinase domain point mutations (4/5 w/ T315I mutation). 22 pts had at least one successful molecular profiling panel.29 patients had initial cytogenetic studies, of whom 28 patients had evaluable karyotypes. 23 pts had best response to IO of CR/CRi (MRD-, n=15; MRD+, n=8). 9 pts had no objective response to ≥1 cycle of IO. Of the 12 Ph- pts w/ selected HR mutations, 11 achieved CR/CRi. Notably, 6/6 pts w/ TP53 mutation/deletion and 5/5 pts w/ IKZF1/3 mutations (3/3 pts w/ both TP53 & IKZF mutations) achieved CR/CRi. Both pts w/ Ras mutations and 2/3 w/ Ph-like B-ALL achieved CR/CRi. 7/11 HR responders underwent alloHCT post-IO (3 had undergone pre-IO alloHCT). Pts w/ Ph- B-ALL w/ HR mutations demonstrated similar CR/CRi rate and OS to pts w/ Ph- B-ALL w/o defined HR mutations (Fig 1A-B). In contrast, only 1/5 pts w/ Ph+ ALL achieved CR/CRi (was MRD+) and 4/5 showed persistent B-ALL. OS was superior among pts w/ Ph- vs Ph+ B-ALL post-IO (8.0 vs 1.9 months, p=0.0068, Fig 1C). Among pts w/ EM disease immediately prior to IO, 3/6 achieved CR/CRi, including CR in 1 pt w/ a cardiac mass. Median DFS was 3.2 months vs. not reached following achievement of MRD+ vs MRD- CR, respectively (p=ns, Fig 1D). Conclusions: HR molecular features associated w/ poor response to chemotherapy were not associated w/ inferior response rate and overall prognosis following IO in this small series. Notably, pts w/ Ph+ ALL (all w/ ABL1 mutations) exhibited suboptimal response, possibly as pts received IO only in advanced disease states following TKI failure. This small report supports investigation of IO in frontline therapy for pts w/ B-ALL w/ HR mutations to spare unnecessary toxicities of chemotherapy and bridge successfully to alloHCT. Disclosures King: Genentech: Other: Advisory Board ; Astrazeneca: Other: Advisory board; Incyte: Other: Advisory Board. Park:Allogene: Consultancy; Amgen: Consultancy; AstraZeneca: Consultancy; Autolus: Consultancy; GSK: Consultancy; Incyte: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy; Takeda: Consultancy. Geyer:Dava Oncology: Honoraria; Amgen: Research Funding. OffLabel Disclosure: Inotuzumab ozogamicin is not FDA approved for pediatric patients with relapsed/refractory B-cell acute lymphoblastic leukemia.

Background: The treatment indications for venetoclax in CLL are broadening quickly. While the initial approval was for relapsed patients with del 17p (Stilgenbauer S, et al. JCO 2018), it has subsequently been extended to all patients (Seymour J, et al. NEJM 2018, Fischer K, et al. NEJM 2019). The duration of therapy with each approval has evolved as well, from continuing therapy until progression/toxicity to 1 year in front-line CLL. The limited durations of therapy were applied to all patients based on trial design and were not dependent on response to treatment. Undetectable minimal residual disease (U-MRD) with venetoclax is associated with improved progression-free survival (PFS), both as a single agent and in combination with rituximab (Stilgenbauer S, et al. JCO 2018, Seymour J, et al. NEJM 2018). Early phase data suggest that patients who discontinue venetoclax after achieving MRD negativity can be monitored off therapy and successfully retreated upon relapse (Seymour J, et al, Lancet Onc 2017). However, patients who discontinue therapy with persistent residual disease have a higher incidence of relapse (Kater A, et al. JCO 2019). Together, these data suggest that the duration of venetoclax therapy should be individualized, based on the depth of response one achieves and not a fixed duration schedule. Therefore, we propose a prospective clinical trial, utilizing MRD assessment with a next generation sequencing (clonoSEQ®) assay to guide clinical decision making in patients with CLL receiving venetoclax-based regimens. Methods: This is a multicenter, phase II clinical stopping trial for 80 venetoclax-treated CLL patients. The clonoSEQ® assay is used to assess MRD, and patients who achieve U-MRD (defined as Patients are eligible if they have CLL/SLL and are currently receiving venetoclax monotherapy or in combination with anti-CD20 (front-line or relapsed). Following informed consent for screening, the ClonoSEQ® ID test will be performed on a sample containing active disease, either fresh (blood or bone marrow) or stored specimens (3-5 bone marrow aspirate slides, 3-5 FFPE slides from a pathologically involved lymph node, or 1 mL involved peripheral blood/bone marrow aspirate). Following ClonoSEQ® ID testing, patients will be evaluated for MRD in the peripheral blood by the ClonoSEQ® MRD assay at two time points, at least 28 days apart. Patients who have received at least 6 months of venetoclax and achieve U-MRD will sign an intervention informed consent and enter a period of treatment-free observation. Close monitoring with serial MRD assessments on the peripheral blood will occur every three cycles for 36 cycles (1 cycle = 28 days; Figure 1). Patients who remain MRD undetectable or become MRD positive will continue to be observed until clinical progression warranting therapy by iwCLL criteria. If a patient develops a clinical indication for treatment, they are recommended to be retreated with the same venetoclax-based regimen. Re-treated patients will undergo standard response/toxicity assessments and serial assessment of MRD status every three cycles. Response and MRD assessments for retreated patients will continue for a total of 12 cycles or to the end of 36 cycles from the time of treatment free observation, whichever occurs first. The primary endpoint of the study is the proportion of patients able to remain off venetoclax-based therapy at 12 cycles following treatment discontinuation. The secondary endpoints include (1) the cumulative incidence of MRD positivity (2) cumulative incidence of retreatment during treatment-free observation (3) PFS and OS as measured from start of treatment-free observation. Should a patient require re-treatment, endpoints of interest include ORR, CR rate, MRD negativity rate, and adverse event profile for venetoclax-based therapy re-treatment. Healthcare outcomes endpoints including economic analysis of cost savings for patients discontinue therapy and quality of life assessment pre- and post-venetoclax discontinuation will be evaluated. Disclosures Ujjani: AbbVie: Honoraria, Research Funding; Genentech: Honoraria; Gilead: Consultancy; PCYC: Research Funding; Astrazeneca: Consultancy; Atara: Consultancy; Pharmacyclics: Honoraria. Roeker:AbbVie: Equity Ownership; Abbott Laboratories: Equity Ownership. Shadman:TG Therapeutics: Research Funding; Gilead: Research Funding; Genentech, Inc.: Consultancy, Research Funding; AstraZeneca: Consultancy; Sound Biologics: Consultancy; Pharmacyclics: Consultancy, Research Funding; ADC Therapeutics: Consultancy; AbbVIe: Consultancy, Research Funding; Merck: Research Funding; Atara: Consultancy; Verastem: Consultancy; Mustang Biopharma: Research Funding; Bigene: Research Funding; Celgene: Research Funding; Sunesis: Research Funding; Acerta: Research Funding; Emergent: Research Funding. Jacob:Adaptive Biotechnologies: Employment, Other: shareholder. Geyer:Amgen: Research Funding; Dava Oncology: Honoraria. Zelenetz:Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; DAVA Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; DAVA Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech/Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech/Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics/AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Beigene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics/AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Verastem: Consultancy, Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy, Membership on an entity's Board of Directors or advisory committees; Verastem: Consultancy, Membership on an entity's Board of Directors or advisory committees; Beigene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees. Mato:Gilead: Research Funding; Acerta: Consultancy; Janssen: Consultancy; AbbVie: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; Celgene: Consultancy; Johnson & Johnson: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB member , Research Funding; LOXO: Consultancy, Research Funding; DTRM Biopharma: Research Funding; Genentech: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding.

Introduction: Blinatumomab is a bispecific, CD19-directed CD3 T-cell engager (BiTE®) that activates endogenous cytotoxic T cells to kill target B cells and is FDA-approved for the treatment of relapsed or refractory (R/R) B-cell precursor acute lymphoblastic leukemia (B-ALL). Subgroup analyses of pivotal trials revealed lower response rates and higher risk of cytokine release syndrome (CRS) in blinatumomab recipients with high pre-treatment tumor (B-ALL) burden. It has therefore been hypothesized that cytoreduction prior to blinatumomab initiation may improve response and reduce risk of severe CRS in patients (pts) with high baseline B-ALL burden. We therefore sought to describe pt and disease characteristics at diagnosis, patterns of pre-blinatumomab cytoreduction, and treatment outcomes in pts with high burden of R/R B-ALL treated with blinatumomab at our institution. Methods: We retrospectively reviewed medical records of adult (≥ 18 years-old) pts with morphologic R/R B-cell ALL (i.e. ≥5% BM blasts and/or radiographically evident EM disease) treated with blinatumomab at Memorial Sloan Kettering Cancer Center (MSKCC) between January 2011 and March 2019 and characterized pts with ≥ 50% bone marrow (BM) blasts by morphology or ≥ 15,000 peripheral blood blasts/µL as having "high-burden" B-ALL. CRS and neurologic toxicity (NTX) were graded per Common Terminology Criteria for Adverse Events v5.0. Objectives included describing cytoreductive therapy given pre-blinatumomab and determining rates of NTX and CRS (any grade and grade ≥3) and morphologic complete response (CR) following 1-2 cycles of blinatumomab. Results: We identified 14 pts with high-burden R/R B-ALL prior to blinatumomab. These pts had a median age of 52 years (range, 23 - 69 years) and median BM blasts of 73% (range, 52 - >95%, n=12 pts with evaluable BM). Of these 14 pts, 8 received cytoreductive therapy prior to blinatumomab initiation. Cytoreductive regimens included dexamethasone alone (n=4), cyclophosphamide + dexamethasone (n=2), dexamethasone and vincristine (n=1), or cyclophosphamide + vincristine + dexamethasone (n=1). One pt transitioned to hospice care prior to completing cycle 1 (C1) of blinatumomab and was considered non-evaluable for response. CR was achieved in 6 of the 13 evaluable pts, including 4 of 7 evaluable pts who received cytoreductive therapy and 2 of 6 pts who did not receive cytoreductive therapy. One pt achieved CR in BM but exhibited refractory extramedullary disease. CRS was observed during C1 of blinatumomab in 11/14 pts (grade 1, n=7; grade 2, n=3; grade 3, n=1). The pt with grade 3 CRS had received blinatumomab without cytoreductive therapy. In 4 pts, blinatumomab was temporarily discontinued for management of CRS. NTX of any grade occurred in 4/13 pts during C1, including 1 pt w/grade 3 NTX (depressed level of consciousness), and was reversible in all cases; the pt with grade 3 NTX had full resolution of symptoms following brief interruption of blinatumomab and administration of dexamethasone. Conclusions: Real-world clinical experience with blinatumomab in pts with high-burden B-ALL at a single institution suggested an efficacy and safety profile comparable to what has been reported in the overall population in clinical trials. Compared to published clinical trial experience, rates and severity of CRS following blinatumomab were similar and rates of NTX appeared slightly higher in this small series. Administration of cytoreductive therapy prior to blinatumomab for pts with high-burden B-ALL appears safe, with no additional toxicities. Larger studies will be required to assess whether pts with high-burden B-ALL treated (vs not treated) with cytoreductive therapy prior to blinatumomab exhibit significantly higher rates of CR. Disclosures King: Incyte: Other: Advisory Board; Genentech: Other: Advisory Board ; Astrazeneca: Other: Advisory board. Bolanos:Amgen Inc.: Employment. Velasco:Amgen Inc.: Employment. Tu:Amgen Inc.: Employment. Zaman:Amgen Inc.: Employment. Geyer:Dava Oncology: Honoraria; Amgen: Research Funding. Park:Allogene: Consultancy; Amgen: Consultancy; AstraZeneca: Consultancy; Autolus: Consultancy; GSK: Consultancy; Incyte: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy; Takeda: Consultancy.

The CD3/CD19-targeted bispecific T-cell engager blinatumomab (BLIN) is active in pts w/ relapsed/refractory B-ALL or persistent minimal residual disease. Notable toxicities include cytokine release syndrome (CRS), a constellation of symptoms related to brisk systemic inflammatory response, and a spectrum of neurologic toxicities (NTX). BLIN prescribing information provides basic CRS/NTX management guidance, but limited reports describe "real-world" toxicity management strategies (TMS) and outcomes. We further previously reported association between higher baseline and peak levels of acute phase reactants (APR; C-reactive protein [CRP]/ferritin), time to APR peak, and incidence of CRS/NTX post-BLIN (King et al. ASH Annual Meeting, 2017). While CRS is also mediated in part by IL-6, routine monitoring of IL-6 levels during BLIN is not currently standard. As such, we sought to determine rates/severity of CRS/NTX at our institution, efficacy of TMS, and utility of APR/IL-6 in predicting CRS/NTX post-BLIN. We reviewed electronic medical records of pts ≥ 18 years (yrs) old w/ previously treated B-ALL receiving BLIN between 1/1/2011 and 3/31/19 at Memorial Sloan Kettering Cancer Center (MSK). NTX was classified/graded w/ CTCAEv5.0 (Common Terminology Criteria for Adverse Events). CRS was graded per CTCAEv5.0 and American Society for Transplantation and Cellular Therapy (ASTCT) criteria. The primary objective was to characterize rates/clinical features of CRS/NTX. Secondary objectives included assessing the nature/efficacy of TMS, and association of APR/IL-6 levels w/ CRS. Maximal (max) fold increase in APR/IL-6 was measured from pre-BLIN baseline to peak value during BLIN cycle 1 (C1). APR/IL-6 levels/fold changes were compared between groups using the Wilcoxon-Mann-Whitney test w/o adjustment for multiple comparisons. 59 pts were identified, including 31 male pts (52%). Median age at start of BLIN was 57 yrs (range, 20-76). Median number of prior therapies was 1, including 8 pts w/ previous allogeneic hematopoietic cell transplant (alloHCT) and 5 w/ prior chimeric antigen receptor T-cell therapy (CAR-T). No pt had baseline organ dysfunction or central nervous system (CNS) disease. All pts were admitted for initiation of BLIN C1. BLIN was started at 9 mcg/day IVCI w/ escalation to 28 mcg/day IVCI on day 8 (per recommended dosing for R/R ALL) in 52 pts and at 28 mcg/day IVCI in 7 pts for MRD (per Gökbuget et al., Blood, 2018). During BLIN C1, 34/59 pts experienced CRS (57%), w/ max grade (G) 1 (n=24), G2 (n=9) or G3 (n=1). CTCAEv5.0/ASTCT grading was concordant in all cases. Eight of 34 (23%) were managed w/ brief interruption of blinatumomab (BIB) for G1 (n=3) and G2 (n=5) CRS. Median duration of BIB was 39 hours (h) (range, 21-91h). Three pts had concomitant NTX and received brief courses of dexamethasone (DEX, daily dose of 24 mg). One pt w/ grade 2 CRS received tocilizumab for hypotension suboptimally responsive to fluid boluses (FB) w/ IL-6 level = 25754 pg/mL. Remaining pts w/ BIB (5/8) received FBs for hypotension. One pt permanently discontinued BLIN during C1 due to rapidly progressive B-ALL. All pts managed w/ BIB were successfully re-challenged w/ BLIN and finished C1 w/o recurrence of CRS. Of the 25/34 (74%) pts w/ CRS not managed w/ BIB, 5 received FBs, w/ 1 pt receiving a FB and a single dose of DEX. Five pts developed recurrent CRS (≥24 hours after resolution); 4/5 recurrences occurred in pts not managed w/ BIB. NTX, excluding isolated headache, was observed in 8/59 pts (14%) during BLIN C1 (Table 1) w/ max G1 (n=4), G2 (n=3), or G3 (n=1). Four pts w/ NTX were managed w/ BIB and a brief course DEX; 3/4 had concomitant CRS. Median time to onset of CRS and NTX were 1 day (d) (range 0-15) and 2 d (range 0-10), respectively. Non-significant trend toward higher peak IL-6 was noted in pts w/ G1 vs. G0 CRS (p=0.07; Fig 1A, note log scale); median peak levels of CRP were higher in pts w/ G1 vs G0 CRS (p=0.01, Fig 1B); median peak ferritin levels were higher in pts w/ G2 vs. G0 CRS (p=0.01, Fig 1C). While CRS was common during C1 of BLIN, supportive management was sufficient in most pts; BIB was an effective strategy and allowed successful BLIN re-challenge. The incidence of ≥G2 NTX was low and all cases of NTX were reversible w/ supportive care or BIB ± DEX. Peak APR levels correlated w/ CRS severity. Authors noted concordance of CRS grading between CTCAE and ASTCT, suggesting the feasibility of a single, BITE-specific grading system. Disclosures King: Astrazeneca: Other: Advisory board; Genentech: Other: Advisory Board ; Incyte: Other: Advisory Board. Park:Amgen: Consultancy; AstraZeneca: Consultancy; Autolus: Consultancy; GSK: Consultancy; Incyte: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy; Takeda: Consultancy; Allogene: Consultancy. Geyer:Amgen: Research Funding; Dava Oncology: Honoraria.

Introduction: Signaling through JAK1 and/or JAK2 is common among tumor and non-tumor cells within peripheral and cutaneous T cell lymphomas (PTCL and CTCL). We conducted a phase II study of the JAK1/2 inhibitor, ruxolitinib, in patients (pts) with PTCL and CTCL and assessed the predictive value of genetic, immunohistochemical (IHC) and multiparametric immunofluorescence (mIF) biomarkers of JAK/STAT pathway activation for ruxolitinib response. Methods: This is an investigator-initiated multi-center phase II study for pts with relapsed or refractory (RR) PTCL or CTCL following at least 1 systemic therapy. Biopsies from each patient were subjected to next-generation sequencing for JAK1, JAK2, STAT3, STAT5 and other relevant genes along with IHC assessment for phosphorylated STAT3 (pSTAT3). Pts enrolled into biomarker-defined cohorts: 1) activating JAK and/or STAT mutations (allele frequency of 0.1 or greater); 2) no JAK/STAT mutation but ≥ 30% pSTAT3 expression among tumor cells by IHC; or 3) neither. Pts received treatment with ruxolitinib 20 mg BID until progression and were assessed for response after cycles 2, 5 and every three cycles thereafter. Tissue samples collected at baseline, on-treatment, and at progression were collected and assessed by mIF (Vectra platform, HALO analysis) using markers specific for lymphoma subtype, macrophage activation, JAK/STAT and PI3 kinase signaling. Results: The study completed enrollment with 53 pts, including 18 in cohort 1, 14 in cohort 2, and 21 in cohort 3. Cohort 3 includes 10 pts for whom JAK/STAT characterization is pending. Disease histologies per cohort are detailed in table 1. Treatment-related serious adverse events included HSV-1 stomatitis (n=1), spontaneous bacterial peritonitis (n=1), febrile neutropenia (n=3), and herpes zoster (n=1). Additional grade 3 or 4 drug-related adverse events affecting >1 pt included neutropenia (n=13), anemia (n=8), thrombocytopenia (n=5), and lymphopenia (n=3). Among the 53 pts, 4 have not yet reached first response assessment and 1 withdrew consent following only 1 week of treatment; therefore 48 are evaluable for response. Among 48 pts, there were 3 (6%) complete responses, 8 (17%) partial responses, and 6 (12.5%) with cytopenia improvement and disease stabilization lasting more than 6 months (SD>6 mo). Overall response rate (ORR) was 23% and overall clinical benefit rate (CBR) (ORR plus SD>6 mo) was 35%. Median duration of response was 7.3 months (range 1.3-26.1 months). ORRs in cohorts 1, 2 and 3 were 28%, 31%, and 12% (cohorts 1&2 vs 3, p=0.28). CBRs in cohorts 1, 2 and 3 were 44%, 46%, and 18% (cohorts 1&2 vs. 3, p=0.07) (table 2). More frequent responses were observed in the following histologies: angioimmunoblastic T cell lymphoma, peripheral T cell lymphoma with T-follicular helper phenotype, T-cell prolymphocytic leukemia, and large granular lymphocyte leukemia (table 3). Nine pre-treatment biopsies were analyzed by mIF from 4 ruxolitinib responders and 5 non-responders. The most notable finding was that responders to ruxolitinib had markedly lower pS6 expression within tumor cells of pre-treatment biopsies (mean pS6 expression 9.03 +/- 4.8 vs 48.19 +/- 6.6 for nonresponders; p=0.0027). In a patient with prolonged CR on ruxolitinib, progression biopsy was characterized by a marked increase in tumor cell pS6 staining. Additional samples are being analyzed and updated results will be reported at the meeting. Conclusion: The JAK1/JAK2 inhibitor ruxolitinib is a well-tolerated and readily available therapy for pts with relapsed/refractory PTCL and CTCL. Among patients with IHC and/or genetic evidence of JAK/STAT activation, ruxolitinib has similar efficacy to approved agents for relapsed/refractory T-cell lymphoma. The association between pS6 expression and response to ruxolitinib suggests that active PI3K/mTOR signaling confers intrinsic and acquired resistance to ruxolitinib. Disclosures Moskowitz: ADC Therapeutics: Consultancy; Takeda Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Erytech Pharma: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Takeda Pharmaceuticals: Consultancy; Merck: Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Incyte: Research Funding; Merck: Research Funding; Takeda Pharmaceuticals: Consultancy; ADC Therapeutics: Consultancy; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Merck: Research Funding; Cell Medica: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; ADC Therapeutics: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Cell Medica: Consultancy; Merck: Research Funding; ADC Therapeutics: Consultancy; Cell Medica: Consultancy; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Erytech Pharma: Consultancy; Cell Medica: Consultancy; Cell Medica: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Erytech Pharma: Consultancy; Cell Medica: Consultancy; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Cell Medica: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Incyte: Research Funding; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Cell Medica: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Incyte: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Erytech Pharma: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Incyte: Research Funding; ADC Therapeutics: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Cell Medica: Consultancy; Merck: Research Funding; ADC Therapeutics: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; ADC Therapeutics: Consultancy; Incyte: Research Funding; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; ADC Therapeutics: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Merck: Research Funding; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Merck: Research Funding; Incyte: Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Merck: Research Funding; Takeda Pharmaceuticals: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding. Jacobsen:Acerta: Consultancy; Novartis: Research Funding; Astra-Zeneca: Consultancy; F. Hoffmann-LaRoche: Research Funding; Merck: Consultancy, Research Funding; Takeda: Honoraria; Pharmacyclics: Research Funding. Ruan:Janssen: Consultancy, Honoraria; Pharmacyclics LLC, an AbbVie company: Research Funding; Kite: Consultancy; Juno: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria, Research Funding. Geyer:Amgen: Research Funding; Dava Oncology: Honoraria. Noy:Medscape: Honoraria; Janssen: Consultancy; Prime Oncology: Honoraria; NIH: Research Funding; Pharamcyclics: Research Funding; Raphael Pharma: Research Funding. Straus:Elsevier (PracticeUpdate): Consultancy, Honoraria; Hope Funds for Cancer Research: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Honoraria. Dogan:Roche: Consultancy, Research Funding; Corvus Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Takeda: Consultancy. Weinstock:Celgene: Research Funding. Horwitz:Aileron: Research Funding; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Kura: Consultancy; Infinity/Verastem: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Aileron: Research Funding; Trillium: Research Funding; Kyowa Hakko Kirin: Consultancy; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astex: Consultancy; Miragen: Consultancy; Affimed: Consultancy; ADCT Therapeutics: Research Funding; Forty-Seven: Research Funding; Portola: Consultancy; Miragen: Consultancy; Mundipharma: Consultancy; Miragen: Consultancy; Seattle Genetics: Consultancy, Research Funding; Millennium/Takeda: Consultancy, Research Funding; Innate Pharma: Consultancy; Affimed: Consultancy; ADCT Therapeutics: Research Funding; Millennium/Takeda: Consultancy, Research Funding; Millennium/Takeda: Consultancy, Research Funding; Infinity/Verastem: Consultancy, Research Funding; Kyowa Hakko Kirin: Consultancy; Trillium: Research Funding; Astex: Consultancy; Astex: Consultancy; Celgene: Consultancy, Research Funding; Infinity/Verastem: Consultancy, Research Funding; Infinity/Verastem: Consultancy, Research Funding; Kura: Consultancy; Kura: Consultancy; Kyowa Hakko Kirin: Consultancy; Trillium: Research Funding; Celgene: Consultancy, Research Funding; ADCT Therapeutics: Research Funding; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astex: Consultancy; Aileron: Research Funding; Forty-Seven: Research Funding; Innate Pharma: Consultancy; Forty-Seven: Research Funding; Mundipharma: Consultancy; Celgene: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Portola: Consultancy; Kyowa Hakko Kirin: Consultancy; Millennium/Takeda: Consultancy, Research Funding; Trillium: Research Funding; Aileron: Research Funding; Kura: Consultancy; Miragen: Consultancy; Innate Pharma: Consultancy; Mundipharma: Consultancy; Mundipharma: Consultancy; ADCT Therapeutics: Research Funding; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Portola: Consultancy; Portola: Consultancy; Forty-Seven: Research Funding; Innate Pharma: Consultancy; Affimed: Consultancy; Affimed: Consultancy. OffLabel Disclosure: Off-label use of ruxolitinib for T-cell lymphoma will be discussed

Introduction: Asparaginase (ASP) has demonstrated a survival benefit in pediatric patients (pts) with acute lymphoblastic leukemia (ALL) and is now part of standard-of-care frontline treatment. As a result, asparaginase preparations have been incorporated into the treatment of adult ALL to improve outcomes. Pegaspargase (PEG-ASP), a modified version of asparaginase with prolonged asparagine depletion, appears to be safe in adults up to age 40 (Stock, et al., Blood, 2019), but is associated with a unique spectrum of toxicities, the risks of which appear to increase with age. Therefore, the safety of PEG-ASP remains a significant concern in older adults w/ ALL. Methods: We conducted a single center retrospective chart review of pts age ≥40 years who received PEG-ASP as part of frontline induction/consolidation or reinduction, between March 2008 and June 2018 at Memorial Sloan Kettering Cancer Center. The primary objective was to evaluate the tolerability and toxicity of PEG-ASP based on the incidence and severity of ASP-related toxicities (hypersensitivity reactions, hypertriglyceridemia, hyperbilirubinemia, transaminitis, pancreatitis, hypofibrinogenemia, etc) according to the Common Terminology Criteria for Adverse Events, version 4.03. Laboratory values recorded were either the peak or the nadir, the more appropriate for toxicity assessment, within a 4-week period following PEG-ASP administration. Secondary objectives were to determine the total number of doses of PEG-ASP administered in comparison to the number of doses intended, and to characterize the rationale for PEG-ASP discontinuation when applicable. Fisher's exact test was used to compare the incidence of PEG-ASP toxicities with respect to pt and treatment characteristics (regimen, age, BMI, gender, Philadelphia chromosome positive (Ph+) vs. Ph-, presence of extramedullary disease, PEG-ASP dose). P values were not adjusted for multiple comparisons. Results: We identified 60 pts with ALL (40 B-ALL and 20 T-ALL) who received at least one dose of PEG-ASP. Nine pts were Ph+. The median pt age at initiation of the treatment was 53, (range, 40 to 80), and 19 pts had a BMI ≥30 kg/m2. Forty-four pts received treatment for newly diagnosed ALL, and 16 pts for relapsed disease. Table 1 lists pt baseline characteristics. Among the 44 pts with newly diagnosed ALL, 27 pts received PEG-ASP as part of pediatric or pediatric-inspired regimens at doses of 2000 - 2500 units/m2, and 1 pt received a modified dose of 1000 units/m2 due to age. The remaining 16 pts received PEG-ASP at doses of 1000 - 2000 units/m2 for consolidation, per established adult regimens (ALL-2 and L-20; Lamanna, et al., Cancer, 2013). Grade 3/4 ASP-related toxicities with a >10% incidence included: hyperbilirubinemia, transaminitis, hypoalbuminemia, hyperglycemia, hypofibrinogenemia, and hypertriglyceridemia. Frontline treatment regimens in which PEG-ASP was used in consolidation cycles only (ALL-2, L-20) were associated w/ a lower incidence of hyperbilirubinemia (p=0.009) and hypertriglyceridemia (p Conclusion: PEG-ASP was incorporated into the treatment of 60 adult ALL pts age ≥40, with manageable toxicity. Seven pts discontinued PEG-ASP due to hypersensitivity reactions and 5 discontinued due to hepatotoxicity, but other reported toxicities did not lead to PEG-ASP discontinuation and the majority of the pts completed all intended doses of PEG-ASP. This study suggests that with careful monitoring, PEG-ASP can safely be administered in adults ≥40 years of age. Disclosures Rajeeve: ASH-HONORS Grant: Research Funding. Tallman:UpToDate: Patents & Royalties; Oncolyze: Consultancy, Membership on an entity's Board of Directors or advisory committees; Delta Fly Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Rigel: Consultancy, Membership on an entity's Board of Directors or advisory committees; Cellerant: Research Funding; Tetraphase: Consultancy, Membership on an entity's Board of Directors or advisory committees; Nohla: Consultancy, Membership on an entity's Board of Directors or advisory committees; BioLineRx: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orsenix: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Research Funding; Biosight: Research Funding; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; KAHR: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees. Geyer:Dava Oncology: Honoraria; Amgen: Research Funding. Park:Takeda: Consultancy; Allogene: Consultancy; Amgen: Consultancy; AstraZeneca: Consultancy; Autolus: Consultancy; GSK: Consultancy; Incyte: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy.

Adenovirus infection is a significant complication in paediatric AlloSCT recipients with a mortality rate for disseminated adenovirus that may exceed 80%. We sought to determine the incidence, risk factors, and associated outcomes of adenovirus infection in 123 consecutive paediatric AlloSCT recipients. Adenovirus was diagnosed by antigen detection or viral culture, and was defined by isolation of virus with presence of correlating clinical symptoms. The probability of developing adenovirus infection was 12.3% (CI(95) 6.0-18.6). There were no statistically significant differences in probability of adenovirus infection in univariate analysis of risk factors including donor source, use of ATG/Alemtuzumab, ≥ Grade II GVHD, among others (age, diagnosis, conditioning regimen). Probability of overall survival for patients that experienced adenovirus infection was 15.4% vs. 50% for those without adenovirus (P = 0.0286). In multivariate analysis, the most important risk factor for an increased risk of death was adenovirus infection [HR 3.15 (CI(95) 1.6-6.18) P = 0.0009]. In this series of paediatric AlloSCT recipients, the development of adenovirus infection was the leading multivariate predictor of treatment-related mortality. Enhanced surveillance with adenovirus PCR and identification of the risk factors associated with poor outcomes from adenovirus infection may identify patients that may benefit from pre-emptive therapeutic interventions including adenovirus-specific cellular immunotherapies.

Immune reconstitution appears to be delayed following myeloablative conditioning (MAC) and umbilical cord blood transplantation (UCBT) in paediatric recipients. Although reduced toxicity conditioning (RTC) versus MAC prior to allogeneic stem cell transplantation is associated with decreased transplant-related mortality, the effects of RTC versus MAC prior to UCBT on immune reconstitution and risk of graft-versus-host disease (GVHD) are unknown. In 88 consecutive paediatric recipients of UCBT, we assessed immune cell recovery and immunoglobulin reconstitution at days +100, 180 and 365 and analysed risk factors associated with acute and chronic GVHD. Immune cell subset recovery, immunoglobulin reconstitution, and the incidence of opportunistic infections did not differ significantly between MAC versus RTC groups. In a Cox model, MAC versus RTC recipients had significantly higher risk of grade II-IV acute GVHD [Hazard Ratio (HR) 6·1, P = 0·002] as did recipients of 4/6 vs. 5-6/6 HLA-matched UCBT (HR 3·1, P = 0·03), who also had significantly increased risk of chronic GVHD (HR 18·5, P = 0·04). In multivariate analyses, MAC versus RTC was furthermore associated with significantly increased transplant-related (Odds Ratio 26·8, P = 0·008) and overall mortality (HR = 4·1, P = 0·0001). The use of adoptive cellular immunotherapy to accelerate immune reconstitution and prevent and treat opportunistic infections and malignant relapse following UCBT warrants further investigation.

The past 20 years of experience with umbilical cord blood transplantation have demonstrated that cord blood is effective in the treatment of a spectrum of diseases, including hematological malignancies, bone marrow failure, hemoglobinopathies, and inborn errors of metabolism. Cord blood can be obtained with ease and then safely cryopreserved for either public or private use without loss of viability. As compared to other unrelated donor cell sources, cord blood transplantation allows for greater human leukocyte antigen disparity without a corresponding increase in graft-vs.-host disease. Moreover, cord blood has a lower risk of transmitting infections by latent viruses and is less likely to carry somatic mutations than other adult cells. Recently, multiple populations of stem cells with primitive stem cell properties have been identified from cord blood. Meanwhile, there is an increasing interest in applying cord blood mononuclear cells or enriched stem cell populations to regenerative therapies. Accumulating evidence has suggested functional improvements after cord blood transplantation in various animal models for treatments of cardiac infarction, diabetes, neurological diseases, etc. In this review, we will summarize the most recent updates on clinical applications of cord blood transplantation and the promises and limitations of cell-based therapies for tissue repair and regeneration.

Background: Chimeric antigen receptor-modified (CAR) T cells have the potential to provide durable clinical benefit in patients with several relapsed or refractory hematologic malignancies. We aimed to characterize institutional resources utilized (other than T cell collection and CAR T cell manufacturing and infusion) around the time of CAR T cell administration. Methods: Adult patients treated on selected investigator-initiated clinical trials of CAR T cell therapy at Memorial Sloan Kettering Cancer Center were identified from the institutional database. Utilization data was collected from the start of admission for CAR T cell infusion through the end of the initial admission for infusion or through 30 days following initial CAR T cell infusion, whichever was longer. The data were sorted by disease type and into the categories of encounters, lab work, radiology, medications, and other diagnostic testing. Descriptive statistics were used to analyze the data. Results: We identified 106 patients on 4 clinical trials receiving inpatient CAR T cell infusions between 6/2007 to 4/2018, with 56 patients (53%) having B-cell acute lymphoblastic leukemia (ALL), 37 (35%) chronic lymphocytic leukemia (CLL) or B-cell non-Hodgkin lymphoma (NHL), and 13 (12%) multiple myeloma (MM). The median age was 53 years (range 22-77), 45 years (range 22-74), 64 years (range 35-77), and 58 years (range 43-68) for the total population, and the ALL, CLL/NHL, and MM groups, respectively, and 65%, 75%, 41%, and 31% were male, respectively. The median length of stay for the admission during which CAR T cells was given was 23 days (range 4 -133), with ALL patients admitted longer (Figure 1). Intensive care unit (ICU) days were limited with a range of 0-43 days, though 43 (41%) spent at least one day in the ICU. Of note, some protocols required infusion of the CAR T cells to be in the ICU. ICU admissions for ALL patients were than for other histologies longer (median 9 days vs 4 days). Outpatient clinic visits through day 30 post CAR T cell infusion occurred in 57 (53%) patients, with more of these in the CLL/NHL patients (median of 2 visits, range 1-4). As expected, laboratory and radiology studies accounted for a large portion of resource utilization with a total of 62,953 laboratory panels and 1,190 radiology studies done during the study time frame. Fourteen percent of the labs were complete blood counts, basic or comprehensive metabolic panels, or liver function tests. For the total population, ALL, CLL/NHL, MM, there were a median of 63.5 (range 13-368), 91.5 (21-368), 47 (13-167), and 51 (range 38-113) of these panels done per patient during the time frame, respectively. Blood cultures accounted for 1.3% of the total laboratory tests. Among the radiology studies, 25% were CT scans, 10% MRIs, 7% PET scans, 5% ultrasounds, and 53% x-rays, with differences in patterns of use by disease type (Figure 2). Cardiac testing (echocardiographs & electrocardiograms) was done in 104 (98%, total 634 tests). Electroencephalogram was performed in 18 patients (17%, total 18 tests). There were 173 bone marrow aspirations/biopsies in 88 patients (83%) and 71 lumbar punctures in 38 patients (36%), many of which were potentially done for disease assessment rather than toxicity management. Finally, 41,331 units of medications were given in this time frame, of which chemotherapy was 328 units (0.8%). The median medication units per patient was 255 (range 35-2091), 423 (range 35-2091), 200 (range 41-1190), and 207 (range 90-666) for the total population, and the ALL, CLL/NHL, and MM patients groups, respectively. Thirty-two doses of tocilizumab were given to 25 patients (24%), with ALL patients receiving 23 of those doses (72%). Conclusion: While providing potential clinical benefit, CAR T cell therapy utilizes resources across the therapeutic spectrum, and increasing use of this therapeutic modality can create challenges in institutional resource capacity. Identifying these resources will allow for better care delivery and allocation of funds. Further refinement of CAR T cell products and improvements in CAR T cell-related toxicity management may permit safer delivery of this therapy and reduce costs per patient. Additional analysis of resource utilization among patients treated with commercial CAR T cell products, as well as comparison with alternative therapies and cost-effectiveness analysis, is warranted. Disclosures Shah: Amgen: Research Funding; Janssen: Research Funding. Park:Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy; Shire: Consultancy; AstraZeneca: Consultancy; Pfizer: Consultancy; Novartis: Consultancy; Kite Pharma: Consultancy; Juno Therapeutics: Consultancy, Research Funding. Sauter:Juno Therapeutics: Consultancy, Research Funding; Sanofi-Genzyme: Consultancy, Research Funding; Spectrum Pharmaceuticals: Consultancy; Novartis: Consultancy; Precision Biosciences: Consultancy; Kite: Consultancy. Palomba:Pharmacyclics: Consultancy; Celgene: Consultancy. Younes:Genentech: Research Funding; BMS: Honoraria, Research Funding; Pharmacyclics: Research Funding; Abbvie: Honoraria; Merck: Honoraria; Takeda: Honoraria; J&J: Research Funding; Incyte: Honoraria; Janssen: Honoraria, Research Funding; Celgene: Honoraria; Roche: Honoraria, Research Funding; Curis: Research Funding; Astra Zeneca: Research Funding; Novartis: Research Funding; Bayer: Honoraria; Seattle Genetics: Honoraria; Sanofi: Honoraria. Geyer:Dava Oncology: Honoraria. Smith:Celgene: Consultancy, Patents & Royalties: CAR T cell therapies for MM, Research Funding. Mailankody:Physician Education Resource: Honoraria; Janssen: Research Funding; Juno: Research Funding; Takeda: Research Funding. Perales:Incyte: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees and Clinical trial support; Merck: Other: Personal fees; Takeda: Other: Personal fees; Abbvie: Other: Personal fees; Novartis: Other: Personal fees. Brentjens:Juno Therapeutics, a Celgene Company: Consultancy, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Bach:Vizient: Other: Personal Fees; Hematology Oncology Pharmacy Assoc: Other: Personal Fees; Excellus Health Plan: Other: Personal Fees; Gilead: Other: Personal Fees; Foundation Medicine: Other: Personal Fees; JMP Securities: Other: Personal Fees; Janssen: Other: Personal Fees; Grail: Other: Personal Fees; American Society for Hospital Pharmacy: Other: Personal Fees; Kaiser Permanente: Research Funding; Third Rock Ventures: Other: Personal Fees; WebMD: Other: Personal Fees; Anthem: Other: Personal Fees; Goldman Sachs: Other: Personal Fees; Novartis: Other: Personal Fees; Defined Health: Other: Personal Fees.

Introduction: Among adolescents and young adults with (w/) acute lymphoblastic leukemia (ALL) or lymphoblastic lymphoma (LBL), treatment using a pediatric (vs. adult) regimen appears to achieve superior event-free (EFS) and overall survival (OS); this observation has driven increased interest in adapting pediatric regimens for middle-aged adults w/ ALL/LBL. However, greater risk of toxicities associated w/ asparaginase complicates administration of pediatric-inspired regimens in adults. We therefore designed a pediatric-inspired chemotherapy regimen w/ doses of pegaspargase (PEG) rationally synchronized to limit overlapping toxicities w/ other chemotherapeutic agents. Methods: We conducted a phase II multi-center trial in adults ages 18-60 w/ newly-diagnosed Philadelphia chromosome-negative (Ph-) ALL/LBL (NCT01920737). Pts w/ Ph+ ALL or Burkitt-type ALL were ineligible. The treatment regimen consisted of 2-phase induction (I-1, I-2), followed by consolidation w/ 2 courses of alternating high-dose methotrexate-based intensification and reinduction, followed by 3 years of maintenance (Figure 1). PEG 2000 IU/m2 was administered in each of the 6 intensive courses of induction/consolidation at intervals of ≥4 weeks. Minimal residual disease (MRD) was assessed in bone marrow (BM) by multiparameter flow cytometry (FACS) on day (d) 15 of I1 and following I-1 and I-2. Any detectable MRD (even Results: 39 pts were enrolled (30M, 9F), w/ B-ALL (n=28), T-ALL (n=7), B-LBL (n=3), and T-LBL (n=5). Median age at start of treatment was 38.3 years (range 20.2-60.4), w/ 18 pts age 40-60. Grade 3-4 toxicities associated w/ PEG are summarized in Table 1. Grade 3-4 hyperbilirubinemia was observed post-PEG in I-1 in 9 pts, but only recurred thereafter in 1/8 pts resuming PEG. Pts completing consolidation on protocol (n=16) received median of 6 doses of PEG (range, 2-6). Four pts developed hypersensitivity to PEG and subsequently received Erwinia asparaginase. PEG was discontinued in 4 additional pts due to hepatotoxicity (n=2), pancreatitis (n=1), and physician preference (n=1). Of pts w/ available response assessments, 35/36 (97%) achieved morphologic complete response (CR) or CR w/ incomplete hematologic recovery (CRi) following I-1 (n=34) or I-2 (n=1). Both pts not achieving CR/CRi after I-I had early T-precursor ALL; one of these pts was withdrawn from study, and the other (w/ M2 marrow after I-1) achieved CR after I-2. Of the pts w/ ALL (excluding LBL) w/ available BM MRD assessments, 11/28 (39%) achieved undetectable MRD by FACS following I-1; 18/22 (82%) achieved undetectable MRD by FACS following I-2. Of the pts w/ LBL w/ available BM MRD assessments, 7/7 (100%) achieved or maintained undetectable MRD by FACS following I-1 and I-2. Ten pts underwent allogeneic hematopoietic cell transplantation (alloHCT) in CR1. Seven pts experienced relapse at median 15.2 months from start of treatment (range, 5.4-30.4), of whom 6 subsequently underwent 1st (n=5) or 2nd (n=1) alloHCT. Of the 11 pts w/ ALL w/ undetectable MRD following I-1, only one has relapsed. Five patients have died, including 2 pts in CR1 (from sepsis and multi-organ system failure), and 3 pts in relapse. At median follow-up of 22.3 months among surviving pts (range, 1.0-48.1), median EFS and OS (Figure 2A&B) have not been reached (EFS not censored at alloHCT). 3-year EFS was 62.1% (95% CI: 38.4-78.9%) and 3-year OS was 80.0% (95% CI: 57.5-91.4%). Conclusions: PEG can be incorporated into pediatric-inspired chemotherapy regimens w/ manageable toxicity for appropriately selected adults up to age 60 w/ Ph- ALL/LBL. While PEG-related AEs are common, few pts require permanent discontinuation of asparaginase. Grade 3-4 hyperbilirubinemia was common, particularly post-I-1, but recurred infrequently when PEG was continued. Two induction courses resulted in a high rate of MRD negativity post-I-2 and translated to a low rate of relapse. Though further follow-up is required, 3-year EFS is encouraging. Data regarding asparaginase enzyme activity and silent inactivation w/ neutralizing anti-PEG antibody will be presented. Ongoing and future studies will additionally investigate whether incorporating novel therapies (e.g. blinatumomab, nelarabine) into frontline consolidation therapy may reduce risk of relapse among adults receiving PEG-containing regimens. Disclosures Geyer: Dava Oncology: Honoraria. Ritchie:Celgene: Consultancy, Other: Travel, Accommodations, Expenses, Speakers Bureau; NS Pharma: Research Funding; Incyte: Consultancy, Speakers Bureau; ARIAD Pharmaceuticals: Speakers Bureau; Astellas Pharma: Research Funding; Bristol-Myers Squibb: Research Funding; Novartis: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; Pfizer: Consultancy, Research Funding. Rao:Kite, a Gilead Company: Employment. Tallman:Daiichi-Sankyo: Other: Advisory board; AROG: Research Funding; Cellerant: Research Funding; AbbVie: Research Funding; BioSight: Other: Advisory board; Orsenix: Other: Advisory board; ADC Therapeutics: Research Funding. Douer:Shire: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead Sciences: Consultancy; Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Consultancy; Pfizer: Honoraria; Spectrum: Consultancy. Park:Kite Pharma: Consultancy; Juno Therapeutics: Consultancy, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy; Novartis: Consultancy; Shire: Consultancy; Pfizer: Consultancy; Adaptive Biotechnologies: Consultancy.

Background Measurable residual disease (MRD) is associated with inferior outcomes in patients with acute myeloid leukemia (AML). MRD monitoring enhances risk stratification and may guide therapeutic intervention. Post-induction MRD is frequently cleared with further therapy and the clearance may lead to better outcomes. In contrast, persistent MRD is associated with poor outcomes. At present it is not possible to predict which patients are likely to clear MRD with further therapy. Here we report a simple, objective, widely applicable and quantitative MFC approach using the ratio of blast/PDC to predict persistent MRD and poor outcomes in AML. Patients and Methods A cohort of 136 adult patients with a confirmed diagnosis of AML by WHO criteria who underwent standard induction therapy at a single center between 4/2014 and 9/2017 was initially included. 69 patients achieved complete morphologic remission (36 MRD-neg. and 33 MRD-pos.). MRD status was assessed by MFC using a different from normal (DfN) approach. PDC were quantified as the percent of total WBC by flow cytometry based on low side scatter, moderate CD45, CD303, bright CD123 and HLA-DR expression. Results The proportion of PDC was markedly decreased in patients with AML (≥20% blasts) (N=136) with a median of 0.016% (interquartile range IQR: 0.0019%-0.071%, Figure 1A), more than 10-fold lower than observed in normal controls (median 0.23%, IQR 0.17%-0.34%) (N=20). While there was no difference between MRD-neg. and normal control groups (median 0.31%, IQR: 0.17%-0.49%; vs. 0.28%, IQR: 0.17%-0.34%), MRD-pos. group had significantly reduced PDC proportion compared to the control (median 0.074%, IQR: 0.022%-0.33%, Wilcoxon rank sum, p=0.019). In an attempt to achieve better separation and to eliminate possible effects of hemodilution, the ratio of blast/PDC was calculated by using the proportions of blasts and PDCs out of total WBCs as quantitated by flow cytometry. A cut-off threshold of the blast/PDC ratio of 10 was chosen to separate each group (Figure 1B). Importantly, a ratio cut-off of 10 had a corresponding specificity of 97.4% for predicting MRD positivity status. MRD positivity was significantly associated with inferior overall survival (OS) and relapse-free survival (RFS) in our study cohort (OS HR 4.11 (95% CI: 1.30-13.03), p=0.016; RFS HR 4.20 (95% CI: 1.49-11.82), p=0.007, Figure 1C and D). The 2-year cumulative incidence of relapse in the MRD-neg. group compared to MRD-pos. group was 10% (95% CI: 2-24%) vs. 37% (95% CI: 18-56%, p=0.014). Importantly, blast/PDC ratio ≥10 was also strongly associated with inferior OS and RFS (OS HR 3.12 (95% CI: 1.13-8.60), p= 0.028; RFS HR 4.05 (95% CI: 1.63-10.11), p=0.003, Figure 1E and F), which is similar in magnitude to MRD positivity. Furthermore, MRD-pos. patients with blast/PDC ratio Conclusion We have established an objective and quantitative MFC method to risk stratify post induction AML patients by risk for relapse, MRD clearance and likelihood of survival. Loss of PDC correlates with residual leukemia, is highly specific for MRD positivity in post-induction patients, and strongly predicts poorer overall survival and higher likelihood of relapse. Loss of PDC also predicts persistent MRD in post-induction MRD-pos. patients despite further therapy, suggesting that MRD-pos. patients with normal PDC may benefit from further therapy prior to transplant, while MRD-pos. patients with loss of PDC may not. Figure 1. Figure 1. Disclosures Goldberg: AROG: Research Funding; Pfizer: Research Funding; Celgene: Consultancy. Geyer:Dava Oncology: Honoraria. Levine:Isoplexis: Equity Ownership; C4 Therapeutics: Equity Ownership; Gilead: Honoraria; Qiagen: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Prelude: Research Funding; Imago: Equity Ownership; Roche: Consultancy, Research Funding; Loxo: Consultancy, Equity Ownership; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Epizyme: Patents & Royalties; Janssen: Consultancy, Honoraria. Tallman:BioSight: Other: Advisory board; AROG: Research Funding; AbbVie: Research Funding; Cellerant: Research Funding; ADC Therapeutics: Research Funding; Orsenix: Other: Advisory board; Daiichi-Sankyo: Other: Advisory board.

Introduction: Hypofibrinogenemia (HF) in acute leukemia has largely been attributed to disseminated intravascular coagulation (DIC). Pathological alterations in hemostasis through various mechanisms by circulating leukemia cells have been implicated in the pathogenesis of DIC, particularly in acute promyelocytic leukemia (APL) (Tallman et al., Leuk Lymphoma, 1993). In adult acute lymphoblastic leukemia (ALL), DIC is rare at presentation, but is significantly more common during induction chemotherapy, with varying degrees of reported morbidity and mortality (Higuchi et al., Leuk Lymphoma, 2005; Sarris et al., Leuk Lymphoma, 1996). Conversely, hyperfibrinogenemia at presentation has also been observed, possibly due to increased synthesis as an acute phase reactant in the setting of inflammation (Al-Mondhiry H et al., Cancer, 1975). Discrepant reports in plasma fibrinogen levels and potentially serious hemostatic complications led us to investigate the incidence of HF and DIC among adults with untreated ALL at our center. Methods: Using a DataLine search and ICD-9 and ICD-10 codes (204.00, 204.01, 204.02, C91.00, C91.01, C91.02), all patients aged 18 years or older with a diagnosis of ALL treated at Memorial Sloan Kettering Cancer Center (MSKCC) between August 30, 1989 and April 27, 2018 were retrospectively identified. HF was defined as a fibrinogen level < 190 mg/dL. The diagnosis of DIC was made using the scoring system for overt DIC from the International Society on Thrombosis and Haemostasis (Toh et al., J Thromb Haemost, 2007). Patients who received any chemotherapy, including asparaginase and glucocorticoids, or who had a potential alternative cause of acquired HF such as sepsis or significant liver disease prior to their initial encounter were excluded. Data collection was approved by the MSKCC Institutional Review Board. Results: A total of 275 adult patients with treatment-naive ALL were identified. The median age at presentation was 44 years. The study population consisted of 122 patients with B-ALL, 81 with T-ALL and 72 with ALL of unspecified lineage. Of these, 187 had a fibrinogen level obtained prior to initiation of therapy. Eight patients (4.3%) had HF at initial assessment with a mean level of 141 mg/dL. Of these 8 patients, 5 had B-ALL, 2 had T-ALL and 1 had ALL of unspecified lineage. Four of these 8 patients required fresh frozen plasma (FFP) and/or cryoprecipitate during their hospitalization for prevention of overt coagulopathy. Three of the 4 patients who required FFP and/or cryoprecipitate went on to receive an asparaginase containing induction regimen. One patient with B-ALL met criteria for overt DIC without clinical complications. One patient with HF experienced WHO grade 2 epistaxis and hematochezia. No deaths in our study population were attributable to DIC at presentation. Discussion: Our study demonstrated that HF and DIC in treatment-naive ALL are uncommon. The rare incidence of DIC in our population is consistent with prior studies in adult ALL (Sarris et al., Blood, 1992). Our findings are also similar to those reported in patients with non-APL acute myeloid leukemia (Weltermann et al., Leukemia, 1998). In contrast, most patients with APL exhibit HF (Lou et al., Leuk Res, 2016). Proposed mechanisms of coagulopathy in APL include primary activation of fibrinolysis, as well as expression of tissue factor and cancer procoagulant by the malignant promyelocytes themselves; these mechanisms appear to be significantly less prevalent in ALL (Breen et al., Br J Haematol, 2012). DIC, when present at initial assessment, is generally subclinical and seldom leads to morbidity and mortality. Although the incidence of HF and DIC was low at diagnosis in our study population, we recommend pre-treatment screening for DIC to identify patients with overt coagulopathy at presentation and to establish baseline values, given the risk of coagulopathic complications during induction chemotherapy for ALL, particularly among patients receiving asparaginase products (Truelove et al., Leukemia, 2012). Further characterization of the ALL microenvironment in patients developing HF and DIC may elucidate mechanisms of procoagulant expression and increased fibrinolysis in this subgroup. Assessing predictors and clinical implications of baseline HF in adults with ALL in a larger series may help to guide early supportive management. Disclosures Geyer: Dava Oncology: Honoraria. Park:Adaptive Biotechnologies: Consultancy; AstraZeneca: Consultancy; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Shire: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy; Pfizer: Consultancy; Juno Therapeutics: Consultancy, Research Funding. Mantha:Janssen Pharmaceuticals: Research Funding; Heidell, Pittoni, Murphy & Bach, LLP: Consultancy; GLG: Consultancy. Tallman:Orsenix: Other: Advisory board; Daiichi-Sankyo: Other: Advisory board; Cellerant: Research Funding; BioSight: Other: Advisory board; AROG: Research Funding; AbbVie: Research Funding; ADC Therapeutics: Research Funding.