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Patients with hematologic malignancies have impaired humoral immunity secondary to their malignancy and its treatment, placing them at risk of severe coronavirus disease-19 (COVID-19) infection and reduced response to vaccination.The authors retrospectively analyzed serologic responses to initial and booster COVID-19 vaccination in 378 patients with hematologic malignancy and subsequently tracked COVID-19-related outcomes.Seroconversion occurred in 181 patients (48%) after initial vaccination; patients who had active malignancy or those who were recently treated with a B-cell-depleting monoclonal antibody had the lowest rates of seroconversion. For initial nonresponders to vaccination, seroconversion after a booster dose occurred in 48 of 85 patients (56%). The seroconversion rate after the booster was similar for patients on (53%) and off (58%) active therapy (p = .82). Thirty-three patients (8.8%) developed a COVID-19 infection, and there were three COVID-19-related deaths (0.8%). Although no significant association was observed between postvaccination seroconversion and the incidence of COVID-19 infection, no patient with seroconversion died from COVID-19, and no patient who received tixagevimab/cilgavimab (N = 25) was diagnosed with a COVID-19 infection.Booster vaccinations can promote seroconversion in a significant proportion of patients who are seronegative after the initial vaccination course regardless of the specific vaccine or on/off treatment status at the time of revaccination. Although postvaccination seroconversion may not be associated with a decrease in any (including asymptomatic) COVID-19 infection, the authors' experience suggested that effective vaccination (including a booster), supplemented by passive immunization using tixagevimab/cilgavimab in case of lack of seroconversion, effectively eliminated the risk of COVID-19 death in the otherwise high-risk population.Patients with hematologic malignancy, especially lymphoma, have an impaired response to coronavirus disease 2019 (COVID-19) vaccination. In this single-institution review, less than one half of the patients studied made detectable antibodies. For those who did not make detectable antibodies after initial vaccination, over one half (65%) were able to produce antibodies after booster vaccination. By the end of February 2022, 33 of the original 378 patients had a documented COVID-19 infection. The only deaths from COVID-19 were in those who had undetectable antibodies, and no patient who received prophylactic antibody therapy developed a COVID-19 infection.

Resistance to standard immunochemotherapy remains an unmet challenge in diffuse large B-cell lymphoma (DLBCL), and aberrant DNA methylation may contribute to chemoresistance. Promising early-phase results were reported with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) plus subcutaneous azacitidine, a hypomethylating agent. In this phase 1 study, we evaluated CC-486 (oral azacitidine) plus 6 cycles of R-CHOP in patients with previously untreated intermediate- to high-risk DLBCL or grade 3B/transformed follicular lymphoma. CC-486 doses of 100, 150, 200, or 300 mg given 7 days before cycle 1 and on days 8-21 of cycles 1-5 were evaluated; additional patients were enrolled in the expansion phase to examine preliminary efficacy. The primary objectives were to determine the safety and the maximum tolerated dose (MTD) of CC-486 in combination with R-CHOP. The most common grade 3/4 toxicities were hematologic, including neutropenia (62.7%) and febrile neutropenia (25.4%); grade 3/4 nonhematologic toxicities were uncommon (

Key Points The NGS-MRD assay detected clonotypic DNA in 100% of CSF samples from patients who had lymphoma with parenchymal CNS involvement.Clonotypic DNA in CSF was present in 36% of newly diagnosed aggressive lymphomas and was associated with a 29% risk of CNS recurrence., Visual Abstract, The diagnosis of parenchymal central nervous system (CNS) invasion and prediction of risk for future CNS recurrence are major challenges in the management of aggressive lymphomas, and accurate biomarkers are needed to supplement clinical risk predictors. For this purpose, we studied the results of a next-generation sequencing (NGS)–based assay that detects tumor-derived DNA for clonotypic immunoglobulin gene rearrangements in the cerebrospinal fluid (CSF) of patients with lymphomas. Used as a diagnostic tool, the NGS-minimal residual disease (NGS-MRD) assay detected clonotypic DNA in 100% of CSF samples from 13 patients with known CNS involvement. They included 7 patients with parenchymal brain disease only, whose CSF tested negative by standard cytology and flow cytometry, and 6 historical DNA aliquots collected from patients at a median of 39 months before accession, which had failed to show clonal rearrangements using standard polymerase chain reaction. For risk prognostication, we prospectively collected CSF from 22 patients with newly diagnosed B-cell lymphomas at high clinical risk of CNS recurrence, of whom 8 (36%) had detectable clonotypic DNA in the CSF. Despite intrathecal prophylaxis, a positive assay of CSF was associated with a 29% cumulative risk of CNS recurrence within 12 months of diagnosis, in contrast with a 0% risk among patients with negative CSF (P = .045). These observations suggest that detection of clonotypic DNA can aid in the diagnosis of suspected parenchymal brain recurrence in aggressive lymphoma. Furthermore, the NGS-MRD assay may enhance clinical risk assessment for CNS recurrence among patients with newly diagnosed lymphomas and help select those who may benefit most from novel approaches to CNS-directed prophylaxis.

Acute myeloid leukemia (AML) is a heterogeneous aggressive hematologic malignancy derived from malignant clones that promote their own growth and survival at the expense of normal hematopoiesis resulting in life-threatening bleeding and infections. Traditional initial AML therapy has been centered on a backbone of intensive chemotherapy often composed of an anthracycline and cytarabine. This strategy has proven most effective in patients less than 60 years of age due to both patient-related tolerability factors as well as changes in AML biology centered on chemotherapy refractory mutational profiles that are seen with advancing age. Recent improvements in frontline AML therapy have been seen in patients 60 years of age and over, a population most typically referred to as “older” adult AML. Herein, we describe the characteristics of “older” adult AML, review the differences in outcomes amongst those 60–75 and those over 75 years of age, and cite challenges in delivering frontline therapies within this group based not only on therapeutic toxicity but also on the patient’s overall level of “fitness” and inherent biology. We also discuss the role of targeted therapies that inhibit specific mutations and have the potential to deliver improved efficacy with less side effects while also recognizing that some selected older AML patients still benefit from intensive induction therapy.

Early in the pandemic, it was recognized that infection with COVID-19 was associated with an increased incidence in both venous and arterial thrombotic events leading to poor patient outcomes. Given the rapid rise of the pandemic, anticoagulation strategies were initially based upon retrospective and observational data with few high-quality randomized control trials to help direct strategies regarding the use of thromboprophylaxis during hospitalization, empiric therapeutic anticoagulation, and extended-duration thromboprophylaxis after discharge. Over the past year, several randomized control trials have now been published evaluating these strategies. In this article, we hope to review the current literature surrounding the use of intermediate-dose thromboprophylaxis, empiric therapeutic anticoagulation, and the use of extended-duration thromboprophylaxis for patients hospitalized with COVID-19.

Chronic myeloid leukemia (CML), acute myeloid leukemia (AML), and chronic lymphocytic leukemia (CLL) are hematological malignancies that remain incurable despite novel treatments. In order to improve current treatments and clinical efficacy, there remains a need for more complex

Alejandro Pando, Loren Fast, Patrycja M Dubielecka, Anna Chorzalska, Sicheng Wen, John Reagan Division of Hematology/Oncology, Department of Medicine, Rhode Island Hospital and the Warren Alpert School of Medicine at Brown University, Providence, RI, USACorrespondence: Loren FastDivision of Hematology/Oncology, Department of Medicine, Rhode Island Hospital and the Warren Alpert School of Medicine at Brown University, 31 S Killingly Road, Foster, RI, 02825, USATel +1 401 533-8658Email Loren_Fast@brown.eduBackground: Extracellular vesicles (EVs) are heterogeneous lipid bilayer particles secreted by cells. EVs contain proteins, RNA, DNA and other cargo that can have immunomodulatory effects. Cancer-derived EVs have been described as having immunomodulating effects in vivo with immunosuppressive and pro-tumor growth capabilities. However, cancer-derived EVs have also been harnessed and utilized for anti-cancer potential.Methods: To assess the immunomodulatory effect of EVs produced by acute myeloid leukemia (AML) cells, we isolated vesicles secreted by the murine AML cell line, C1498, and investigated their effect on in vitro and in vivo immune responses.Results: These leukemia-derived EVs were found to induce increased proliferation of CD3+ cells and enhanced cytolytic activity of CD3+ cells directed toward leukemic cells in vitro. Injection of leukemia-derived EVs into syngeneic naïve mice induced T cell responses in vivo and resulted in enhanced immune responses upon T cell re-stimulation in vitro.Conclusion: These findings indicate that C1498-derived EVs have immunomodulatory effects on cell-mediated immune responses that could potentially be utilized to facilitate anti-leukemia immune responses.Keywords: extracellular vesicles, acute myeloid leukemia, immune responses

The "triplet" regimen of lenalidomide, bortezomib, and dexamethasone (RVD) showed survival advantage over lenalidomide-dexamethasone (RD) in clinical trials, but older patients with myeloma often receive doublet regimens (RD or bortezomib-dexamethasone, VD), or VD plus cyclophosphamide (VCD). We compared these first-line regimens using real-world data from Medicare beneficiaries receiving therapy between 2007 and 2015. In each comparative analysis, we balanced confounding characteristics using a propensity score. Outcomes included overall (OS) and event-free survival (EFS, reporting hazard ratios [HR] with 95% confidence intervals [CI]), adverse events, and costs. We identified 6076 patients with median age 76 and median OS of 2.6 years. In the comparison of RVD vs RD/VD doublets, RVD showed significantly better OS (HR = 0.83; 95% CI, 0.72-0.95) and EFS (HR = 0.68; 95% CI, 0.61-0.76). So, RVD was associated with more frequent hospitalizations, anemia, and neuropathy, but no increase in thromboembolism or secondary cancers. Costs were higher with RVD. In the comparison of RD vs VD, RD demonstrated better EFS (HR = 0.74; 95% CI, 0.68-0.81) and marginally better OS (HR = 0.91; 95% CI, 0.83-0.99). And, RD resulted in significantly more thromboembolic events, less neuropathy, and no significant difference in hospitalizations, transfusions, or secondary cancers. In the comparison of VCD vs VD, we observed no significant difference in any outcome. Superior survival favors RVD over doublet regimens, but even in 2015 RVD was applied for only about 25% of Medicare beneficiaries with myeloma. For patients not eligible for RVD due to toxicity, VCD offers no survival benefit over VD. Lenalidomide-dexamethasone may be the preferred line doublet considering its advantage over VD.

Acute myeloid leukemia (AML) patients undergoing consolidation chemotherapy with intermediate or high-dose cytarabine (IDAC/HiDAC) are often placed on prophylactic antibacterials. This practice is largely based on the benefits of prophylaxis (PPX) during induction chemotherapy. However, recent concerns regarding antibacterial prophylaxis have emerged including risk of Clostridioides difficile colitis, medication toxicities, and the potential for fostering multidrug-resistant pathogens. We therefore retrospectively explored whether antibacterial PPX is beneficial during cytarabine consolidation. Adult AML patients who received IDAC/HiDAC at our institution from January 2007 to March 2018 were evaluated for receipt of antibacterial PPX. The primary endpoint was rate of febrile neutropenia (FN); secondary endpoints were rates of unplanned hospitalization, bacteremia, infection from resistant organisms, C. difficile colitis, and death from infection. One hundred twenty patients with data from 229 IDAC/HiDAC cycles were included. Patients who received antibacterial PPX were more often hospitalized during cytarabine cycle 1 (C1) than those who received no PPX. Patients who received PPX had significantly more episodes of bacteremia, in addition to infections from resistant, predominantly Gram-positive organisms during cycle 1 of consolidation than those without PPX. Antibacterial PPX during IDAC/HiDAC consolidation treatment at our institution did not decrease the rates of FN, hospitalization, or bacteremia and was associated with higher risk of infection from drug-resistant bacteria in C1. Prospective studies examining antibacterial prophylaxis during cytarabine consolidation for AML patients are necessary, with strong consideration made for institution-specific protocols.

Background SARS-CoV-2 infection has noted derangements in coagulation markers along with significant thrombotic complications. Post-mortem examinations show severe endothelial injury and widespread thrombotic microangiopathy in the pulmonary vasculature. Early reports describing the use of prophylactic anticoagulation demonstrated improved survival, leading to the adoption of prophylactic and therapeutic anticoagulation guided by D-dimer levels. The clinical usefulness of D-dimer values, trends, and more intensive anticoagulation remains an area of clinical interest. Objectives Assess the outcomes and laboratory trends in COVID-19 patients stratified by intensity of anticoagulation at time of admission. Patients and methods Retrospectively review the differences in clinical outcomes and laboratory trends in patients hospitalized with COVID-19 in the Lifespan Health System. Results Between 27 February and 24 April 2020, 468 patients were hospitalized. Initial use of high-intensity thromboprophylaxis was associated with improved 30-day mortality (adjusted RR 0.26; 95% confidence interval [CI], 0.07–0.97; p = 0.045) without a significant increased rate of bleeding (p = 0.11). In severe COVID-19, D-dimer significantly increased during hospitalization with standard thromboprophylaxis (p, Highlights • High-intensity prophylaxis was associated with improved 30-day mortality • High-intensity prophylaxis includes LMWH 40 mg twice daily or unfractionated heparin 7500 units subcutaneous thrice daily. • In severe COVID-19, D-dimer significantly increased during hospitalization with standard prophylaxis. • In severe COVID-19, D-dimer was stable or decreased with high-intensity prophylaxis or therapeutic anticoagulation. • In severe COVID-19, high-intensity prophylaxis or therapeutic anticoagulation did not lead to increased bleeding.

Background Newly diagnosed multiple myeloma patients have many available treatment options. While lenalidomide, bortezomib, and dexamethasone (RVD) is the preferred initial treatment for many patients, several other agents may provide similar efficacy with less toxicity and improved ease of administration. Methods We evaluated the safety and efficacy of the all-oral regimen of ixazomib, cyclophosphamide, and dexamethasone with the use of metronomic cyclophosphamide dosing in the treatment of patients with newly diagnosed multiple myeloma. Results The study was stopped prior to planned enrollment due to slow recruitment, with 12 patients available for final analysis. The overall response rate was 58.3% with 2 patients achieving a very good partial response (16.7%) and 5 patients achieving a partial response (41.7%). Median progression-free survival was 16 months, and median overall survival was 43 months. There were no episodes of grade 3 or greater peripheral neuropathy. Grade 3 or greater dermatologic toxicity was experienced in 50% of patients. Conclusion Although limited enrollment prevented full efficacy evaluation, our data do not support further study of metronomic cyclophosphamide in combination with ixazomib and dexamethasone in the treatment of newly diagnosed multiple myeloma. The activity of this regimen in the relapsed/refractory setting requires further study (ClinicalTrials.gov Identifier: NCT02412228).

Extracellular vesicles (EVs) are excreted from all cells in the human body and are heterogeneous lipid bilayer particles containing proteins, RNA, DNA, and other cargo. T cells are primary players of the adaptive immune system and have a significant role in anti-cancer immunotherapies. Tumor derived EVs have diverse effects on host cells including modulating the immune response. In this study, we investigate the role acute myeloid leukemia (AML) derived EVs have on modulation of gene expression levels in three different T cell populations (CD8+, CD4+, and CD4 + CD39 + T cells). AML derived EVs modulate gene expression levels in all three cell populations with transcripts associated with major immunoregulatory pathways being significantly altered. Genes whose expression were significantly upregulated or downregulated were analyzed for gene ontogeny category expression and for the impact of the changes on specific immunoregulatory pathways. CD8 + T cells were modulated to a larger extent than other T cell populations and gene expression levels associated with proliferation and differentiation were influenced by AML-derived EVs.

Background Myelofibrosis (MF), a rare disorder characterized by bone marrow fibrosis, has been implicated as a cause of pulmonary hypertension (PH). To date, studies examining this association have not looked at the impact of PH on survival in MF. We examined the relationship between MF and PH by echocardiogram (echo) using a retrospective patient database and examined the influence of PH on overall survival. Patients and Methods In this single-center retrospective chart review, we identified 65 patients with biopsy-proven primary and secondary MF, 31 of whom underwent transthoracic echo. After accounting for chronic obstructive pulmonary disease and left-sided or valvular heart dysfunction, which excluded 6 patients, we identified 14 patients (56%) who had echo evidence of group 5 PH (ie, PH due to unclear or multifactorial mechanisms), 8 with primary MF and 6 with secondary MF. MF patients with PH trended toward being predominantly female, being older, and less often having constitutional symptoms compared to the non-PH cohort. Results There was no effect of the presence of PH on overall survival in the entire MF cohort or in any subgroup analyzed, including primary MF versus secondary MF and primary MF intermediate risk patients. Conclusion Given the high prevalence of MF-associated PH, there may be a larger role for routine echo screening in MF patients. Further, the underlying association between PH and MF may signify an endothelial plasticity or increased telomerase activity as part of the pathogenesis of MF.

Traumatic brain injury (TBI) is a common cause of death and acquired disability in adults and children. Identifying biomarkers for mild TBI (mTBI) that can predict functional impairments on neuropsychiatric and neurocognitive testing after head trauma is yet to be firmly established. Extracellular vesicles (EVs) are known to traffic from the brain to the oral cavity and can be detected in saliva. We hypothesize the genetic profile of salivary EVs in patients who have suffered head trauma will differ from normal healthy controls, thus constituting a unique expression signature for mTBI. We enrolled a total of 54 subjects including for saliva sampling, 23 controls with no history of head traumas, 16 patients enrolled from an outpatient concussion clinic, and 15 patients from the emergency department who had sustained a head trauma within 24 hr. We performed real‐time PCR of the salivary EVs of the 54 subjects profiling 96 genes from the TaqMan Human Alzheimer's disease array. Real‐time PCR analysis revealed 57 (15 genes, p

COVID-19 infection has been associated with an increased incidence of thrombotic events leading to poor patient outcomes. Given the rapid rise of the COVID-19 pandemic, the ability to conduct prospective trials has been limited and data regarding the use of standard-dose versus intermediate-dose thromboprophylaxis, use of empiric therapeutic anticoagulation, and use of extended-duration thromboprophylaxis after discharge has been largely based upon observational data without any high-quality prospective data guiding their use. In this article, we will review the incidence and frequency of arterial and venous thrombotic events along with the current literature surrounding the use of intermediate-dose thromboprophylaxis, empiric therapeutic anticoagulation, and use of extended-duration thromboprophylaxis for patients hospitalized with COVID-19.

IntroductionVenetoclax along with hypomethylating agents (HMAs) is the new standard therapy for older patients with acute myeloid leukemia (AML) not fit for intensive frontline induction chemotherapy. Venetoclax is associated with fatal episodes of tumor lysis syndrome (TLS) in chronic lymphocytic leukemia (CLL), and recommendations are for its initiation for CLL and AML in the inpatient setting with close monitoring. Herein, we evaluated the safety of outpatient venetoclax ramp up when given in addition to HMAs for the treatment of AML. Methods We conducted a retrospective review of patients diagnosed with AML at our institution from 12/1/2016 until 7/1/2020. We identified patients who received HMAs and venetoclax for AML, either as frontline or relapsed/refractory therapy. Records were reviewed for evidence of laboratory or clinical tumor lysis episodes in all patients. Results Between 12/1/2016 and 7/1/2020 43 patients at our institution received venetoclax/HMA for the treatment of AML. Thirty-nine patients (91%) had venetoclax initiation and ramp up in the outpatient setting. One episode of laboratory TLS (2.5%) was identified. This patient required admission to the hospital for rasburicase and IV fluids with resolution of the laboratory effects without resultant clinical TLS. There were no episodes of clinical TLS in either group. 30-day mortality from venetoclax initiation was 0% in both groups. Conclusion Our experience with HMAs and venetoclax showed that outpatient ramp up of venetoclax is safe with a very low risk of laboratory TLS (2.5%) and no evidence of clinical TLS within our cohort.

Heparin-induced thrombocytopenia (HIT) remains a difficult clinical diagnosis, even with the under-utilized standardized scoring systems, like the '4T' score, to aid in clinical decision-making. Our quality improvement study sought to assess the use of '4T' score, improve the use of HIT antibody (HITA) testing and improvement management of possible HIT by implementing an in-line calculator with guidance within our electronic medical record (EMR) at our institution. We retrospectively reviewed patient charts between October 2017 and October 2018, assessing practices before and after implementation of the '4T' in-line calculator in April 2018. HITA were ordered inappropriately (for 4T4) in 141 (67%) of 210 instances (75 before and 66 after). We found no statistically significant difference in positive predictive value (PPV) or 4T documentation in provider notes after its implementation. We were able to identify problematic areas in HIT management, such as the ordering of non-heparin anticoagulants, and implement additional changes addressing these problems.

Using the Surveillance, Epidemiology, and End Results database (2004-2015), we compared adjuvant chemotherapy use and survival for three common solid tumors in patients with and without history of lymphoma (DLBCL: diffuse large B cell, HL: Hodgkin lymphoma). Among patients with breast (

Background Direct oral anticoagulants (DOACs) have entered the treatment paradigms of various conditions based upon large randomized controlled trials. However, use of DOACs for thrombosis at unusual sites, such as cerebral venous thrombosis (CVT), is less clear as the ability to conduct large randomized controlled trials is limited by its rarity. Furthermore, its use in the setting of malignancy or in the elderly remains an area of ongoing research. Objective Our aim was to assess the outcomes in CVT patients treated with DOACs compared to warfarin. We also sought to elucidate whether its use was safe in the setting of malignancy or in the elderly. Methods Retrospectively assess the differences in clinical outcomes in patients hospitalized with CVT in the Lifespan Health System. Results Between 1 July 2004 and 1 March 2020, 46 adult patients with CVT fulfilled inclusion criteria. No significant differences in outcomes were observed between the DOAC (N = 8) and vitamin K antagonist (VKA) (N = 38) cohorts. The use of DOACs did not result in an increased rate of acute complications, recurrent venous thromboembolism (VTE) and/or CVT, World Health Organization (WHO) grade 3 or 4 bleeding rates, or differences in clinical improvement per the modified Rankin scale. Furthermore, in patients with underlying metastatic cancer (N = 2) or in patients > 80 (N = 1) who received a DOAC, there was no increase in adverse events or significant differences in outcome when compared to warfarin. Conclusion Patients who received a DOAC in the treatment of CVT demonstrated no differences in outcomes when compared to warfarin.

Acute myeloid leukemia (AML) patients undergoing consolidation chemotherapy with intermediate or high-dose cytarabine (IDAC/HiDAC) are often placed on prophylactic antibacterials. This practice is largely based on the benefits of prophylaxis (PPX) during induction chemotherapy. However, recent concerns regarding antibacterial prophylaxis have emerged including risk of Clostridioides difficile colitis, medication toxicities, and the potential for fostering multidrug-resistant pathogens. We therefore retrospectively explored whether antibacterial PPX is beneficial during cytarabine consolidation. Adult AML patients who received IDAC/HiDAC at our institution from January 2007 to March 2018 were evaluated for receipt of antibacterial PPX. The primary endpoint was rate of febrile neutropenia (FN); secondary endpoints were rates of unplanned hospitalization, bacteremia, infection from resistant organisms, C. difficile colitis, and death from infection. One hundred twenty patients with data from 229 IDAC/HiDAC cycles were included. Patients who received antibacterial PPX were more often hospitalized during cytarabine cycle 1 (C1) than those who received no PPX. Patients who received PPX had significantly more episodes of bacteremia, in addition to infections from resistant, predominantly Gram-positive organisms during cycle 1 of consolidation than those without PPX. Antibacterial PPX during IDAC/HiDAC consolidation treatment at our institution did not decrease the rates of FN, hospitalization, or bacteremia and was associated with higher risk of infection from drug-resistant bacteria in C1. Prospective studies examining antibacterial prophylaxis during cytarabine consolidation for AML patients are necessary, with strong consideration made for institution-specific protocols.

Invasive fungal infections (IFIs) are a major cause of morbidity and mortality in patients undergoing induction chemotherapy for acute myeloid leukemia (AML). In this patient population, antifungal prophylaxis (AP) has been associated with decreased incidence of IFIs and better survival. However, some centers have not adopted AP during induction chemotherapy for AML, as it is unclear whether AP improves outcomes in settings where the incidence of invasive mold infections is low. We retrospectively assessed the differences in clinical outcomes and resource utilization in patients undergoing 7 + 3 induction chemotherapy for AML, after implementing a policy of AP as part of a dedicated inpatient malignant hematology service (HS) at Rhode Island Hospital. Between January 1, 2007 and April 1, 2019, 56 patients with AML received AP during 7 + 3 induction chemotherapy and 52 patients did not, without significant differences in their baseline characteristics. Use of AP was associated with less proven or probable IFI (0% vs. 6%, P = 0.1) and lower all-cause in-hospital mortality (7% vs. 21%, P 0.05), without significant increases in resource utilization or toxicities. Empiric and targeted antifungal therapies were more frequently started in the non-AP group (69%) than changed in the AP group (41%, P 0.005). Having a dedicated inpatient malignant hematology service was also associated with improved outcomes. However, use of AP was associated with better survival (30-day post-induction survival log-rank P 0.05), prior to the implementation of this clinical service as well, which is suggestive of an independent benefit from AP.

Background Immunotherapeutic protocols have focused on identification of stimuli that induce effective anti-leukemic immune responses. One potent immune stimulus is the encounter with allogeneic cells. Our group previously showed that the infusion of haploidentical donor white blood cells (1–2 × 108 CD3+ cells/kg) into patients with refractory hematological malignancies induced responses of varying magnitude in over half of the patients. Because donor cells were eliminated within 2 weeks in these patients, it is presumed that the responses of recipient lymphocytes were critically important in achieving prolonged anti-leukemic responses. Methods The role of patient CD3+ cells in anti-leukemic responses was examined by isolating peripheral blood mononuclear cells from newly diagnosed leukemic patients. Immunophenotyping was performed on these peripheral blood mononuclear cells. CD3+ cells were isolated from the peripheral blood mononuclear cells and tested for their ability to proliferate and lyse autologous leukemic cells when stimulated with unrelated allogeneic cells. Results Allostimulated CD3+ cells effectively generated cytolytic responses to autologous CD3-cells in 11/21 patients. Increased numbers of CD4+ cells expressing high levels of granzyme A, B and perforin and CD8+CD39+ cells were found in nonresponsive CD3+ cells. Conclusions These results indicate that CD3+ cells from leukemic patients are capable of generating anti-leukemic responses when stimulated with unrelated allogeneic cells. This model can be used to identify approaches using alloreactive responses by patient lymphocytes to enhance in vivo anti-leukemic responses.

Background A 55-year-old male presented with myelodysplastic/myeloproliferative neoplasm and severe splenomegaly. The patient is blood group O, D+ with a negative indirect antiglobulin test. Transfusion of 5 units of red blood cells (RBCs) increased the hemoglobin (Hb) level from 6.7 to 7.2 g/dL. No active bleeding or hemolysis was evident. The patient was readmitted 1 week later with a Hb level of 3.3 g/dL. An additional 6 units of RBCs showed only an increase from 3.3 to 3.5 g/dL. Partial splenic embolization was performed, which resulted in a stabilization of the Hb level at approximately 7 g/dL. Because of this, total splenectomy was performed, which resulted in a gradual increase in Hb level to approximately 13 g/dL. The patient remains transfusion independent 160 days postsplenectomy. Results RBC transfusion increases Hb concentration by 1 g/dL per unit in a typical adult. This increase is attenuated in the presence of ongoing hemolysis or active blood loss. Occasionally, a low-RBC-volume unit transfused to a recipient with a large intravascular blood volume may show an unexpectedly small increase. In rare situations, however, the etiology of a greatly attenuated response is more perplexing. The pattern of Hb concentration posttransfusion was suggestive of splenic sequestration in our patient. Conclusion Severe refractoriness to RBC transfusion attributable to severe hypersplenism is a rare event. Our case suggests that splenic artery embolization may be a useful initial approach in individual cases and a potential predictor of the utility of a subsequent surgical splenectomy.

The therapeutic armamentarium for multiple myeloma has grown significantly over the past decade. We characterized ongoing multiple myeloma clinical trials utilizing ClinicalTrials.gov . A search of ClinicalTrials.gov on 21 April 2017 returned 239 therapeutic interventional trials in multiple myeloma. A majority (84.1%) of trials are early-phase (I/II). Immunotherapies are significantly more likely to be studied in Phase I trials than Phase II trials (p = 0.0049). Primary sponsor (academic, cooperative group, industry) is significantly associated with phase of trial (p = 0.0334). Quality of life assessment is included as a secondary objective in only 10.1% of trials. Areas of need are continued advancement of immunotherapies, late-phase studies utilizing a triplet control group, and an objective focus on quality of life.

The introduction of tyrosine kinase inhibitors (TKI) has transformed chronic myeloid leukemia (CML) into a chronic disease with long‐term survival exceeding 85%. However, resistance of CML stem cells to TKI may contribute to the 50% relapse rate observed after TKI discontinuation in molecular remission. We previously described a model of resistance to imatinib mesylate (IM), in which K562 cells cultured in high concentrations of imatinib mesylate showed reduced Bcr‐Abl1 protein and activity levels while maintaining proliferative potential. Using quantitative phosphoproteomic analysis of these IM‐resistant cells, we have now identified significant upregulation of tumor progression locus (Tpl2), also known as cancer Osaka thyroid (COT1) kinase or Map3k8. Overexpression of Tpl2 in IM‐resistant cells was accompanied by elevated activities of Src family kinases (SFKs) and NF‐κB, MEK‐ERK signaling. CD34+ cells isolated from the bone marrow of patients with CML and exposed to IM in vitro showed increased MAP3K8 transcript levels. Dasatinib (SFK inhibitor), U0126 (MEK inhibitor), and PS‐1145 (IκB kinase (IKK) inhibitor) used in combination resulted in elimination of 65% of IM‐resistant cells and reduction in the colony‐forming capacity of CML CD34+ cells in methylcellulose assays by 80%. In addition, CML CD34+ cells cultured with the combination of inhibitors showed reduced MAP3K8 transcript levels. Overall, our data indicate that elevated Tpl2 protein and transcript levels are associated with resistance to IM and that combined inhibition of SFK, MEK, and NF‐κB signaling attenuates the survival of IM‐resistant CML cells and CML CD34+ cells. Therefore, combination of SFK, MEK, and NF‐κB inhibitors may offer a new therapeutic approach to overcome TKI resistance in CML patients.

In aggressive lymphomas, discrepancies in survival reported from experimental and observational studies may reflect selective non-enrolment of high-risk patients in trials. We examined the association between time from diagnosis to chemotherapy and overall survival in diffuse large B-cell (DLBCL), Burkitt (BL), mantle cell (MCL) and peripheral T-cell lymphoma (PTCL), using National Cancer Data Base records of 130 549 patients treated in 2004-2014. Across the histologies, patients who started chemotherapy within 7 days of diagnosis had more often high International Prognostic Index (IPI) or advanced-stage disease. The discrepancy in 3-year survival between groups treated within 7 or >30 days from diagnosis ranged from 14% in BL to 30% in MCL. After adjusting for the IPI, time to treatment was significantly associated with shorter overall survival. Using the group treated >30 days from diagnosis as reference, patients treated within 7 days had a hazard ratio of 1·38 [95% confidence interval (CI), 1·28-1·48] in DLBCL, 1·42 (95% CI, 1·22-1·66) in BL, 2·23 (95% CI, 1·79-2·78) in MCL and 1·46 (95% CI, 1·18-1·81) in PTCL. Time from diagnosis to treatment may reflect high-risk features uncaptured by standard prognostic assessments. Clinical trials should accommodate patients who need urgent therapy to improve external validity and detect treatment effects in high-risk groups.

Introduction The etiology of hypercalcemia in non-Hodgkin lymphoma (NHL) has been most often attributed to either elevated serum levels of 1,25-dihydroxycholecalciferol (calcitriol) or parathyroid-related protein (PTHrP). In a single-center retrospective review, we evaluated the incidence of, and outcomes associated with, hypercalcemia in NHL. Patients and Methods The medical records of patients with a histologically confirmed diagnosis of NHL and ≥ 1 episode of hypercalcemia were evaluated for demographic and lymphoma-specific factors, including the response to therapy and overall survival. Results Fifty-four patients with NHL met the inclusion criteria. Most patients (57.4%) had diffuse large B-cell lymphoma, of which, 70% were the nongerminal center subtype. Approximately one half (42.6%) of the included patients had undergone serologic investigation into the etiology of hypercalcemia; however, only 17 patients (31.5%) had both a serum PTHrP and a calcitriol level properly collected. Of the 17 cases for which both a serum calcitriol and a PTHrP were collected, most (61.1%) were found to have neither an elevation of serum calcitriol nor an elevation of PTHrP. The degree of calcitriol elevation correlated with worse progression-free survival ( P = .04) but not overall survival. Conclusion The major mechanism by which NHL patients develop hypercalcemia is not mediated by calcitriol or PTHrP. Hypercalcemia is most prevalent in patients with diffuse large B-cell lymphoma of the nongerminal cell subtype. Patients with calcitriol-mediated hypercalcemia showed a trend toward worse outcomes, suggesting that calcitriol might be a marker of high-grade lymphoma, transformation to such, or a surrogate for more advanced disease.

Extracellular vesicles (EV) are nano-sized membrane enclosed vehicles that are involved in cell-to-cell communication and carry cargo that is representative of the parent cell. Recent studies have highlighted the significant roles leukemia EVs play in tumor progression, and ways in which they can lead to treatment evasion, thus meriting further investigation. Leukemia EVs are involved in crosstalk between the leukemia cell and its surroundings, transforming it into a cancer favorable microenvironment. Due to the diverse biological content found in leukemia EVs, they have an assortment of effects on the cells they interact with and can be harnessed as candidates for diagnostic and therapeutic treatments. This review focuses on EVs in the context of leukemia and the means by which they modulate their microenvironment, hematopoiesis, and the immune system to facilitate malignancy. We will also address current and prospective EV-based therapeutics.

Background: Recent studies reported low rates of seroconversion response to COVID-19 vaccination in patients (pts) with hematologic malignancies (HMs). Vaccine choice among the 3 FDA-authorized products (BNT162b2/Pfizer-BioNTech, mRNA-1273/Moderna, or Ad26.COV2.S/J&J), prior therapy, and disease-specific factors may affect seroconversion. Addressing these factors may improve seroconversion rates and identify pts at risk of severe COVID-19 infection despite vaccination. Methods: We conducted a retrospective study of adults with HMs vaccinated in our center between 2/2021 and 7/2021, excluding pts with prior COVID-19 infection. Seroconversion was assessed by the qualitative SARS-CoV-2 Total Antibody Test (IgG/IgM against Receptor Binding Domain [RBD], Wondfo USA, Willowbrook, IL). A subset of samples was tested by the semi-quantitative Abbott AdviseDx SARS-CoV-2 IgG II assay (IgG against RBD). For univariate associations (UVA) we used Fisher's exact test for categorical variables, and fractional polynomial fits for continuous variables to examine non-linearity. Multivariable analysis (MVA) used a robust Poisson model reporting risk ratio (RR) with 95% confidence intervals (CI). Results: Among 239 eligible pts, median age was 70 (range, 28-94), and 112 (47%) were female. HMs included aggressive B-cell lymphomas (n=74, 31%), indolent B-cell lymphomas (n=52, 22%), chronic lymphocytic leukemia (CLL, n=30, 13%), other lymphomas (n-19, 8%), plasma cell neoplasms (n=43, 18%), and myeloid cancers (n=21, 9%); 140 pts (59%) received BNT162b2/Pfizer, 74 (31%) mRNA-1273/Moderna, and 23 (10%) Ad26.COV2.S/J&J vaccines (2 pts had undetermined vaccine type). HM was active in 100 pts (42%), whereas 108 (45%) pts were in remission after treatment, and 31 (13%) on watchful waiting (WW, never treated); 141 (59%) had a prior exposure to an anti-B-cell monoclonal antibody, and 22 (9%) prior stem cell transplantation. Overall, 99 pts (41%; binomial 95% CI, 35-48%) showed post-vaccination seroconversion upon testing at median 10 weeks from first vaccine. Seroconversion was significantly less frequent among pts with lymphomas compared with plasma cell or myeloid neoplasms (overall P=.020; Fig A). It was also less frequent after prior anti-B-cell antibody exposure (29% vs 59%, P In a MVA (Fig. J), vaccination with mRNA-1273 remained significantly associated with higher rate of seroconversion compared with BNT162b2 (RR=0.59; 95%CI, 0.44-0.79) or Ad26.COV2.S (RR=0.35; 95%CI, 0.16-0.77). Higher seroconversion rate was also associated with remission (RR=1.98; 95%CI, 1.42-2.76) or WW status (RR=1.72; 95%CI 1.02-2.89) compared with active disease, and higher lymphocyte count. Exposure to anti-B-cell antibodies remained associated with lack of seroconversion (RR=0.66; 95%CI, 0.44-0.99). Seroconversion was borderline less frequent in CLL than lymphomas, and higher with plasma cell or myeloid disorders. Results were similar in the subset of pts (n=191) with prior treatment, adjusting for time from last chemotherapy(data not shown). The anti-COVID-19 IgG titers on semiquantitative test (n=47, all after mRNA-based vaccines) were also lower in pts with active disease compared with those in remission (P=.065) or under WW (P=.028), and in those with prior anti-B-cell antibody (P=.0095). Conclusions: Pts with HMs demonstrate overall low rates of seroconversion after vaccination against COVID-19, particularly when they have active disease or are on/after B-cell depleting monoclonal antibody therapy. The mRNA vaccines (particularly mRNA-1273) appear to have elicited superior responses compared with the adenovirus-based product. Pts with active HMs or those within 2 years of last therapy should be particularly aware of the risk of infection despite vaccines and should be considered for strategies to enhance anti-COVID-19 immunity regardless of age. Figure 1 Figure 1. Disclosures Olszewski: TG Therapeutics: Research Funding; PrecisionBio: Research Funding; Celldex Therapeutics: Research Funding; Acrotech Pharma: Research Funding; Genentech, Inc.: Research Funding; Genmab: Research Funding.

Background: The known driver mutations in PMF (including JAK2, CALR, and MPL) do not explain the highly inflammatory phenotype associated with this disease. Moreover, JAK2 inhibitors provide symptomatic relief in PMF, but they are not curative, indicating that our understanding of the molecular pathology of MPNs is incomplete. High-resolution insights into the mutational landscape of MPNs may inform new diagnostic and therapeutic approaches. Methods: We performed 60x whole-genome sequencing (WGS) on CD34+ hematopoietic stem/progenitor cells and matched in vitro-expanded CD3+ lymphocytes from 10 patients (pts) with PMF, of whom 5 had JAK2 V617F, 2 had MPL W515L, and 3 had CALR (del52 or ins5) mutations. Paired-end WGS was performed using BGISEQ-500 platform. Clean reads with Q20 and Q30 at 96.4% and 87.1%, respectively, were aligned to the human GRCh37 reference genome. 99.9% reads mapped successfully and 90.6% mapped uniquely. Mean sequencing depth for CD3+ and CD34+ cells were 72x and 83x, respectively (Fig A). Bioinformatic pipeline strategy is summarized on Fig B. We also examined complement activity in sera from 10 PMF pts using CH50 (a screening test for total complement activation) and C3 and C4 component activity. We further evaluated the effect of complement-neutralizing anti-C3 and anti-C5 (C3/C5 NeuAbs) on JAK/STAT and NF-κB signaling in mononuclear cells (MNCs) isolated from peripheral blood of these PMF pts. Results: ~3.4e6 SNPs were identified (n=10): 99.9% were represented in dbSNP, 98.1% were annotated in GnomAD, and 4,587 were novel. Among ~8.6e5 InDels, 91.9% were represented in dbSNP, 53.8% in GnomAD, and ~6.9e4, were novel. We identified 3,540 copy-number variations (CNVs) and 3,365 SVs. Rare non-synonymous variants (RNSV) were defined as SNVs with a maximum minor allele frequency Conclusions: Using WGS, we discovered an inactivating RNSV in CFI G119R in 20% of pts with PMF. In a separate cohort of PMF patients we detected elevated serum complement activation. Furthermore, PMF-specific dysregulation of STAT3 and NF-κB activation could be modulated by exposure to C3/C5 NeuAbs. This is a first, to our knowledge, report linking the overactivation of the complement cascade to inflammation-related pathogenesis of PMF. Figure 1 Figure 1. Disclosures Hobbs: Novartis: Consultancy; Bayer: Research Funding; Celgene/Bristol Myers Squibb: Consultancy; AbbVie.: Consultancy; Constellation Pharmaceuticals: Consultancy, Research Funding; Incyte Corporation: Research Funding; Merck: Research Funding. Oh: Abbvie: Membership on an entity's Board of Directors or advisory committees; Blueprint Medicines: Membership on an entity's Board of Directors or advisory committees; Celgene Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Constellation: Membership on an entity's Board of Directors or advisory committees; CTI Biopharma: Membership on an entity's Board of Directors or advisory committees; Disc Medicine: Membership on an entity's Board of Directors or advisory committees; Geron: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Kartos Therapeutics: Membership on an entity's Board of Directors or advisory committees; PharamaEssentia: Membership on an entity's Board of Directors or advisory committees; Sierra Oncology: Membership on an entity's Board of Directors or advisory committees. Di Paola: CSL Behring: Consultancy, Honoraria.

Introduction: Hydroxyurea (HU) was the first FDA-approved therapy for sickle cell anemia (SCA) and remains the most well-established disease-modifying therapy, reducing painful crisis and improving morbidity and mortality. HU improves outcomes through the upregulation of fetal hemoglobin (HbF). Dosing is highly variable with doses ranging from 80,000. Macrocytosis is often used as a surrogate marker for compliance and effect. Despite its well-established effectiveness, clinical use remains limited with only 12% of adults with SCA taking HU. The reasons for this are multifactorial but include skepticism by both providers and patients regarding its effectiveness in the adult population. Some experts suggest up to 30% of adults are non-responders with no significant HbF change, and many believe that the effect of HU fades with time. Dosing strategies are usually quite conservative to prevent excessive myelosuppression, though dose is highly correlated with clinical effect and ultimate %HbF. There is very limited real-world data regarding long term effectiveness of HU in adults with SCA over time. Methods: We retrospectively analyzed the records of the 109 adults with SCA currently treated in our multidisciplinary sickle cell clinic. Data from 1/1/2011-6/30/2021 was collected, including genotype, HU prescription status, current and maximum laboratory values (HbF, MCV, ANC), and number of admissions for painful crisis. We performed Wilcoxon rank sum testing between pts prescribed and not prescribed HU and measures of HbF (peak, average and current) and number of admissions for painful crisis over the study period. Results: Among 106 pts (3 excluded from analysis, 2 for lack of data and 1 for post-transplant status), 79 are currently prescribed HU (75%). Among our 63 pts with HbSS genotype 58 are prescribed HU (92%). Average HbF over time for all pts prescribed HU was 11.9%. Average peak HbF was 18.1% and average current HbF is 12.4%. In the pts not prescribed HU HbF average, peak and current levels were 5.5%, 6.7%, and 5.0% respectively. HU prescription was significantly associated with increased HbF at peak, average, and current levels (p-value 100 at time of peak HbF were associated with higher peak levels than pts with MCV 9.9m/kg were associated with significantly higher HbF levels however there was no significant difference between dose levels 10-19.9mg/kg and 20-29.9 or 20-29.9 and 30-39.9mg/kg (p-values 0.02, 0.68 and 0.84 respectively). Among pts prescribed HU, 34 obtained ANC levels 100 and ANC Conclusion: In our adult multidisciplinary sickle cell clinic prescribing rates are well above current HU usage for adults with SCA. Our data notes that elevated HbF levels can be maintained over long periods of time. HU prescription was significantly associated with increased HbF levels and reduced admissions for painful crisis. This was despite a majority of pts not meeting target prescribing levels of ANC 100. While higher peak HbF levels were significantly associated with higher HU doses, this was only true for doses above 9.9 mg/kg. Further investigation is needed to explore the factors contributing to suboptimal HbF and MCV response, including careful assessment with medication adherence and dose selection. Overall, these data illustrate the importance of dosing and suggest that one size dosing of HU for adults with SCA does not fit all. We hypothesize that there may be a role individualized dosing strategies in adults with SCA, incorporating factors such as pharmacokinetics and renal function to achieve the optimal dose for each patient. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

IgM myeloma is a rare hematologic malignancy for which the clinicopathological features and patient outcomes have not been extensively studied. We carried out a multicenter retrospective study in patients with diagnosis of IgM myeloma defined by >10% marrow involvement by monoclonal plasma cells, presence of an IgM monoclonal paraproteinemia of any size, and anemia, renal dysfunction, hypercalcemia, lytic lesions and/or t(11;14) identified by FISH. A total of 134 patients from 20 centers were included in this analysis. The median age at diagnosis was 65.5 years with a male predominance (68%). Anemia, renal dysfunction, elevated calcium and skeletal lytic lesions were found in 37, 43, 19, and 70%, respectively. The median serum IgM level was 2,895 mgdL(-1) with 19% of patients presenting with levels >6,000 mgdL(-1). International Staging System (ISS) stages 1, 2, and 3 were seen in 40 (33%), 54 (44%), and 29 (24%) of patients, respectively. The malignant cells expressed CD20 (58%) and cyclin D1 (67%), and t(11;14) was the most common cytogenetic finding (39%). The median overall survival (OS) was 61 months. Higher ISS score was associated with worse survival (P=0.02). Patients with IgM myeloma present with similar characteristics and outcomes as patients with more common myeloma subtypes.

Background: CNS invasion in aggressive lymphoma (including diffuse large B-cell [DLBCL], double-hit [DHL], Burkitt [BL] and plasmablastic lymphoma [PBL]) remains a major diagnostic and therapeutic challenge. Parenchymal CNS invasion requires a brain biopsy to diagnose, and conventional CSF evaluations lack sensitivity. Furthermore, determining which patients (pts) without CNS disease at diagnosis might be at high risk of future CNS relapse, and thus would most benefit from aggressive CNS prophylaxis, is difficult. Predictors that use clinical variables (e.g. the CNS-IPI) can select a high-risk group with ~10% risk of CNS relapse, but ~50% of events occur in low/intermediate-risk groups. We evaluated a novel CSF assay that detects clonotype-specific cell-free DNA (cfDNA) by next-generation sequencing (NGS) combined with multiplex PCR (Chang T et al, BMC Cancer 2020). This assay can identify minimal residual disease (MRD) in the plasma of pts with DLCBL and can predict systemic relapse (Roschewski et al, Lancet Oncol 2015). Methods: To examine the diagnostic sensitivity of the NGS-MRD assay in the CSF, we prospectively collected CSF from 6 pts with lymphomas who had known parenchymal or leptomeningeal CNS invasion. We also tested stored DNA from historical CSF samples of 8 pts with CNS lymphoma who tested negative by conventional IGH-PCR. We then enrolled 19 pts with newly diagnosed high-risk lymphomas without CNS invasion to examine the prognostic value of the NGS-MRD assay in the CSF collected at diagnosis. In the two-step assay, tumor-specific clonotype sequences were first identified from genomic DNA in primary tumor specimens using NGS of rearranged IGK, IGH (VJ or DJ), and IGL loci. Tumor-specific clonotypes were then selected for tracking in the CSF (split into acellular CSF fluid and cell pellet) and in paired plasma samples. The assay quantitated copy numbers of each tracked sequence per mL of acellular CSF or per 106 cells in the pellet, as well as tumor clonotype frequency (%) per all B-cells. Results: The NGS-MRD detected tumor-specific clonotype in 100% of CSF samples from pts with known CNS lymphoma (n=6; Fig A), including pts with isolated parenchymal-only CNS disease that was not detected by CSF cytology, flow cytometry, or IGH-PCR. For pts with CNS parenchymal disease, median cfDNA copy count in the CSF fluid was 2 /mL (range, 0.4-929) and median clonotype frequency was 9.0% (range, 0.03-68.9%). For pts with leptomeningeal disease, these values were 2233 /mL (1.2-5620) and 37% (1.7-98.4%), respectively (Fig. B). Furthermore, the NGS-MRD assay detected tumor clonotypes in DNA isolates from 6 historical CSF samples (collected in 2014-2018) of pts with known CNS disease, in which lymphoma was not detectable by conventional IGH-PCR (2 additional historical samples failed DNA quality check). Among 19 newly diagnosed pts with no known CNS invasion (median age 57, 42% women, median LDH 352 IU/L), 12 (63%) had DLBCL with high risk of CNS relapse by virtue of high CNS-IPI or epidural tumor, and 7 had other high-risk histologies (2 DHL, 2 BL, HIV+ PBL, and 2 lymphoblastic leukemias). The CSF NGS-MRD assay was positive for tumor-specific clonotype in 8 pts (42%). Median cfDNA copy count in the CSF fluid was 3 /mL (range, 0.9-15.6) and median clonotype frequency was 18.6% (range, 1.4-28.5%). We observed no significant correlation between the amount of cfDNA and number of red cells /mL of CSF (a measure of potential CSF contamination by blood during collection procedure; Fig. C) or between the amount of cfDNA in plasma and in CSF (Fig. D). With median follow-up of 11 months, no pts with negative baseline NGS-MRD assay in CSF relapsed, whereas 2 of 10 with a positive assay had a CNS relapse (12-month incidence, 29%; Fig. E), despite both pts having negative CNS imaging, CSF cytology, flow cytometry, and IGH-PCR at diagnosis. Conclusions: In this proof-of-concept study, the NGS-MRD CSF assay showed 100% sensitivity for diagnosing intraparenchymal CNS invasion in aggressive lymphomas that were not detected in the CSF using conventional methods. In a prospective cohort of newly diagnosed pts without baseline CNS invasion but at high clinical risk for CNS relapse, the assay identified lymphoma-derived cfDNA in 42% of cases. The 100% sensitivity and 100% negative predictive value of the assay for subsequent CNS relapse warrants further prospective evaluation as a potential tool for personalizing CNS-directed prophylaxis. Disclosures Olszewski: Spectrum Pharmaceuticals: Research Funding; TG Therapeutics: Research Funding; Adaptive Biotechnologies: Research Funding; Genentech, Inc.: Research Funding. Mullins:Adaptive Biotechnologies: Current Employment, Other: shareholder.

Introduction Venetoclax (VEN), a BCL-2 inhibitor, along with hypomethylating agents (HMAs) has become standard therapy for older patients (pts) with acute myeloid leukemia (AML) not fit for intensive frontline therapy based on recent Phase 3 data reporting a median overall survival (OS) of 14.7 months. Initially used in CLL, VEN is associated with fatal episodes of tumor lysis syndrome (TLS). Package insert and expert opinion recommendations are for its initiation in the inpatient setting, with a dose escalation of 100mg day 1, 200mg day 2, and 400mg day 3 with IV hydration and close monitoring of TLS markers. In the initial phase 1b trial that resulted in its approval for use in pts with AML all pts were admitted to the hospital for initial venetoclax ramp up and received at least 72 hours of prior TLS prophylaxis, as well as initiation of venetoclax only if the white blood cell count was less than 25,000. No episodes of TLS were documented. Herein, we evaluated the safety of outpatient VEN ramp up when given in addition to HMAs for the treatment of AML. Methods We conducted a retrospective review of pts diagnosed with AML at our institution from 12/1/2016 until 7/1/2020. We identified pts who received HMAs and VEN, either as up-front treatment for newly diagnosed AML or as salvage therapy for relapsed or refractory disease, and stratified pts based on whether venetoclax was initiated in the inpatient or outpatient setting. We then examined baseline AML characteristics including initial blast count, cytogenetics and molecular profiles as well as baseline TLS markers prior to the initiation of VEN. Finally, using the Cairo-Bishop Criteria we examined the number of episodes of laboratory or clinical tumor lysis in all pts. Fisher's exact test and Wilcoxon rank-sum tests were performed to examine differences in categorical and continuous variables. Results Between 12/1/2016 and 7/1/2020 43 pts at received VEN in addition to an HMA for the treatment of AML (Table 1). 39 pts (91%) had VEN initiation and ramp up in the outpatient setting. Amongst all pts 24 received azacitadine, 11 decitabine, and 8 received both HMAs at some point during therapy. Twenty-two pts received HMA and VEN as frontline treatment while the other 21 received it as salvage therapy. There were 28 pts who received venetoclax within 28 days of starting the HMA, 25 of whom received it as an outpatient and 3 as an inpatient. Pretreatment labs were notable for median normal values of potassium, phosphate, uric acid, calcium and creatinine (Table 1). The median pretreatment creatinine levels between the two groups were not significantly different. Median pre-treatment WBC count was noted to be significantly higher in the inpatient cohort (37.9 vs 5.5, p-value of 0.01). Cytogenetic and molecular characteristics are included in the table with the only significant difference being a larger percentage of DNMT3A mutation in the inpatient group. While identification of TLS was somewhat limited by incomplete data on all pts, there was only one identified episode of laboratory TLS (2.5%) with an elevated phosphate and uric acid. This occurred in the outpatient group in a patient whose pretreatment WBC count was greater than 25,000. This pt required admission to the hospital for rasburicase and IV fluids with resolution of the laboratory effects without resultant clinical TLS. There were no episodes of clinical TLS in either group. 30-day mortality from starting VEN was 0% in both groups. While the Cairo-Bishop Criteria require the presence of 2 lab abnormalities to diagnose TLS we did a further analysis to evaluate for the presence of even a single lab abnormality associated with TLS. We identified 3 additional pts (7.5%) in the outpatient cohort who had the presence of only one lab abnormality associated with TLS within the 7 days after initiating treatment. None of these pts required any further TLS directed treatment or hospitalization. Conclusion Our experience with HMAs and VEN showed that outpatient ramp up of venetoclax is safe with a very low risk of laboratory TLS (2.5%) and no evidence of clinical TLS within our cohort. Even with an expanded definition of TLS we only identified 3 additional pts who developed laboratory abnormalities associated with TLS. Our results suggest that, in addition to HMA, VEN ramp up can be safely delivered with monitoring to pts with a WBC count less than 25,000 in the outpatient setting. Disclosures Olszewski: Genentech, Inc.: Research Funding; Spectrum Pharmaceuticals: Research Funding; TG Therapeutics: Research Funding; Adaptive Biotechnologies: Research Funding.

Background: Acute Myeloid Leukemia (AML) has a five-year survival rate of 25% and its high mortality is linked to poor response to treatment and relapse. Our understanding of the molecular mechanisms controlling relapse and AML progression is limited. Animal models indicate that AML cells significantly modulate their bone marrow microenvironment inducing gradual loss of endosteal and vascular niches, both playing critical roles in support and maintenance of normal hematopoiesis. The goal of this study was to determine microenvironmental factors driving the gradual retraction of endosteal and vascular niches directly in the AML core bone marrow biopsies, and assess the treatment effect on hematopoietic and non-hematopoietic cells. Methods: Transcriptomics and histopathologic evaluations of matched human AML core bone marrow biopsies obtained at diagnosis (n=12) and day 14 post-induction therapy (n=12) with daunorubicin and cytarabine (7+3) were performed. Based on post-treatment frequency of blasts in the AML bone marrow aspirate, patients were classified as responders ( 5% blasts). Three of 6 responders (3 men, 3 women, average age 59 yrs) had normal karyotype, and three of 6 non-responders (1 man, 5 women, average age 52.6 yrs), had normal karyotype. RNA was isolated from the core bone marrow biopsies and subjected to Clariom D Human Affymetrix arrays. Transcriptomics data were analyzed using Affymetrix Transcriptome Analysis Console with LIMMA R package and Gene Set Enrichment Analysis (GSEA). H&E stained bone marrow biopsy slides were subjected to blinded histopathological assessment. Results: Transcriptomic data analysis of responder vs. non-responder samples at diagnosis indicated significant loss of transcripts associated with heme metabolism (HBB, HBD, GYPE, CA1) suggesting decrease in frequency of erythroid progenitors (Fig.A). Trends of decreased frequency of erythroid progenitors were noted in both bone marrow biopsies and aspirates of diagnostic non-responder samples (Fig.B). Decreased frequency of lymphoid cells was also noted (Fig.B). Interestingly, while post-treatment we noted a relative increase in frequencies of lymphoid cells in both responder and non-responder samples, the increase was more prominent in responders (Fig.B). Trilineage hematopoiesis appeared affected more in diagnostic and post-treatment responder samples. Transcriptome analyses of diagnostic vs. post-treatment responder samples indicated significant increase in transcripts associated with activity within endosteal niche (SPARC, SPP1, DCN, VCAN, BGN) and significant loss of transcripts associated with DNA replication (TOP2, HELLS, E2F8) (Fig.C), the latter was consistent with treatment-related loss of cellularity. Only modest increase in SPARC, SPP1 or BGN levels and no significant decrease in DNA-replication associated transcripts were noted in non-responder post-treatment samples (Fig.1D). These data indicate greater loss of AML cells and greater activity within the endosteal niche in responder in comparison to non-responder samples. Finally, analyses performed on post-treatment responder vs. non-responder samples showed significant decrease in SPARC, SPP1, DCN, VCAN, BGN in non-responder post-treatment samples (Fig.E, F). Endosteal niche in histopathologic evaluation at diagnosis was generally unremarkable in both responder and non-responder samples with only rare osteoblasts present. In contrast, post-treatment, we found an elevated number of osteoblasts in responders in comparison to non-responder samples (Fig.G, H). Conclusions: Transcriptomic and histopathologic analyses of AML bone marrow biopsies procured at diagnosis and post-treatment from responder or non-responders indicate inverse correlation between the activity of endosteal niche and levels of transcripts involved in osteoblast maturation and homeostasis. Significant suppression of mesenchymal/osteoblast component of the niche is observed in non-responder samples. To our knowledge this is a first report showing the correlation between levels of osteopontin (SPP1), osteonectin (SPARC) and biglycan (BGN) and response to chemotherapy directly in the AML core bone marrow biopsies. Our data suggest that osteo-stimulatory factors could be used to achieve better therapeutic outcomes in AML. Disclosures No relevant conflicts of interest to declare.