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The use of Post-Transplant Cyclophosphamide (PTCy) as Graft Versus Host Disease (GVHD) prophylaxis has resulted in reductions in GVHD and improved outcomes in allogeneic hematopoietic cell transplant (HCT) using HLA-mismatched related donors. We report the 3-year outcomes of the first multi-center prospective clinical trial using PTCy in the setting of mismatched unrelated donor (MMUD) bone marrow HCT. The study enrolled 80 patients (Either myeloablative (MAC) (N=40) or reduced intensity conditioning (RIC) (N=40)) with the primary endpoint of 1-year overall survival (OS). The median follow-up for this report is 34 months (range 12-46) in RIC and 36 months (range 18-49) in MAC. Three-year OS and non-relapse mortality (NRM) were 70% and 15%, and 62% and 10% in the RIC and MAC strata, respectively. No GVHD was reported after 1 year. Relapse incidence was 29% and 51% in RIC and MAC strata. OS did not differ based on HLA match grade (63% in the 7/8 strata and 71% in the 4-6/8 strata). These encouraging outcomes, sustained 3 years post-HCT, support the continued exploration of MMUD HCT using a PTCy platform. Important future areas to address include relapse reduction and furthering our understanding of optimal donor selection based on HLA and non-HLA factors.

Objective/background: Clinical predictors of delayed engraftment following autologous hematopoietic cell transplantation (AHCT) are poorly described in the literature. The purpose of this study was to identify pretransplant characteristics contributing to delayed engraftment (DE) following AHCT. Methods: A retrospective, single institution study of 1162 consecutive patients undergoing AHCT from January 1996 to August 2016 was studied for DE. DE was defined as platelet count ≤ 50,000/µl, hemoglobin ≤ 8 g/dL, or absolute neutrophil count ≤ 1000/mm3. Results: Of the 1162 AHCT recipients, 263 (22.6%) were identified as having DE at 30-days post-AHCT with 80.0% being solely due to delayed platelet engraftment. Patients with Non-Hodgkin lymphoma (NHL) represented 18% of the original cohort, but accounted for 45% of those with DE, whereas multiple myeloma patients represented 59% of the initial cohort, but only 29% of those that had DE. At 3 months post-AHCT, transfusion dependence (p = .0083) prior to AHCT, low-infused CD34+ cell dose

Summary Background Data to inform surveillance and treatment for leukaemia predisposition syndromes are scarce and recommendations are largely based on expert opinion. This study aimed to investigate the clinical features and outcomes of patients with myelodysplastic syndrome or acute myeloid leukaemia and Shwachman-Diamond syndrome, an inherited bone marrow failure disorder with high risk of developing myeloid malignancies. Methods We did a multicentre, retrospective, cohort study in collaboration with the North American Shwachman-Diamond Syndrome Registry. We reviewed patient medical records from 17 centres in the USA and Canada. Patients with a genetic (biallelic mutations in the SBDS gene) or clinical diagnosis (cytopenias and pancreatic dysfunction) of Shwachman-Diamond syndrome who developed myelodysplastic syndrome or acute myeloid leukaemia were eligible without additional restriction. Medical records were reviewed between March 1, 2001, and Oct 5, 2017. Masked central review of bone marrow pathology was done if available to confirm leukaemia or myelodysplastic syndrome diagnosis. We describe the clinical features and overall survival of these patients. Findings We initially identified 37 patients with Shwachman-Diamond syndrome and myelodysplastic syndrome or acute myeloid leukaemia. 27 patients had samples available for central pathology review and were reclassified accordingly (central diagnosis concurred with local in 15 [56%] cases), 10 had no samples available and were classified based on the local review data, and 1 patient was excluded at this stage as not eligible. 36 patients were included in the analysis, of whom 10 (28%) initially presented with acute myeloid leukaemia and 26 (72%) initially presented with myelodysplastic syndrome. With a median follow-up of 4·9 years (IQR 3·9–8·4), median overall survival for patients with myelodysplastic syndrome was 7·7 years (95% CI 0·8–not reached) and 0·99 years (95% CI 0·2–2·4) for patients with acute myeloid leukaemia. Overall survival at 3 years was 11% (95% CI 1–39) for patients with leukaemia and 51% (29–68) for patients with myelodysplastic syndrome. Management and surveillance were variable. 18 (69%) of 26 patients with myelodysplastic syndrome received upfront therapy (14 haematopoietic stem cell transplantation and 4 chemotherapy), 4 (15%) patients received no treatment, 2 (8%) had unavailable data, and 2 (8%) progressed to acute myeloid leukaemia before receiving treatment. 12 patients received treatment for acute myeloid leukaemia—including the two patients initially diagnosed with myelodysplastic who progressed— two (16%) received HSCT as initial therapy and ten (83%) received chemotherapy with intent to proceed with HSCT. 33 (92%) of 36 patients (eight of ten with leukaemia and 25 of 26 with myelodysplastic syndrome) were known to have Shwachman-Diamond syndrome before development of a myeloid malignancy and could have been monitored with bone marrow surveillance. Bone marrow surveillance before myeloid malignancy diagnosis was done in three (33%) of nine patients with leukaemia for whom surveillance status was confirmed and 11 (46%) of 24 patients with myelodysplastic syndrome. Patients monitored had a 3-year overall survival of 62% (95% CI 32–82; n=14) compared with 28% (95% CI 10–50; n=19; p=0·13) without surveillance. Six (40%) of 15 patients with available longitudinal data developed myelodysplastic syndrome in the setting of stable blood counts. Interpretation Our results suggest that prognosis is poor for patients with Shwachman-Diamond syndrome and myelodysplastic syndrome or acute myeloid leukaemia owing to both therapy-resistant disease and treatment-related toxicities. Improved surveillance algorithms and risk stratification tools, studies of clonal evolution, and prospective trials are needed to inform effective prevention and treatment strategies for leukaemia predisposition in patients with Shwachman-Diamond syndrome. Funding National Institute of Health.

Background: Patients with RRMM receive multiple lines of therapy in their disease course and often become refractory to or are intolerant of newer approved therapies (eg, IMiDs, anti-CD38 monoclonal antibody [mAb] therapy, proteasome inhibitors [PIs]), limiting effective treatment options (Kumar et al. Leukemia. 2017; 31:2443). Efficacy outcomes decrease with each line of therapy, showing a need for agents with novel mechanisms of action to improve treatment responses and survival outcomes (Gandhi et al. Leukemia. 2019;33:2266). Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate (PDC) that targets aminopeptidases and rapidly releases alkylating agents into tumor cells. In the phase 2 HORIZON study (OP-106; NCT02963493), melflufen plus dexamethasone demonstrated encouraging efficacy in heavily pretreated patients with RRMM refractory to pomalidomide and/or an anti-CD38 mAb (overall response rate [ORR], 29%; median progression-free survival [PFS], 4.2 months; median overall survival [OS], 11.6 months) with a clinically manageable safety profile characterized primarily by hematologic adverse events (Richardson et al. EHA 2020. Abs. EP945). A contemporary representative control cohort is often used to indirectly compare outcomes of patients in clinical trials versus real-world data. The retrospective MAMMOTH study investigated the natural history and outcomes of patients with RRMM refractory to anti-CD38 mAb therapy after treatment with conventional agents (Gandhi et al. Leukemia. 2019;33:2266), providing a benchmark for the evolving state of the RRMM treatment landscape. Outcomes in clinical studies of novel agents in RRMM have been compared with MAMMOTH previously (Costa et al. ASH 2019. Abs. 3125), but not specifically in patients with RRMM refractory to anti-CD38 mAb therapy. To contextualize the clinical benefit of melflufen plus dexamethasone compared with conventional agents for patients with RRMM refractory to anti-CD38 mAb therapy, an analysis was conducted evaluating efficacy outcomes in HORIZON versus MAMMOTH. Methods: HORIZON patients with RRMM refractory to anti-CD38 mAb in the last line of therapy in the intention-to-treat population at final analysis (data cutoff date, 14 Jan 2020) were included in this analysis (N=63). Patients received melflufen 40 mg (intravenously on day 1 of each 28-day cycle) plus dexamethasone 40 mg weekly until disease progression or unacceptable toxicity. The MAMMOTH dataset included patients who progressed while on anti-CD38 mAb therapy (N=275) and were subsequently treated (N=249). ORR was assessed by the investigator per the International Myeloma Working Group criteria. PFS was defined as the time between the first dose of therapy and disease progression or death. OS was defined as the time from refractoriness to anti-CD38 mAb therapy to death from any cause in contrast to clinical studies in which OS is generally measured from first dose of subsequent therapy. Results: Patients in HORIZON and MAMMOTH had similar baseline median age and profile of daratumumab and isatuximab refractoriness (Table). Patients in HORIZON were more heavily pretreated than those in MAMMOTH (median number of prior therapies [range], 5 [2-10] versus 4 [1-16]). Patients in MAMMOTH were often treated with triplet therapy as first subsequent therapy after anti-CD38 mAb therapy failure (Table). ORR for HORIZON patients who failed last-line therapy with an anti-CD38 mAb (N=63) was 35% versus 31% for all anti-CD38 mAb therapy-refractory patients who received conventional agents in MAMMOTH. Median PFS was 4.6 months (95% CI, 3.7-6.4) versus 3.4 months (95% CI, 2.8-4.0), and median OS from last line was 15.4 months (95% CI, 12.0-25.6) versus 9.3 months (95% CI, 8.1-10.6) for these patients in HORIZON and MAMMOTH, respectively. Conclusion: This indirect comparison of patients with RRMM refractory to anti-CD38 mAb therapy in HORIZON and MAMMOTH suggests longer survival outcomes with melflufen plus dexamethasone (median PFS and OS of 4.6 and 15.4 months, respectively) versus those with conventional agents, despite HORIZON having more heavily pretreated patients. This analysis underscores the high burden of disease and unmet needs for patients with RRMM and the feasibility of novel combination therapy in this setting. Disclosures Blade Creixenti: Takeda: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Mateos:Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: 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; GlaxoSmithKline: Honoraria; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: 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; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive: Honoraria, Membership on an entity's Board of Directors or advisory committees. Oriol:GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Amgen: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Larocca:GSK: Honoraria; Takeda: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: 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; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria. Cavo:Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; GlaxoSmithKline: Honoraria, Speakers Bureau; Karyopharm: Honoraria; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Rodríguez-Otero:Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Abbvie: Consultancy; Kite: Consultancy; Sanofi: Consultancy; Celgene/Bristol Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Medscape: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; GlaxoSmithKline: Consultancy, Current Employment, Current equity holder in publicly-traded company; Oncopeptides: Consultancy. Leleu:GSK: Honoraria; Sanofi: Honoraria; Novartis: Honoraria; Carsgen: Honoraria; Incyte: Honoraria; Merck: Honoraria; Amgen: Honoraria; Karyopharm: Honoraria; AbbVie: Honoraria; BMS-celgene: Honoraria; Janssen: Honoraria; Oncopeptide: Honoraria. Nadeem:Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Adaptive: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES. Hassoun:Novartis: Consultancy; Celgene: Research Funding; Takeda: Research Funding. Touzeau:Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; GlaxoSmithKline: Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Sanofi: Honoraria, Research Funding. Amor:Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; GSK: Membership on an entity's Board of Directors or advisory committees. Maisel:Takeda: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Texas Oncology: Current Employment; Karyopharm: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Texas Oncology: Current Employment; Celgene: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau. Mazumder:The Oncology Institute: Current Employment; Amgen: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau. Raptis:INTEGRA: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; UPMC: Current Employment. Puig:BRISTOL-MYERS SQUIBB: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; AMGEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; CELGENE: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; JANSSEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; TAKEDA: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; THE BINDING SITE: Consultancy, Honoraria. Zavisic:Oncopeptides AB: Current Employment, Current equity holder in publicly-traded company. Thuresson:Oncopeptides: Consultancy, Current equity holder in publicly-traded company; Statisticon: Current Employment. Harmenberg:Oncopeptides AB: Consultancy, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Medivir AB: Current equity holder in publicly-traded company; Ultupharma AB: Current equity holder in private company. Richardson:Celgene/BMS, Oncopeptides, Takeda, Karyopharm: Research Funding. OffLabel Disclosure: This is an indirect comparison of clinical studies, including a phase 2 investigational study of melflufen in RRMM

Background: Advances in therapy have improved outcomes in multiple myeloma (MM), but enhancement in overall survival (OS) has resulted in patients living with the burden of symptoms and complications of relapsed/refractory MM (RRMM) and prior lines of therapy (Vogl et al. Leuk Lymphoma. 2018;59:398; Kumar et al. Leukemia. 2017;31:2443). Elderly patients represent a particularly difficult-to-treat population with RRMM due to the additional presence of comorbidities, reduced fitness level, and treatment with concomitant medications (Larocca et al. Leukemia. 2018;32:1697). There is an unmet need for efficacious and convenient treatment options with manageable side effects to optimize tolerability for elderly patients with RRMM. Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate (PDC) that targets aminopeptidases and rapidly releases alkylating agents into tumor cells. In the phase 2 HORIZON study (OP-106; NCT02963493), melflufen plus dexamethasone (dex) demonstrated encouraging efficacy and a clinically manageable safety profile in patients with heavily pretreated RRMM (Richardson et al. EHA 2020. Abs. EP945). This analysis examines the efficacy and safety of melflufen plus dex in the subset of patients aged ≥75 years in the HORIZON study. Methods: Patients with RRMM must have received ≥2 prior lines of therapy, including an IMiD and a proteasome inhibitor, and been refractory to pomalidomide and/or an anti-CD38 monoclonal antibody. Pts received melflufen 40 mg intravenously on day 1 and dex 40 mg per week (20 mg in patients aged ≥75 years) during each 28-day treatment cycle until disease progression or unacceptable toxicity. The primary endpoint was overall response rate (ORR; ≥ partial response [PR]; investigator-assessed per International Myeloma Working Group criteria). Secondary endpoints included progression-free survival (PFS), OS, duration of response (DOR), and safety. An analysis was conducted in the intention-to-treat population for patients aged ≥75 years. Results: As of the data cutoff date (January 14, 2020), 157 patients were enrolled and treated; 25 (16%) were aged ≥75 years. Baseline characteristics for older patients were generally similar to that of the overall population and were indicative of a heavily pretreated population with a poor prognosis. Among patients aged ≥75 years, the median age was 77 years (range, 75-86); 32% had International Staging System stage 3; and 24% had extramedullary disease. Patients had received a median of 5 prior lines of therapy (range, 2-8), and 76% had triple-class-refractory MM. Efficacy results were consistent with those of the overall population and were not affected negatively by advanced patient age. ORR was 32% and 29% in patients aged ≥75 years and in the overall population, respectively (Table). In responding patients, median DOR was not reached in patients aged ≥75 years and was 5.5 months in the overall population. In patients aged ≥75 years and the overall population, median PFS was 5.6 months and 4.2 months, respectively, and median OS was 13.5 months and 11.6 months, respectively. In patients aged ≥75 years and the overall population, respectively, grade 3/4 AEs occurred in 96% and 89% of patients, most commonly neutropenia (44% and 53%), white blood cell count decrease (44% and 26%), thrombocytopenia (40% and 57%), and anemia (40% and 43%); the most common nonhematologic grade 3/4 AEs were pneumonia (20% and 10%), hypertension (12% and 2%), febrile neutropenia (12% and 6%), and hypophosphatemia (12% and 5%). Serious AEs occurred in 40% of patients aged ≥75 years and in 49% of the overall population, most commonly, pneumonia (16% [4 events] and 9% [14 events]); all other serious AEs in patients aged ≥75 years were observed in 1 patient each (4%). There were no treatment-related deaths. Conclusion: Melflufen, once monthly infusion, plus weekly dex demonstrated clinically meaningful efficacy and a manageable safety profile in older patients with heavily pretreated RRMM. In patients aged ≥75 years, treatment resulted in durable responses, with a safety profile consistent with that in previous reports. Further study is warranted to confirm these results suggesting that melflufen may be an efficacious, convenient, and tolerable therapy for elderly patients with RRMM who have limited treatment options. Disclosures Larocca: Amgen: Honoraria; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: 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; GSK: Honoraria; Takeda: Membership on an entity's Board of Directors or advisory committees. Richardson:Celgene/BMS, Oncopeptides, Takeda, Karyopharm: Research Funding. Oriol:Janssen: Consultancy; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees. Blade Creixenti:Takeda: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Cavo:Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; GlaxoSmithKline: Honoraria, Speakers Bureau; Karyopharm: Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Rodríguez-Otero:Janssen, BMS: Other: Travel, accommodations, expenses; BMS, Janssen, Amgen: Honoraria; Janssen, BMS, AbbVie, Sanofi, GSK, Oncopeptides, Kite, Amgen: Consultancy, Honoraria; Celgene-BMS: Consultancy, Honoraria; Mundipharma: Research Funding. Leleu:Amgen: Honoraria; AbbVie: Honoraria; Janssen: Honoraria; Oncopeptide: Honoraria; Carsgen: Honoraria; Incyte: Honoraria; Merck: Honoraria; Karyopharm: Honoraria; GSK: Honoraria; Sanofi: Honoraria; Novartis: Honoraria; BMS-celgene: Honoraria. Nadeem:Adaptive: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees. Hassoun:Celgene: Research Funding; Takeda: Research Funding; Novartis: Consultancy. Touzeau:Takeda: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; GlaxoSmithKline: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses. Amor:Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; GSK: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees. Maisel:Takeda: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Texas Oncology: Current Employment; Karyopharm: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Texas Oncology: Current Employment; Celgene: Honoraria, Speakers Bureau. Mazumder:Celgene: Honoraria, Speakers Bureau; The Oncology Institute: Current Employment; Amgen: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau. Raptis:INTEGRA: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; UPMC: Current Employment. Puig:JANSSEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; THE BINDING SITE: Consultancy, Honoraria; AMGEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; BRISTOL-MYERS SQUIBB: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; CELGENE: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; TAKEDA: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding. Thuresson:Statisticon: Current Employment; Oncopeptides: Consultancy, Current equity holder in publicly-traded company. Harmenberg:Oncopeptides AB: Consultancy, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Ultupharma AB: Current equity holder in private company; Medivir AB: Current equity holder in publicly-traded company. Gustavsson:PiezoMotor AB: Current equity holder in publicly-traded company; Sangus Jazz AB: Current equity holder in private company; Bristol-Myers Squibb: Divested equity in a private or publicly-traded company in the past 24 months; Celgene: Divested equity in a private or publicly-traded company in the past 24 months; XSpray AB: Divested equity in a private or publicly-traded company in the past 24 months; Vinnova: Honoraria; Episurf AB: Current equity holder in publicly-traded company; Nanexa AB: Current equity holder in publicly-traded company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides AB: Current Employment, Current equity holder in publicly-traded company. Mateos:GlaxoSmithKline: Honoraria; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: 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; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: 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; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: This is a phase 2 investigational study of melflufen in RRMM.

Background: In patients with relapsed/refractory multiple myeloma (RRMM), 29%-59% have high-risk (HR) cytogenetic abnormalities that are associated with poor treatment outcomes (Kumar et al. Leukemia. 2017;31:2443; Gandhi et al. Leukemia. 2019;33:2266). Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate (PDC) that targets aminopeptidases and rapidly releases alkylating agents into tumor cells. Melflufen plus dexamethasone (dex) showed clinically meaningful efficacy and a manageable safety profile in patients with heavily pretreated and poor-risk RRMM in the phase 2 HORIZON study (OP-106; NCT02963493; Richardson et al. EHA 2020. Abs. EP945). The overall response rate (ORR) was 29%, median progression-free survival (PFS) was 4.2 months, and median overall survival (OS) was 11.6 months. The most common nonhematologic grade 3/4 adverse event (AE) was pneumonia (10%). This is an analysis of the cytogenetic profile and a comparison of the efficacy for patients with and without HR cytogenetic abnormalities in the HORIZON study. Methods: Patients with RRMM had received ≥2 lines of prior therapy, including an IMiD and a proteasome inhibitor, and were refractory to pomalidomide and/or an anti-CD38 monoclonal antibody. Patients received melflufen 40 mg (intravenously on day 1 of each 28-day cycle) and dex 40 mg/wk until progressive disease or unacceptable toxicity. The primary endpoint was ORR (≥ partial response [PR]; investigator-assessed per International Myeloma Working Group criteria); secondary endpoints included PFS, OS, duration of response (DOR), and safety. At screening, cytogenetics were evaluated using plasma cells from bone marrow aspirate by interphase fluorescence in situ hybridization and by conventional karyotyping. HR cytogenetic abnormalities were classified by the presence of t(4;14), t(14;16), t(14;20), del(17/17p), or gain(1q) (Sonneveld et al. Blood. 2016;127:2955). Results: Of the 157 patients enrolled and treated (data cutoff date, January 14, 2020), 59 (38%) had HR cytogenetic abnormalities at screening. Cytogenetic status was missing/unknown in 31 patients (20%). Among patients with HR cytogenetics, gain(1q) was seen in 41 (69%), del(17p) in 31%, t(4:14) in 31%, t(14:16) in 7%, and t(14:20) in none. Although baseline characteristics were generally similar between patients with and without HR cytogenetics (Table), fewer patients with HR cytogenetics had triple-class-refractory MM (69%) than those without HR cytogenetics (80%). The ORR (95% CI) was 20% (11-33) in patients with HR cytogenetics and 35% (25-45) in patients without HR cytogenetics. Among responding patients with HR cytogenetics (n=12), 4 achieved a very good PR and 8 a PR, with a median DOR of 6.7 months (95% CI, 3.0-not evaluable). Median DOR was 5.1 months (95% CI, 3.9-7.5) in patients without HR cytogenetics (n=34). Median PFS was 3.1 months (95% CI, 2.1-5.4) and 4.4 months (95% CI, 3.8-5.1), respectively, and OS was 11.5 months (95% CI, 8.5-13.6) and 13.2 months (95% CI, 8.1-17.6), respectively, in patients with and without HR cytogenetics. Among patients with HR cytogenetics, the ORR was 24% (95% CI, 11-40) in patients with 1 HR cytogenetic abnormality (n=38) and 14% (95% CI, 3-36) in patients with ≥2 HR cytogenetic abnormalities (n=21). Median PFS was 2.9 months (95% CI, 1.9-7.6) and 4.4 months (95% CI, 1.9-6.5), and OS was 11.6 months (95% CI, 7.7-21.1) and 11.5 months (95% CI, 4.5-13.9) in patients with 1 and ≥2 HR cytogenetic abnormalities, respectively. In patients with HR cytogenetics (n=59) and the overall population (N=157), grade 3/4 AEs were reported in 92% and 89%, respectively; the most common grade 3/4 AEs were thrombocytopenia (51% and 57%), neutropenia (47% and 53%), and anemia (36% and 43%); the most common nonhematologic grade 3/4 AE was pneumonia (17% and 10%). Serious AEs occurred in 54% of patients with HR cytogenetics and in 49% of patients in the overall population, most commonly pneumonia (17% and 9%, respectively). Conclusions: In the HORIZON study, melflufen plus dex also showed efficacy in patients with HR cytogenetics. The safety profile of melflufen plus dex in patients with HR cytogenetics was consistent with that of the overall population. Taken together, these data support further evaluation of melflufen plus dex in RRMM with HR cytogenetics. Disclosures Mateos: GlaxoSmithKline: Honoraria; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: 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; Takeda: 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; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Oriol:Janssen: Consultancy; Amgen: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees. Larocca:Amgen: Honoraria; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: 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; GSK: Honoraria; Takeda: Membership on an entity's Board of Directors or advisory committees. Blade Creixenti:Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Cavo:BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; GlaxoSmithKline: Honoraria, Speakers Bureau; Karyopharm: Honoraria; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Rodríguez-Otero:Kite: Consultancy; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Sanofi: Consultancy; Abbvie: Consultancy; Medscape: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Celgene/Bristol Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); GlaxoSmithKline: Consultancy, Current Employment, Current equity holder in publicly-traded company; Oncopeptides: Consultancy. Leleu:BMS-celgene: Honoraria; Janssen: Honoraria; Sanofi: Honoraria; GSK: Honoraria; AbbVie: Honoraria; Oncopeptide: Honoraria; Karyopharm: Honoraria; Amgen: Honoraria; Carsgen: Honoraria; Incyte: Honoraria; Merck: Honoraria; Novartis: Honoraria. Nadeem:Adaptive: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Amgen: Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES. Hassoun:Takeda: Research Funding; Celgene: Research Funding; Novartis: Consultancy. Touzeau:Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Sanofi: Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Takeda: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding. Amor:Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees. Maisel:Texas Oncology: Current Employment; Texas Oncology: Current Employment; Amgen: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau. Mazumder:Takeda: Honoraria, Speakers Bureau; The Oncology Institute: Current Employment; Celgene: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau. Raptis:INTEGRA: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; UPMC: Current Employment. Puig:CELGENE: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; AMGEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; JANSSEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; THE BINDING SITE: Consultancy, Honoraria; TAKEDA: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; BRISTOL-MYERS SQUIBB: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau. Harmenberg:Oncopeptides AB: Consultancy, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Medivir AB: Current equity holder in publicly-traded company; Ultupharma AB: Current equity holder in private company. Gustavsson:Vinnova: Honoraria; XSpray AB: Divested equity in a private or publicly-traded company in the past 24 months; Celgene: Divested equity in a private or publicly-traded company in the past 24 months; Bristol-Myers Squibb: Divested equity in a private or publicly-traded company in the past 24 months; Sangus Jazz AB: Current equity holder in private company; PiezoMotor AB: Current equity holder in publicly-traded company; Episurf AB: Current equity holder in publicly-traded company; Nanexa AB: Current equity holder in publicly-traded company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides AB: Current Employment, Current equity holder in publicly-traded company. Thuresson:Oncopeptides: Consultancy, Current equity holder in publicly-traded company; Statisticon: Current Employment. Richardson:Celgene/BMS, Oncopeptides, Takeda, Karyopharm: Research Funding. OffLabel Disclosure: This is a phase 2 investigational study of melflufe in RRMM.

Background: Pts with RRMM are a very sick population due to disease symptoms, comorbidities, side effects from treatments, and age-related fragility (Chim et al. Leukemia. 2018;32:252). Pts often experience adverse events (AEs) that affect their quality of life and reduce treatment compliance; hematologic AEs are frequent. Inpatient services for the management of AEs are often necessary and a major cost driver, with costs rising per AE episode (highest for hematologic AEs; Felber et al. ASH 2019. Abs. 4725). Additionally, a real-world study suggested that >50% of pts with hematologic AEs require readmittance to the hospital after initial treatment (Yeaw et al. ISPOR 2020. Abs. PCN78). Published data to date come from real-world evidence, with limited reports from clinical trials. Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate (PDC) that targets aminopeptidases and rapidly releases alkylating agents into tumor cells. In the pivotal, phase 2, HORIZON study (OP-106; NCT02963493), melflufen plus dex showed clinically meaningful efficacy and a safety profile consisting primarily of clinically manageable hematologic AEs in pts with heavily pretreated RRMM (Richardson et al. EHA 2020. Abs EP945). This analysis aids to further elucidate the healthcare resource utilization of pts with RRMM treated with melfulfen in a clinical trial by evaluating the impact of AEs on hospitalizations in HORIZON. Methods: Pts with RRMM who had received ≥2 lines of prior therapy, including an IMiD and a proteasome inhibitor and were refractory to pomalidomide and/or an anti-CD38 monoclonal antibody were treated with melflufen and dex as described (Richardson et al. EHA 2020. Abs EP945). Data for specific AEs potentially related to the study drugs (melflufen and/or dex; TRAEs) requiring hospitalizations >24 h were compared with all potential TRAEs and within each preferred term with >1 event reported regardless of hospitalization. AEs were classified as TRAE if reported as related or possibly related to either study drug by the treating physician. Results: At the data cutoff date (14 Jan 2020), 157 pts were enrolled and had received ≥1 dose of study treatment; 35 (22%) had been hospitalized due to a TRAE. Pts hospitalized due to TRAEs had a median age of 63 y (range, 43-84); 31% had International Staging System stage 3 disease; 49% had high-risk cytogenetics; and 77% had triple-class-refractory MM. In the overall population (N=157), the most frequent grade 3/4 treatment-emergent AEs (TEAEs) were thrombocytopenia (57%), neutropenia (53%), and anemia (43%). Serious AEs occurred in 49% of pts, most commonly pneumonia (9%) and febrile neutropenia (5%). Of all 3713 TEAEs, 118 (3.2%) led to hospitalization. Of 2688 TRAEs, 58 (2.2%) resulted in hospitalization. Pneumonia and febrile neutropenia TRAEs resulted in the most hospitalizations, with 11 events (78.6% of pneumonia TRAEs; 0.41% of all TRAEs) and 10 events (83.3% of febrile neutropenia TRAEs; 0.37% of all TRAEs), respectively (Table). Grade 3/4 hematologic TRAEs resulting in hospitalization included thrombocytopenia (9 hospitalizations; 1.4% of thrombocytopenia TRAEs; 0.33% of all TRAEs) and neutropenia (2 hospitalizations; 0.3% of neutropenia TRAEs; 0.07% of all TRAEs). All TRAEs that resulted in hospitalization were grade 3/4 except for 2 events (1 pyrexia [grade 1]; 1 pneumonia [grade 2]). For 3 of 9 thrombocytopenia events and 1 of 2 neutropenia events, it was unclear whether the hospitalization was >24 h; however, they were included in current analysis. Conclusion: Within this heavily pretreated pt population, most TRAEs could be managed without the need for hospitalization. Hematologic AEs were common but led to few hospitalizations overall. Although 11 cases (78.6%) of TRAEs of pneumonia required hospitalization, these events represent only 0.41% of all TRAEs, and infections are normally expected in advanced RRMM (Blimark et al. Plasma Cell Disorders. 2015;100:107). Use of inpatient services are a major driver of economic burden in RRMM and have been shown to be highly utilized in less heavily pretreated populations than HORIZON (Yeaw et al. ISPOR 2020. Abs. PCN7; Felber et al. ASH 2019. Abs. 4725). Results of this analysis suggest limited use of inpatient services for TRAEs with melflufen plus dex. Further analyses of real-world data on melflufen are warranted to confirm the results presented from this analysis. Disclosures Nadeem: Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Adaptive: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES. Richardson:Celgene/BMS, Oncopeptides, Takeda, Karyopharm: Research Funding. Mateos:Adaptive: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: 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; Roche: 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. Oriol:GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy. Larocca:GSK: Honoraria; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Takeda: Membership on an entity's Board of Directors or advisory committees. Blade Creixenti:Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees. Rodríguez-Otero:Celgene/Bristol Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); GlaxoSmithKline: Consultancy, Current Employment, Current equity holder in publicly-traded company; Oncopeptides: Consultancy; Abbvie: Consultancy; Kite: Consultancy; Medscape: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Sanofi: Consultancy; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Leleu:Oncopeptide: Honoraria; Karyopharm: Honoraria; Sanofi: Honoraria; GSK: Honoraria; Amgen: Honoraria; Novartis: Honoraria; BMS-celgene: Honoraria; AbbVie: Honoraria; Carsgen: Honoraria; Incyte: Honoraria; Merck: Honoraria; Janssen: Honoraria. Hassoun:Novartis: Consultancy; Takeda: Research Funding; Celgene: Research Funding. Touzeau:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Sanofi: Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; GlaxoSmithKline: Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses. Amor:GSK: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Maisel:Texas Oncology: Current Employment; Amgen: Honoraria, Speakers Bureau; Texas Oncology: Current Employment; Celgene: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau. Mazumder:Celgene: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; The Oncology Institute: Current Employment. Raptis:UPMC: Current Employment; INTEGRA: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES. Puig:BRISTOL-MYERS SQUIBB: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; CELGENE: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; AMGEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; THE BINDING SITE: Consultancy, Honoraria; JANSSEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; TAKEDA: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding. Sandberg:Oncopeptides AB: Current Employment; Novo Nordisk AS: Divested equity in a private or publicly-traded company in the past 24 months, Ended employment in the past 24 months. Pelaez:Märsta Läkarhus AB: Ended employment in the past 24 months; Oncopeptides: Consultancy. Jaques:Pharma Biotech Consultants: Consultancy; Oncopeptides: Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Pfizer: Consultancy; Morphosys AG: Consultancy; Oncopeptides: Ended employment in the past 24 months. Orre:Oncopeptides: Current Employment. Cavo:GlaxoSmithKline: Honoraria, Speakers Bureau; Karyopharm: Honoraria; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. OffLabel Disclosure: This is phase 2 investigational study of melflufen in RRMM.

Background: With advances in therapy, outcomes have generally improved for pts with MM; however, pts with late-stage RRMM have limited treatment options and poor outcomes (Kumar et al. Leukemia. 2017;31:2443; Gandhi et al. Leukemia. 2019;33:2266). Pts with late-stage RRMM, often older and having comorbidities, require efficacious and tolerable therapies to maintain HRQoL (Richardson et al. Blood. 2019;134[suppl 1]:3487). Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate (PDC) that targets aminopeptidases and rapidly releases alkylating agents into tumor cells. In the pivotal, phase 2, HORIZON study (NCT02963493) melflufen plus dex showed an overall response rate of 29%, median progression-free survival of 4.2 months, median overall survival of 11.6 months, and a manageable safety profile (N=157; Richardson et al. EHA 2020. Abs EP945). A previous baseline (BL) HRQoL analysis concluded that the HORIZON population is representative of RRMM populations, with a poor overall HRQoL relative to other populations with advanced cancers (Richardson et al. ASH 2019. Abs 3487). This analysis evaluates HRQoL in pts with RRMM throughout treatment with melflufen plus dex in the HORIZON study. Methods: Eligible pts received melflufen 40 mg on d1 of each 28-day cycle plus dex 40 mg/wk (20 mg in pts aged ≥75 y). HRQoL was added as a secondary endpoint as an amendment to the HORIZON protocol, which allowed collection of data from a subset of pts using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 V.3 (EORTC QLQ-C30) and the EuroQOL 5 Dimension-3 Level (EQ-5D) questionnaires. EORTC QLC-C30 evaluates functional domains and symptoms on a scale from 0-100 (higher functional scores = better function; higher symptom scores = more symptomatology/problems). The EQ-5D index is evaluated on a scale from 0 (death) to 1 (perfect health) and the EQ-5D VAS is evaluated on a scale from 0 (death) to 100 (perfect health). Questionnaires were administered before dosing at BL (cycle [C] 1) and predose at intervals throughout the study. Descriptive data for pts with post-BL assessments at C2, C4, and C6 are presented herein. Pts with only BL questionnaire assessments were excluded from this analysis. Select EORTC QLQ-C30 and EQ-5D results are presented. This analysis is ongoing. Results: At HRQoL data cutoff (May 28, 2020), of the 64 pts with post-BL HRQoL assessments, 19 remained on therapy. Among 64 pts in the HRQoL subgroup, median age was 67 y (range, 46-84); 17% had International Staging System stage 3 disease; and 36% had high-risk cytogenetics at study entry. Pts had received a median of 5 prior lines of therapy (range, 2-10). At C2, C4, and C6, 97.9%, 98.9%, and 99.4% of pts with ongoing treatment completed HRQoL assessments. Mean EORTC QLQ-C30 summary score and mean EQ-5D scores were relatively constant from BL through C6 (Figure). EORTC QLQ-C30 global health status/QoL and emotional functioning had mean scores of 58.6 and 78.4, respectively, at BL and 63.0 and 83.7, respectively, at C6 (Table). Mean symptom scores at BL and C6 for pain were 39.1 and 29.0, respectively, and for fatigue were 39.4 and 38.2, respectively. The EQ-5D VAS and EQ-5D index scores were generally consistent throughout treatment, with mean scores of 61.4 and 0.75, respectively, at BL and 62.3 and 0.74, respectively, at C6. Among pts with HRQoL data and the overall population (n=64 and N=157, respectively; Jan 14, 2020 data cutoff date), 92% and 89% had ≥1 grade 3/4 AEs, respectively; most common AEs were white blood cell count decreased (42% and 26%), thrombocytopenia (41% and 57%), and anemia (39% and 43%); most common nonhematologic grade 3/4 AEs was pneumonia (14% and 10%). SAEs occurred in 47% of pts in the HRQoL group and 49% of patients overall, most commonly pneumonia (14% and 9%); there were no treatment-related deaths. Conclusion: The EORTC QLQ-C30 global health status/QoL score and EQ-5D VAS and index scores were consistent from BL throughout treatment, suggesting that melflufen plus dex preserves HRQoL in pts with RRMM. The safety profile of melflufen plus dex consisted primarily of clinically manageable hematologic AEs in the overall pt population. No new safety signals were observed in the HRQoL-evaluable population. These findings are encouraging as treatment-related AEs may negatively affect HRQoL in RRMM. Data should be interpreted with caution due to the attrition of pts over time. Disclosures Oriol: Sanofi: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Janssen: Consultancy. Richardson:Celgene/BMS, Oncopeptides, Takeda, Karyopharm: Research Funding. Mateos:Amgen: 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; Sanofi: 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; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. 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Rodríguez-Otero:Abbvie: Consultancy; Kite: Consultancy; Amgen: Honoraria; Medscape: Membership on an entity's Board of Directors or advisory committees; Celgene/Bristol Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Sanofi: Consultancy; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Oncopeptides: Consultancy; GlaxoSmithKline: Consultancy, Current Employment, Current equity holder in publicly-traded company. 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Maisel:Incyte: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Texas Oncology: Current Employment; Amgen: Honoraria, Speakers Bureau; Texas Oncology: Current Employment; Celgene: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau. Mazumder:Takeda: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; The Oncology Institute: Current Employment. Raptis:INTEGRA: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; UPMC: Current Employment. Puig:AMGEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; TAKEDA: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; BRISTOL-MYERS SQUIBB: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; JANSSEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; CELGENE: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; THE BINDING SITE: Consultancy, Honoraria. Strang:Karolinska Institutet: Current Employment; Oncopeptides: Consultancy. Sandberg:Novo Nordisk AS: Divested equity in a private or publicly-traded company in the past 24 months, Ended employment in the past 24 months; Oncopeptides AB: Current Employment. Jaques:Pfizer: Consultancy; Morphosys AG: Consultancy; Oncopeptides: Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Pharma Biotech Consultants: Consultancy; Oncopeptides: Ended employment in the past 24 months. Thuresson:Oncopeptides: Consultancy, Current equity holder in publicly-traded company; Statisticon: Current Employment. Orre:Oncopeptides: Current Employment. Leleu:GSK: Honoraria; Novartis: Honoraria; Amgen: Honoraria; Sanofi: Honoraria; Janssen: Honoraria; AbbVie: Honoraria; Oncopeptide: Honoraria; Karyopharm: Honoraria; Carsgen: Honoraria; Incyte: Honoraria; Merck: Honoraria; BMS-celgene: Honoraria. OffLabel Disclosure: This is a phase 2 investigational study of melflufen in RRMM.

Patients with myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML) are generally older and have more comorbidities. Therefore, identifying personalized treatment options for each patient early and accurately is essential. To address this, we developed a computational biology modeling (CBM) and digital drug simulation platform that relies on somatic gene mutations and gene CNVs found in malignant cells of individual patients. Drug treatment simulations based on unique patient-specific disease networks were used to generate treatment predictions. To evaluate the accuracy of the genomics-informed computational platform, we conducted a pilot prospective clinical study (NCT02435550) enrolling confirmed MDS and AML patients. Blinded to the empirically prescribed treatment regimen for each patient, genomic data from 50 evaluable patients were analyzed by CBM to predict patient-specific treatment responses. CBM accurately predicted treatment responses in 55 of 61 (90%) simulations, with 33 of 61 true positives, 22 of 61 true negatives, 3 of 61 false positives, and 3 of 61 false negatives, resulting in a sensitivity of 94%, a specificity of 88%, and an accuracy of 90%. Laboratory validation further confirmed the accuracy of CBM-predicted activated protein networks in 17 of 19 (89%) samples from 11 patients. Somatic mutations in the TET2, IDH1/2, ASXL1, and EZH2 genes were discovered to be highly informative of MDS response to hypomethylating agents. In sum, analyses of patient cancer genomics using the CBM platform can be used to predict precision treatment responses in MDS and AML patients.

Data are limited on whether to adjust high-dose chemotherapy before autologous hematopoietic cell transplant (autoHCT) in obese patients. This study explores the effects of dose adjustment on the outcomes of obese patients, defined as body mass index (BMI) >= 30 kg/m(2). Dose adjustment was defined as a reduction in standard dosing >= 20%, based on ideal, reported dosing and actual weights. We included 2 groups of US patients who had received autoHCT between 2008 and 2014. Specifically, we included patients with multiple myeloma (MM, n = 1696) treated with high-dose melphalan and patients with Hodgkin or non-Hodgkin lymphomas (n = 781) who received carmustine, etoposide, cytarabine, and melphalan conditioning. Chemotherapy dose was adjusted in 1324 patients (78%) with MM and 608 patients (78%) with lymphoma. Age, sex, BMI, race, performance score, comorbidity index, and disease features (stage at diagnosis, disease status, and time to transplant) were similar between dose groups. In multivariate analyses for MM, adjusting for melphalan dose and for center effect had no impact on overall survival (P = .894) and treatment-related mortality (TRM) (P = .62), progression (P = .12), and progression-free survival (PFS; P= .178). In multivariate analyses for lymphoma, adjusting chemotherapy doses did not affect survival (P = .176), TRM (P = .802), relapse (P = .633), or PFS (P = .812). No center effect was observed in lymphoma. This study demonstrates that adjusting chemotherapy dose before autoHCT in obese patients with MM and lymphoma does not influence mortality. These results do not support adjusting chemotherapy dose in this population. (C) 2018 American Society for Blood and Marrow Transplantation.

We analyzed late fatal infections (LFIs) in allogeneic stem cell transplantation (HCT) recipients reported to the Center for International Blood and Marrow Transplant Research. We analyzed the incidence, infection types, and risk factors contributing to LFI in 10,336 adult and 5088 pediatric subjects surviving for ≥2 years after first HCT without relapse. Among 2245 adult and 377 pediatric patients who died, infections were a primary or contributory cause of death in 687 (31%) and 110 (29%), respectively. At 12 years post-HCT, the cumulative incidence of LFIs was 6.4% (95% confidence interval [CI], 5.8% to 7.0%) in adults, compared with 1.8% (95% CI, 1.4% to 2.3%) in pediatric subjects; P < .001). In adults, the 2 most significant risks for developing LFI were increasing age (20 to 39, 40 to 54, and ≥55 years versus 18 to 19 years) with hazard ratios (HRs) of 3.12 (95% CI, 1.33 to 7.32), 3.86 (95% CI, 1.66 to 8.95), and 5.49 (95% CI, 2.32 to 12.99) and a history of chronic graft-versus-host disease GVHD (cGVHD) with ongoing immunosuppression at 2 years post-HCT compared with no history of GVHD with (HR, 3.87; 95% CI, 2.59 to 5.78). In pediatric subjects, the 3 most significant risks for developing LFI were a history of cGVHD with ongoing immunosuppression (HR, 9.49; 95% CI, 4.39 to 20.51) or without ongoing immunosuppression (HR, 2.7; 95% CI, 1.05 to 7.43) at 2 years post-HCT compared with no history of GVHD, diagnosis of inherited abnormalities of erythrocyte function compared with diagnosis of acute myelogenous leukemia (HR, 2.30; 95% CI, 1.19 to 4.42), and age >10 years (HR, 1.92; 95% CI, 1.15 to 3.2). This study emphasizes the importance of continued vigilance for late infections after HCT and institution of support strategies aimed at decreasing the risk of cGVHD. ispartof: BIOLOGY OF BLOOD AND MARROW TRANSPLANTATION vol:25 issue:2 pages:362-368 ispartof: location:United States status: published

PURPOSE Hematopoietic cell transplantation (HCT) is curative for hematologic disorders, but outcomes are historically inferior when using HLA-mismatched donors. Despite unrelated donor registries listing > 38 million volunteers, 25%-80% of US patients lack an HLA-matched unrelated donor, with significant disparity across ethnic groups. We hypothesized that HCT with a mismatched unrelated donor (MMUD) using post-transplant cyclophosphamide (PTCy), a novel strategy successful in overcoming genetic disparity using mismatched related donors, would be feasible and increase access to HCT. PATIENTS AND METHODS We performed a prospective phase II study of MMUD bone marrow HCT with PTCy for patients with hematologic malignancies. The primary end point was 1-year overall survival (OS), hypothesized to be 65% or better. 80 patients enrolled at 11 US transplant centers (December 2016-March 2019). Following myeloablative or reduced-intensity conditioning–based HCT, patients received PTCy on days +3, +4, with sirolimus and mycophenolate mofetil starting on day +5. We compared outcomes to Center for International Blood and Marrow Transplant Research contemporary controls receiving PTCy. RESULTS Notably, 48% of patients enrolled were ethnic minorities. 39% of pairs were matched for 4-6 out of 8 HLA alleles. The primary end point was met, with 1-year OS of 76% (90% CI, 67.3 to 83.3) in the entire cohort, and 72% and 79% in the myeloablative and reduced-intensity conditioning strata, respectively. Secondary end points related to engraftment and graft-versus-host-disease were reached. Multivariate analysis comparing the study group with other mismatched HCT controls found no significant differences in OS. CONCLUSION Our prospective study demonstrates the feasibility and effectiveness of HCT with an MMUD in the setting of PTCy. Remarkably, nearly half of the study participants belonged to an ethnic minority population, suggesting this approach may significantly expand access to HCT.

To understand the mechanisms that mediate germline genetic leukemia predisposition, we studied the inherited ribosomopathy Shwachman-Diamond syndrome (SDS), a bone marrow failure disorder with high risk of myeloid malignancies at an early age. To define the mechanistic basis of clonal hematopoiesis in SDS, we investigate somatic mutations acquired by patients with SDS followed longitudinally. Here we report that multiple independent somatic hematopoietic clones arise early in life, most commonly harboring heterozygous mutations in EIF6 or TP53. We show that germline SBDS deficiency establishes a fitness constraint that drives selection of somatic clones via two distinct mechanisms with different clinical consequences. EIF6 inactivation mediates a compensatory pathway with limited leukemic potential by ameliorating the underlying SDS ribosome defect and enhancing clone fitness. TP53 mutations define a maladaptive pathway with enhanced leukemic potential by inactivating tumor suppressor checkpoints without correcting the ribosome defect. Subsequent development of leukemia was associated with acquisition of biallelic TP53 alterations. These results mechanistically link leukemia predisposition to germline genetic constraints on cellular fitness, and provide a rational framework for clinical surveillance strategies., Understanding the molecular basis of leukaemia predisposition is essential for intervention. The authors here investigate germline genetic leukaemia predisposition by studying Shwachman-Diamond syndrome and report compensatory inactivating mutations in EIF6 and transforming biallelic TP53 alterations.

PURPOSE Severe (grade 3-4) acute graft-versus-host disease (AGVHD) is a major cause of death after unrelated-donor (URD) hematopoietic cell transplant (HCT), resulting in particularly high mortality after HLA-mismatched transplantation. There are no approved agents for AGVHD prevention, underscoring the critical unmet need for novel therapeutics. ABA2 was a phase II trial to rigorously assess safety, efficacy, and immunologic effects of adding T-cell costimulation blockade with abatacept to calcineurin inhibitor (CNI)/methotrexate (MTX)-based GVHD prophylaxis, to test whether abatacept could decrease AGVHD. METHODS ABA2 enrolled adults and children with hematologic malignancies under two strata: a randomized, double-blind, placebo-controlled stratum (8/8-HLA-matched URD), comparing CNI/MTX plus abatacept with CNI/MTX plus placebo, and a single-arm stratum (7/8-HLA-mismatched URD) comparing CNI/MTX plus abatacept versus CNI/MTX CIBMTR controls. The primary end point was day +100 grade 3-4 AGVHD, with day +180 severe-AGVHD-free-survival (SGFS) a key secondary end point. Sample sizes were calculated using a higher type-1 error (0.2) as recommended for phase II trials, and were based on predicting that abatacept would reduce grade 3-4 AGVHD from 20% to 10% (8/8s) and 30% to 10% (7/8s). ABA2 enrolled 142 recipients (8/8s, median follow-up = 716 days) and 43 recipients (7/8s, median follow-up = 708 days). RESULTS In 8/8s, grade 3-4 AGVHD was 6.8% (abatacept) versus 14.8% (placebo) ( P = .13, hazard ratio = 0.45). SGFS was 93.2% (CNI/MTX plus abatacept) versus 82% (CNI/MTX plus placebo, P = .05). In the smaller 7/8 cohort, grade 3-4 AGVHD was 2.3% (CNI/MTX plus abatacept, intention-to-treat population), which compared favorably with a nonrandomized matched cohort of CNI/MTX (30.2%, P < .001), and the SGFS was better (97.7% v 58.7%, P < .001). Immunologic analysis revealed control of T-cell activation in abatacept-treated patients. CONCLUSION Adding abatacept to URD HCT was safe, reduced AGVHD, and improved SGFS. These results suggest that abatacept may substantially improve AGVHD-related transplant outcomes, with a particularly beneficial impact on HLA-mismatched HCT.

Single-cell RNA-sequencing (scRNA-seq) provides a unique opportunity to study heterogeneous cell populations within tissues, including the intestinal epithelium, to gain detailed molecular insights into their biology. Many new putative markers of intestinal stem cells and their progeny have been described using single-cell transcriptomics, which has contributed to the identification of novel subpopulations of mature cell types and insight into their developmental trajectories. This approach has revealed tremendous cellular heterogeneity within the intestinal epithelium that is concordant with its diverse and multifaceted functions. We discuss the function of these subpopulations during tissue homeostasis, as well as putative subpopulations with inducible regenerative potential following tissue injury.

Shwachman-Diamond syndrome (SDS) is an inherited bone marrow failure syndrome with predisposition to developing leukemia. We found that multiple independent somatic hematopoietic clones arise early in life, most commonly harboring heterozygous mutations inEIF6orTP53.EIF6mutations cause functional compensation for the germline deficiency by alleviating the SDS ribosome joining defect, improving translation, and reducing p53 activation.TP53mutations decrease checkpoint activation without affecting ribosome assembly. We link development of leukemia with acquisition of biallelicTP53alterations. Our results define distinct pathways of clonal selection driven by germline fitness constraint and provide a mechanistic framework for clinical surveillance.

We examined the risk of subsequent neoplasms (SNs) and late mortality in children and adolescents undergoing allogeneic hematopoietic cell transplantation (HCT) for nonmalignant diseases (NMDs). We included 6028 patients (median age, 6 years; interquartile range, 1-11; range

Single-cell RNA-sequencing (scRNA-seq) provides a unique opportunity to study heterogeneous cell populations within tissues, including the intestinal epithelium, to gain detailed molecular insights into their biology. Many new putative markers of intestinal stem cells and their progeny have been described using single-cell transcriptomics, which has contributed to the identification of novel subpopulations of mature cell types and insight into their developmental trajectories. This approach has revealed tremendous cellular heterogeneity within the intestinal epithelium that is concordant with its diverse and multifaceted functions. We discuss the function of these subpopulations during tissue homeostasis, as well as putative subpopulations with inducible regenerative potential following tissue injury.

Maintenance (MT) may be prescribed after autologous stem cell transplant (ASCT) but there are often concerns about the impact on quality of life (QoL). QoL was compared between baseline patients (30-100 days post-ASCT and had not commenced MT); MT patients (100 days post-ASCT and receiving MT), and no MT (100 days post-ASCT and not receiving MT). Patients completed the EuroQoL five dimension (EQ-5D), the European Organization for Research and Treatment of Cancer QoL Questionnaire Core 30 (EORTC QLQ-C30), and the QoL Questionnaire Myeloma 20 module (QLQ-MY20). Differences between groups were explored with ordinary least squares regressions. Across US and Canada, 303 patients participated. Regression analyses found few differences between MT and no MT. Only diarrhea (EORTC-QLQ C30) and future perspectives (MY-20) domains differentiated; patients on MT scored worse for diarrhea (+9.43; p = .0358) and future perspectives (-11.39; p = .0196). Collectively, the results suggest that MT is not associated with a notable QoL detriment.

Optimal donor selection is critical for successful allogeneic hematopoietic cell transplantation (HCT). Donor sex and parity are well-established risk factors for graft-versus-host disease (GVHD), with male donors typically associated with lower rates of GVHD. Well-matched unrelated donors (URDs) have also been associated with increased risks of GVHD as compared with matched sibling donors. These observations raise the question of whether male URDs would lead to more (or less) favorable transplant outcomes as compared with parous female sibling donors. We used the Center for International Blood and Marrow Transplant Research registry to complete a retrospective cohort study in adults with acute myeloid leukemia, acute lymphoblastic leukemia, or myelodysplastic syndrome, who underwent T-cell replete HCT from these 2 donor types (parous female sibling or male URD) between 2000 and 2012. Primary outcomes included grade 2 to 4 acute GVHD (aGVHD), chronic GVHD (cGVHD), and overall survival. Secondary outcomes included disease-free survival, transplant-related mortality, and relapse. In 2813 recipients, patients receiving male URD transplants (n = 1921) had 1.6 times higher risk of grade 2 to 4 aGVHD (P < .0001). For cGVHD, recipient sex was a significant factor, so donor/recipient pairs were evaluated. Female recipients of male URD grafts had a higher risk of cGVHD than those receiving parous female sibling grafts (relative risk [RR] = 1.43, P < .0001), whereas male recipients had similar rates of cGVHD regardless of donor type (RR = 1.09, P = .23). Donor type did not significantly affect any other end point. We conclude that when available, parous female siblings are preferred over male URDs.

We studied the association between non-HLA donor characteristics (age, sex, donor-recipient relationship, blood group [ABO] match, and cytomegalovirus [CMV] serostatus) and transplant outcomes after T-cell-replete HLA-haploidentical transplantation using posttransplantation cyclophosphamide (PT-Cy) in 928 adults with hematologic malignancy transplanted between 2008 and 2015. Siblings (n = 358) and offspring (n = 450) were the predominant donors, with only 120 patients having received grafts from parents. Although mortality risks were higher with donors aged 30 years or older (hazard ratio, 1.39; P < .0001), the introduction of patient age to the Cox regression model negated the effect of donor age. Two-year survival adjusted for CMV seropositivity, disease, and disease risk index was lower in patients aged 55 to 78 years after transplantation of grafts from donors younger than 30 years (53%) or aged at least 30 years (46%) compared with younger patients who received grafts from donors younger than 30 years (61%) and at least 30 years (60%; P < .0001). Similarly, 2-year survival in patients aged 55 to 78 years was lower after transplantation of grafts from siblings (45%) or offspring (48%) compared with patients aged 18 to 54 years after transplantation of grafts from siblings (62%), offspring (58%), and parents (61%; P < .0001). Graft failure was higher after transplantation of grafts from parents (14%) compared with siblings (6%) or offspring (7%; P = .02). Other non-HLA donor characteristics were not associated with survival or graft failure. The current analyses suggest patient and disease, rather than non-HLA donor characteristics, predominantly influence survival in adults.

Hematopoietic cell transplantation (HCT) is a potentially curative treatment for children and adults with malignant and nonmalignant diseases. Despite increasing survival rates, long-term morbidity after HCT is substantial. Neurocognitive dysfunction is a serious cause of morbidity, yet little is known about neurocognitive dysfunction after HCT. To address this gap, collaborative efforts of the Center for International Blood and Marrow Transplant Research and the European Society for Blood and Marrow Transplantation undertook an expert review of neurocognitive dysfunction after HCT. In this review we define what constitutes neurocognitive dysfunction, characterize its risk factors and sequelae, describe tools and methods to assess neurocognitive function in HCT recipients, and discuss possible interventions for HCT patients with this condition. This review aims to help clinicians understand the scope of this health-related problem, highlight its impact on well-being of survivors, and help determine factors that may improve identification of patients at risk for declines in cognitive functioning after HCT. In particular, we review strategies for preventing and treating neurocognitive dysfunction in HCT patients. Finally, we highlight the need for well-designed studies to develop and test interventions aimed at preventing and improving neurocognitive dysfunction and its sequelae after HCT.

Correspondence: Donor body mass index does not predict graft versus host disease following hematopoietic cell transplantation

Hematopoietic cell transplantation (HCT) is a potentially curative treatment for children and adults with malignant and non-malignant diseases. Despite increasing survival rates, long-term morbidity following HCT is substantial. Neurocognitive dysfunction is a serious cause of morbidity, yet little is known about neurocognitive dysfunction following HCT. To address this gap, collaborative efforts of the Center for International Blood and Marrow Transplant Research and the European Society for Blood and Marrow Transplantation undertook an expert review of neurocognitive dysfunction following HCT. In this review, we define what constitutes neurocognitive dysfunction, characterize its risk factors and sequelae, describe tools and methods to assess neurocognitive function in HCT recipients, and discuss possible interventions for HCT patients with this condition. This review aims to help clinicians understand the scope of this health-related problem, highlight its impact on well-being of survivors, and to help determine factors that may improve identification of patients at risk for declines in cognitive functioning after HCT. In particular, we review strategies for preventing and treating neurocognitive dysfunction in HCT patients. Lastly, we highlight the need for well-designed studies to develop and test interventions aimed at preventing and improving neurocognitive dysfunction and its sequelae following HCT.

Context Prognosis for patients with RRMM and EMD is poor (Mangiacavalli et al. Ann Hematol. 2017;96:73). Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate (PDC) that targets aminopeptidases and thereby rapidly releases alkylating agents inside tumor cells. Melflufen plus dexamethasone showed meaningful efficacy and manageable safety in RRMM (HORIZON, NCT02963493; Richardson et al. J Clin Oncol. 2021;39:757-767). Objective To evaluate patients with EMD in HORIZON. Methods Patients with RRMM had ≥2 prior lines of therapy (e.g., immunomodulatory agent, proteasome inhibitor) and were refractory to pomalidomide and/or an anti-CD38 monoclonal antibody. Patients received melflufen 40 mg (intravenous; day 1 of each 28-day cycle) and dexamethasone 40 mg/week until progressive disease/unacceptable toxicity. The primary endpoint was overall response rate (ORR); secondary endpoints included progression-free survival (PFS), overall survival (OS), duration of response (DOR), and safety. Results As of January 14, 2020, 55 of 157 patients treated had EMD (49% soft tissue; 51% bone-related plasmacytoma). Median age was 64 years (range, 43–82); 35% had high-risk cytogenetics; 33% had International Staging System stage III; median prior lines of therapy was 5 (range, 2–12); 60% were refractory to prior alkylators; and 91% had triple-class refractory MM. In patients with EMD and overall, respectively, ORR was 23.6% and 29.3%; median DOR was 5.5 and 5.5 months; median PFS was 2.9 and 4.2 months; and median OS was 6.5 and 11.6 months. In patients with EMD who achieved ≥ partial response (PR; n=13) and ≥ stable disease (n=28), respectively, median PFS was 17.3 and 5.3 months, and median OS was 18.5 and 13.6 months. Interpretation of ≥ PR results may be limited due to low event number. Grade 3/4 treatment-emergent adverse events (TEAEs) occurred in 78% of patients with EMD and 89% overall. In patients with EMD, the most common grade 3/4 TEAEs were anemia (42%), thrombocytopenia (40%), and neutropenia (38%). No treatment-related deaths were reported. Conclusions In HORIZON, melflufen plus dexamethasone showed encouraging activity and no new safety concerns in the largest cohort of patients with RRMM with EMD reported to date. These data support further evaluation of melflufen plus dexamethasone in RRMM with EMD.

Relapsed acute myeloid leukemia (AML) is a significant challenge after allogeneic hematopoietic cell transplant (HCT). Multiparameter flow cytometry (MFC), conventional cytogenetics (CG), and fluorescence in situ hybridization (FISH) are routinely performed on bone marrow specimens prior to HCT to assess disease status. We questioned the extent by which pre-HCT evidence of minimal residual disease (MRD) detected by these standard assays, corresponded with post-HCT relapse. We conducted a single center, retrospective study of 166 AML patients who underwent HCT. Thirty-eight of one hundred sixty-six (23%) patients in complete remission (CR) or CR with incomplete count recovery (CRi) had MRD detectable by MFC, CG, or FISH. MRD was more frequently seen in patients with poor risk karyotype at diagnosis (P = 0.011). MRD-negative patients (MRDneg) had significantly longer overall survival (OS) and relapse-free survival than patients who were MRD positive (MRDpos) (P = 0.002 and 0.013, respectively). In patients with MRDpos prior to HCT, the presence of acute graft vs. host disease (GVHD) (grade ≥ 2) or chronic GVHD significantly improved progression free survival (PFS) (hazard ratio (HR) = 0.053 (95% confidence interval (CI): 0.01–0.279), P = 0.0005) and OS (HR = 0.211 (95% CI: 0.081–0.547), P = 0.0014).

The adult intestinal stem cells (ISCs), their hierarchies, mechanisms of maintenance and differentiation have been extensively studied. However, when and how ISCs are established during embryogenesis remains unknown. We show here that the transcription regulator Id2 controls the specification of embryonic Lgr5 + progenitors in the developing murine small intestine. Cell fate mapping analysis revealed that Lgr5 + progenitors emerge at E13.5 in wild‐type embryos and differ from the rest on the intestinal epithelium by a characteristic ISC signature. In the absence of Id2, the intestinal epithelium differentiates into Lgr5 + cells already at E9.5. Furthermore, the size of the Lgr5 + cell pool is significantly increased. We show that Id2 restricts the activity of the Wnt signalling pathway at early stages and prevents precocious differentiation of the embryonic intestinal epithelium. Id2‐deficient embryonic epithelial cells cultured ex vivo strongly activate Wnt target genes as well as markers of neoplastic transformation and form fast growing undifferentiated spheroids. Furthermore, adult ISCs from Id2‐deficient mice display a distinct transcriptional signature, supporting an essential role for Id2 in the correct specification of ISCs.

Background: Shwachman-Diamond Syndrome (SDS) is a bone marrow failure disorder caused by impaired removal of EIF6 from the nascent 60S ribosome subunit, resulting in defective ribosome assembly. SDS patients have a high risk of myeloid neoplasms (MN) and the prognosis of those that develop MN is poor. Knowledge of the kinetics and functional consequences of somatic mutation acquisition in SDS may offer insight into mechanism of transformation and the potential for therapuetic intervention. Methods: We performed whole exome sequencing of 45 samples from 30 patients, and validated recurrent somatically mutated genes using targeted sequencing with error suppression in prospectively collected samples from 110 patients in the North American SDS Registry. We correlated mutation status with clinical outcome and performed functional studies to understand the consequence of somatic mutations in SDS. Results: We detected somatic mutations in 74 of 98 (76%) patients with germline biallelic SBDS mutations (median 2 mutations/patient, range 0-21). We found no mutations in patients with SDS-like disease; those who have clinical features of SDS without disease defining mutations. Of the 83 patients with SDS without a MN diagnosis, 60 (72%) had detectable clonal hematopoiesis (CH), 40 of whom had more than one mutation (median 3, range 1-21). The most frequently mutated genes were EIF6 (60/98, 61%),TP53 (44/98, 45%), PRPF8 (12/98, 12%), and CSNK1A1 (6/98, 6%). Among SDS patients with TP53 mutated CH, 90.9% (30 of 33) had concurrent EIF6 mutations. To determine whether EIF6 and TP53 mutations occur in the same or different clones, we performed single cell DNA sequencing. Among the 47 clones identified with either EIF6 or TP53 mutations, 24 had a sole EIF6 mutation, and 21 had a sole TP53 mutation, showing that these mutations arise in separate clones. To study the functional consequences of EIF6 missense mutations, we cloned 7 patient-derived mutations and generated cell lines expressing wild-type or mutant EIF6 cDNA. We found six mutants (I13N, R67W, G69S, P73R, A194T, G196R) reduced levels of EIF6 protein compared with wild type EIF6, despite comparable abundance of mRNA. The most common recurrent mutation, N106S, was found in 20% of patients and, by contrast to others listed above, did not change protein expression. This mutation is located at the EIF6/60S protein interface and disrupted the interaction of N106S-EIF6 with the 60S subunit as measured by polysome profiling followed by western blotting. To compare the effects of EIF6 versus TP53 somatic mutations in context of SDS deficient translation, we measured ribosome maturation and translation in SDS cells containing shRNAs targeting EIF6 or TP53. EIF6 knockdown ameliorated the SDS defect, reflected by improved ribosome joining (normalization of the 80:60s ratio) and enhanced protein translation (increased O-propargyl-puromycin incorporation), whereas TP53 knockdown had no effect. Knockdown of EIF6 in SDS deficient cells decreased p53 pathway activation as demonstrated by decreased CDKN1A expression. TP53 mutations were significantly associated with MN diagnosis (p=0.023), but were also common in SDS CH and typically stable over time. To identify the characteristics associated with transformation, we analyzed exomes from 7 patients with TP53 mutated myeloid malignancy for allelic imbalances at the TP53 locus and found that all 7 had biallelic alteration of TP53. Using single cell DNA sequencing from serial samples, we observed that TP53 LOH can precede transformation by several years and can distinguish pre-leukemic clones from indolent clones with monoallelic TP53 alterations. Somatic EIF6 mutations were not found in the leukemic clones. These results suggest early detection of TP53 LOH may distinguish clones with leukemic potential. Conclusions: In SDS, impairment of ribosome maturation drives selection of clones with somatic EIF6 or TP53 mutations. EIF6 mutations promote competitive fitness by rescuing the SDS ribosome defect and decreasing p53 pathway activation, and do not contribute to malignant transformation. TP53 mutations decrease checkpoint activation without affecting ribosome assembly. These results provide genetic evidence that germline SBDS deficiency causes a global, disease-specific HSC fitness constraint that drives parallel development of somatic CH and provides a mechanistic rationale for clinical surveillance. Disclosures Dale: Emendo BioTherapeutics: Consultancy; X4 Pharmaceuticals: Research Funding; X4 Pharmaceuticals: Honoraria. Gansner:Alnylam Pharmaceuticals: Current Employment, Current equity holder in private company. Edwards:Jazz Pharmaceuticals: Consultancy, Honoraria. Fleming:DISC Medicine: Consultancy, Membership on an entity's Board of Directors or advisory committees. Lindsley:MedImmune: Research Funding; Takeda Pharmaceuticals: Consultancy; Bluebird Bio: Consultancy; Jazz Pharmaceuticals: Consultancy, Research Funding.

Introduction: VRD (bortezomib, lenalidomide, dexamethasone) and VCD (bortezomib, cyclophosphamide, dexamethasone) are the two most commonly used triplet induction regimens in transplant eligible patients with multiple myeloma (MM). VCD is commonly used in patients with renal dysfunction at diagnosis. Given the variable results seen in head to head comparison of these (or similar) regimens to date, no definitive conclusion can be made on whether they are equivalent. This large CIBMTR registry study compares the outcomes with VRD vs. VCD induction therapy in patients undergoing upfront autologous stem cell transplant (ASCT). Methods: Patients were included if they underwent upfront ASCT for MM from January 2013 to December 2018 within 6 months of diagnosis, received VRD or VCD induction therapy and achieved at least a partial response pre-transplant. Of 1,135 patients, 914 patients received VRD and 221 received VCD therapy. Cox proportional hazards models were created for progression-free survival (PFS) and overall survival (OS). The following covariates were adjusted in the models: induction regimen (main effect), age, sex, race, performance score, hematopoietic cell transplant-comorbidity index (HCT-CI), estimated glomerular filtration rate (eGFR) at diagnosis, immunoglobulin subtype, cytogenetics, ISS stage, response status at transplant, melphalan dose, and maintenance therapy. Results: As shown in Table 1, patients in the VRD and VCD cohorts had similar age at transplant, adjusted HCT-CI scores, and distribution of high-risk cytogenetics. Patients in the VCD group were more likely to have renal impairment and ISS stage III disease. An eGFR (mL/min/1.73m2) at diagnosis < 60 was seen in 26% of VRD patients vs. 48% of VCD patients. ISS stage III was seen in 17% vs. 34% of patients, respectively. Treatment and Response: Pre-transplant response in the VRD cohort was: complete response (CR)- 17%, very good partial response (VGPR)- 48% and partial response (PR)- 35%. Response in the VCD cohort was: CR- 17%, VGPR- 42% and PR- 41%. Conditioning dose was melphalan 200 mg/m2 in 80% of patients receiving VRD vs. 69% in the VCD group. Post-transplant response was at least VGPR in 74% vs. 75% of patients, respectively. Maintenance in the VRD group was: lenalidomide based (+/- bortezomib)- 80%, bortezomib based- 5%, other-3% and none- 12% of patients. In the VCD group, maintenance was: lenalidomide based- 63%, bortezomib based- 11%, other- 1% and none- 24%. Survival: Patients receiving VRD induction had superior outcomes compared to VCD induction with median PFS from transplant of 44.6 (38.0-55.8) months vs 34.1 (25.8-44.7) months, p 0.004 respectively. Median OS was not reached for either group, with 5-year OS 79 (74-83)% for VRD and 60 (50-69)% for VCD, p Conclusions: In patients with MM undergoing upfront transplant after VRD or VCD induction, no difference in outcomes was seen based on the induction therapy received after adjusting for other prognostic factors. As several MM patients with renal dysfunction are started on VCD, it is reassuring to see that VCD was not associated with inferior PFS, likely due to the eventual transition to maintenance therapy in the majority due to subsequent improvement of renal function. The use of maintenance treatment was uniformly associated with superior outcomes. Disclosures Sidana: Janssen: Consultancy. Kumar:Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Kite Pharma: Consultancy, Research Funding; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Dr. Reddy's Laboratories: Honoraria; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Novartis: Research Funding; Sanofi: Research Funding; MedImmune: Research Funding; Karyopharm: Consultancy; BMS: Consultancy, Research Funding; Tenebio: Other, Research Funding; Genecentrix: Consultancy; Carsgen: Other, Research Funding; Cellectar: Other; Merck: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy. Giralt:Johnson & Johnson: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Actinuum: Other: Advisory board, Research Funding; Amgen: Other: Advisory Board, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; OMEROS: Research Funding; SPECTRUM Pharma: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Membership on an entity's Board of Directors or advisory committees, Research Funding; PFIZER: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jensenn: Membership on an entity's Board of Directors or advisory committees, Research Funding; TAKEDA: Membership on an entity's Board of Directors or advisory committees, Research Funding; MILTENYI: Research Funding; JAZZ Pharmaceutical: Membership on an entity's Board of Directors or advisory committees. Qazilbash:Janssen: Research Funding; Bioclinica: Consultancy; Amgen: Research Funding; Angiocrine: Research Funding; Bioline: Research Funding. Shah:GSK, Amgen, Indapta Therapeutics, Sanofi, BMS, CareDx, Kite, Karyopharm: Consultancy; BMS, Janssen, Bluebird Bio, Sutro Biopharma, Teneobio, Poseida, Nektar: Research Funding. D'Souza:Janssen: Consultancy; Akcea: Consultancy; Imbrium: Consultancy; Merck: Research Funding; Pfizer: Consultancy; Teneobio: Research Funding; Amgen: Research Funding.

Background: Current treatments for MM consist of multidrug regimens combining a variety of drug classes including IMiDs, proteasome inhibitors (PIs), monoclonal antibodies (mAbs), alkylators, XP01 inhibitors, histone deacetylase inhibitors, and corticosteroids. Despite advances in therapy, outcomes remain poor for pts with RRMM. Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate (PDC) that targets aminopeptidases and rapidly releases alkylating agents into tumor cells. In the pivotal, phase 2 HORIZON study (NCT02963493), melflufen plus dex showed meaningful efficacy and a safety profile characterized primarily by clinically manageable hematologic adverse events (AEs) in heavily pretreated and poor-risk pts with RRMM (Richardson et al. EHA 2020. Abs. EP945). Preclinical data show that melflufen is 50-fold more potent than melphalan against MM cells due to an increased intracellular alkylator concentration (Wickstrom et al. Oncotarget. 2017;8:666641). Melflufen has a mechanism of action distinct from alkylators, with cytotoxicity independent of p53 activity (Slipicevic et al. AACR 2020. Abs. 1843). In this analysis, the clinical activity of melflufen is examined in a subset of pts exposed to prior alkylator therapy. Methods: Pts with RRMM had received ≥2 prior lines, including an IMiD and PI, and were refractory to pomalidomide and/or an anti-CD38 mAb. Pts received melflufen 40 mg on d1 of each 28-d cycle plus dex 40 mg/wk until progressive disease or unacceptable toxicity. The primary endpoint was overall response rate (ORR; ≥ partial response [PR]; assessed by the investigator per International Myeloma Working Group criteria). Secondary endpoints included duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. Refractoriness was defined as disease that failed to achieve a minimal response or progressed while on primary or salvage therapy or progressed within 60 d of last therapy. Results: Of 157 pts included (data cutoff date, Jan 14, 2020), 138 (88%) had been exposed to and 92 (59%) were refractory to prior alkylator therapy. Baseline characteristics for pts refractory to prior alkylators were generally consistent with those of the overall population apart from more advanced International Staging System score (ISS 3, 34% and 25%), number of prior lines of therapy (6 and 5), and triple-class-refractoriness (83% and 76%). As in the overall population, a high proportion of pts refractory to alkylators had high-risk cytogenetics (40%) and extramedullary disease (36%), representing a difficult-to-treat group. Overall, 60% of pts refractory to alkylators had been exposed to (median time since last exposure, 1.3 y) and 27% were refractory to an alkylator in ≥1 line, and 22% were refractory to an alkylator in the last line. The ORR (95% CI) was 20.7% (12.9-30.4) in pts refractory to prior alkylators and 29.3% overall (Table). Among responding pts refractory to prior alkylators (n=19), 1 achieved a stringent complete response, 6 a very good PR, and 12 a PR. Median DOR (95% CI) was 4.2 mo (3.2-7.6) in pts refractory to prior alkylators and 5.5 mo (3.9-7.6) overall. Median PFS (95% CI) was 3.7 mo (3.0-4.5) and 4.2 mo (3.4-4.9), respectively, and OS was 9.7 mo (6.2-13.2) and 11.6 mo (9.3-15.4), respectively, in pts refractory to prior alkylators and overall. ORR (95% CI) was 20.0% (10.0-33.7) and 21.4% (10.3-36.8) in pts who had received alkylator treatment for 6 mo, respectively; ORR in pts exposed to melphalan was 26.3% (95% CI, 16.9-37.7). The safety profile of melflufen plus dex in pts refractory to prior alkylators was consistent with that in the overall population. In pts refractory to prior alkylators and the overall population, grade 3/4 AEs were reported in 91% and 89% of pts, respectively most commonly thrombocytopenia (61% and 57%), neutropenia (57% and 53%), and anemia (43% and 43%). The most common nonhematologic AE was pneumonia (11% and 10%). Serious AEs occurred in 55% of pts refractory to prior alkylators and 49% of pts overall; most commonly pneumonia (9% and 9%) and febrile neutropenia (7% and 5%). Conclusion: Melflufen has a distinct mechanism of action from that of melphalan and other alkylators and in combination with dex showed efficacy in pts with disease refractory to prior alkylator therapy with a manageable safety profile. These results are consistent with those of previous preclinical and clinical studies. Disclosures Rodríguez-Otero: Janssen, BMS: Other: Travel, accommodations, expenses; Celgene-BMS: Consultancy, Honoraria; Mundipharma: Research Funding; BMS, Janssen, Amgen: Honoraria; Janssen, BMS, AbbVie, Sanofi, GSK, Oncopeptides, Kite, Amgen: Consultancy, Honoraria. Mateos:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: 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; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Oriol:Janssen: Consultancy; Sanofi: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees. Larocca:Amgen: Honoraria; Takeda: Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: 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. Blade Creixenti:Janssen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Cavo:AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Karyopharm: Honoraria; GlaxoSmithKline: Honoraria, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Leleu:AbbVie: Honoraria; Novartis: Honoraria; Amgen: Honoraria; GSK: Honoraria; Sanofi: Honoraria; Oncopeptide: Honoraria; Karyopharm: Honoraria; Incyte: Honoraria; Merck: Honoraria; BMS-celgene: Honoraria; Janssen: Honoraria; Carsgen: Honoraria. Nadeem:Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Amgen: Membership on an entity's Board of Directors or advisory committees; Adaptive: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES. Hassoun:Novartis: Consultancy; Celgene: Research Funding; Takeda: Research Funding. Touzeau:Amgen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; GlaxoSmithKline: Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Sanofi: Honoraria, Research Funding. Amor:Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Maisel:Takeda: Honoraria, Speakers Bureau; Texas Oncology: Current Employment; Amgen: Honoraria, Speakers Bureau; Texas Oncology: Current Employment; Celgene: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau. Mazumder:Takeda: Honoraria, Speakers Bureau; The Oncology Institute: Current Employment; Celgene: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau. Raptis:INTEGRA: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; UPMC: Current Employment. Puig:JANSSEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; TAKEDA: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; AMGEN: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; CELGENE: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; BRISTOL-MYERS SQUIBB: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding, Speakers Bureau; THE BINDING SITE: Consultancy, Honoraria. Thuresson:Statisticon: Current Employment; Oncopeptides: Consultancy, Current equity holder in publicly-traded company. Harmenberg:Ultupharma AB: Current equity holder in private company; Medivir AB: Current equity holder in publicly-traded company; Oncopeptides AB: Consultancy, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Other: TRAVEL, ACCOMMODATIONS, EXPENSES. Harlin:Oncopeptides AB: Consultancy, Current equity holder in publicly-traded company. Richardson:Celgene/BMS, Oncopeptides, Takeda, Karyopharm: Research Funding. OffLabel Disclosure: This is a phase 2 investigational study of melflufen in RRMM.

Background Despite international unrelated donor (URD) registries listing >36 million volunteer donors, 25-80% of U.S. patients lack an HLA-matched (8/8 alleles) URD, with greater disparities in access for ethnic minorities. We hypothesized that hematopoietic cell transplantation (HCT) with a mismatched unrelated donor (MMUD) using post-transplant cyclophosphamide (PTCY), a strategy successful in overcoming genetic disparity in related haplo-identical donor HCT (haplo HCT) would be associated with similar outcomes to haplo HCT and expand access to HCT. Selecting a MMUD may have benefits over a haplo donor, such as removing risk associated with donor specific antibodies, and allowing for preferential selection of other favorable donor factors, such as younger age. Methods The NMDP/BTM performed a prospective phase II study of MMUD bone marrow (BM) HCT with PTCY for patients with hematologic malignancies, with the primary hypothesis that 1-year overall survival (OS) would be 65% or greater. Patients with a suitable HLA matched sibling or URD were excluded. Matching for 4-7/8 at HLA-A, -B, -C, and -DRB1 was permitted. 80 patients enrolled (40 myeloablative conditioning (MAC) - using cyclophosphamide/TBI (n=6), busulfan/cyclophosphamide (n=3) or fludarabine/ busulfan (n=31); 40 reduced intensity conditioning (RIC) - using fludarabine/cyclophosphamide/TBI) at 11 U.S. transplant centers between Dec 2016 and March 2019. Patients received a fresh BM graft, PTCY on days +3, +4, with sirolimus/mycophenolate mofetil starting on day +5. Regimen intensity was at the center's discretion. We compared outcomes to three groups of contemporaneous controls, all receiving PTCY, whose data was collected by CIBMTR: MMUD using peripheral blood stem cells (PBSC) (n=143), and haplo using BM (n=398) or PBSC (n=1191). All analyses used standard stepwise Cox regression modeling, performed separately for MAC and RIC cohorts. The main variable of interest was the donor/graft type (all groups compared to the trial cohort of MMUD BM). Statistical significance is p=0.05. Results The study achieved its primary endpoint with 1-year OS of 76% (90% CI: 67.3-83.3) in the entire cohort; survival and GVHD-/relapse-free survival (GRFS, defined in table 1) were 72% and 37% in the MAC cohort and 79% and 53% in the RIC cohort, respectively. Additional study outcomes are shown in Table 1. Median patient age was 49 years old (yo) (range: 18-66, MAC) and 60 yo (range: 23-70, RIC). HCT were performed for acute leukemia (n=58), MDS (n=2), lymphoma (n=17) and CLL (n=3). Disease risk index was low (n=11), intermediate (n=63), high (n=13) or very high (n=4). KPS was Conclusion Our prospective study demonstrated that outcomes using MMUD in the setting of PTCY are similar to those obtained using a haplo donor. Approximately half of the study participants were ethnic minorities, a figure consistent with expectations based on donor availability within registries, but exceeding expectations in accrual to a prospective study. These results support the feasibility of using volunteer MMUDs to expand access to HCT, especially for ethnically diverse patients. Next steps include expanding the MMUD PTCY approach to incorporate PBSC as a graft source and prospectively studying questions related to selection based on donor characteristics and additional GVHD prophylaxis agents. Disclosures Shaw: Orca Bio: Consultancy. Khimani:Bristol Myers Squibb-Moffitt-Alliance: Research Funding. Shah:Cell Vault: Research Funding; Celgene: Consultancy, Honoraria; Verastim: Consultancy; Lily: Consultancy, Honoraria; TG Therapeutics: Consultancy; Incyte: Consultancy; Miltenyi Biotec: Honoraria, Research Funding; Kite Pharma: Consultancy, Honoraria. Farhadfar:CSL Behring: Research Funding; Incyte pharmaceutical: Other: Member of GVHD advisory forum. Hardy:Kite/Gilead: Other: Advisory Board Member; Incyte Corporation: Other: Advisory Board Member; American Gene Technologies: Other: DSMB Member. Perales:Medigene: Membership on an entity's Board of Directors or advisory committees, Other; NexImmune: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Other; Bellicum: 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; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Nektar Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Consultancy, Honoraria; Kite/Gilead: Honoraria, Research Funding; Miltenyi Biotec: Research Funding; Incyte Corporation: Honoraria, Research Funding; MolMed: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Omeros: Honoraria, Membership on an entity's Board of Directors or advisory committees; Cidara Therapeutics: Other; Celgene: Honoraria. Komanduri:Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Adaptimmune: Membership on an entity's Board of Directors or advisory committees; Atara: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Takeda: Consultancy; Kiadis: Consultancy. Luznik:Merck: Research Funding, Speakers Bureau; AbbVie: Consultancy; WindMil Therapeutics: Patents & Royalties: Patent holder; Genentech: Research Funding. Pidala:Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; CTI Biopharma: 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; Novartis: Research Funding; Takeda: Research Funding; Janssen: Research Funding; Johnson and Johnson: Research Funding; Pharmacyclics: Research Funding; Abbvie: Research Funding; BMS: Research Funding. Devine:Magenta Therapeutics: Consultancy. Bolanos-Meade:Incyte: Other: DSMB Fees.

Context: Outcomes in RRMM remain poor (Kumar et al. Leukemia. 2017; 31:2443), and treatment options are limited for RRMM refractory to multiple drug classes (Gandhi et al. Leukemia. 2019; 33:2266). Melphalan flufenamide (melflufen) is a first-in-class anticancer peptide-drug conjugate that rapidly delivers an alkylating payload into tumor cells. A phase 1/2 study established the dosage of melflufen plus dexamethasone in RRMM (Richardson et al. Lancet Haematol. 2020; 7:e395). Objective: Evaluate the efficacy and safety of melflufen plus dexamethasone in RRMM in the pivotal, single-arm, multicenter, phase 2 HORIZON study ( NCT02963493 ). Methods: Patients who had RRMM, ≥2 prior lines of therapy (≥1 IMiD + ≥1 proteasome inhibitor [PI]), and were refractory to pomalidomide and/or an anti-CD38 mAb received melflufen plus dexamethasone until progressive disease or unacceptable toxicity. Primary endpoint: overall response rate (ORR; investigator-assessed per IMWG criteria). Secondary endpoints: duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. Subgroup analyses: triple-class–refractory (TCR) disease (refractory to or intolerant of ≥1 IMiD + ≥1 PI + ≥1 anti-CD38 mAb) and extramedullary disease (EMD). Results: Of 157 patients treated (intention-to-treat [ITT]); 26 remain on study (data cutoff: January 14, 2020). Median age: 65 years (range, 35-86); 25% had ISS stage III disease; and 35% had EMD. Median prior lines of therapy: 5 (range, 2-12); 76% had TCR disease. In the ITT, ORR was 29% (95% CI, 22-37); median (95% CI) DOR was 5.5 months (3.9-7.6); PFS was 4.2 months (3.4-4.9); and OS was 11.6 months (9.3-15.4). In patients with TCR disease and EMD, ORR was 26% (95% CI, 18-35) and 24% (95% CI, 13-37), respectively; DOR, PFS, and OS will be presented. Most common grade 3/4 adverse events (AEs): neutropenia (79%), thrombocytopenia (76%), and anemia (43%). Most common nonhematologic grade 3/4 AEs: pneumonia (10%) and hypophosphatemia (5%). AEs led to melflufen dose reduction and discontinuation in 27% and 22% of patients, respectively. Most common serious AEs were pneumonia (9%) and febrile neutropenia (5%). No treatment-related deaths. Conclusion: Melflufen plus dexamethasone showed clinically meaningful efficacy with a manageable safety profile in heavily pretreated RRMM, including in patients with TCR disease and EMD.

Background Despite increasing donor options for allogeneic transplantation, including matched/mismatched related donors, matched unrelated donors and cord blood units, a proportion of patients do not find a donor. This is especially relevant in patients from racial/ethnic minorities. Post-transplant cyclophosphamide (PTCY) has successfully overcome barriers related to HLA-mismatching in the related donor setting. We hypothesized that transplantation with a mismatched unrelated donor (MMUD) using PTCY would be feasible and associated with high engraftment and acceptable GVHD incidence. Methods We performed a prospective Phase II study of MMUD bone marrow (BM) transplantation with PTCY for patients with hematologic malignancies. Patients with a suitable HLA matched related or URD were excluded. Patients received a fresh BM graft, followed by PTCY on days +3, +4, Sirolimus/MMF starting on Day+5. Matching for 4-7/8 at HLA-A, -B, -C, and –DRB1 was permitted. We enrolled 80 patients (40 full intensity conditioning [FIC]; 40 reduced intensity conditioning [RIC]) at 11 transplant centers in the U.S. between Dec 2016 and March 2019. Regimen intensity was at the center's discretion. Results Characteristics are shown in Table 1. Importantly, 48% of patients were non-white/Hispanic, 55% had an HCT-CI >2 and 34% had a KPS of 1 HLA allele, 59% were under 30. Overall survival and non-relapse mortality at 100 days were 92% and 5% in the FIC arm, and 90% and 7.5% in the RIC arm (Table 2). Neutrophil recovery was 98% in both arms, with no primary graft failure in the FIC arm, and 7.5% in the RIC arm. Peripheral blood donor chimerism was >75% at all timepoints. Acute GVHD grade III-IV at day 100 was relatively high at 25% in the FIC arm but very low at 2.6% in the RIC arm. Viral reactivations were high (Table 3). Conclusion These early (day 100) results of our prospective study show high rates of engraftment with acceptable rates of GVHD in recipients of MMUD transplantation with PTCY, despite a high degree of HLA mismatch. An important finding is that ethnic minorities represent almost 50% of the study population, showing that this approach expands access to patients in need of potentially curative therapy. BK and HHV-6 virus reactivation/infection were common, the clinical significance of which requires further study. Understanding the risks for and impact of graft failure and acute GVHD is being studied as follow up continues.

Allogeneic hematopoietic cell transplant is a potential curative therapy for acute lymphoblastic leukemia (ALL). Delineating the graft-versus-leukemia (GVL) effect as a function of graft-versus-host disease (GVHD) offers the potential to improve survival. We examined 5215 transplant recipients with ALL reported to the Center for International Blood and Marrow Transplant Research registry. Overall survival (OS) was compared according to the presence and severity of GVHD and evaluated in 3 cohorts: 2593 adults in first or second complete remission (CR1/CR2), 1619 pediatric patients in CR1/CR2, and 1003 patients with advanced (CR ≥3 or active disease) ALL. For patients in CR1/CR2, development of acute GVHD (aGVHD) or chronic GVHD (cGVHD) was associated with lower risk of relapse than no GVHD (hazard ratio [HR], 0.49-0.69). Patients with advanced ALL developing grades III and IV aGVHD or cGVHD were also at lower risk of relapse (HRs varied from 0.52 to 0.67). Importantly, adult and children in CR1/CR2 with grades I and II aGVHD without cGVHD experienced the best OS compared with no GVHD (reduction of mortality with HR, 0.83-0.76). Increased nonrelapse mortality accompanied grades III and IV aGVHD (HRs varied from 2.69 to 3.91) in all 3 cohorts and abrogated any protection from relapse, resulting in inferior OS. Patients with advanced ALL had better OS (reduction in mortality; HR, 0.69-0.73) when they developed cGVHD with or without grades I and II aGVHD. In conclusion, GVHD was associated with an increased GVL effect in ALL. GVL exerted a net beneficial effect on OS only if associated with low-grade aGVHD in CR1/CR2 or with cGVHD in advanced ALL.

Summary Organoids allow the recapitulation of intestinal homeostasis and cancerogenesis in vitro; however, RNA sequencing (RNA-seq)-based methods for drug screens are missing. We develop targeted organoid sequencing (TORNADO-seq), a high-throughput, high-content drug discovery platform that uses targeted RNA-seq to monitor the expression of large gene signatures for the detailed evaluation of cellular phenotypes in organoids. TORNADO-seq is a fast, highly reproducible time- and cost-effective ($5 per sample) method that can probe cell mixtures and their differentiation state in the intestinal system. We apply this method to isolate drugs that enrich for differentiated cell phenotypes and show that these drugs are highly efficacious against cancer compared to wild-type organoids. Furthermore, TORNADO-seq facilitates in-depth insight into the mode of action of these drugs. Our technology can easily be adapted to many other systems and will allow for more systematic, large-scale, and quantitative approaches to study the biology of complex cellular systems.

Although melphalan at a dose of 140 mg/m(2) (MEL140) is an acceptable conditioning regimen for autologous stem cell transplantation (ASCT) in multiple myeloma (MM) patients, very few studies compared it to the most commonly used dose of 200 mg/m(2) (MEL200). A retrospective review of records of MM patients (2001-2010) identified 33 patients who received MEL140 and 96 patients who received MEL200. As expected, significantly higher percentage of patients in the MEL140 arm were65 years or had cardiac ejection fraction50%, had Karnofsky score80, or had creatinine2 at the time of ASCT (P≤.01). There were no significant differences in incidence of treatment related mortality and morbidity. At a median follow-up of 74 months from ASCT, there were no significant differences in relapse free survival (RFS) and overall survival (OS) between the two groups. Similar proportion had myeloma status improve to ≥VGPR at 3 months post-ASCT. Usage of post-ASCT maintenance was similar. In multivariate cox proportional hazards model, only disease status of ≥VGPR at the time of ASCT significantly improved RFS (P=.024), but not OS (P=.104). In conclusion, MM patients who received MEL140 had similar long-term outcomes to MEL200 patients despite their older age and co-morbidities.

Previous studies have identified healthcare practices that may place undue pressure on related donors (RDs) of hematopoietic cell products and an increase in serious adverse events associated with morbidities in this population. As a result, specific requirements to safeguard RD health have been introduced to Foundation for the Accreditation of Cellular Therapy/The Joint Accreditation Committee ISCT and EBMT (FACT-JACIE) Standards, but the impact of accreditation on RD care has not previously been evaluated. A survey of transplant program directors of European Group for Blood and Marrow Transplantation member centers was conducted by the Donor Health and Safety Working Committee of the Center for International Blood and Marrow Transplant Research to test the hypothesis that RD care in FACT-JACIE accredited centers is more closely aligned with international consensus donor care recommendations than RD care delivered in centers without accreditation. Responses were received from 39% of 304 centers. Our results show that practice in accredited centers was much closer to recommended standards as compared with nonaccredited centers. Specifically, a higher percentage of accredited centers use eligibility criteria to assess RDs (93% versus 78%; P = .02), and a lower percentage have a single physician simultaneously responsible for an RD and their recipient (14% versus 35%; P = .008). In contrast, where regulatory standards do not exist, both accredited and nonaccredited centers fell short of accepted best practice. These results raise concerns that despite improvements in care, current practice can place undue pressure on donors and may increase the risk of donation-associated adverse events. We recommend measures to address these issues through enhancement of regulatory standards as well as national initiatives to standardize RD care.