Bashey, Asad

Abstract The role of haploidentical hematopoietic cell transplantation (HCT) using posttransplant cyclophosphamide (PTCy) for acute lymphoblastic leukemia (ALL) is being defined. We performed a retrospective, multivariable analysis comparing outcomes of HCT approaches by donor for adults with ALL in remission. The primary objective was to compare overall survival (OS) among haploidentical HCTs using PTCy and HLA-matched sibling donor (MSD), 8/8 HLA-matched unrelated donor (MUD), 7 /8 HLA-MUD, or umbilical cord blood (UCB) HCT. Comparing haploidentical HCT to MSD HCT, we found that OS, leukemia-free survival (LFS), nonrelapse mortality (NRM), relapse, and acute graft-versus-host disease (aGVHD) were not different but chronic GVHD (cGVHD) was higher in MSD HCT. Compared with MUD HCT, OS, LFS, and relapse were not different, but MUD HCT had increased NRM (hazard ratio [HR], 1.42; P = .02), grade 3 to 4 aGVHD (HR, 1.59; P = .005), and cGVHD. Compared with 7/8 UD HCT, LFS and relapse were not different, but 7/8 UD HCT had worse OS (HR, 1.38; P = .01) and increased NRM (HR, 2.13; P ≤ .001), grade 3 to 4 aGVHD (HR, 1.86; P = .003), and cGVHD (HR, 1.72; P ≤ .001). Compared with UCB HCT, late OS, late LFS, relapse, and cGVHD were not different but UCB HCT had worse early OS (≤18 months; HR, 1.93; P < .001), worse early LFS (HR, 1.40; P = .007) and increased incidences of NRM (HR, 2.08; P < .001) and grade 3 to 4 aGVHD (HR, 1.97; P < .001). Haploidentical HCT using PTCy showed no difference in survival but less GVHD compared with traditional MSD and MUD HCT and is the preferred alternative donor HCT option for adults with ALL in complete remission.

Background: Blasts and leukemic stem cells of acute myeloid leukemia (AML) as well as several other hematologic malignancies express CD123, potentially providing a target for novel therapies. Vibecotamab (XmAb14045, SQZ622) is a potent bispecific antibody targeting both CD123 and CD3 that stimulates targeted T cell-mediated killing of CD123-expressing cells, regardless of T cell antigen specificity. It is a full-length immunoglobulin molecule designed to be dosed intermittently. Methods: Patients with relapsed or refractory AML, B-cell acute lymphoblastic leukemia (B-ALL), blast phase chronic myelogenous leukemia, or blastic plasmacytoid dendritic cell neoplasm were eligible to enroll on this first-in-human, multicenter, open-label phase 1 dose-escalation study (XmAb14045-01) with standard 3+3 design. The primary objective was to estimate the maximum tolerated dose (MTD) or recommended dose and schedule of vibecotamab. Secondary objectives included safety, preliminary antileukemic activity, and pharmacokinetics/pharmacodynamics of vibecotamab. Treatment was administered weekly in 28-day cycles, using a weight-based dose with 3 escalating doses in the first week followed by escalating weekly doses. Therapy was continued for as long as tolerated and there was continuing evidence of therapeutic benefit in the opinion of the investigator. Treatment response was assessed by the 2017 European LeukemiaNet (ELN) criteria after Cycle 1 and after each odd-numbered cycle. CRS was graded using the CRS revised grading system (Lee et al., Blood, 2014). Results: At data cut-off, 104 patients with AML, 1 with B-cell ALL, and 1 with CML as their primary diagnosis have been treated at dosages from 0.003 to 12.0 µg/kg vibecotamab. Patients had a median age of 63 years and were heavily pretreated (median of 3 prior therapies [range 1-8], including 32 (30%) who had undergone prior allogeneic stem cell transplantation). The recommended initial priming dose is 0.75 µg/kg; no MTD has been identified. CRS or its component symptoms was the most common treatment-emergent adverse event (TEAE). CRS occurred in 62 of 106 patients (85% grade 1-2, 15% grade ≥3), the majority on the first dose. Additional events consistent with CRS or infusion related reaction were seen in 24% of subjects (chills, fever, tachycardia, hypotension, etc.), and they were mostly mild or moderate severity. No myelosuppression requiring dose modification or evidence of tumor lysis syndrome was seen. Response of CR (2), CRi (3) or MLFS (2) was observed in 7/51 patients (ORR=14%) treated at higher dose levels (0.75 µg/kg). Stable Disease was observed in an additional 36 patients (71%). No CR, CRi, or morphologic leukemia-free state (MLFS) responses were observed at lower doses. Antileukemic activity occurred quickly; 6 out of 7 responders achieved at least a MLFS response after first cycle. A characterization of responders versus non-responders revealed responding patients harbor a lower burden of disease and specific T-cell subtypes. No association was found between response status and CD123 target expression on AML blasts. Conclusions: Vibecotamab demonstrated evidence of antileukemic activity in heavily pretreated patients with relapsed/refractory AML treated at the ≥0.75 µg/kg doses cohorts, with a 14% response rate. CRS was the most common toxicity but was generally manageable with premedications. The study is ongoing with further optimization of dose and schedule. Biomarker data suggest a population of AML patients that are more likely to respond. Additional information will be provided at the time of the meeting. Disclosures Ravandi: Celgene: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Macrogenics: Research Funding. Stock:Adaptive Biotechnologies: Consultancy, Membership on an entity's Board of Directors or advisory committees; Research to Practice: Honoraria; American Society of Hematology: Honoraria; Leukemia and Lymphoma Society: Research Funding; Novartis: Research Funding; Abbvie: Honoraria, Research Funding; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kite: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; UpToDate: Honoraria. Foran:Xencor: Research Funding; H3Biosciences: Research Funding; Agios: Honoraria, Research Funding; Trillium: Research Funding; Takeda: Research Funding; Kura Oncology: Research Funding; Aptose: Research Funding; Aprea: Research Funding; Actinium: Research Funding; Boehringer Ingelheim: Research Funding; Abbvie: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Revolution Medicine: Consultancy. Mawad:Adaptive Biotechnologies: Speakers Bureau; Abbvie: Speakers Bureau. Blum:Celyad: Research Funding; Amerisource Bergen: Honoraria; Syndax: Membership on an entity's Board of Directors or advisory committees; Leukemia and Lymphoma Society: Research Funding; Xencor: Research Funding. Yang:Xencor: Current Employment, Current equity holder in publicly-traded company; Jazz Pharmaceuticals: Current equity holder in publicly-traded company, Ended employment in the past 24 months. Pastore:Novartis NIBR East Hanover New Jersey: Current Employment, Current equity holder in publicly-traded company; Memorial Sloan Kettering Cancer Center: Ended employment in the past 24 months. Johnson:Xencor: Current Employment, Current equity holder in publicly-traded company. Zheng:Xencor: Current Employment, Current equity holder in publicly-traded company; Tocagen: Ended employment in the past 24 months. Yilmaz:Pint Pharma: Honoraria; Pfizer: Research Funding; Daicho Sankyo: Research Funding. Mims:Syndax Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Kura Oncology: Membership on an entity's Board of Directors or advisory committees; Leukemia and Lymphoma Society: Other: Senior Medical Director for Beat AML Study; Jazz Pharmaceuticals: Other: Data Safety Monitoring Board; Agios: Consultancy; Novartis: Speakers Bureau.

Background: Primary and secondary [post-essential thrombocythemia (ET) or polycythemia vera (PV)] Myelofibrosis (MF) are clonal hematopoietic neoplasms marked by constitutive JAK-STAT activation, bone marrow fibrosis, cytopenias, and constitutional symptom burden. Allogeneic hematopoietic cell transplantation (HCT) is the only curative option in this disease. Median overall survival (OS) after JAK inhibitor (JAKi) discontinuation is poor, ranging from 6-24 months (Harrision et al. Ann Hematol. 2020). Haploidentical (Haplo)-HCT with post-transplant cyclophosphamide (PTCy) has improved donor availability, but data on post-HCT outcomes in MF remain scarce. Herein, we describe clinical outcomes of patients (pts) with MF who underwent haplo-HCT with PTCy. Methods: We conducted a multi-institutional study where we retrospectively reviewed charts to obtain pt, disease, and treatment characteristics of MF pts who underwent haplo-HCT from 2000 to 2019. Graft-versus-host-disease (GVHD), relapse, and non-relapse mortality (NRM) were described as cumulative incidences. OS and relapse free survival (RFS) were estimated using the Kaplan-Meier method. Univariate analyses were conducted with Cox or Fine and Gray regression. Results: Fifty-eight adult pts from 11 centers underwent haplo-HCT and were included in the analysis. Pt, disease, and HCT characteristics are listed in Table 1. Thirty-four (59%) pts were over 60 years of age at the time of HCT. Of the 53 pts in whom driver mutation data was available, JAK2 was reported in 34 (64%), CALR in 10 (19%), MPL in 4 (8%), and 5 (9%) were triple-negative. Twenty-two (38%) pts had HCT-CI ≥ 3. Median CD34+ cell dose was 6.81 (range: 2.3-28.6) x 106/kg. All pts received PTCy as a part of GVHD prophylaxis regimen. Median follow-up in this study was 28 (range: 3.3-75.7) months. Neutrophil and platelet engraftment was reported in 53 (91%) and 47 (81%) pts at a median time of 20 (range: 14-70) and 31 (range: 15-225) days, respectively. Five pts (9%) had graft failure. The cumulative incidences of all-grade acute and chronic GVHD were in 44% (95% CI: 31-56%) at 6 months and 31% (95% CI: 18-44%) at 2 years. Grade 3-4 acute GVHD was seen in 5 (9%) pts. Post-HCT relapse/disease persistence occurred in 12 (21%) pts with a median of 416 (range: 28-917) days. The 2-year estimates of OS, RFS, relapse and NRM were 69% (95% CI: 55-80%), 52% (95% CI: 37-65%), 21% (95% CI: 11-34%) and 27% (95% CI: 16-39%) respectively (Fig 1). On univariate analyses (Table 2), older age (HR 2.17, P=.012) and a higher HCT-CI (HR 1.4, P<.001) was associated with higher NRM. Higher HCT-CI was also associated with higher all-cause mortality (HR 1.38, P=.003). Bone marrow as a graft source was associated with a higher risk of relapse (HR 5.04, P<0.001, Fig 2), but did not significantly affect OS (HR 0.78, 95% CI: 0.18-3.46), RFS (HR 1.89, 95% CI: 0.71-5.02) or NRM (HR 0.58, 95% CI: 0.09-3.84). JAKi use prior to HCT, spleen size or type of driver mutation did not significantly affect outcomes. Conclusions: Based on this study, we conclude that haplo-HCT with PTCy is a valid option in pts with MF. The graft failure rates appear to be similar to those reported with sibling and unrelated donors. Older age, higher HCT-CI and bone marrow as graft source were associated with inferior outcomes. JAKi use prior to HCT or type of driver mutation did not significantly affect outcomes. Disclosures Grunwald: Trovagene: Consultancy; Daiichi Sankyo: Consultancy; Merck: Consultancy; Agios: Consultancy; Janssen: Research Funding; Cardinal Health: Consultancy; Incyte: Consultancy, Research Funding; Daiichi Sankyo: Consultancy; Forma Therapeutics: Research Funding; Amgen: Consultancy; Celgene: Consultancy; Incyte: Consultancy, Research Funding; Celgene: Consultancy; Celgene: Consultancy; Pfizer: Consultancy; Incyte: Consultancy, Research Funding; Merck: Research Funding; Astellas: Consultancy; Genentech/Roche: Research Funding; Premier: Consultancy; Premier: Consultancy; Astellas: Consultancy; Premier: Consultancy; Daiichi Sankyo: Consultancy; Agios: Consultancy; Abbvie: Consultancy; Merck: Consultancy; Pfizer: Consultancy; Trovagene: Consultancy; Trovagene: Consultancy; Abbvie: Consultancy; Abbvie: Consultancy; Agios: Consultancy; Forma Therapeutics: Research Funding; Forma Therapeutics: Research Funding; Astellas: Consultancy; Amgen: Consultancy; Amgen: Consultancy; Merck: Consultancy; Cardinal Health: Consultancy; Pfizer: Consultancy; Cardinal Health: Consultancy; Janssen: Research Funding; Genentech/Roche: Research Funding; Genentech/Roche: Research Funding. Dholaria:J&J: Research Funding; Takeda: Research Funding; Angiocrine: Research Funding; bms: Research Funding; Poseida: Research Funding. Abedin:Jazz Pharmaceuticals: Honoraria; Agios: Honoraria; Helsinn Healthcare: Honoraria; Pfizer: Research Funding; Helsinn Healthcare: Research Funding; Actinium Pharmaceuticals: Research Funding. Gupta:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy; Incyte: Honoraria, Research Funding; Bristol MyersSquibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sierra Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees. DeZern:MEI: Consultancy; Celgene: Consultancy, Honoraria; Astex: Research Funding; Abbvie: Consultancy. Gerds:Sierra Oncology: Research Funding; Pfizer: Research Funding; Celgene: Consultancy, Research Funding; CTI Biopharma: Consultancy, Research Funding; AstraZeneca/MedImmune: Consultancy; Incyte Corporation: Consultancy, Research Funding; Apexx Oncology: Consultancy; Roche/Genentech: Research Funding; Imago Biosciences: Research Funding; Gilead Sciences: Research Funding. Jain:Bristol Myer Squibb: Other: for advisory board participation; Takeda: Consultancy, Honoraria; CareDx: Other: Advisory Board.

Abstract Allogeneic hematopoietic cell transplantation (HCT) is the only curative therapy for myelofibrosis (MF). In this large multicenter retrospective study, overall survival (OS) in MF patients treated with allogeneic HCT (551 patients) and without HCT (non-HCT) (1377 patients) was analyzed with Cox proportional hazards model. Survival analysis stratified by the Dynamic International Prognostic Scoring System (DIPSS) revealed that the first year of treatment arm assignment, due to upfront risk of transplant-related mortality (TRM), HCT was associated with inferior OS compared with non-HCT (non-HCT vs HCT: DIPSS intermediate 1 [Int-1]: hazard ratio [HR] = 0.26, P < .0001; DIPSS-Int-2 and higher: HR, 0.39, P < .0001). Similarly, in the DIPSS low-risk MF group, due to upfront TRM risk, OS was superior with non-HCT therapies compared with HCT in the first-year post treatment arm assignment (HR, 0.16, P = .006). However, after 1 year, OS was not significantly different (HR, 1.38, P = .451). Beyond 1 year of treatment arm assignment, an OS advantage with HCT therapy in Int-1 and higher DIPSS score patients was observed (non-HCT vs HCT: DIPSS-Int-1: HR, 2.64, P < .0001; DIPSS-Int-2 and higher: HR, 2.55, P < .0001). In conclusion, long-term OS advantage with HCT was observed for patients with Int-1 or higher risk MF, but at the cost of early TRM. The magnitude of OS benefit with HCT increased as DIPSS risk score increased and became apparent with longer follow-up.

Introduction: Anti-PD-1 monoclonal antibodies (mAbs) are highly active in relapsed/refractory classical Hodgkin lymphoma (cHL), but most patients (pts) will still relapse. Given this, allogeneic stem cell transplantation (alloHSCT) remains an important option for pts after PD-1 blockade, as it offers the possibility of cure. Prior reports have suggested that alloHSCT after PD-1 mAbs may be associated with severe immune-related complications including acute graft-versus-host disease (GVHD), veno-occlusive disease (VOD) and cytokine release/febrile non-infectious syndrome (CRS). Prior studies of alloHSCT after PD-1 blockade in cHL have been limited by the small number of pts and short follow-up, preventing an accurate assessment of long-term outcomes and complications, risk factors for early toxicity, and the impact of transplant strategies such as choice of GVHD prophylaxis. We therefore assembled a large retrospective international cohort of cHL pts who underwent alloHSCT after PD-(L)1 blockade to better answer these questions, including an assessment of the impact of post-transplant cyclophosphamide (PTCy) on efficacy and toxicity. Methods: Medical records and databases were reviewed at 26 European and United States transplant centers to identify pts with cHL who underwent an alloHSCT any time after receiving a PD-1 or PD-L1 mAb. Response assessment was performed by local investigators according to Lugano 2014 criteria. Overall survival (OS), progression-free survival (PFS), cumulative incidence (CumInc) of relapse (CIR), non-relapse mortality (NRM), acute (a) and chronic (c) GVHD were estimated, as was the association between baseline variables and these outcomes. Results: Between 2014 and 2019, 150 pts were identified who underwent alloHSCT after a median of 10 (range, 1-74) doses of nivolumab (n=118), pembrolizumab (n=31), or avelumab (n=1). The median age was 31 (range 17-68) and pts had received a median of 4 (range, 2-11) lines of therapy prior to PD-(L)1 blockade. 138 pts (92%) had failed BV and 111 (74%) autologous HSCT. The best overall response to PD-(L)1 mAbs was CR for 62 pts (41%), PR for 55 (37%), SD for 17 (11%), PD for 15 (10%) and unknown for 1 (1%). Median time from last dose of PD-(L)1 mAb to alloHSCT was 80 days (range, 17-756) with 70 pts (47%) receiving intervening systemic therapy. At alloHSCT, 90 pts were in CR (60%), 45 in PR (30%), 5 in SD (3%), and 10 in PD (7%). Donors were haploidentical (n=71, 47%), matched sibling (n=29, 19%), matched unrelated (n=39, 26%), mismatched unrelated (n=7, 5%), cord blood (n=2, 1%), or unknown (n=2, 1%). Stem cell source was bone marrow (n=38, 25%), peripheral blood (n=110, 73%), or cord blood (n=2, 1%). GVHD prophylaxis included PTCy in 88 pts (59%) (69/71 (97%) with haploidentical donors; 19/79 (24%) with other donors). With a median post-alloHSCT follow-up for survivors of 23.8 months (range, 1-67), the 2y OS and PFS were 79% (95CI 71-86%) and 65% (95CI 55-73%), respectively, while the 2y CumIncs of relapse and NRM were 21% (95CI 13-29%) and 14%, (95CI, 8-22%), respectively (Fig. 1A-B). 27 pts have died, 3 due to disease and 24 to NRM, including aGVHD (n=7) and VOD (n=2). Veno-occlusive disease (VOD) occurred in 5 pts (day 100 CumInc 4%) and 29 pts (19%) developed CRS (grade 1 n=16; grade 2 n=7; grade 3 n=4; grade 4 n=2). The 6-month CumIncs of grade 2-4, grade 3-4 and grade 4 aGVHD were 39%, 16% and 8%, respectively. Hyperacute GVHD (onset ≤ 14 days after alloHSCT) occurred in 4% of pts and was fatal in 2 pts. The 2y CumInc of cGVHD was 45%. Neither receipt of > 10 doses (median) of anti-PD-(L)1 mAb nor undergoing alloHSCT ≤80 days (median) after last dose of PD-(L)1 mAb were associated with PFS or OS. However, pts with a shorter time to transplant (≤80 days) appeared to have a higher risk of severe (grade 3-4) aGVHD (6m CumInc 24% vs 9%, p=0.006). Recipients of PTCy in this cohort had lower 2y CumIncs of cGVHD (34% vs 58%, p=0.01) and relapse (12% vs 31%, p=0.02), superior 2y PFS (76% vs 54%, p=0.015), and similar rates of severe aGVHD (15% vs 18%, p=0.5), 2y NRM (12% vs 16%, p=0.5), and 2y OS (82% vs 78%, p=0.6). Conclusions: With extended follow-up of a large international cohort, our results argue that alloSCT performed after PD-(L)1 mAbs is a feasible strategy associated with an excellent PFS and a very low CIR for this disease. The use of PT-Cy appears to be associated with improved outcomes and may at present represent the optimal transplant strategy in this pt population. Figure Disclosures Corradini: kite: Honoraria; Abbvie: Honoraria; Servier: Honoraria; Sanofi: Honoraria; Takeda: Honoraria; Roche: Honoraria; Novartis: Honoraria; KiowaKirin: Honoraria; Janssen: Honoraria; Gilead: Honoraria; Daiichi Sankyo: Honoraria; Celgene: Honoraria; Amgen: Honoraria. Ho:Jazz Pharmaceuticals: Research Funding; Jazz Pharmaceuticals: Consultancy; Omeros Corporation: Membership on an entity's Board of Directors or advisory committees. Jaglowski:Kite: Consultancy, Other: advisory board, Research Funding; Novartis: Consultancy, Other: advisory board, Research Funding; Juno: Consultancy, Other: advisory board; Unum Therapeutics Inc.: Research Funding. Herrera:Adaptive Biotechnologies: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Gilead Sciences: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; AstraZeneca: Research Funding; Merck: Consultancy, Research Funding; Genentech, Inc.: Consultancy, Research Funding; Pharmacyclics: Research Funding; Immune Design: Research Funding; Kite Pharma: Consultancy, Research Funding. Blaise:Jazz Pharmaceuticals: Honoraria; Sanofi: Honoraria; Pierre Fabre medicaments: Honoraria; Molmed: Consultancy, Honoraria. Hamadani:Pharmacyclics: Consultancy; Sanofi Genzyme: Research Funding, Speakers Bureau; Merck: Research Funding; Otsuka: Research Funding; Janssen: Consultancy; Medimmune: Consultancy, Research Funding; ADC Therapeutics: Consultancy, Research Funding; Takeda: Research Funding; Celgene: Consultancy. Ansell:LAM Therapeutics: Research Funding; Affimed: Research Funding; Affimed: Research Funding; Trillium: Research Funding; Trillium: Research Funding; Seattle Genetics: Research Funding; Mayo Clinic Rochester: Employment; Mayo Clinic Rochester: Employment; Bristol-Myers Squibb: Research Funding; Affimed: Research Funding; Mayo Clinic Rochester: Employment; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; Affimed: Research Funding; LAM Therapeutics: Research Funding; Mayo Clinic Rochester: Employment; Seattle Genetics: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; Affimed: Research Funding; Trillium: Research Funding; Trillium: Research Funding; Bristol-Myers Squibb: Research Funding; Regeneron: Research Funding; Affimed: Research Funding; Mayo Clinic Rochester: Employment; Bristol-Myers Squibb: Research Funding; Regeneron: Research Funding; Regeneron: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; LAM Therapeutics: Research Funding; Regeneron: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Trillium: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; Mayo Clinic Rochester: Employment; Regeneron: Research Funding; Trillium: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; LAM Therapeutics: Research Funding; LAM Therapeutics: Research Funding; LAM Therapeutics: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Trillium: Research Funding; Affimed: Research Funding. Nieto:Astra-Zeneca: Research Funding; Affimed: Consultancy; Affimed: Research Funding; Novartis: Research Funding. Feldman:Celgene: Honoraria, Research Funding, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Other: Travel expenses, Speakers Bureau; Pfizer: Research Funding; AbbVie: Honoraria, Other: Travel expenses, Speakers Bureau; Portola Pharma: Research Funding; Kite Pharma: Honoraria, Other: Travel expenses, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Pharmacyclics: Honoraria, Other: Travel expenses, Speakers Bureau; Kyowa Hakko Kirin: Research Funding; Eisai: Research Funding; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Cell Medica: Research Funding; Roche: Research Funding; Corvus: Research Funding; Viracta: Research Funding; Trillium: Research Funding; Roche: Research Funding; Takeda: Honoraria, Speakers Bureau. McGuirk:ArticulateScience LLC: Other: Assistance with manuscript preparation; Bellicum Pharmaceuticals: Research Funding; Kite Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gamida Cell: Research Funding; Pluristem Ltd: Research Funding; Juno Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Research Funding; Novartis: Research Funding; Fresenius Biotech: Research Funding. Mohty:Jazz Pharmaceuticals: Honoraria, Research Funding. Stamatoulas Bastard:Celgene: Honoraria; Takeda: Consultancy. Houot:Bristol Myers Squibb: Honoraria; Merck Sharp Dohme: Honoraria. Manson:Bristol Myers Squibb: Honoraria. Orvain:Incyte: Honoraria; Novartis: Honoraria; Jazz Pharmaceuticals: Other: Travel & accommodations; Pfizer: Other: Travel & accommodations. Bouabdallah:Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Frigault:Novartis: Consultancy; Kite/Gilead: Honoraria; Nkarta: Consultancy; Incyte: Consultancy; Juno/Celgene: Consultancy; Foundation Medicine: Consultancy; Xenetic: Consultancy. Chen:Takeda: Consultancy; Kiadis: Consultancy; Magenta: Consultancy; Abbvie: Consultancy; Incyte: Consultancy. Lynch:T.G. Therapeutics: Research Funding; Rhizen Pharmaceuticals S.A: Research Funding; Takeda Pharmaceuticals: Research Funding; Juno Therapeutics: Research Funding; Incyte Corporation: Research Funding; Johnson Graffe Keay Moniz & Wick LLP: Consultancy. Smith:AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck Sharp & Dohme Corp: Consultancy, Research Funding; Acerta Pharma BV: Research Funding; Portola Pharmaceuticals: Research Funding; Pharmacyclics: Research Funding; Bristol-Myers Squibb (spouse): Research Funding; Denovo Biopharma: Research Funding; Genentech: Research Funding; Ignyta (spouse): Research Funding; Incyte Corporation: Research Funding; Ayala (spouse): Research Funding; Seattle Genetics: Research Funding. Byrne:Karyopharm: Research Funding. Cohen:Hutchison: Research Funding; Astra Zeneca: Research Funding; Janssen Pharmaceuticals: Consultancy; Seattle Genetics, Inc.: Consultancy, Research Funding; Bristol-Meyers Squibb Company: Research Funding; Takeda Pharmaceuticals North America, Inc.: Research Funding; Gilead/Kite: Consultancy; Genentech, Inc.: Consultancy, Research Funding; UNUM: Research Funding; ASH: Research Funding; LAM Therapeutics: Research Funding; Lymphoma Research Foundation: Research Funding. Svoboda:AstraZeneca: Consultancy; Celgene: Research Funding; Incyte: Research Funding; Pharmacyclics: Consultancy, Research Funding; Kyowa: Consultancy; Merck: Research Funding; BMS: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding. Santoro:Bayer: Consultancy, Speakers Bureau; MSD: Speakers Bureau; Arqule: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; AstraZeneca: Speakers Bureau; Gilead: Consultancy, Speakers Bureau; Servier: Consultancy, Speakers Bureau; Takeda: Speakers Bureau; BMS: Speakers Bureau; Roche: Speakers Bureau; Abb-Vie: Speakers Bureau; Amgen: Speakers Bureau; Celgene: Speakers Bureau; Novartis: Speakers Bureau; BMS: Consultancy; Lilly: Speakers Bureau; Sandoz: Speakers Bureau; Eisai: Consultancy, Speakers Bureau. Armand:Sigma Tau: Research Funding; Otsuka: Research Funding; Pfizer: Consultancy; ADC Therapeutics: Consultancy; Tensha: Research Funding; Affimed: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; Adaptive: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Infinity: Consultancy; Genentech: Research Funding. Zinzani:Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Portola: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Immune Design: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sandoz: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celltrion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy; Eusapharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Verastem: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kyowa Kirin: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TG Therapeutics: Honoraria, Speakers Bureau. Carlo-Stella:Servier: Consultancy, Honoraria, Other: Travel, accommodations; Genenta Science srl: Consultancy; Boehringer Ingelheim: Consultancy; F. Hoffmann-La Roche Ltd: Honoraria, Other: Travel, accommodations, Research Funding; Novartis: Consultancy, Research Funding; ADC Therapeutics: Consultancy, Other: Travel, accommodations, Research Funding; Sanofi: Consultancy, Research Funding; Rhizen Pharmaceuticals: Research Funding; Celgene: Research Funding; Amgen: Honoraria; AstraZeneca: Honoraria; Janssen Oncology: Honoraria; MSD: Honoraria; BMS: Honoraria; Janssen: Other: Travel, accommodations; Takeda: Other: Travel, accommodations.

PURPOSETo compare the outcomes of patients with Hodgkin or non-Hodgkin lymphoma undergoing nonmyeloablative haploidentical or unrelated cord blood (UCB) hematopoietic cell transplantation.PATIENTS AND METHODSWe retrospectively studied 740 patients with Hodgkin lymphoma (n = 283, 38%) and non-Hodgkin lymphoma (n = 457, 62%) age 18-75 years who received transplantations from 2009 to 2016. Data were reported to the Lymphoma Working Party of the European Society for Blood and Marrow Transplantation, Eurocord, or Center for International Blood and Marrow Transplant Research. Of the 526 patients who received haploidentical transplantation, 68% received bone marrow and 32% received peripheral blood. All patients received a uniform transplantation conditioning regimen (2 Gy of total-body irradiation, cyclophosphamide, and fludarabine) and graft-versus-host disease prophylaxis (calcineurin inhibitor and mycophenolate). In addition, patients who received a haploidentical transplantation received posttransplantation cyclophosphamide.RESULTSCompared with haploidentical bone marrow and peripheral-blood transplantations and adjusted for age, lymphoma subtype, and disease status, survival was lower after UCB transplantation (hazard ratio [HR], 1.55; P = .001; and HR, 1.59; P = .005, respectively). Similarly, progression-free survival was lower after UCB transplantations compared with haploidentical bone marrow and peripheral-blood transplantations (HR, 1.44; P = .002; and HR, 1.86; P < .0001), respectively. The 4-year overall and progression-free survival rates after UCB transplantation were 49% and 36%, respectively, compared with 58% and 46% after haploidentical bone marrow transplantation and 59% and 52% after peripheral-blood transplantation, respectively. Lower survival was attributed to higher transplantation-related mortality after UCB transplantation compared with haploidentical bone marrow and peripheral-blood transplantation (HR, 1.91; P = .0001; and HR, 2.27; P = .0002, respectively).CONCLUSIONWhen considering HLA-mismatched transplantation for Hodgkin or non-Hodgkin lymphoma, the data support haploidentical related donor transplantation over UCB transplantation.

Abstract Background: Blasts and leukemic stem cells of acute myeloid leukemia (AML) as well as several other hematologic malignancies express CD123, potentially providing a target for novel therapies. XmAb14045 (also known as SQZ622) is a potent bispecific antibody targeting both CD123 and CD3 that stimulates targeted T cell-mediated killing of CD123-expressing cells, regardless of T cell antigen specificity. It is a full-length immunoglobulin molecule designed to be dosed intermittently, in contrast to smaller constructs that are referred to as "DART" or "BiTE" bispecific antibodies that require a continuous infusion. Methods: Patients with relapsed or refractory AML, B cell acute lymphoblastic leukemia (B-ALL), blast phase chronic myelogenous leukemia, or blastic plasmacytoid dendritic cell neoplasm were eligible to enroll on this first-in-human, multicenter, open-label phase 1 dose-escalation study (XmAb14045-01) with standard 3+3 design. The primary objective was to estimate the maximum tolerated dose (MTD) or recommended dose and schedule of XmAb14045. Secondary objectives included safety, preliminary antileukemic activity, and pharmacokinetics/pharmacodynamics of XmAb14045. Treatment was administered weekly in 28 day cycles, using a weight-based dose with a single dose level in Part A and, in Part B, an initial priming dose on Day 1 followed by an escalated dose on subsequent weeks. Premedication to prevent cytokine release syndrome (CRS) was instituted as needed and included a steroid, acetaminophen, and diphenhydramine. Patients were premedicated at all XmAb14045 doses ≥0.075 µg/kg. Therapy was continued for as long as tolerated and there was continuing evidence of therapeutic benefit in the opinion of the investigator. Treatment response was assessed by the 2017 European LeukemiaNet (ELN) criteria after Cycle 1 and after each odd-numbered cycle. CRS was graded using the CRS revised grading system (Lee et al., Blood, 2014). Results: At data cut-off, 64 patients have been treated to date, 63 with relapsed/refractory AML and 1 with B-ALL. Patients had a median age of 61 years and were heavily pretreated (median of 3 prior therapies [range 1-8], including 19 [30%] who had undergone prior allogeneic stem cell transplantation). The recommended dose for Part A was 1.3 µg/kg after a single dose-limiting toxicity of Grade 4 CRS at 2.3 µg/kg; no MTD has been identified. CRS or its component symptoms was the most common treatment-emergent adverse event (TEAE). CRS episodes began within approximately 1-4 hours of the start of drug infusion and occurred in 49 of 64 patients (77%). Seven patients (11%) developed Grade ≥3 CRS, the majority of these on the first dose. There were no CRS-related deaths. Excluding CRS-related events, additional TEAEs occurring in >10% of patients included fatigue (31%), febrile neutropenia (30%), peripheral edema (30%), cough (23%), elevated hepatic transaminases (19%; all recovered without sequelae), pneumonia (17%), stomatitis (14%), hyperglycemia (13%), and sepsis (11%). No myelosuppression requiring dose modification or evidence of tumor lysis syndrome was seen. In Part A, single agent antileukemic activity was documented with a best response of CR (2) or CRi (1) in 3/13 AML patients (CR/CRi rate 23%) treated at the two highest dose levels studied to date (1.3 and 2.3 µg/kg weekly); no CR, CRi, or morphologic leukemia-free state (MLFS) responses were seen at lower doses. Antileukemic activity occurred quickly; all responders had achieved at least an MLFS response after 4 doses (1 cycle). Two responders were bridged to stem cell transplantation, and the third was ineligible for medical reasons but remains in remission at 14+ weeks after initiating therapy. Conclusions: XmAb14045 demonstrated evidence of antileukemic activity in heavily pretreated patients with relapsed/refractory AML treated in Part A at the 1.3 and 2.3 µg/kg doses administered once weekly, with a 23% CR/CRi rate. CRS was the most common toxicity but was generally manageable with premedications. The study is ongoing with further optimization of dose, schedule, and premedication regimen for CRS anticipated during accrual to dose escalation cohorts in Part B. ClinicalTrials.gov Identifier: NCT02730312 Disclosures Ravandi: Xencor: Research Funding; Abbvie: Research Funding; Amgen: Honoraria, Research Funding, Speakers Bureau; Sunesis: Honoraria; Astellas Pharmaceuticals: Consultancy, Honoraria; Abbvie: Research Funding; Seattle Genetics: Research Funding; Macrogenix: Honoraria, Research Funding; Jazz: Honoraria; Sunesis: Honoraria; Seattle Genetics: Research Funding; Bristol-Myers Squibb: Research Funding; Astellas Pharmaceuticals: Consultancy, Honoraria; Orsenix: Honoraria; Xencor: Research Funding; Orsenix: Honoraria; Jazz: Honoraria; Bristol-Myers Squibb: Research Funding; Amgen: Honoraria, Research Funding, Speakers Bureau; Macrogenix: Honoraria, Research Funding. Foran:Xencor, Inc.: Research Funding; Agios: Research Funding. Stock:Jazz Pharmaceuticals: Consultancy. Mawad:Swedish Cancer Institute: Employment. Blum:Astellas: Consultancy; Pfizer: Consultancy; Boehringer Ingelheim: Research Funding; Forma: Research Funding; Xencor: Research Funding; Tolero: Research Funding. Saville:Xencor, Inc.: Employment, Equity Ownership. Johnson:Xencor, Inc.: Employment, Equity Ownership. Vanasse:Novartis: Employment, Equity Ownership. Ly:Xencor, Inc.: Employment, Equity Ownership. Mims:Novartis: Consultancy; Agios Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees.

Abstract Purpose: To develop a prognostic model and cytogenetic risk classification for previously treated patients with chronic lymphocytic leukemia (CLL) undergoing reduced intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (HCT). Experimental Design: We performed a retrospective analysis of outcomes of 606 patients with CLL who underwent RIC allogeneic HCT between 2008 and 2014 reported to the Center for International Blood and Marrow Transplant Research. Results: On the basis of multivariable models, disease status, comorbidity index, lymphocyte count, and white blood cell count at HCT were selected for the development of prognostic model. Using the prognostic score, we stratified patients into low-, intermediate-, high-, and very-high-risk [4-year progression-free survival (PFS) 58%, 42%, 33%, and 25%, respectively, P &lt; 0.0001; 4-year overall survival (OS) 70%, 57%, 54%, and 38%, respectively, P &lt; 0.0001]. We also evaluated karyotypic abnormalities together with del(17p) and found that del(17p) or ≥5 abnormalities showed inferior PFS. Using a multivariable model, we classified cytogenetic risk into low, intermediate, and high (P &lt; 0.0001). When the prognostic score and cytogenetic risk were combined, patients with low prognostic score and low cytogenetic risk had prolonged PFS (61% at 4 years) and OS (75% at 4 years). Conclusions: In this large cohort of patients with previously treated CLL who underwent RIC HCT, we developed a robust prognostic scoring system of HCT outcomes and a novel cytogenetic-based risk stratification system. These prognostic models can be used for counseling patients, comparing data across studies, and providing a benchmark for future interventions. For future study, we will further validate these models for patients receiving targeted therapies prior to HCT.

Abstract HLA-haploidentical hematopoietic cell transplantation (Haplo-HCT) using posttransplantation cyclophosphamide (PT-Cy) has improved donor availability. However, a matched sibling donor (MSD) is still considered the optimal donor. Using the Center for International Blood and Marrow Transplant Research database, we compared outcomes after Haplo-HCT vs MSD in patients with acute myeloid leukemia (AML) in first complete remission (CR1). Data from 1205 adult CR1 AML patients (2008-2015) were analyzed. A total of 336 patients underwent PT-Cy–based Haplo-HCT and 869 underwent MSD using calcineurin inhibitor–based graft-versus-host disease (GVHD) prophylaxis. The Haplo-HCT group included more reduced-intensity conditioning (65% vs 30%) and bone marrow grafts (62% vs 7%), consistent with current practice. In multivariable analysis, Haplo-HCT and MSD groups were not different with regard to overall survival (P = .15), leukemia-free survival (P = .50), nonrelapse mortality (P = .16), relapse (P = .90), or grade II-IV acute GVHD (P = .98). However, the Haplo-HCT group had a significantly lower rate of chronic GVHD (hazard ratio, 0.38; 95% confidence interval, 0.30-0.48; P &lt; .001). Results of subgroup analyses by conditioning intensity and graft source suggested that the reduced incidence of chronic GVHD in Haplo-HCT is not limited to a specific graft source or conditioning intensity. Center effect and minimal residual disease–donor type interaction were not predictors of outcome. Our results indicate a lower rate of chronic GVHD after PT-Cy–based Haplo-HCT vs MSD using calcineurin inhibitor–based GVHD prophylaxis, but similar other outcomes, in patients with AML in CR1. Haplo-HCT is a viable alternative to MSD in these patients.

BACKGROUNDEarly treatment failure (ETF) in follicular lymphoma (FL), defined as relapse or progression within 2 years of frontline chemoimmunotherapy, is a newly recognized marker of poor survival and identifies a high‐risk group of patients with an expected 5‐year overall survival (OS) rate of approximately 50%. Transplantation is an established option for relapsed FL, but its efficacy in this specific ETF FL population has not been previously evaluated.METHODSThis study compared autologous hematopoietic stem cell transplantation (auto‐HCT) with either matched sibling donor (MSD) or matched unrelated donor (MUD) allogeneic hematopoietic cell transplantation (allo‐HCT) as the first transplantation approach for patients with ETF FL (age ≥ 18 years) undergoing auto‐HCT or allo‐HCT between 2002 and 2014. The primary endpoint was OS. The secondary endpoints were progression‐free survival, relapse, and nonrelapse mortality (NRM).RESULTSFour hundred forty FL patients had ETF (auto‐HCT, 240; MSD hematopoietic stem cell transplantation [HCT], 105; and MUD HCT, 95). With a median follow‐up of 69 to 73 months, the adjusted probability of 5‐year OS was significantly higher after auto‐HCT (70%) or MSD HCT (73%) versus MUD HCT (49%; P = .0008). The 5‐year adjusted probability of NRM was significantly lower for auto‐HCT (5%) versus MSD (17%) or MUD HCT (33%; P < .0001). The 5‐year adjusted probability of disease relapse was lower with MSD (31%) or MUD HCT (23%) versus auto‐HCT (58%; P < .0001).CONCLUSIONSPatients with high‐risk FL, as defined by ETF, undergoing auto‐HCT for FL have low NRM and a promising 5‐year OS rate (70%). MSD HCT has lower relapse rates than auto‐HCT but similar OS. Cancer 2018;124:2541‐51. © 2018 American Cancer Society.