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Historically, Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has been associated with poor outcomes, and allogeneic hematopoietic cell transplantation (allo-HCT) is recommended in first complete remission (CR1). However, in the tyrosine kinase inhibitor (TKI) era, rapid attainment of a complete molecular remission (CMR) is associated with excellent outcomes without allo-HCT, suggesting transplant may not be required for these patients. To test this hypothesis, we retrospectively identified adult patients with Ph+ ALL treated with induction therapy, including TKIs, and attained CMR within 90 days of diagnosis at 5 transplant centers in the United States. We compared outcomes of those who did and did not receive allo-HCT in first remission. We identified 230 patients (allo-HCT: 98; non-HCT: 132). The allo-HCT cohort was younger with better performance status. On multivariable analysis (MVA), allo-HCT was not associated with improved overall survival (adjusted hazard ratio [aHR]: 1.05; 95% CI, 0.63-1.73) or relapse-free survival (aHR: 0.86; 95% CI, 0.54-1.37) compared with non-HCT treatment. Allo-HCT was associated with a lower cumulative incidence of relapse (aHR: 0.32; 95% CI, 0.17-0.62) but higher non-relapse mortality (aHR: 2.59; 95% CI, 1.37-4.89). Propensity score matching analysis confirmed results of MVA. Comparison of reduced-intensity HCT to non-HCT showed no statistically significant difference in any of the above endpoints. In conclusion, adult patients with Ph+ ALL who achieved CMR within 90 days of starting treatment did not derive a survival benefit from allo-HCT in CR1 in this retrospective study.

We hypothesized that combining adoptively transferred autologous T cells with a cancer vaccine strategy would enhance therapeutic efficacy by adding antimyeloma idiotype (Id)–keyhole limpet hemocyanin (KLH) vaccine to vaccine-specific costimulated T cells. In this randomized phase 2 trial, patients received either control (KLH only) or Id-KLH vaccine, autologous transplantation, vaccine-specific costimulated T cells expanded ex vivo, and 2 booster doses of assigned vaccine. In 36 patients (KLH, n = 20; Id-KLH, n = 16), no dose-limiting toxicity was seen. At last evaluation, 6 (30%) and 8 patients (50%) had achieved complete remission in KLH-only and Id-KLH arms, respectively (P = .22), and no difference in 3-year progression-free survival was observed (59% and 56%, respectively; P = .32). In a 594 Nanostring nCounter gene panel analyzed for immune reconstitution (IR), compared with patients receiving KLH only, there was a greater change in IR genes in T cells in those receiving Id-KLH relative to baseline. Specifically, upregulation of genes associated with activation, effector function induction, and memory CD8+ T-cell generation after Id-KLH but not after KLH control vaccination was observed. Similarly, in responding patients across both arms, upregulation of genes associated with T-cell activation was seen. At baseline, all patients had greater expression of CD8+ T-cell exhaustion markers. These changes were associated with functional Id-specific immune responses in a subset of patients receiving Id-KLH. In conclusion, in this combination immunotherapy approach, we observed significantly more robust IR in CD4+ and CD8+ T cells in the Id-KLH arm, supporting further investigation of vaccine and adoptive immunotherapy strategies. This trial was registered at www.clinicaltrials.gov as #NCT01426828.

Introduction While clonal hematopoiesis (CH) can precede the development of AML, preleukemic CH can persist after attaining remission. In rare cases, non-leukemic CH can also emerge after remission. Long-term clonal dynamics of persistent CH or emerging CH (together, post-remission CH) in AML patients during consolidation therapies or maintenance therapies is not well understood. Furthermore, the clinical implications of post-remission CH have not been systematically studied. Since AML patients receive various types of post-remission consolidation therapies, including allogeneic stem cell transplant (allo-SCT), analysis of clonal dynamics of post-remission CH offers unique opportunity to study the response of CH to therapies. Such knowledge may be translated into the development of therapeutic strategy targeting CH. Here, we analyzed multiple longitudinal samples from AML patients after remission and analyzed clonal behavior of post-remission CH during consolidation and maintenance therapies. Methods We studied 164 AML patients who attained complete remission (CR) after induction therapies and analyzed baseline and CR marrow by targeted deep sequencing of 295 genes (median 403x depth). Among the patients who were identified to have post-remission CH, we analyzed multiple longitudinal marrows and tracked clonal dynacmis of post-remission CH. We defined “persistent CH” when patients had mutations that were originally detected in AML and persisted after CR with variant allele frequency (VAF) > 2.5%. On the other hand, we defined “ emerging CH” when the patients had new mutations arising after attaining CR. Results Among the 164 AML patients, 79 (48%) patients were found to have post-remission CH at first CR. Of those, we were able to analyze multiple post-remission marrows in 54 patients (median 6 samples/patient, IQR 4-7.75),of which 44 (66%) had persistent CH and 1 (1.9%) had emerging CH, and 9 (17%) had both. The median age of these 54 patients cohort was 59 (IQR: 51-68). 34 (63%) patients attained CR after intensive chemotherapies (IC, idarubicin with high-dose cytarabine based), whereas 20 (37%) patients received low-intensity chemotherapies as induction (hypomethylating agent [HMA]-based N=3, low dose cytarabine-based N=17). All 34 patients treated with IC induction subsequently received consolidation chemotherapies with high-dose cytarabine (HDAC) regimens for median 2 cycles (IQR 2-3.25). Among the 20 patients treated with low-intensity chemotherapies, all patients received consolidation therapies with HMA-based regimen. A subset of patients received maintenance therapies under clinical trials: lenalidomide (N = 1), venetoclax (N = 2), and nivolumab (N = 1). 29 patients underwent allo-SCT (23 with myeloablative conditioning [MAC], and 6 with reduced-intensity conditioning [RIC]). The most frequently mutated genes for persistent CH were DNMT3A (N = 23), followed by TET2 (N = 17), IDH2 (N = 10), and SRSF2 (N = 10). For emerging CH, we observed emergence of JAK2 (N = 2), RUNX1 (N = 2), TET2 (N = 2), BRAF (N = 1), BCOR (N = 1), TP53 (N = 1), KDM6A (N = 1), and NRAS (N = 1). Longitudinal clonal analysis revealed that post-remission CH persisted in 52 of 54 (96%) patients during consolidation and maintenance therapies. Neither cytarabine based chemotherapies, HMA, venetoclax, lenalidomide, and nivolumab, reduced the VAF of post-remission CH, except in 2 (4%) patients, in which post-remission CH (IDH2 and TET2 mutations) were cleared with high dose cytarabine regimen. Although consolidation or maintenance therapies did not reduce post-remission CH, 17 out of 19 (89.4%) patients who underwent for allo-SCT had clearance of post-remission CH with both MAC and RIC. Overall, post-remission CH did not impact the risk of relapse or overall survival. Furthermore, post-remission CH did not affect long-term blood counts (neutrophil counts, hemoglobin, and platelet counts). Conclusion Post-remission CH persisted long-term in AML patients during consolidation and maintenance therapies without having significant impact on blood counts, relapse, and survival. Therapies with cytarabine-based chemotherapies and HMA did not affect the clonal size of post-remission CH, suggesting that these therapies may not be useful to treat CH in pre-leukemic context either. The novel therapeutic approach is warranted to target CH. Disclosures DiNardo: celgene: Consultancy, Honoraria; abbvie: Consultancy, Honoraria; syros: Honoraria; notable labs: Membership on an entity's Board of Directors or advisory committees; daiichi sankyo: Honoraria; agios: Consultancy, Honoraria; medimmune: Honoraria; jazz: Honoraria. Kadia: Bioline RX: Research Funding; Celgene: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; AbbVie: Consultancy, Research Funding. Ravandi: Selvita: Research Funding; Macrogenix: Consultancy, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Xencor: Consultancy, Research Funding; Menarini Ricerche: Research Funding; Cyclacel LTD: Research Funding. Konopleva: Astra Zeneca: Research Funding; Agios: Research Funding; Ablynx: Research Funding; Kisoji: Consultancy, Honoraria; Reata Pharmaceuticals: Equity Ownership, Patents & Royalties; Genentech: Honoraria, Research Funding; Ascentage: Research Funding; F. Hoffman La-Roche: Consultancy, Honoraria, Research Funding; Cellectis: Research Funding; Amgen: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; Eli Lilly: Research Funding; Forty-Seven: Consultancy, Honoraria; Stemline Therapeutics: Consultancy, Honoraria, Research Funding; Calithera: Research Funding. Kantarjian: Takeda: Honoraria; AbbVie: Honoraria, Research Funding; BMS: Research Funding; Jazz Pharma: Research Funding; Pfizer: Honoraria, Research Funding; Ariad: Research Funding; Amgen: Honoraria, Research Funding; Cyclacel: Research Funding; Daiichi-Sankyo: Research Funding; Immunogen: Research Funding; Astex: Research Funding; Agios: Honoraria, Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding. Champlin: Johnson and Johnson: Consultancy; Sanofi-Genzyme: Research Funding; Actinium: Consultancy. Garcia-Manero: Onconova: Research Funding; H3 Biomedicine: Research Funding; Astex: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Helsinn: Research Funding; Novartis: Research Funding; AbbVie: Research Funding; Amphivena: Consultancy, Research Funding; Merck: Research Funding. Takahashi: Symbio Pharmaceuticals: Consultancy.

Recent compelling evidence showed that innate immune effector cells could recognize allogeneic grafts and prime an adaptive immune response. Signal regulatory protein α (SIRPα) is an immunoglobulin superfamily receptor that is expressed on myeloid cells; the interaction between SIRPα and its ubiquitously expressed ligand CD47 elicits an inhibitory signal that suppresses macrophage phagocytic function. Additional studies showed that donor-recipient mismatch in SIRPα variants might activate monocytic allorecognition, possibly as the result of non-self SIRPα-CD47 interaction. However, the frequency of SIRPα variation and its role in hematopoietic stem cell transplantation (HSCT) remains unexplored. We studied 350 patients with acute myeloid leukemia/myelodysplastic syndrome who underwent HLA-matched related HSCT and found that SIRPα allelic mismatches were present in 39% of transplantation pairs. SIRPα variant mismatch was associated with a significantly higher rate of chronic graft-versus-host disease (GVHD; hazard ratio [HR], 1.5; P = .03), especially de novo chronic GVHD (HR, 2.0; P = .01), after adjusting for other predictors. Those with mismatched SIRPα had a lower relapse rate (HR, 0.6; P = .05) and significantly longer relapse-free survival (RFS; HR, 0.6; P = .04). Notably, the effect of SIRPα variant mismatch on relapse protection was most pronounced early after HSCT and in patients who were not in remission at HSCT (cumulative incidence, 73% vs 54%; HR, 0.5; P = .01). These findings show that SIRPα variant mismatch is associated with HSCT outcomes, possibly owing to innate allorecognition. SIRPα variant matching could provide valuable information for donor selection and risk stratification in HSCT.

With the continuous increase in the use of haploidentical donors for transplantation, the selection of donors becomes increasingly important. Haploidentical donors have been selected primarily based on clinical characteristics, while the effects of killer cell immunoglobulin-like receptors (KIRs) on outcomes of haploidentical-hematopoietic stem cell transplantation (haplo-HSCT) with post-transplant cyclophosphamide (PTCy) remain inconclusive. The present study aimed to thoroughly evaluate the effect of KIRs and binding ligands assessed by various models, in addition to other patient/donor variables, on clinical outcomes in haplo-HSCT. In a cohort of 354 patients undergoing their first haplo-HSCT, we found that a higher Count Functional inhibitory KIR score (CF-iKIR) was associated with improved progression-free survival (adjusted hazard ratio [HR], 0.71; P = .029) and overall survival (OS) (HR, 0.66; P = .016), while none of the other models predicted for survival in these patients. Moreover, using exploratory classification and regression tree analysis, we found that donor age 58 years was associated with the worst OS. In the rest of our cohort (80%), cytomegalovirus-reactive recipients with a donor P = .044), 44.5% (HR, 2.01; P = .003), and 18.5% (HR, 5.44; P

Chimeric antigen receptor (CAR) T-cell therapy has emerged recently as a standard of care treatment for patients with relapsed or refractory acute lymphoblastic leukemia (ALL) and several subtypes of B-cell non-Hodgkin lymphoma (NHL). However, its use remains limited to highly specialized centers, given the complexity of its administration and its associated toxicities. We previously reported our experience in using a novel Sleeping Beauty (SB) CD19-specific CAR T-cell therapy in the peri-transplant setting, where it exhibited an excellent safety profile with encouraging survival outcomes. We have since modified the SB CD19 CAR construct to improve its efficacy and shorten its manufacturing time. We report here the phase 1 clinical trial safety results. Fourteen heavily treated patients with relapsed/refractory ALL and NHL were infused. Overall, no serious adverse events were directly attributed to the study treatment. Three patients developed grades 1-2 cytokine release syndrome and none of the study patients experienced neurotoxicity. All dose levels were well tolerated and no dose-limiting toxicities were reported. For efficacy, 3 of 8 (38%) patients with ALL achieved CR/CRi (complete remission with incomplete count recovery) and 1 (13%) patient had sustained molecular disease positivity. Of the 4 patients with DLBCL, 2 (50%) achieved CR. The SB-based CAR constructs allow manufacturing of targeted CAR T-cell therapies that are safe, cost-effective and with encouraging antitumor activity.

Immune checkpoint therapy has resulted in remarkable improvements in the outcome for certain cancers. To broaden the clinical impact of checkpoint targeting, we devised a strategy that couples targeting of the cytokine-inducible Src homology 2–containing (CIS) protein, a key negative regulator of interleukin 15 (IL-15) signaling, with fourth-generation “armored” chimeric antigen receptor (CAR) engineering of cord blood–derived natural killer (NK) cells. This combined strategy boosted NK cell effector function through enhancing the Akt/mTORC1 axis and c-MYC signaling, resulting in increased aerobic glycolysis. When tested in a lymphoma mouse model, this combined approach improved NK cell antitumor activity more than either alteration alone, eradicating lymphoma xenografts without signs of any measurable toxicity. We conclude that targeting a cytokine checkpoint further enhances the antitumor activity of IL-15–secreting armored CAR-NK cells by promoting their metabolic fitness and antitumor activity. This combined approach represents a promising milestone in the development of the next generation of NK cells for cancer immunotherapy. Key Points: • CRISPR-Cas9 CISH deletion enhances the metabolic fitness and antitumor activity of armored IL-15–secreting CB-derived CAR-NK cells.

Pretransplant conditioning with Fludarabine (Flu)-Busulfan (Bu) is safe, but clofarabine (Clo) has improved antileukemic activity. Hypothesis: Flu+Clo-Bu (FCB) yields superior progression-free survival (PFS) after allogeneic transplantation. We randomized 250 AML/MDS patients aged 3–70, Karnofsky Score ≥80, with matched donors, to FCB (n = 120) or Flu-Bu (n = 130), stratifying complete remission (CR) vs. No CR, (NCR). HCT-CI scores varied, from 0 to 10. All evaluable patients engrafted. Median follow-up was 66 months (interquartile range: 58–80). Three-year relapse incidence (RI), 25% with FCB, vs. 39% with Flu-Bu (p = 0.018), offset by higher non-relapse mortality, 22.6% (95%CI: 16–30.2%) vs. 12.3% (95%CI: 6.5–19%). Three-year PFS was 52% (95%CI: 44–62%) (FCB), vs. 48% (95%CI: 41–58%) (Flu-Bu). FCB benefited CR patients less, NCR patients age ≤ 60 had 3-year 34% RI (95%CI: 19–49%) (FCB) vs. 56% (95%CI: 38–70%) after Flu-Bu (p = 0.037). NCR patients >60 years had 3-year RI 10.0% (FCB), vs. 56.0%, after Flu-Bu (p = 0.003). Bayesian regression analysis including treatment-covariate interactions showed FCB superiority in NCR patients with low HCT-CI (0–2). Serious adverse event profiles were similar for the regimens. Conditioning with FCB did not improve PFS overall, but improved disease control in NCR patients, mandating confirmatory trials. Remission status and HCT-CI should be considered when using FCB.

How to best use tyrosine kinase inhibitors (TKIs) of BCR-ABL after allogeneic stem cell transplantation for Philadelphia chromosome–positive acute lymphoblastic leukemia (ALL) is unknown but will almost certainly not be addressed by a definitive randomized trial. Saini and colleagues provide a large body of observational data to reinforce earlier circumstantial evidence favoring prophylactic use of TKIs for at least 2 years posttransplant.

The optimal conditioning regimen for older patients with acute myeloid leukemia (AML) remains unclear. In this study, we compared outcomes of AML patients >60 years of age undergoing allogenic hematopoietic stem cell transplantation at our institution. All 404 consecutively treated patients received 1 of the following conditioning regimens: (1) fludarabine+melphalan 100 mg/m2 (FM100), (2) fludarabine+melphalan 140 mg/m2 (FM140), (3) fludarabine+IV busulfan AUC ≥ 5000/d × 4 d (Bu≥20000), and (4) fludarabine+IV busulfan AUC 4000/d × 4 d (Bu16000). A propensity score analysis (PSA) was used to compare outcomes between these 4 groups. Among the 4 conditioning regimens, the FM100 group had a significantly better long-term survival with 5-year progression-free survival of 49% vs 30%, 34%, and 23%, respectively. The benefit of the FM100 regimen resulted primarily from the lower nonrelapse mortality associated with this regimen, an effect more pronounced in patients with lower performance status. The PSA confirmed that FM100 was associated with better posttransplantation survival, whereas no significant differences were seen between the other regimen groups. In summary, older patients with AML benefited from a reduced-intensity conditioning regimen with lower melphalan doses (FM100), which was associated with better survival, even though it was primarily used in patients who could not receive a more intense conditioning regimen.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative therapy for hematologic malignancies. Alloreactivity after HSCT is known to be mediated by adaptive immune cells expressing rearranging receptors. Recent studies demonstrated that the innate immune system could likewise sense the non-self signals and subsequently enhance the alloimmune response. We recently demonstrated that the donor/recipient mismatch of signal regulatory protein α (SIRPα), an immunoglobulin receptor exclusively expressed on innate cells, is associated with a higher risk of cGVHD and relapse protection in a cohort of acute myeloid leukemia patients who underwent allo-HSCT. Whether these effects also occur in other hematologic malignancies remains unclear. In the present study, we compared outcomes by SIRPα match status in a cohort of 310 patients who received allo-HSCT from an HLA matched-related donor for the treatment of lymphoid malignancies. Multivariable analysis showed that SIRPα mismatch was associated with a significantly higher rate of cGVHD (hazard ratio [HR] 1.8, P= .002), cGVHD requiring systemic immunosuppressive therapy (HR 1.9, P= .005), a lower rate of disease progression (HR 0.5, P= .003) and improved progression-free survival (HR 0.5, P= .001). Notably, the effects of SIRPα mismatch were observed only in the patients who achieved >95% of donor T-cell chimerism. The mismatch in SIRPα is associated with favorable relapse protection and concurrently increased risk of cGVHD in patients who undergo allo-HSCT for lymphoid malignancies, and the optimal donor could be selected based on the finding of the study to mitigate the risk of GVHD and relapse.

Background: There has been an increased use of novel agents in the induction therapy for transplant-eligible AL amyloidosis over past decade. Hematologic response after an autologous hematopoietic stem cell transplantation (ASCT) is predictive of better outcomes, including organ response and overall survival. However, limited data exist about the outcomes of patients who are refractory to induction chemotherapy but proceed with upfront ASCT). We present here the outcomes of AL amyloidosis refractory to induction therapy. Methods: This retrospective study included all consecutive AL patients who had their ASCT at our institution between 01/2008 and 12/2018 and received induction therapy. We excluded patients who were untreated at the time of transplant. Primary objective: assess the hematologic response, progression-free survival (PFS) and overall survival (OS). Secondary objective: compare PFS and OS of AL amyloidosis by response to induction therapy (refractory vs sensitive). Refractory disease was defined as patient who had stable disease (SD) or progressive disease (PD) after at least 1 line of induction therapy. Hematologic response was defined per the 2012 consensus criteria. Survival estimates were calculated using Kaplan-Meier method. Results: One-hundred-and-eleven patients with a median age of 61 (range, 27-77) years met eligibility criteria. Thirty-three (30%) were refractory and 78 (70%) were sensitive to induction therapy. Table 1 summarizes patient and disease characteristics of all study patients and for the refractory vs sensitive groups. Overall, the two groups were comparable except for significantly more kidney involvement in the refractory group (97% of patients). Induction therapies were similar in the two groups, with bortezomib/cyclophosphamide/dexamethasone (VCD) being the most commonly used regimen (46%). With a median follow-up of 3.11 (range, 0.18-11.15) years, the 3-year PFS and OS for all study patients were 67% and 78%, respectively. At 3 months after transplant, 74% of the patients in the refractory group achieved an objective hematologic response (OHR; defined as PR or better). Of these, 29% achieved VGPR/CR and 45% achieved PR. As expected, more patients in the sensitive group achieved OHR (97%) and VGPR/CR (76%). The respective 3-year PFS and OS were 49% and 73% in the refractory group compared to 75% and 83% in the sensitive group (p=0.0068 for PFS; p=0.0790 for OS). Univariate analysis (UVA) was performed for the variables listed in Table 1 and multivariable analyses included only factors with p value Conclusion: AL amyloid patients refractory to induction therapy seem to benefit from high-dose chemotherapy and ASCT in terms of both response rates and survival. Durable responses for refractory disease are notable in patients who achieved >VGPR after ASCT. Prospective studies comparing transplant versus non-transplant approaches are warranted for these high-risk patients. Figure 1 Figure 1. Disclosures Hosing: Nkarta Therapeutics: Membership on an entity's Board of Directors or advisory committees. Popat: Bayer: Research Funding; Abbvie: Research Funding; Novartis: Research Funding; Incyte: Research Funding. Lee: Bristol Myers Squibb: Consultancy; Celgene: Consultancy; Genentech: Consultancy; Janssen: Consultancy, Research Funding; Karyopharm: Consultancy; Legend Biotech: Consultancy; GlaxoSmithKline: Consultancy, Research Funding; Sanofi: Consultancy; Oncopetides: Consultancy; Takeda Pharmaceuticals: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Regeneron: Research Funding. Orlowski: Asylia Therapeutics, Inc., BioTheryX, Inc., and Heidelberg Pharma, AG.: Other: Laboratory research funding; Asylia Therapeutics, Inc.: Current holder of individual stocks in a privately-held company, Patents & Royalties; Amgen, Inc., BioTheryX, Inc., Bristol-Myers Squibb, Celgene, Forma Therapeutics, Genzyme, GSK Biologicals, Janssen Biotech, Juno Therapeutics, Karyopharm Therapeutics, Inc., Kite Pharma, Neoleukin Corporation, Oncopeptides AB, Regeneron Pharmaceuticals, I: Membership on an entity's Board of Directors or advisory committees; CARsgen Therapeutics, Celgene, Exelixis, Janssen Biotech, Sanofi-Aventis, Takeda Pharmaceuticals North America, Inc.: Other: Clinical research funding; Amgen, Inc., BioTheryX, Inc., Bristol-Myers Squibb, Celgene, EcoR1 Capital LLC, Genzyme, GSK Biologicals, Janssen Biotech, Karyopharm Therapeutics, Inc., Neoleukin Corporation, Oncopeptides AB, Regeneron Pharmaceuticals, Inc., Sanofi-Aventis, and Takeda P: Consultancy, Honoraria. Qazilbash: Janssen: Research Funding; Biolline: Research Funding; Angiocrine: Research Funding; Amgen: Research Funding; NexImmune: Research Funding; Bristol-Myers Squibb: Other: Advisory Board; Oncopeptides: Other: Advisory Board.

Background: Myeloablative conditioning can be given safely to older patients by simply administering busulfan over a longer period (fractionated busulfan regimen) than the standard four-day regimen (Popat et al Lancet Haematology 2018). This longer duration of conditioning regimen allows addition of targeted agents like Venetoclax, which may be synergistic with conditioning chemotherapy and may further improve disease control with this regimen. We therefore added Venetoclax to our ongoing prospective clinical trial with f-Bu-Flu-Cladribine conditioning (NCT02250937). After enrolling 83 patients, the study was amended and venetoclax was added for the next 33 patients. Here we report the safety and preliminary efficacy of venetoclax and fractionated busulfan regimen. Methods: Between 2/2019 and 3/2021, 33 patients with AML (n=21) or MDS (n=10) up to 70 years of age with adequate organ function and 8/8-HLA matched related or unrelated donor were enrolled on a prospective trial. The conditioning regimen was f-Bu to target an area under the concentration vs time curve (AUC) of 20,000 ± 12% μmol.min given over a period of 2-3 weeks. The first two doses of busulfan (80 mg/m2 IV each) were administered either consecutively (days -13 and -12) or with further fractionation, one week apart (days -20 and -13) on outpatient basis. Then, inpatient fludarabine 10 mg/m 2, and cladribine 10 mg/m 2 were given followed by Bu on days -6 to -3. Venetoclax 400mg daily was given from day -22 to -3. Azoles were avoided during this period. GVHD prophylaxis was PTCy 50mg/kg on days 3 and 4 and tacrolimus from day 5. Results: The median age was 59 years (range, 23-69); High or very high disease risk index was present in 21%; Comorbidity index score of >3 was present in 45%; Donor was a sibling in 39%; and peripheral blood stem cells was the graft source in 100%. The median follow up was 8 months. At 1-year, overall survival was 84% (95% confidence interval, 71-100), progression-free survival 77% (64-94), relapse 13% (1-25), and non-relapse mortality 10% (0-20) [Table 1, Figure 1]. Incidence of acute GVHD grade 2-4 was 28% (12-43) and grade 3-4 acute GVHD was 3% (0-9) at day 100. All patients engrafted. The median time to neutrophil engraftment was 15 days (13 -19) and median time to platelet engraftment was 23 days (11-85). Full donor chimerism at day 30 was noted in 76%. Common grade 3 or 4 toxicity were neutropenic fever (58%), mucositis (18%) and pulmonary toxicity in 21%. Conclusion: Venetoclax can be safely added to the fractionated busulfan regimen. Early data on efficacy appear promising. Figure 1 Figure 1. Disclosures Popat: Bayer: Research Funding; Abbvie: Research Funding; Novartis: Research Funding; Incyte: Research Funding. Mehta: CSLBehring: Research Funding; Syndax: Research Funding; Incyte: Research Funding; Kadmon: Research Funding. Hosing: Nkarta Therapeutics: Membership on an entity's Board of Directors or advisory committees. Gulbis: EUSA Pharma: Other: Advisory board participation. Rezvani: AvengeBio: Other: Scientific Advisory Board ; Pharmacyclics: Other: Educational grant, Research Funding; GemoAb: Other: Scientific Advisory Board ; Navan Technologies: Other: Scientific Advisory Board; Bayer: Other: Scientific Advisory Board ; Caribou: Other: Scientific Advisory Board; Takeda: Other: License agreement and research agreement, Patents & Royalties; Virogin: Other: Scientific Advisory Board ; GSK: Other: Scientific Advisory Board ; Affimed: Other: License agreement and research agreement; education grant, Patents & Royalties, Research Funding. Qazilbash: Bristol-Myers Squibb: Other: Advisory Board; Oncopeptides: Other: Advisory Board; Amgen: Research Funding; Angiocrine: Research Funding; NexImmune: Research Funding; Biolline: Research Funding; Janssen: Research Funding. Kadia: Cure: Speakers Bureau; Novartis: Consultancy; Dalichi Sankyo: Consultancy; Cellonkos: Other; Ascentage: Other; Genfleet: Other; Sanofi-Aventis: Consultancy; Genentech: Consultancy, Other: Grant/research support; Astellas: Other; Liberum: Consultancy; BMS: Other: Grant/research support; Amgen: Other: Grant/research support; Aglos: Consultancy; Pfizer: Consultancy, Other; AstraZeneca: Other; AbbVie: Consultancy, Other: Grant/research support; Pulmotech: Other; Jazz: Consultancy. Konopleva: Calithera: Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding; Ascentage: Other: grant support, Research Funding; Cellectis: Other: grant support; Ablynx: Other: grant support, Research Funding; Agios: Other: grant support, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; AstraZeneca: Other: grant support, Research Funding; Stemline Therapeutics: Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Forty Seven: Other: grant support, Research Funding; Sanofi: Other: grant support, Research Funding; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; KisoJi: Research Funding. Shpall: Axio: Consultancy; Magenta: Consultancy; Novartis: Consultancy; Bayer HealthCare Pharmaceuticals: Honoraria; Adaptimmune: Consultancy; Navan: Consultancy; Takeda: Patents & Royalties; Novartis: Honoraria; Affimed: Patents & Royalties; Magenta: Honoraria.

Background: Myeloablative conditioning can be given safely to older patients by simply administering busulfan (Bu) over a longer period (fractionated (f)-Bu) with fludarabine (Flu) than the standard four-day regimen. (Popat et al Lancet Haematology 2018). We added thiotepa (Thio) to this f-Bu/Flu regimen in patients with haploidentical (haplo) donors to promote engraftment and to reduce relapse. With encouraging results, Thio was then added in matched unrelated (MUD) and sibling (MSD) donor recipients also. However, the optimal doses of Thio and Bu were undefined. To further optimize the regimen, we tested two different f-Bu/Flu/Thio regimens in parallel prospective cohorts: (a) higher dose Bu with lower dose Thio, and (b) lower dose Bu with a higher dose Thio. Patients were enrolled on these cohorts based on age and co-morbidity index (HCT-CI). Herein, we report on the safety and preliminary efficacy of these regimens (NCT02861417). Methods: Patients 60 years with HCT-CI 3, or >60 years with HCT-CI >2, or >70 years irrespective of HCT-CI received f-BU to target AUC of 16,000 with Thio 5mg/kg (Bu16K/Thio5; Cohort 2). In both cohorts, the first two doses of Bu (80 mg/m2 IV each) were given as outpatient on days -20 and -13. The last four Bu doses were given as inpatient following each dose of Flu 40 mg/m2 on days -6 through -3. Thio was given on day -7. GVHD prophylaxis was post-transplant cyclophosphamide (PTCy) 50mg/kg on days 3 and 4, tacrolimus and MMF. Results: 66 patients were enrolled - 25 in cohort 1 and 41 in cohort 2, with a median age 60 years (range, 22-69) vs 62 years (range, 30-74), respectively (P=0.14). Diagnoses were AML/MDS (64% vs 54%), CML/MPD (24% vs 22%), ALL (12% vs 22%) and 1 myeloma; P=0.24. Most had intermediate disease risk index (80% vs 73%, P=0.57); median HCT-CI was 1 (range, 0-6) vs 3 (range, 0-9); P Primary graft failure occurred in 1 patient in cohort 1 and none in cohort 2. The median time to neutrophil engraftment was 17.5 days (range, 14-26) vs 18 days (range, 12-26); P=0.12, respectively; platelet engraftment > 20K was 30 days in both groups; P=0.75. Median donor chimerism at day 30 was 100% in both groups. The incidence of acute GVHD grade III-IV was 4% vs 5%; P=0.88 at day 100; extensive chronic GVHD at 1 year was 13% vs 10%; P=0.83. At 1-year overall survival was 72% vs 78%; P=0.95; relapse was 12% each; non-relapse mortality was 20% vs 17%; P=0.97 [Table 1, Fig 1]. Common grade >3 toxicities were neutropenic fever (64% vs 42%; P=0.13), bacterial infection (44% vs 34%; P=0.45), nausea (12% vs 2%; P=0.15), mucositis (8% vs 5%; P=0.63), pneumonitis (12% vs 7%; P=0.67), hemorrhagic cystitis (8% vs 5%) and sinusoidal obstructive syndrome (8% vs 2.4%). Conclusion: In this population of older patients and/or high co-morbidities, both myeloablative regimens with f-Bu/Flu with thiotepa and PTCy were well tolerated and led to low NRM, low risk of relapse and encouraging survival. Although both regimens led to similar outcomes, the f-Bu/Flu/Thio regimen with Bu16K and thiotepa 5 mg/kg dose may be preferred as this was used in patients who were older and/or had high co-morbidities. Figure 1 Figure 1. Disclosures Popat: Bayer: Research Funding; Abbvie: Research Funding; Novartis: Research Funding; Incyte: Research Funding. Mehta: CSLBehring: Research Funding; Kadmon: Research Funding; Syndax: Research Funding; Incyte: Research Funding. Hosing: Nkarta Therapeutics: Membership on an entity's Board of Directors or advisory committees. Rezvani: Caribou: Other: Scientific Advisory Board; Virogin: Other: Scientific Advisory Board ; AvengeBio: Other: Scientific Advisory Board ; GSK: Other: Scientific Advisory Board ; Bayer: Other: Scientific Advisory Board ; Navan Technologies: Other: Scientific Advisory Board; GemoAb: Other: Scientific Advisory Board ; Takeda: Other: License agreement and research agreement, Patents & Royalties; Pharmacyclics: Other: Educational grant, Research Funding; Affimed: Other: License agreement and research agreement; education grant, Patents & Royalties, Research Funding. Qazilbash: Oncopeptides: Other: Advisory Board; Janssen: Research Funding; Bristol-Myers Squibb: Other: Advisory Board; NexImmune: Research Funding; Amgen: Research Funding; Angiocrine: Research Funding; Biolline: Research Funding. Shpall: Affimed: Patents & Royalties; Adaptimmune: Consultancy; Novartis: Consultancy; Magenta: Consultancy; Magenta: Honoraria; Axio: Consultancy; Takeda: Patents & Royalties; Navan: Consultancy; Novartis: Honoraria; Bayer HealthCare Pharmaceuticals: Honoraria.

Background: Inotuzumab Ozogamicin (INO) is a humanized anti-CD22 monoclonal antibody that has emerged as an attractive therapeutic target for CD22+ b-cell lymphoid malignancies. We prospectively studied the safety and efficacy of INO when added to our standard nonmyeloablative allogeneic stem cell transplant (alloSCT) conditioning regimen of BFR (bendamustine, fludarabine and rituximab) (Khouri IF, et al. Blood 2014;124:2306). We also compared results to patients who received BFR+alloSCT without INO in prior trial. Methods: INO was infused intravenously (IV) on day -13 outpatient, with a dose cohort of 0.6, 1.2 or 1.8 mg/m2, to determine the maximum tolerated dose. Bendamustine 130 mg/m2 IV daily on days -5 to -3 together with 30 mg/m2 IV of fludarabine on days -5 to -3 were given prior to transplantation. Rituximab was given at a dose of 375 mg/m2 IV on days -6, +1, and +8. Tacrolimus and mini-methotrexate were used for graft versus host disease (GVHD) prophylaxis. In addition, thymoglobulin 1 mg/kg IV was given on days -2, and -1 in patients receiving a matched unrelated donor (MUD) transplant. Results: AlloSCT with INO.The study group included 26 patients treated between December 2012 and September 2019. Median age was 59 (range, 26-70) years. Eleven (42% had an HCT-CI >3. Disease types: CLL [n=7 (27%) ; 2 with TP53 mutations, 2 others with 17p-; 4 with unmutated immunoglobulin heavy chain gene], Richter's (n=4, 15%), mantle cell lymphoma (MCL) [n=8 (31%); 6/6 patients tested had Ki 67 >30%; 1 had blastoid histology and 1 had 17p-], follicular lymphoma (n=5, 19%), and diffuse large b cell (DLBCL[n= 2 (8%); including 1 double-expressor subtype]. Median prior treatments was 2.5 (range, 1-6). CLL patients were previously treated with ibrutinib (n=6, 86%; 5 had the drug discontinued due to refractoriness to ibrutinib, one had poor tolerance, and 1 was bridged to transplant), idelalisib (n=2, refractory), venetoclax (n=4; sensitive), CAR-T cell (n=1, refractory). One patient with Richter refractory to nivolumab+chemotherapy. Four MCL patients were previously treated with ibrutinib (2 had progression, 2 were bridged to transplant). At study entry, 18 (69%) patients were in CR, 7 (27%) in PR, and 1 (4%) had SD. Eleven (42%) received their transplants from HLA-compatible siblings and 15 (58%) from MUDs. The number of patients who received the 0.6, 1.2 or 1.8 mg/m2 of INO were 4, 2 and 20 patients, respectively. No DLT was observed. Neutrophil counts recovered to > 0.5 x 109/L a median of 6 days after transplantation (range, 0-12). Eleven patients (42%) never experienced an ANC < 0.5 x 109/L and 20 (77%) never experienced a platelet counts < 20K x 109/L. All patients engrafted donor cells and no secondary graft failure occurred. By day 30, median donor myeloid and T-cells were 92% and 99%, respectively. Both increased to 100% by day 90. The CI acute grade 2-4 GVHD, 3-4 GVHD and 1-year chronic extensive GVHD were 27%, 4 % (none had grade 4) and 31%, respectively. Non-relapse mortality (NRM) at 5-years was 11.7%. With a median follow-up time of 49 (range, 4-83) months, the 5-year OS and PFS rates were 84% and 81%, respectively (Figure 1). Control group: AlloSCT without INO. We compared results to a group of patients (n=56) with relapsed lymphoid malignancies who received alloSCT at our center on a preceding prospective trial between April 2009 and February 2013, using BFR conditioning without INO and the same GVHD prophylaxis. There was no statistically significant difference in patients, disease or transplant characteristics between the 2 groups. We also found no statistically significant differences in engraftment times, % donor cell, 5-year NRM (12.5%), risk of acute 2-4 or 3-4 GVHD. Liver toxicity encountered between the two groups is summarized in Table 1. The 5-year OS and PFS was 75% and 62%, respectively (Figure 2). Conclusions: Our results show that INO at a dose level of 1.8 mg/m2 is well-tolerated when combined with the BFR nonmyeloablative allogeneic conditioning regimen for lymphoid malignancies. No added toxicity or increased myelosuppression were observed compared to patients who received BFR alone. An ongoing trial at our center includes patients with acute lymphoblastic leukemia evaluating INO added during conditioning and post- alloSCT for maintenance. Disclosures Khouri: Bristol Myers Squibb: Research Funding; Pfizer: Research Funding. Jain:Fate Therapeutics: Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Aprea Therapeutics: Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Kadia:Abbvie: Honoraria, Research Funding; Cellenkos: Research Funding; Pulmotec: Research Funding; Amgen: Research Funding; Cyclacel: Research Funding; Incyte: Research Funding; BMS: Honoraria, Research Funding; Celgene: Research Funding; Astellas: Research Funding; Ascentage: Research Funding; Pfizer: Honoraria, Research Funding; Astra Zeneca: Research Funding; Novartis: Honoraria; JAZZ: Honoraria, Research Funding; Genentech: Honoraria, Research Funding. Pemmaraju:Roche Diagnostics: Honoraria; Samus Therapeutics: Research Funding; Blueprint Medicines: Honoraria; Celgene: Honoraria; SagerStrong Foundation: Other: Grant Support; LFB Biotechnologies: Honoraria; Novartis: Honoraria, Research Funding; DAVA Oncology: Honoraria; Affymetrix: Other: Grant Support, Research Funding; MustangBio: Honoraria; Daiichi Sankyo: Research Funding; Plexxikon: Research Funding; Incyte Corporation: Honoraria; Cellectis: Research Funding; Stemline Therapeutics: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Pacylex Pharmaceuticals: Consultancy. Bashir:Celgene: Research Funding; StemLine: Research Funding; Acrotech: Research Funding; Takeda: Other: Advisory Board, Research Funding; Purdue: Other: Advisory Board; Amgen: Other: Advisory Board; KITE: Other: Advisory Board. Kebriaei:Novartis: Other: Served on advisory board; Kite: Other: Served on advisory board; Ziopharm: Other: Research Support; Pfizer: Other: Served on advisory board; Jazz: Consultancy; Amgen: Other: Research Support. Popat:Bayer: Research Funding; Novartis: Research Funding. Nastoupil:Genentech, Inc.: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Karus Therapeutics: Research Funding; Gamida Cell: Honoraria; Bayer: Honoraria; Gilead/KITE: Honoraria; Novartis: Honoraria, Research Funding; Merck: Research Funding; Janssen: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; TG Therapeutics: Honoraria, Research Funding; LAM Therapeutics: Research Funding. Flowers:BeiGene: Consultancy; Burroughs Wellcome Fund: Research Funding; TG Therapeutics: Research Funding; Bayer: Consultancy; Denovo Biopharma: Consultancy; AbbVie: Consultancy, Research Funding; Acerta: Research Funding; Leukemia and Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; V Foundation: Research Funding; Kite: Research Funding; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy, Research Funding; Gilead: Consultancy, Research Funding; OptumRx: Consultancy; Eastern Cooperative Oncology Group: Research Funding; Cancer Prevention and Research Institute of Texas: Research Funding; National Cancer Institute: Research Funding; Spectrum: Consultancy; Pharmacyclics/Janssen: Consultancy; Karyopharm: Consultancy; Millennium/Takeda: Consultancy, Research Funding; Celgene: Consultancy, Research Funding. Kantarjian:Novartis: Research Funding; Jazz Pharma: Research Funding; Agios: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Cyclacel: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Research Funding; Immunogen: Research Funding; Astex: Research Funding; Takeda: Honoraria; AbbVie: Honoraria, Research Funding; BMS: Research Funding; Ariad: Research Funding. Champlin:Actinium: Consultancy; Takeda: Patents & Royalties; Genzyme: Speakers Bureau; DKMS America: Membership on an entity's Board of Directors or advisory committees; Johnson and Johnson: Consultancy; Omeros: Consultancy; Cytonus: Consultancy. Jabbour:Pfizer: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding. OffLabel Disclosure: Use Of Inotuzumab Ozogamicin in conditioning for allogeneic transplantation

Background: The combination of low intensity therapy with mini-hyper-CVD and INO with or without Blina has led to significant improvement in survival and outcomes of pts with R-R ALL. ASCT following salvage therapy is considered standard of care in pts with R-R ALL. The aim of this study is to compare the outcomes of pts with R-R ALL treated with this combination followed by ASCT to those who did not receive subsequent ASCT. Methods: The chemotherapy was lower in intensity than conventional hyper-CVAD and referred to as mini-hyper-CVD (details in a separate abstract). INO was given on Day 3 of each of the first 4 courses at 1.8-1.3 mg/m2 for course 1 followed by 1.3-1.0 mg/m2 for subsequent courses. Following the enrollment of 67 pts, INO was reduced and fractionated into biweekly doses (0.6 mg/m2 and 0.3 mg/m2 during course 1 and 0.3 mg/m2 and 0.3 mg/m2 during subsequent courses), and Blina was added for up to 4 courses after INO therapy. The decision to proceed with ASCT was at the discretion of the treating physician and after discussion with the pt. Median time to ASCT was 4 months (range, 2 to 10 months). We performed a landmark analysis at 4 months and compared survival of pts on protocol who received ASCT and those who did not. We used a prognostic model to stratify pts into 2 categories: high- vs low-risk. This model relies on cytogenetics and CD22 expression to predict survival (detailed in another abstract). Pts with CD22 expression ≥70% and cytogenetics without KMT2A rearrangements, or low-hypodiploidy / near triploidy were considered low-risk disease. We compared the survival of pts who received ASCT to those who did not among each risk category. Results: Ninety-six pts with R-R ALL were treated. Forty-four pts (46%) with a median age of 34 years (range, 18 to 64 years) underwent ASCT (13 related donors; 16 match unrelated donors, 13 haploidentical, 2 cord stem cells). Of them, 35 (79%) underwent ASCT in Salvage 1 (S1). At the time of ASCT, all 44 pts were morphologic response (39 CR, 5 CRp), 38 among them (86%) in negative MRD status. To date, 19/44 pts (43%) remain alive in remission following ASCT [17 complete response (CR); 2 alive after relapse]. The remaining 25 pts (57%) died of vaso-occlusive disease (VOD; 2 pts), relapse (17 pts) or ASCT complications (6 pts). The median time from start of therapy to ASCT was 18 weeks (range 8 to 44 weeks); this median was 15 weeks (range: 8-44 weeks) for pts who received the original combination and 18 weeks (range: 9-31 weeks) for pts who received the weekly lower dose of INO followed by Blina. In a landmark analysis, the median OS for pts who received ASCT and those who did not was 35 months and 17 months, respectively. The 3-year OS rates were 48% (95% CI, 32%-63%) and 37% (95% CI, 19%-55%), respectively (p=0.4) (Figure 1). In pts who received ASCT in S1, the 3-year OS rate was 55.2% (95% CI, 36.7%-70.4%) with a median OS of 47 months. In univariate analysis of factors predicting survival, ASCT as a time-dependent variable was not associated with better survival [HR 0.775; 95% CI, 0.430-1.396; p=0.396]. VOD was observed in 7/44 pts (16%) who received subsequent ASCT versus 3/52 pts (6%) who did not and in 9/67 pts (13%; 22/67 received subsequent ASCT) treated with mini-hyper-CVD-INO compared with 1/29 pts (3%) treated with mini-hyper-CVD-INO-Blina (15/29 received a subsequent ASCT). This may be the result of lower dose schedules and distancing ASCT from last course of INO. For risk stratification, 82 pts were evaluable; 30 were considered high-risk. In low-risk pts, there was no difference in OS whether or not pts received ASCT (p=0.777). With a 4-month landmark analysis, the 3-year OS rates were 62% and 60% for pts who received ASCT and those who did not, respectively. Among the high-risk pts, the 1-year OS rates were 25% and 11% (p=0.14), respectively (Figure 2). Conclusions: The combination of mini-hyper-CVD and INO with or without Blina is very effective in pts with R-R ALL. ASCT ASCT should be potentially considered in pts with high-risk disease (KMT2A rearrangement, low-hypodiploidy / near triploidy, CD22 expression Disclosures Rafei: United States Provisiona: Patents & Royalties: I have a filed patent. Kantarjian:Ariad: Research Funding; Novartis: Research Funding; Agios: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; BMS: Research Funding; Astex: Research Funding; Pfizer: Honoraria, Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Research Funding; Takeda: Honoraria; Cyclacel: Research Funding; Jazz Pharma: Research Funding; Daiichi-Sankyo: Research Funding; Immunogen: Research Funding. Sasaki:Daiichi Sankyo: Consultancy; Pfizer Japan: Consultancy; Novartis: Consultancy, Research Funding; Otsuka: Honoraria. Short:AstraZeneca: Consultancy; Amgen: Honoraria; Astellas: Research Funding; Takeda Oncology: Consultancy, Honoraria, Research Funding. Ravandi:Xencor: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Astellas: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding. Khouri:Bristol Myers Squibb: Research Funding; Pfizer: Research Funding. Kebriaei:Ziopharm: Other: Research Support; Novartis: Other: Served on advisory board; Kite: Other: Served on advisory board; Jazz: Consultancy; Amgen: Other: Research Support; Pfizer: Other: Served on advisory board. Champlin:Takeda: Patents & Royalties; Genzyme: Speakers Bureau; DKMS America: Membership on an entity's Board of Directors or advisory committees; Cytonus: Consultancy; Omeros: Consultancy; Johnson and Johnson: Consultancy; Actinium: Consultancy. Jain:Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Aprea Therapeutics: Research Funding; Fate Therapeutics: Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Pfizer: Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; ADC Therapeutics: Research Funding. Issa:Syndax: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Celegene: Research Funding. Pemmaraju:Affymetrix: Other: Grant Support, Research Funding; Pacylex Pharmaceuticals: Consultancy; SagerStrong Foundation: Other: Grant Support; Incyte Corporation: Honoraria; Novartis: Honoraria, Research Funding; LFB Biotechnologies: Honoraria; Stemline Therapeutics: Honoraria, Research Funding; Celgene: Honoraria; AbbVie: Honoraria, Research Funding; MustangBio: Honoraria; Roche Diagnostics: Honoraria; Blueprint Medicines: Honoraria; DAVA Oncology: Honoraria; Samus Therapeutics: Research Funding; Cellectis: Research Funding; Daiichi Sankyo: Research Funding; Plexxikon: Research Funding. Kadia:JAZZ: Honoraria, Research Funding; Cyclacel: Research Funding; Amgen: Research Funding; Cellenkos: Research Funding; BMS: Honoraria, Research Funding; Ascentage: Research Funding; Abbvie: Honoraria, Research Funding; Astellas: Research Funding; Incyte: Research Funding; Pulmotec: Research Funding; Celgene: Research Funding; Genentech: Honoraria, Research Funding; Astra Zeneca: Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Honoraria. Garcia-Manero:AbbVie: Honoraria, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Research Funding; Novartis: Research Funding; Jazz Pharmaceuticals: Consultancy; Onconova: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; H3 Biomedicine: Research Funding; Amphivena Therapeutics: Research Funding; Celgene: Consultancy, Honoraria, Research Funding. DiNardo:AbbVie: Consultancy, Honoraria, Research Funding; Calithera: Research Funding; MedImmune: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; ImmuneOnc: Honoraria; Takeda: Honoraria; Jazz: Honoraria; Syros: Honoraria; Notable Labs: Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Honoraria, Research Funding; Novartis: Consultancy; Daiichi Sankyo: Consultancy, Honoraria, Research Funding. Daver:Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: 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; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: 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; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: 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. Thompson:Pharmacyclics: Research Funding; Genentech: Consultancy; AbbVie: Research Funding; Adaptive Biotechnologies: Consultancy, Research Funding; Janssen-Cilag: Honoraria. Konopleva:Cellectis: Research Funding; Calithera: Research Funding; AbbVie: Consultancy, Research Funding; Eli Lilly: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Kisoji: Consultancy; Genentech: Consultancy, Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Sanofi: Research Funding; AstraZeneca: Research Funding; Forty-Seven: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Amgen: Consultancy; Ascentage: Research Funding; Ablynx: Research Funding; Rafael Pharmaceutical: Research Funding; Agios: Research Funding. O'Brien:Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc. Vaniam Group, AbbVie, Alexion, Verastem, Eisai, Juno Therapeutics, Vida Ventures: Consultancy; Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Consultancy, Research Funding; Kite, Regeneron, Acerta: Research Funding. Jabbour:Amgen: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding. OffLabel Disclosure: Blinatumomab Inotuzumab used in the setting of a clinical trial of a combination of mini-hyper-CVD + inotuzumab +/- blinatumomab in patients with acute lymphoblastic leukemia

Introduction: Allogeneic hematopoietic cell transplantation (HCT) in first complete remission (CR1) is the standard of care for adult patients with Philadelphia Chromosome Positive (Ph+) Acute Lymphoblastic Leukemia (ALL). The addition of tyrosine kinase inhibitors (TKI) to therapy have resulted in significantly higher rates of complete molecular remissions (CMR) and better overall outcomes. Given the increased toxicity associated with HCT, we aimed to study the benefit of HCT in adult patients with Ph+ ALL in CR1 in CMR. Methods: We performed a multi-institutional, retrospective analysis of 186 patients ≥18 years of age who received induction therapy including TKI for Ph+ ALL from January 2001 through December 2018 and achieved a CMR CR1. Patients achieving CMR within 3 months of diagnosis were included. Sixty-six patients underwent HCT consolidation (HCT group) and 120 patients did not receive HCT in CR1 (no HCT group). Primary outcomes of interest were overall survival (OS), relapse free survival (RFS), cumulative incidence of relapse (CIR), non-relapse mortality (NRM), and GVHD free relapse free survival (GRFS). GRFS was defined as being alive without grade III-IV acute GVHD, extensive or systemic chronic GVHD requiring therapy, or relapse. Although GRFS in no HCT group should be exactly as RFS, GRFS comparison was done to compare the composite outcome of quality of life in addition to survival in two groups. Landmark analysis was performed at 3 months to ensure CMR in all subjects at time 0. Survival end points were estimated using Kaplan-Meier method and analyzed with the log-rank test and Cox proportional hazard regression models. Gray's test was used for the comparison of cumulative incidence between cohorts. Results: Patient characteristics at diagnosis are summarized in Table 1. Compared to the non-transplanted patients, HCT patients were younger (median age 45 years vs. 56 years, p 90% in 90% of patients vs. 60%, p In both univariate and multivariate analysis, there was no statistically significant difference in OS or RFS between the two treatment groups (Figure 1A and 1B). Compared to the non-transplanted patients, HCT patients had higher rates of NRM (HR: 3.57; 95% CI: 1.62-7.85), lower rates of CIR (Figure 1C), and a trend toward lower GRFS (Figure 1D). Five-year estimates of the probabilities of OS, RFS, CIR, and GRFS were 65%, 59%, 21%, and 38% for allo-HCT group and 58%, 54%, 28%, and 54% for no allo-HCT group, respectively. Conclusions: Comparing transplant versus chemotherapy only consolidation in CR1, this multicenter retrospective study shows that adult patients with Ph+ ALL in CMR have similar estimates of OS and RFS. Lower CIR in the HCT group was offset by higher NRM, resulting in similar RFS. Results of this study need to be confirmed in a prospective randomized trial. Disclosures Ghobadi: Kite: Consultancy, Research Funding; BMS: Consultancy; Amgen: Consultancy, Research Funding; EUSA: Consultancy; WUGEN: Consultancy. Kantarjian:Janssen: Honoraria; Pfizer: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Jazz: Research Funding; Immunogen: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Honoraria, Research Funding; Sanofi: Research Funding; Oxford Biomedical: Honoraria; BMS: Research Funding; Amgen: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Ascentage: Research Funding; BioAscend: Honoraria; Aptitute Health: Honoraria; Adaptive biotechnologies: Honoraria; Delta Fly: Honoraria. Jabbour:AbbVie: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding. Short:Astellas: Research Funding; Amgen: Honoraria; AstraZeneca: Consultancy; Takeda Oncology: Consultancy, Honoraria, Research Funding. Uy:Daiichi Sankyo: Consultancy; Astellas Pharma: Honoraria; Agios: Consultancy; Pfizer: Consultancy; Jazz Pharmaceuticals: Consultancy; Genentech: Consultancy. DiPersio:Magenta Therapeutics: Membership on an entity's Board of Directors or advisory committees. Champlin:Actinium: Consultancy; Johnson and Johnson: Consultancy; DKMS America: Membership on an entity's Board of Directors or advisory committees; Genzyme: Speakers Bureau; Takeda: Patents & Royalties; Cytonus: Consultancy; Omeros: Consultancy. Ravandi:Macrogenics: Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding. Kebriaei:Amgen: Other: Research Support; Jazz: Consultancy; Pfizer: Other: Served on advisory board; Kite: Other: Served on advisory board; Novartis: Other: Served on advisory board; Ziopharm: Other: Research Support.

Background: The combination of low-intensity therapy (mini-hyper-CVD) with inotuzumab ozogamicin with or without sequential blinatumomab is effective in patients with relapsed/refractory Philadelphia-chromosome negative acute lymphoblastic leukemia (ALL). The development of a prognostic model on the novel combination therapy may identify patients who requires additional or alternative therapies. Methods: Patients (pts) with relapsed/refractory Philadelphia chromosome-negative ALL who were treated with the combination of mini-hyper-CVD with inotuzumab ozogamicin plus/minus blinatumomab were analyzed. Briefly, the odd cycles of mini-hyper-CVD (cycles 1, 3, 5, 7) comprised cyclophosphamide (150 mg/m2 every 12 h on days 1-3), vincristine (2 mg flat dose on days 1 and 8), and dexamethasone (20 mg on days 1-4 and days 11-14) without anthracyclines. The even cycles (cycles 2, 4, 6, 8) comprised methotrexate (250 mg/m2 on day 1) and cytarabine (0.5 g/m2 given every 12 h on days 2 and 3). Rituximab and intrathecal chemotherapy were given for first 4 courses. Inotuzumab ozogamicin was originally given on day 3 of the first four cycles at the dose of 1.3-1.8 mg/m2 at cycle 1, followed by 1.0-1.3 mg/m2 in subsequent cycles. The protocol was amended to minimize the risk of veno-occlusive disease. Inotuzumab ozogamicin was given on days 2 and 8 at the dose of 0.6 and 0.3 mg/m2 at cycle 1, respectively, followed by days 2 and 8 at the dose of 0.3 and 0.3 mg/m2 at subsequent cycles; blinatumomab was continuously infused over 28 days every 42-day cycle for 4 cycles. Backward multivariate Cox regression analysis was performed with a cutoff p value of 0.100 by univariate for variable selections from univariate to multivariate analysis. The optimal cutoffs were defined at the point with the most significant division by the log-rank test. CD22 expression was determined using multicolor flow cytometry analysis and reported as percentage of positive leukemic cells as a fraction of total gated events relative to internal control parameters. A new prognostic model was built based on identified prognostic factors by multivariate analysis. The developed prognostic model was planned to be validated with two independent dataset with salvage chemotherapy and inotuzumab single-agent. Results: We analyzed 96 pts enrolled on the clinical trial of mini-hyper-CVD + inotuzumab ozogamicin +/- sequential blinatumomab from February, 2013 to September, 2019 (Table 1). Overall, the median follow-up is 36 months (range, 0.1-87.5). The overall response rate was 80% with negative measurable residual disease rate of 83% overall (52% at response after induction therapy). Multivariate analysis showed the percentage of CD22 expression less than 70% (P Conclusion: The combination of low-intensity therapy with inotuzumab ozogamicin with or without sequential blinatumomab is highly effective. The presence of Ho-Tr, KMT2A rearrangement, or CD22 expression less than 70% confers poor outcome and identifies pts with poor-risk features who may be considered for alternative strategies such as CAR T-cells therapies and clinical trials. Disclosures Sasaki: Pfizer Japan: Consultancy; Otsuka: Honoraria; Novartis: Consultancy, Research Funding; Daiichi Sankyo: Consultancy. Kantarjian:Daiichi-Sankyo: Honoraria, Research Funding; Immunogen: Research Funding; Janssen: Honoraria; Oxford Biomedical: Honoraria; Abbvie: Honoraria, Research Funding; Adaptive biotechnologies: Honoraria; Aptitute Health: Honoraria; BioAscend: Honoraria; Delta Fly: Honoraria; Jazz: Research Funding; Ascentage: Research Funding; Amgen: Honoraria, Research Funding; BMS: Research Funding; Sanofi: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Ravandi:Celgene: Consultancy, Honoraria; Macrogenics: Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria. Short:Astellas: Research Funding; Takeda Oncology: Consultancy, Honoraria, Research Funding; Amgen: Honoraria; AstraZeneca: Consultancy. Kebriaei:Amgen: Other: Research Support; Jazz: Consultancy; Ziopharm: Other: Research Support; Pfizer: Other: Served on advisory board; Novartis: Other: Served on advisory board; Kite: Other: Served on advisory board. Jain:Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Research Funding; Pfizer: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Fate Therapeutics: Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Aprea Therapeutics: Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Konopleva:Forty-Seven: Consultancy, Research Funding; AstraZeneca: Research Funding; Genentech: Consultancy, Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Sanofi: Research Funding; Ablynx: Research Funding; Ascentage: Research Funding; Calithera: Research Funding; Amgen: Consultancy; Cellectis: Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Kisoji: Consultancy; Eli Lilly: Research Funding; Agios: Research Funding; AbbVie: Consultancy, Research Funding; Rafael Pharmaceutical: Research Funding. Garcia-Manero:AbbVie: Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy; Amphivena Therapeutics: Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Onconova: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; H3 Biomedicine: Research Funding; Novartis: Research Funding; Merck: Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria. Champlin:Genzyme: Speakers Bureau; Actinium: Consultancy; Cytonus: Consultancy; Omeros: Consultancy; Takeda: Patents & Royalties; Johnson and Johnson: Consultancy; DKMS America: Membership on an entity's Board of Directors or advisory committees. Kadia:Astellas: Research Funding; Novartis: Honoraria; Cyclacel: Research Funding; Astra Zeneca: Research Funding; Incyte: Research Funding; Amgen: Research Funding; Ascentage: Research Funding; JAZZ: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Cellenkos: Research Funding; Celgene: Research Funding; Pfizer: Honoraria, Research Funding; Pulmotec: Research Funding; Abbvie: Honoraria, Research Funding; Genentech: Honoraria, Research Funding. Rafei:United States Provisiona: Patents & Royalties: I have a filed patent. O'Brien:Sunesis: Research Funding; Gilead: Consultancy; Pharmacyclics: Research Funding; TG Therapeutics: Research Funding; Pfizer: Research Funding; Astellas: Consultancy; Amgen: Consultancy; Janssen Oncology: Consultancy; Vaniam Group LL: Consultancy; AbbVie: Consultancy; Verastem: Consultancy; Acerta: Research Funding; Regeneron: Research Funding; Vida Ventures: Consultancy; KITE: Research Funding; Celgene: Consultancy; Eisai: Consultancy; Juno Therapeutics: Consultancy; GlaxoSmithKline: Consultancy; Aptose Biosciences: Consultancy; Alexion: Consultancy. Jabbour:Adaptive Biotechnologies: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding.

Background: Cardiac involvement by light chain amyloidosis (AL) is generally associated with an unfavorable outcome. Bortezomib-based induction, and high-dose melphalan followed by autologous hematopoietic stem cell transplantation (auto-HCT) in eligible patients is associated with best long-term outcomes. We report the outcome of cardiac AL patients who underwent auto-HCT at our institution. Methods: We retrospectively reviewed all patients with cardiac AL who received auto-HCT between January 1997 and December 2018 at our institution. Hematologic and cardiac organ responses were evaluated according to the Consensus Guidelines for AL (R Comenzo et al. Leukemia 2012). Revised Mayo staging system was used for cardiac staging (S Kumar et al. JCO 2012). Progression free survival (PFS) and overall survival (OS) were calculated from the date of transplant. Survival was estimated using Kaplan Meier method and compared using log rank test. Cox proportional hazard models were used for adjusted survival analysis. Results: 57 patients were identified and baseline characteristics summarized in Table 1. Thirty eight patients (67%) at diagnosis and 17 (30%) at auto-HCT were evaluable by the revised Mayo staging system. Eleven (19%), 14 (25%), 17 (30%), and 13 (23%) patients had stage 1, 2, 3 and 4 disease, respectively, while the stage was unknown in 2 (3%) patients. Twenty-four (42%) patients received induction with a combination of cyclophosphamide, bortezomib, and dexamethasone (CyBorD), 14 (25%) received bortezomib and dexamethasone, and 2 (3%) received other bortezomib-based induction (Table 1). Based on hematologic response criteria, 3 (5%), 15 (27%) and 22 (39%) patients achieved complete response (CR), a very good partial response (VGPR), or partial response (PR) to induction, with an overall response rate (ORR) of 71%. All patients underwent peripheral blood stem cell (PBSC) mobilization with filgrastim, with or without plerixafor. Thirty-nine (68%) patients received melphalan 200mg/m2 and 18 (32%) received melphalan 140mg/m2 as preparative regimen. Nineteen patients (33%) received maintenance therapy post auto-HCT. One-hundred day and 1-year post auto-HCT non-relapse mortality rate was 5% (3 patients). Best post auto-HCT hematologic ORR was 92%, with 19 (34%), 20 (35%), and 13 (23%) patients achieving CR, VGPR and PR, respectively. Based on the consensus guidelines for cardiac response in AL using NT-proBNP or NYHA class, 51 patients (89%) had a cardiac organ response at their last evaluation (Table 2). Median follow up in surviving patients was 32.9 months (range 5.1 - 140.6). The 3-year PFS was 53.5% [95% CI 38.6-68.4%], and 3-year OS was 67.8% [53.9-81.7%]. On univariate analysis, melphalan 200 vs. 140 (p=0.017, HR 0.387 95%CI 0.178- 0.844) was associated with a better PFS, but none of the variables had an impact on PFS or OS on a multivariate Cox regression analysis, perhaps due to a small sample size. Conclusion: In this retrospective analysis we showed that in transplant-eligible patients with advanced cardiac AL, high-dose melphalan and auto-HCT is associated with a low (5%) NRM, an organ response rate of almost 90%, and a 3-year OS of almost 70%. Disclosures Bashir: Takeda: Other: Advisory Board, Research Funding; Acrotech: Research Funding; Celgene: Research Funding; StemLine: Research Funding; KITE: Other: Advisory Board; Purdue: Other: Advisory Board; Amgen: Other: Advisory Board. Nieto:Secura Bio: Other: Grant Support; Astra Zeneca: Other: Grant Support; Novartis: Other: Grant Support; Affimed: Consultancy, Other: Grant Support. Hosing:NKARTA Inc.: Consultancy. Popat:Bayer: Research Funding; Novartis: Research Funding. Lee:Takeda: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; GlaxoSmithKline: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Genentech: Consultancy; Genentech: Consultancy; Daiichi Sankyo: Research Funding; Sanofi: Consultancy; Regeneron: Research Funding. Patel:Takeda: Consultancy, Research Funding; Precision Biosciences: Research Funding; Oncopeptides: Consultancy; Poseida: Research Funding; Janssen: Consultancy, Research Funding; Nektar: Consultancy, Research Funding; Cellectis: Research Funding; Celgene: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding. Manasanch:Merck: Research Funding; Sanofi: Honoraria; GSK: Honoraria; Takeda: Honoraria; Quest Diagnostics: Research Funding; Adaptive Biotechnologies: Honoraria; JW Pharma: Research Funding; Novartis: Research Funding; BMS: Honoraria; Sanofi: Research Funding. Thomas:X4 Pharma: Research Funding; Ascentage: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Genentech: Research Funding; Xencor: Research Funding; Pharmacyclics: Other: Advisory Boards. Kaufman:Karyopharm: Honoraria; Janssen: Research Funding; Bristol Myers Squibb: Research Funding. Orlowski:Sanofi-Aventis, Servier, Takeda Pharmaceuticals North America, Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Laboratory research funding from BioTheryX, and clinical research funding from CARsgen Therapeutics, Celgene, Exelixis, Janssen Biotech, Sanofi-Aventis, Takeda Pharmaceuticals North America, Inc.: Research Funding; Amgen, Inc., AstraZeneca, BMS, Celgene, EcoR1 Capital LLC, Forma Therapeutics, Genzyme, GSK Biologicals, Ionis Pharmaceuticals, Inc., Janssen Biotech, Juno Therapeutics, Kite Pharma, Legend Biotech USA, Molecular Partners, Regeneron Pharmaceuticals, Inc.,: Honoraria, Membership on an entity's Board of Directors or advisory committees; STATinMED Research: Consultancy; Founder of Asylia Therapeutics, Inc., with associated patents and an equity interest, though this technology does not bear on the current submission.: Current equity holder in private company, Patents & Royalties. Champlin:Takeda: Patents & Royalties; Genzyme: Speakers Bureau; DKMS America: Membership on an entity's Board of Directors or advisory committees; Cytonus: Consultancy; Omeros: Consultancy; Johnson and Johnson: Consultancy; Actinium: Consultancy. Qazilbash:Bioclinica: Consultancy; Amgen: Research Funding; Angiocrine: Research Funding; Bioline: Research Funding; Janssen: Research Funding.

Background: Relapse is the major cause of failure after autologous stem cell transplantation (autoSCT) for patients (pts) with lymphoma. Targeting immune checkpoints with ipilimumab (Ipi) could result in lasting responses but only in few pts. We have previously reported that combination strategies of Ipi with lenalidomide (LEN) 10 mg (Ipi+LEN) resulted in enhanced immune activity manifested by a significant increase in the numbers of ICOS+CD4+FoxP3- T cells (Khouri I et al. Clin Cancer Res 2018:1011-1018). We have demonstrated proof-of-principle of this activity in one pt with refractory double hit lymphoma (DHL) (failed an autoSCT then relapsed after an allogeneic SCT) and another pt with CLL (failed ibrutinib, CART cell, and allogeneic SCT). Both pts then achieved complete remission with Ipi+LEN that has lasted 5+ and 4+ years, respectively. Hence, we have used Ipi+LEN to prevent relapse after autoSCT in pts with high-risk lymphoma, including double-expressor (DEL)/DHL who have been reported to have a 0% progression-free survival (PFS) rate at 4-years after autoSCT (Herrera et al. J Clin Oncol. 2017; 35:24-33). Patients andMethods: In this prospective trial, pts with lymphoma were enrolled within 6 months post-autoSCT. Inclusion criteria included: age 18 to 80 years; an ECOG PS 0-2; adequate liver (bilirubin and liver enzyme concentrations up to two times the upper limit of normal), renal (serum creatinine < 1.6 mg/dl) , cardiac (ejection fraction 45%), and pulmonary (diffusing capacity of the lung for carbon monoxide 40% of predictive value) function; no active infections; ANC ≥ 1.5x109/L and a platelet count ≥ 75x109/L. Treatment consisted of LEN 10 mg PO daily for 21 days (cycles 1) alternating with Ipi 3 mg/kg IV on day 1 (Cycle 2) for up to 8 cycles. LEN dose reduction was permitted to 5 mg based on standard clinical practice. Results: Twenty-three pts were enrolled in the study. The median age at autoSCT was 56 years (range, 33-74). Fifteen (65%) were males and 5 (22%) pts had an HCT-CI ≥ 3. The median # of prior chemotherapies excluding their SCT was 2 (range, 1-5). Two pts had failed a prior autoSCT and were enrolled after a second transplant. Histologies included [DEL/DHL (n=8, 35%), DLBCL nonDEL/nonDHL (n=6, 23%), mantle cell lymphoma (MCL) (n=4, 17%; including 2 with 2 prior transplants, 1 with CNS involvement, 2 had blastoid histology, 1 in partial response to induction chemotherapy), follicular lymphoma (n=1; 4%; 3 prior therapies) Hodgkin's disease (n=2, 9%; including 1 with persistent PET+ post-transplant), angioimmunoblastic t-cell lymphoma (n=2, 9%). Most pts received R-BEAM (n=17, 74%) or BEAM (n=3, 13%) conditioning for their autoSCT. Median # of cycles of immunotherapy received after autoSCT was 5 (range, 2-8). Two pts are continuing their pre-planned treatment. Median follow-up duration was 35 months (range, 4-78 months). The 3-year rates of overall survival (OS) and PFS were 92% and 73%, respectively (Figure 1). Only 1 death was observed: this occurred in a pt with MCL who received 2 prior autoSCT and then developed post-transplant lymphoproliferative disorder without any evidence of MCL recurrence. The most common other grade 3-4 AEs were 10 events of neutropenia, anemia (1), perianal infection (1), and one developed pulmonary embolism on therapy. All AEs resolved. An immune-related AE occurred in one patient (dermatitis, gr 3) after the second ipilimumab dose and resolved with steroids. DEL/DHL group (n=8): This group was heavily pre-treated. The median # of prior chemotherapies excluding their SCT was 3 (range, 1-5). Five have failed DA-REPOCH, one had failed R-Hyper-CVAD and one was induced with R-CHOP. With a median follow-up of 35 months (range, 4-78months), all pts remain alive. One patient with DEL/DHL who was transplanted during second remission relapsed at 1.6 months after initiating therapy (just after finishing the cycle 2). All others remain in complete remission (Figure 2). Conclusions: Maintenance therapy with Ipi+LEN after autoSCT for high-risk lymphoma shows encouraging survival rates, including pts with DEL/DHL who usually have dismal outcomes. The treatment has favorable toxicity profile. These results warrant a randomized trial for confirmation. Disclosures Khouri: Bristol Myers Squibb: Research Funding; Pfizer: Research Funding. Jabbour:Genentech: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding. Lee:Seattle Genetics: Research Funding; Oncternal Therapeutics: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Aptitude Health: Speakers Bureau; Guidepoint Blogal: Consultancy; Celgene: Research Funding; Takeda: Research Funding. Nastoupil:Pfizer: Honoraria, Research Funding; Gilead/KITE: Honoraria; Merck: Research Funding; Genentech, Inc.: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; TG Therapeutics: Honoraria, Research Funding; LAM Therapeutics: Research Funding; Gamida Cell: Honoraria; Bayer: Honoraria; Celgene: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Karus Therapeutics: Research Funding. Iyer:Merck: Research Funding; Afffimed: Research Funding; Spectrum: Research Funding; Target Oncology: Honoraria; Legend Biotech: Consultancy; CRISPR: Research Funding; Curio Biosciences: Honoraria; Rhizen: Research Funding; Seattle Genetics, Inc.: Research Funding; Trillium: Research Funding; Daiichi Sankyo: Consultancy. Flowers:TG Therapeutics: Research Funding; Millennium/Takeda: Consultancy, Research Funding; Leukemia and Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; Burroughs Wellcome Fund: Research Funding; V Foundation: Research Funding; National Cancer Institute: Research Funding; Bayer: Consultancy; Kite: Research Funding; Eastern Cooperative Oncology Group: Research Funding; AbbVie: Consultancy, Research Funding; Cancer Prevention and Research Institute of Texas: Research Funding; Celgene: Consultancy, Research Funding; Acerta: Research Funding; BeiGene: Consultancy; Spectrum: Consultancy; Pharmacyclics/Janssen: Consultancy; Karyopharm: Consultancy; OptumRx: Consultancy; Gilead: Consultancy, Research Funding; Denovo Biopharma: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy, Research Funding. Champlin:Genzyme: Speakers Bureau; Johnson and Johnson: Consultancy; Omeros: Consultancy; Actinium: Consultancy; Takeda: Patents & Royalties; DKMS America: Membership on an entity's Board of Directors or advisory committees; Cytonus: Consultancy. Sharma:BioAlta: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Achelois: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Apricity Health: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Constellation: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Dragonfly Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Forty-Seven Inc.: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Hummingbird: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Lava Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Lytix Biopharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Marker Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Oncolytics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Glympse: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Polaris: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Jounce Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; BioNTech: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Codiak BioSciences: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; ImaginAb: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Infinity Pharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Maintenance therapy with Ipilimumab and Lenalidomide after transplantation

Background: The outcome of patients with relapsed-refractory (R-R) acute lymphoblastic leukemia (ALL) is poor. Inotuzumab ozogamicin and blinatumomab are highly active single agents in R-R ALL. The combination of inotuzumab with low-intensity mini-hyper-CVD chemotherapy showed encouraging results in this patient population. The sequential addition of blinatumomab might optimize the efficacy of the regimen, reduce its toxicities, and further improve outcomes in R-R ALL. The aim of the analysis is to evaluate the efficacy and safety of inotuzumab ozogamicin plus low-intensity chemotherapy with or without blinatumomab in R-R ALL. Methods: Patients with relapsed-refractory Philadelphia chromosome-negative ALL were eligible. The mini-hyper-CVD (cycles 1, 3, 5, 7) were comprised of cyclophosphamide (150 mg/m2 every 12 h on days 1-3), vincristine (2 mg flat dose on days 1 and 8), and dexamethasone (20 mg on days 1-4 and days 11-14) without anthracyclines. Even cycles (cycles 2, 4, 6, 8) were comprised of methotrexate (250 mg/m2 on day 1) and cytarabine (0.5 g/m2 given every 12 h on days 2 and 3). Rituximab and intrathecal chemotherapy were given for the first 4 courses. Inotuzumab ozogamicin was originally given on day 3 of the first four cycles at the dose of 1.3-1.8 mg/m2 at cycle 1, followed by 1.0-1.3 mg/m2 in subsequent cycles. After 67 pts were treated, an amendment was made to incorporate 4 cycles of blinatumomab after 4 cycles of mini-hyper-CVD + inotuzumab ozogamicin. Inotuzumab ozogamicin was given on days 2 and 8 at the dose of 0.6 and 0.3 mg/m2 at cycle 1, respectively, followed by days 2 and 8 at the dose of 0.3 and 0.3 mg/m2 at subsequent cycles; blinatumomab was continuously infused over 28 days every 42-day cycle for 4 cycles. The decision to proceed with allogeneic hematopoietic cell transplantation (HCT) was based on the discretion of the treating physician after discussion with the patient. Results: From 2/2013 to 9/2019, 96 patients were enrolled and treated including 29 patients with mini-hyper-CVD + inotuzumab + blinatumomab. The median follow-up is 36 months (range, 0.1-87.5). Patient characteristics and outcome are summarized in Table 1. The median age was 37 years (range, 17-87), and 20% of patients had received prior HCT. The overall response rate was 80% (CR, 57%, CRp/CRi, 20%). These rates were 91% in salvage(S) 1 (primary refractory, 100%; CR1 duration 12 months, 94%) 61% inS2, and 57% in S3 or higher. Among 75 evaluable patients for minimal residual disease (MRD) assessment, 62 patients (83%) achieved negative MRD by multi-color flow cytometry with higher rates of MRD negativity in S1 (89%). Forty four patients (46%) received HCT. Three-year CR duration and overall survival (OS) rates were 32% and 33%, respectively (Figure 1). The 3-year OS rates for patients treated in S 1 and S 2+ were 42% and 13%, respectively (p=0.002). Historical comparison showed median OS of 13 months versus 6 months in hyper-CVD + inotuzumab ozogamicin +/- blinatumomab versus inotuzumab ozogamicin single agent, respectively (p Conclusion: The long-term follow-up of the combination of inotuzumab ozogamicin plus/minus blinatumomab with low-intensity mini-hyper-CVD chemotherapy continues to show promising results in patients with relapsed/refractory ALL. The risk of VOD can be minimized with a fractionated inotuzumab ozogamicin followed by blinatumomab schedule. Disclosures Sasaki: Novartis: Consultancy, Research Funding; Otsuka: Honoraria; Pfizer Japan: Consultancy; Daiichi Sankyo: Consultancy. Kantarjian:Aptitute Health: Honoraria; Pfizer: Honoraria, Research Funding; Sanofi: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive biotechnologies: Honoraria; Oxford Biomedical: Honoraria; Novartis: Honoraria, Research Funding; BMS: Research Funding; Delta Fly: Honoraria; Janssen: Honoraria; Daiichi-Sankyo: Honoraria, Research Funding; Ascentage: Research Funding; Jazz: Research Funding; BioAscend: Honoraria; Abbvie: Honoraria, Research Funding; Immunogen: Research Funding; Amgen: Honoraria, Research Funding. Ravandi:Macrogenics: Research Funding; Celgene: Consultancy, Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria. Short:Astellas: Research Funding; Takeda Oncology: Consultancy, Honoraria, Research Funding; Amgen: Honoraria; AstraZeneca: Consultancy. Kebriaei:Jazz: Consultancy; Amgen: Other: Research Support; Ziopharm: Other: Research Support; Pfizer: Other: Served on advisory board; Kite: Other: Served on advisory board; Novartis: Other: Served on advisory board. Jain:TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Cellectis: Research Funding; ADC Therapeutics: Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Incyte: Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Aprea Therapeutics: Research Funding; Fate Therapeutics: Research Funding; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Konopleva:Ascentage: Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Kisoji: Consultancy; Forty-Seven: Consultancy, Research Funding; Agios: Research Funding; Eli Lilly: Research Funding; Rafael Pharmaceutical: Research Funding; Calithera: Research Funding; Ablynx: Research Funding; AstraZeneca: Research Funding; Sanofi: Research Funding; Cellectis: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; AbbVie: Consultancy, Research Funding; Amgen: Consultancy; Genentech: Consultancy, Research Funding. Garcia-Manero:Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Novartis: Research Funding; Amphivena Therapeutics: Research Funding; Onconova: Research Funding; H3 Biomedicine: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Champlin:Takeda: Patents & Royalties; Omeros: Consultancy; DKMS America: Membership on an entity's Board of Directors or advisory committees; Cytonus: Consultancy; Johnson and Johnson: Consultancy; Actinium: Consultancy; Genzyme: Speakers Bureau. Kadia:Genentech: Honoraria, Research Funding; Astellas: Research Funding; Cyclacel: Research Funding; Cellenkos: Research Funding; Astra Zeneca: Research Funding; JAZZ: Honoraria, Research Funding; Celgene: Research Funding; Pulmotec: Research Funding; Abbvie: Honoraria, Research Funding; Amgen: Research Funding; BMS: Honoraria, Research Funding; Incyte: Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Honoraria; Ascentage: Research Funding. Daver:Fate Therapeutics: Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trovagene: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; ImmunoGen: Research Funding; Novartis: 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; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees. Rafei:United States Provisiona: Patents & Royalties: I have a filed patent. O'Brien:Pharmacyclics: Research Funding; TG Therapeutics: Research Funding; Acerta: Research Funding; Vida Ventures: Consultancy; Pfizer: Research Funding; Celgene: Consultancy; Eisai: Consultancy; KITE: Research Funding; Regeneron: Research Funding; Amgen: Consultancy; Vaniam Group LL: Consultancy; AbbVie: Consultancy; Verastem: Consultancy; Janssen Oncology: Consultancy; Gilead: Consultancy; Sunesis: Research Funding; Alexion: Consultancy; Aptose Biosciences: Consultancy; Juno Therapeutics: Consultancy; GlaxoSmithKline: Consultancy; Astellas: Consultancy. Jabbour:Takeda: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding.

Although bortezomib and rituximab have synergistic activity in patients with lymphoma, and can both attenuate graft-versus-host disease (GVHD), the drugs have not been used together in patients undergoing allogeneic stem-cell transplantation (alloSCT). In this phase 1/2 trial, we assessed the safety and activity of bortezomib added to the rituximab (R) plus BEAM (carmustine, etoposide, cytarabine, melphalan) regimen in patients with relapsed lymphoma undergoing alloSCT. Primary GVHD prophylaxis consisted of tacrolimus and methotrexate. Bortezomib (1 – 1.3 mg/m(2) per dose) was administered intravenously on days −13, −6, −1, and +2. We performed inverse probability weighting analysis to compare GVHD and survival results to a historical control group that received R-BEAM without bortezomib. Thirty-nine patients were assessable for toxic effects and response. The median age was 54 years. The most common diagnosis was diffuse large B-cell lymphoma (41%). Twenty-two patients (56%) and 17 patients (44%) received their transplants from matched related and unrelated matched donors, respectively. The maximum tolerated bortezomib dose was 1 mg/m(2). The weighted cumulative incidences of grade II-IV and grade III or IV acute GVHD were 50% and 34%, respectively; these incidences and survival rates were not significantly different from those of the control group. Median survival has not been reached in patients age ≤50 years and who had a long follow-up time of 60.7 months. The R-BEAM regimen has a survival benefit in lymphoma patients age ≤50 years undergoing alloSCT. The addition of bortezomib has no impact on survival or incidence of GVHD.

PURPOSE BK virus-associated hemorrhagic cystitis (BKV-HC) is a common complication of allogenic hematopoietic stem cell transplantation (AHSCT), particularly in recipients of alternative donor transplants, which are being performed in increasing numbers. BKV-HC typically results in painful hematuria, urinary obstruction, and renal dysfunction, without a definitive therapeutic option. METHODS We performed a clinical trial (ClinicalTrials.gov identifier: NCT02479698 ) to assess the feasibility, safety, and efficacy of administering most closely HLA-matched third-party BKV-specific cytotoxic T lymphocytes (CTLs), generated from 26 healthy donors and banked for off-the-shelf use. The cells were infused into 59 patients who developed BKV-HC following AHSCT. Comprehensive clinical assessments and correlative studies were performed. RESULTS Response to BKV-CTL infusion was rapid; the day 14 overall response rate was 67.7% (40 of 59 evaluable patients), which increased to 81.6% among evaluable patients at day 45 (40 of 49 evaluable patients). No patient lost a previously achieved response. There were no cases of de novo grade 3 or 4 graft-versus-host disease, graft failure, or infusion-related toxicities. BKV-CTLs were identified in patient blood samples up to 3 months postinfusion and their in vivo expansion predicted for clinical response. A matched-pair analysis revealed that, compared with standard of care, after accounting for prognostic covariate effects, treatment with BKV-CTLs resulted in higher probabilities of response at all follow-up timepoints as well as significantly lower transfusion requirement. CONCLUSION Off-the-shelf BKV-CTLs are a safe and effective therapy for the management of patients with BKV-HC after AHSCT.

BackgroundCOVID-19 Convalescent plasma (CCP) is safe and effective, particularly if given at an early stage of the disease. Our study aimed to identify an association between survival and specific antibodies found in CCP.Patients and MethodsPatients ≥18 years of age who were hospitalized with moderate to severe COVID-19 infection and received CCP at the MD Anderson Cancer Center between 4/30/2020 and 8/20/2020 were included in the study. We quantified the levels of anti-SARS-CoV-2 antibodies, as well as antibodies against antigens of other coronavirus strains, in the CCP units and compared antibody levels with patient outcomes. For each antibody, a Bayesian exponential survival time regression model including prognostic variables was fit, and the posterior probability of a beneficial effect (PBE) of higher antibody level on survival time was computed.ResultsCCP was administered to 44 cancer patients. The median age was 60 years (range 37-84) and 19 (43%) were female. Twelve patients (27%) died of COVID-19-related complications. Higher levels of two non-SARS-CoV-2-specific antibodies, anti-HCoV-OC43 spike IgG and anti-HCoV-HKU1 spike IgG, had PBE = 1.00, and 4 SARS-CoV-2-specific antibodies had PBEs between 0.90 and 0.95. Other factors associated with better survival were shorter time to CCP administration, younger age, and female sex.ConclusionsCommon cold coronavirus spike IgG antibodies anti-HCoV-OC43 and anti-HCoV-HKU1 may target a common domain for SARS-CoV-2 and other coronaviruses. They provide a promising therapeutic target for monoclonal antibody production.

Natural killer (NK) cells are innate lymphocytes recognized for their important role against tumor cells. NK cells expressing chimeric antigen receptors (CARs) have enhanced effector function against various type of cancer and are attractive contenders for the next generation of cancer immunotherapies. However, a number of factors have hindered the application of NK cells for cellular therapy, including their poor in vitro growth kinetics and relatively low starting percentages within the mononuclear cell fraction of peripheral blood or cord blood (CB). To overcome these limitations, we genetically-engineered human leukocyte antigen (HLA)-A− and HLA-B− K562 cells to enforce the expression of CD48, 4-1BBL, and membrane-bound IL-21 (mbIL21), creating a universal antigen presenting cell (uAPC) capable of stimulating their cognate receptors on NK cells. We have shown that uAPC can drive the expansion of both non-transduced (NT) and CAR-transduced CB derived NK cells by >900-fold in 2 weeks of co-culture with excellent purity (>99.9%) and without indications of senescence/exhaustion. We confirmed that uAPC-expanded research- and clinical-grade NT and CAR-transduced NK cells have higher metabolic fitness and display enhanced effector function against tumor targets compared to the corresponding cell fractions cultured without uAPCs. This novel approach allowed the expansion of highly pure GMP-grade CAR NK cells at optimal cell numbers to be used for adoptive CAR NK cell-based cancer immunotherapy.