Citations

Abstract Purpose: Older patients with relapsed/refractory (R/R) large B-cell lymphoma (LBCL) may be considered ineligible for curative-intent therapy including high-dose chemotherapy with autologous stem-cell transplantation (HDT-ASCT). Here, we report outcomes of a preplanned subgroup analysis of patients ≥65 years in ZUMA-7. Patients and Methods: Patients with LBCL refractory to or relapsed ≤12 months after first-line chemoimmunotherapy were randomized 1:1 to axicabtagene ciloleucel [axi-cel; autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy] or standard of care (SOC; 2–3 cycles of chemoimmunotherapy followed by HDT-ASCT). The primary endpoint was event-free survival (EFS). Secondary endpoints included safety and patient-reported outcomes (PROs). Results: Fifty-one and 58 patients aged ≥65 years were randomized to axi-cel and SOC, respectively. Median EFS was greater with axi-cel versus SOC (21.5 vs. 2.5 months; median follow-up: 24.3 months; HR, 0.276; descriptive P < 0.0001). Objective response rate was higher with axi-cel versus SOC (88% vs. 52%; OR, 8.81; descriptive P < 0.0001; complete response rate: 75% vs. 33%). Grade ≥3 adverse events occurred in 94% of axi-cel and 82% of SOC patients. No grade 5 cytokine release syndrome or neurologic events occurred. In the quality-of-life analysis, the mean change in PRO scores from baseline at days 100 and 150 favored axi-cel for EORTC QLQ-C30 Global Health, Physical Functioning, and EQ-5D-5L visual analog scale (descriptive P < 0.05). CAR T-cell expansion and baseline serum inflammatory profile were comparable in patients ≥65 and <65 years. Conclusions: Axi-cel is an effective second-line curative-intent therapy with a manageable safety profile and improved PROs for patients ≥65 years with R/R LBCL.

Summary The prognosis of relapsed/refractory (R/R) anaplastic large cell lymphoma (ALCL) is poor. Large studies evaluating outcomes of allogeneic haematopoietic cell transplantation (allo‐HCT) in systemic R/R ALCL are not available. Using the Center for International Blood and Marrow Transplant Research (CIBMTR) database, we evaluated outcomes of 182 adults (aged ≥18 years) with R/R ALCL undergoing allo‐HCT between 2008 and 2019. Non‐relapse mortality (NRM), disease relapse/progression (REL), progression‐free survival (PFS), and overall survival (OS) were modelled using Cox proportional hazards models. The median (range) follow‐up of survivors was 62 (3–148) months. The 1‐year NRM was 18%. The 5‐year REL, PFS and OS were 32%, 41% and 56% respectively. On multivariable regression analysis African American race (hazard ratio [HR] 2.7, 95% confidence interval [CI] 1.6–4.8; p < 0.001) and refractory disease at allo‐HCT (HR 3.2, 95% CI 1.6–6.2; p < 0.001) were predictive of inferior OS. Similarly, African‐American race (HR 2.1, 95% CI 1.3–3.4; p = 0.003), other minority race (HR 2.5, 95% CI 1.2–5.3; p = 0.02) and refractory disease (HR 2.2, 95% CI 1.2–4.3; p = 0.01) were predictive of inferior PFS. These data, demonstrate that allo‐HCT can result in durable disease control in a sizable proportion of patients with R/R ALCL. Refractory disease and racial minority status predicted inferior allo‐HCT outcomes. Whether the inferior outcomes of racial minorities with R/R ALCL after allo‐HCT are driven by differences in disease biology or disparities in post allo‐HCT care, or both, requires further investigation.

7571 Background: In clinical trials of CAR T-cell therapies and real-world studies published to date, there is a paucity of data on outcomes by race and ethnicity. Here, we examined outcomes by race and ethnicity among LBCL pts who received axi-cel in the real-world setting. Methods: A total of 1389 pts with LBCL were identified from a non-interventional post-authorization safety study with pts receiving commercial axi-cel between 10/2017 and 08/2020. Race (African American or Asian vs White) and ethnicity (Hispanic vs non-Hispanic) were self-reported by pts. Pts with rescinded consent, enrolled in trials, having prior non-HCT cellular therapy, primary CNS lymphoma, unknown comorbidity or data in query were excluded. Median follow-up was 12.7 mo. Outcomes included ORR, CR rate, DOR, PFS and OS, grade ≥ 3 CRS (Lee 2014 criteria) and ICANS (ASTCT consensus grade). ORR and CR were evaluated in pts with ≥ 180 days of follow-up. Kaplan-Meier estimates were calculated for PFS and OS. Multivariable analyses comparing race and ethnicity were conducted via logistic and Cox regression. Results: Among all, 1127 (81%) were White, 70 (5%) African American and 81 (6%) Asian; 152 (11%) were Hispanic including 104 White, 2 Black, and 1 Asian Hispanic. African Americans, compared to White, were younger (median age 55.5 vs 62.8 years), more likely to have pulmonary impairment (41% vs 28%) and tended to have longer time from diagnosis (≥ 12 mo 71% vs 59%). Hispanic pts were younger (median age 58.5 vs 62.6 years) than non-Hispanic pts. ORR was 74% (CR 57%, 12-mo PFS and OS 48% and 63%) for White, 57% (CR 45%, 12-mo PFS and OS 36% and 62%) for African American, 67% (CR 53%, 12-mo PFS and OS 55% and 65%) for Asian and 73% (CR 55%, 12-mo PFS and OS 50% and 65%) for Hispanic pts. Grade ≥ 3 CRS and ICANS occurred in 7% and 18% of African American, 10% and 19% of Asian, and 8% and 27% of White pts, respectively. Hispanic pts had lower rates of grade ≥ 3 CRS and ICANS (4% and 15%) vs non-Hispanic (9% and 27%). African American race was associated with inferior ORR (OR 0.40; 95% CI, 0.24-0.69) and CR rate (OR 0.55; 95% CI 0.32-0.93) vs White. Asian pts had favorable DOR compared to both White (HR 0.46; 95% CI 0.24-0.87) and African American (HR 0.39; 95% CI 0.17-0.88). No statistical differences were found in OS and PFS across races, nor in any efficacy outcome between Hispanic and non-Hispanic pts. Asian (OR 0.52; 95% CI 0.29-0.96 vs White) and Hispanic pts (OR 0.51; 95% CI 0.31-0.85 vs non-Hispanic) had lower risk of grade ≥ 3 ICANS. Conclusions: Overall, axi-cel showed favorable OS, PFS and safety profile regardless of race and ethnicity in the real-world setting. No notable differences in outcomes were observed for Hispanic or Asian pts. Lower response rates in African American pts noted here warrant further investigation including any underrepresentation not explained by a lower incidence rate for DLBCL (SEER), access to care, and disease burden.

PURPOSE Calcineurin inhibitors (CNI) are standard components of graft-versus-host disease (GVHD) prophylaxis after hematopoietic cell transplantation (HCT). Prior data suggested that CNI-free approaches using donor T-cell depletion, either by ex vivo CD34 selection or in vivo post-transplant cyclophosphamide (PTCy) as a single agent, are associated with lower rates of chronic GVHD (cGVHD). METHODS This multicenter phase III trial randomly assigned patients with acute leukemia or myelodysplasia and an HLA-matched donor to receive CD34-selected peripheral blood stem cell, PTCy after a bone marrow (BM) graft, or tacrolimus and methotrexate after BM graft (control). The primary end point was cGVHD (moderate or severe) or relapse-free survival (CRFS). RESULTS Among 346 patients enrolled, 327 received HCT, 300 per protocol. Intent-to-treat rates of 2-year CRFS were 50.6% for CD34 selection (hazard ratio [HR] compared with control, 0.80; 95% CI, 0.56 to 1.15; P = .24), 48.1% for PTCy (HR, 0.86; 0.61 to 1.23; P = .41), and 41.0% for control. Corresponding rates of overall survival were 60.1% (HR, 1.74; 1.09 to 2.80; P = .02), 76.2% (HR, 1.02; 0.60 to 1.72; P = .95), and 76.1%. CD34 selection was associated with lower moderate to severe cGVHD (HR, 0.25; 0.12 to 0.52; P = .02) but higher transplant-related mortality (HR, 2.76; 1.26 to 6.06; P = .01). PTCy was associated with comparable cGVHD and survival outcomes to control, and a trend toward lower disease relapse (HR, 0.52; 0.28 to 0.96; P = .037). CONCLUSION CNI-free interventions as performed herein did not result in superior CRFS compared with tacrolimus and methotrexate with BM. Lower rates of moderate and severe cGVHD did not translate into improved survival.

Abstract Introduction: The gut microbiome is a potentially modifiable factor in treatment related outcomes in allogeneic hematopoietic cell transplant (HCT). Prior studies have linked pre- or mid-treatment gut microbiome diversity with risk for treatment related morbidity and mortality. However, these studies have been limited by the inclusion of one or only a few institutions and the lack of longitudinal sampling with high quality metadata. These limitations complicate the interpretation of microbiome alterations over the course of HCT. Methods: To overcome these, we devised and implemented a large-scale biospecimen collection protocol in conjunction with BMT CTN 1703, a randomized, multicenter, Phase III trial of tacrolimus/methotrexate vs. post-transplant cyclophosphamide/tacrolimus/mycophenolate mofetil in reduced intensity conditioning (RIC) allogeneic HCT (NCT03959241). Patients enrolled on 1703 were optionally co-enrolled in the companion immune and microbiome profiling study, 1801 (MI-IMMUNE). This involved blood, urine and stool sampling before conditioning (PCON), then weekly starting on day 0 through day 77 (through day 84 for blood), and on days 98, 180, 270, 365 and 730. For all enrolled participants where the donor consented, residual donor cells were saved from the empty hematopoietic stem cell product bag for later analysis. Additionally, the protocol included one-time blood, urine and stool sample collection from consented matched related donors (MRDs) prior to stem cell collection. Starting with protocol version 4.0 on February 1, 2021, participation in 1801 stool collection was required for the first six out of eighteen sample collection timepoints. Participation in later stool and urine timepoint collections remained optional. Here we review the feasibility of creating a multi-institutional biobank. Additionally, we assess the success of our strategies by calculating sample collection compliance and standard deviation in compliance across centers for each timepoint. Results: On June 18, 2021, BMT CTN 1703/1801 closed to accrual with 431 patients enrolled on 1703; 323 patients from 36 centers were co-enrolled on 1801. 304 (94%) provided study samples, making this the largest prospective microbiome and immune profiling study in HCT patients to date. As of July 6, 2021, 3,683 blood, 2,668 urine, and 2,098 stool samples had been collected. Across the first 6 timepoints for all participating centers, blood, urine and stool sample collection averaged 93%, 82%, and 74% compliance, respectively. Of the 99 (30%) patients enrolled on 1801 with a MRD, 34 (34%) donors consented to sample collection. Sample collection compliance was lower for MRDs than for patients on the study with 76%, 74%, and 62% of expected blood, urine and stool samples collected, respectively, from this group. For stool collection exclusively, a median of 5 samples were collected per patient across the first 6 timepoints (median of 6 across all timepoints) with 93 (31%) of patients completing a full sample set through Day 28. 139 (46%) patients provided at least one sample after day 28; these represented 37% of the total samples collected to date. The PCON sample, which provides an important measure of pre-treatment gut microbiome diversity, had the third highest compliance with 74% of patients providing a sample. Surprisingly, Day 28 had the lowest compliance (66%) and highest standard deviation (37%) possibly because this timepoint often falls around the time of hospital discharge. Between PCON and day 28, the standard deviation between sites in the average collection compliance (24%) and number of samples collected per patient (1.1) was small indicating the successful adoption of stool collection across institutions. Table 1 summarizes sample collection statistics. Conclusion: Overall this study has resulted in a large, novel biobank of blood, urine and stool samples from patients undergoing RIC allogeneic HCT at 36 centers across the US. This will serve as a valuable resource for investigating the role of the gut microbiome in long term health outcomes following HCT. Although the results of 1801 are forthcoming given ongoing sample collection, the size and composition of the biobank to date clearly demonstrate the feasibility of implementing multi-institutional stool collection. This study represents a critical step towards the large-scale adoption of microbiome sampling as a diagnostic tool. Figure 1 Figure 1. Disclosures Chhabra: GSK: Honoraria. Clark: Kadmon: Consultancy. Horowitz: Mesoblast: Research Funding; Shire: Research Funding; Vertex: Research Funding; Stemcyte: Research Funding; Vor Biopharma: Research Funding; Janssen: Research Funding; Miltenyi Biotech: Research Funding; Kiadis: Research Funding; Sobi: Research Funding; Kite/Gilead: Research Funding; Pfizer, Inc: Research Funding; Jazz Pharmaceuticals: Research Funding; Magenta: Consultancy, Research Funding; Medac: Research Funding; Novartis: Research Funding; GlaxoSmithKline: Research Funding; Daiicho Sankyo: Research Funding; Xenikos: Research Funding; Omeros: Research Funding; Orca Biosystems: Research Funding; Pharmacyclics: Research Funding; Regeneron: Research Funding; Tscan: Research Funding; Takeda: Research Funding; CSL Behring: Research Funding; Genentech: Research Funding; Gamida Cell: Research Funding; Chimerix: Research Funding; Bristol-Myers Squibb: Research Funding; bluebird bio: Research Funding; Astellas: Research Funding; Amgen: Research Funding; Allovir: Consultancy; Actinium: Research Funding; Sanofi: Research Funding; Seattle Genetics: Research Funding. Jenq: Microbiome DX: Consultancy; Merck: Consultancy; Prolacta: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kaleido: Consultancy, Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seres: Consultancy, Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; LisCure: Consultancy, Membership on an entity's Board of Directors or advisory committees; MaaT Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karius: Consultancy. Levine: Equillium Bio: Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Research Funding; Kamada: Research Funding; Biogen: Research Funding; Omeros: Membership on an entity's Board of Directors or advisory committees; Symbio: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Talaris Therapeutics: Membership on an entity's Board of Directors or advisory committees; Viracor: Patents & Royalties: GVHD biomarker patent with royalties from Viracor; Mesoblast: Consultancy, Research Funding; X4 Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Murthy: CRISPR Therapeutics: Research Funding. Riches: ATARA Biotherapeutics: Other: Payment; BioIntelect: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Other: Payment. Sung: Merck: Research Funding; Novartis: Research Funding; Enterome: Research Funding; Seres: Research Funding; AVROBIO: Consultancy; Abbott Nutrition: Honoraria; Clasado: Other: Research Product; DSM: Other: Research Product. Al Malki: Neximmune: Consultancy; Jazz Pharmaceuticals, Inc.: Consultancy; Rigel Pharma: Consultancy; Hansa Biopharma: Consultancy; CareDx: Consultancy. Rezvani: Kaleido: Other: One-time scientific advisory board; Nohla Therapeutics: Other: One-time scientific advisory board; Pharmacyclics-Abbvie: Research Funding; US Department of Justice: Consultancy. Bolaños-Meade: Incyte Corp: Consultancy. Holtan: Incyte: Consultancy, Research Funding; Generon: Consultancy. Saber: Govt. COI: Other. Hamadani: Sanofi, Genzyme, AstraZeneca, BeiGene: Speakers Bureau; Janssen, Incyte, ADC Therapeutics, Omeros, Morphosys, Kite: Consultancy; Takeda, Spectrum Pharmaceuticals and Astellas Pharma: Research Funding. Kean: Bluebird Bio: Research Funding; Bristol Myers Squibb: Patents & Royalties: From clinical trial data, Research Funding; Vertex: Consultancy; Novartis: Consultancy; Gilead: Research Funding; Regeneron: Research Funding; EMD Serono: Consultancy. Perales: Cidara: Honoraria; Servier: Honoraria; Incyte: Honoraria, Other; Equilium: Honoraria; Takeda: Honoraria; Novartis: Honoraria, Other; Nektar Therapeutics: Honoraria, Other; NexImmune: Honoraria; MorphoSys: Honoraria; Omeros: Honoraria; Karyopharm: Honoraria; Sellas Life Sciences: Honoraria; Merck: Honoraria; Miltenyi Biotec: Honoraria, Other; Medigene: Honoraria; Bristol-Myers Squibb: Honoraria; Kite/Gilead: Honoraria, Other; Celgene: Honoraria.

Abstract Background and Rationale: Axi-cel is a standard-of-care treatment for relapsed or refractory LBCL after 2 or more lines of systemic therapy. Some patients who would have been ineligible for ZUMA-1 criteria due to comorbidities have been treated with axi-cel in the real-world setting. We interrogated a large registry of patients treated with standard-of-care axi-cel for a definitive report on the impact of age or certain comorbidities on safety and efficacy outcomes after axi-cel infusion. Methods: From October 2017 to August 2020, 1500 patients were enrolled in the postapproval safety observational study of axi-cel treated at 79 centers. Patients eligible for the protocol and followed up for at least 6 months with complete data entry by the time of analyses were included. One patient rescinded consent and 1 was deemed ineligible. Patients previously treated with immune effector cell therapy (n=31), with incomplete follow-up reporting (n=92), or alive but last contacted &lt;180 days postinfusion (n=32) were excluded from analysis. Main efficacy outcomes included complete and objective response rates (CR and ORR), duration of response (DOR), progression-free and overall survival (PFS and OS). Safety endpoints of interest included cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Outcomes were assessed and compared by age and preselected coexisting disease or organ impairment within 3 months prior to the infusion included in the hematopoietic cell transplantation comorbidity index. Multivariate logistic and Cox regression models were used to assess the impact of age or coexistent organ dysfunction on outcomes via odds ratio (OR) or hazard ratio (HR) and their 95% CIs. Results A total of 1343 patients were included in the analysis with a median 25.1 months (range, 10.3-42.7 months) for potential follow-up, defined from infusion to data cutoff date, and a median 11.8 months (range, 0.1-38.8 months) for actual follow-up time, defined from infusion to date of death or last contact. Of these, 38% were 65 years or older (median 62 years), 4% had a performance score ≥2, 13% had cardiac comorbidities, 16% had a prior cancer, 9% were obese, 2% had moderate to severe hepatic comorbidities, and 2% had renal comorbidities. Transformed lymphoma, double or triple-hit by fluorescence in situ hybridization, prior autologous transplant and refractory disease were present in 28%, 15%, 27% and 66%, respectively. Bridging therapy was administered in 21% of patients. Overall, ORR was 74%, (CR 56%), and probabilities of DOR, PFS, and OS at 18 months were 61% (95% CI, 57-65%), 42% (95% CI, 39-45%) and 52% (95% CI, 49-55%), respectively. Overall rates of CRS and ICANS were 83% and 55%, respectively. ORR was 78% (CR 62%, median OS 17.5 [95% CI, 16.0-not evaluated (NE)] months) for patients ≥65 years, ORR 57% (CR 29%; median OS 4.3 [95% CI, 2.5-8.3] months) for patients with hepatic dysfunction, ORR 70% (CR 43%; median OS 8.9 [95% CI, 3.8-NE] months) for patients with renal dysfunction; and ORR 47% (CR 20%, median OS 4 [95% CI, 2.6-6.9] months) for patients with Eastern Cooperative Oncology Group (ECOG) 2 or 3. Multivariate analyses indicated that advanced age (≥65 years vs &lt;65 years; OR 1.38; 95% CI, 1.05-1.83), moderate to severe pulmonary disease (yes vs no; OR 0.74; 95% CI, 0.55-0.98), and ECOG (2-3 vs 0-1; OR 0.31, 95% CI, 0.18-0.53) impacted ORR (Table). Age ≥65 years did not have an impact on survival (HR 1.05, 95% CI, 0.88-1.26), although it was associated with CRS (OR 1.42, 95% CI, 1.03-1.96) and ICANS (OR 1.78, 95% CI, 1.39-2.28). Coexistent cardiac disease (HR 1.44, 95% CI, 1.12-1.83), renal disease (HR 2.13, 95% CI, 1.32-3.46) and hepatic dysfunction (HR 2.65, 95% CI, 1.69-4.14) had an impact on OS, but not on response, CRS, and ICANS. ECOG significantly impacted all efficacy outcomes. None of the other comorbidities tested significantly impacted outcomes. Conclusion: Advanced age (≥65 years) was not associated with worse efficacy outcomes after axi-cel, despite higher rates of CRS and ICANS, which require closer monitoring. Performance status rather than age should be accounted for in patient selection and treatment decisions with axi-cel. Most coexistent organ dysfunctions have no clinically significant impact on axi-cel objective response and safety outcomes. Figure 1 Figure 1. Disclosures Locke: Moffitt Cancer Center: Patents & Royalties: field of cellular immunotherapy; Allogene Therapeutics: Consultancy, Other: Scientific Advisory Role, Research Funding; Amgen: Consultancy, Other: Scientific Advisory Role; Bluebird Bio: Consultancy, Other: Scientific Advisory Role; EcoR1: Consultancy; Emerging Therapy Solutions: Consultancy; Gerson Lehrman Group: Consultancy; Iovance Biotherapeutics: Consultancy, Other: Scientific Advisory Role; Takeda: Consultancy, Other; Novartis: Consultancy, Other, Research Funding; Wugen: Consultancy, Other; GammaDelta Therapeutics: Consultancy, Other: Scientific Advisory Role; Umoja: Consultancy, Other; Cellular Biomedicine Group: Consultancy, Other: Scientific Advisory Role; Calibr: Consultancy, Other: Scientific Advisory Role; Cowen: Consultancy; BMS/Celgene: Consultancy, Other: Scientific Advisory Role; Legend Biotech: Consultancy, Other; Kite, a Gilead Company: Consultancy, Other: Scientific Advisory Role, Research Funding; Janssen: Consultancy, Other: Scientific Advisory Role. Jacobson: Axis: Speakers Bureau; Nkarta: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Other: Travel support, Research Funding; AbbVie: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Other: Travel support; Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Other: Travel support; Precision Biosciences: Consultancy, Honoraria, Other: Travel support; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support; Lonza: Consultancy, Honoraria, Other: Travel support; Humanigen: Consultancy, Honoraria, Other: Travel support; Clinical Care Options: Speakers Bureau. Ma: Kite, a Gilead Company: Current Employment. Dong: Kite, a Gilead Company: Current Employment. Hu: Kite, a Gilead Company: Research Funding; Novartis: Research Funding; Celgene: Research Funding. Siddiqi: BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Oncternal: Research Funding; Janssen: Speakers Bureau; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AstraZeneca: 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; Pharmacyclics LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; TG Therapeutics: Research Funding. Ahmed: Seagen: Research Funding; Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; Xencor: Research Funding. Ghobadi: Atara: Consultancy; Wugen: Consultancy; Amgen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Celgene: Consultancy. Miklos: Pharmacyclics: Patents & Royalties; Kite, a Gilead Company, Amgen, Atara, Wugen, Celgene, Novartis, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Bioscience, Adicet, Pharmacyclics, Janssen, Takeda, Adaptive Biotechnologies and Miltenyi Biotechnologies: Consultancy; Pharmacyclics, Amgen, Kite, a Gilead Company, Novartis, Roche, Genentech, Becton Dickinson, Isoplexis, Miltenyi, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Biosciences, Adicet, Adaptive Biotechnologies: Research Funding; Adaptive Biotechnologies, Novartis, Juno/Celgene-BMS, Kite, a Gilead Company, Pharmacyclics-AbbVie, Janssen, Pharmacyclics, AlloGene, Precision Bioscience, Miltenyi Biotech, Adicet, Takeda: Membership on an entity's Board of Directors or advisory committees. Lin: Kite, a Gilead Company: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Legend: Consultancy; Vineti: Consultancy; Sorrento: Consultancy; Gamida Cell: Consultancy; Janssen: Consultancy, Research Funding; Juno: Consultancy; Bluebird Bio: Consultancy, Research Funding; Novartis: Consultancy; Merck: Research Funding; Takeda: Research Funding. Perales: Bristol-Myers Squibb: Honoraria; Takeda: Honoraria; Nektar Therapeutics: Honoraria, Other; Miltenyi Biotec: Honoraria, Other; MorphoSys: Honoraria; NexImmune: Honoraria; Sellas Life Sciences: Honoraria; Cidara: Honoraria; Merck: Honoraria; Omeros: Honoraria; Servier: Honoraria; Celgene: Honoraria; Novartis: Honoraria, Other; Kite/Gilead: Honoraria, Other; Incyte: Honoraria, Other; Medigene: Honoraria; Karyopharm: Honoraria; Equilium: Honoraria. Lunning: Daiichi-Sankyo: Consultancy; TG Therapeutics: Consultancy; Kite, a Gilead Company: Consultancy; ADC Therapeutics: Consultancy; Spectrum: Consultancy; Beigene: Consultancy; Celgene, a Bristol Myers Squibb Co.: Consultancy; Legend: Consultancy; AbbVie: Consultancy; AstraZeneca: Consultancy; Morphosys: Consultancy; Verastem: Consultancy; Novartis: Consultancy; Myeloid Therapeutics: Consultancy; Janssen: Consultancy; Acrotech: Consultancy; Kyowa Kirin: Consultancy; Karyopharm: Consultancy. Hill: Gentenech: Consultancy, Honoraria, Research Funding; Incyte/Morphysis: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Support, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; AstraZenica: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Epizyme: Consultancy, Honoraria; Celgene (BMS): Consultancy, Honoraria, Research Funding. Nikiforow: Kite/Gilead: Other: ad HOC Advisory Boards; Novartis: Other: ad Hoc Advisory Boards; Iovance: Other: ad Hoc Advisory Boards; Glaxo Smith Kline (GSK): Other: ad Hoc Advisory Boards. Xu: Gilead Sciences: Other: stock or other ownership ; Kite, A Gilead Company: Current Employment. Pasquini: Bristol Myers Squibb: Consultancy, Research Funding; Novartis: Research Funding; Kite Pharma: Research Funding; GlaxoSmithKline: Research Funding.

Abstract Background: CD19 CAR T cell therapies have demonstrated high initial complete remission (CR) rates of 70-80% in relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) with durable remissions observed in a subset of patients. Despite the remarkable initial CR rate, relapses occur in 20-45% of patients and with increasing use of CD19 CAR T cell therapies in ALL, a key remaining clinical question is the role of post-CAR HCT. Methods: Patients up to 26 years treated with the commercial (i.e., tisagenlecleucel) or investigational CD19 CAR T cell products from 2014 to 2019 in the United States were included. The objectives were to examine the impact of post-CAR HCT on mortality, disease-free survival (DFS), leukemia relapse, GVHD and transplant related mortality among HCT recipients. The intent of HCT was analyzed as consolidation when there was no evidence of post-CAR T cell relapse prior to HCT. Cox regression multivariable analysis used HCT as time-dependent variable along with age, performance status and time from diagnosis to CAR-T cell infusion to evaluate its impact on outcomes. Results: We identified 347 patients who received CD19 CAR T cells from 86 centers. Median age was 13 (range, 0.4-26 years) with 39% of patients from Hispanic or Latino ethnic origin. Patients were high risk and heavily pretreated; 56% had poor cytogenetics, 51% had ≥3 line of prior therapies and 34% had prior HCT. Most of the patients (74%) received tisagenlecleucel. Disease burden at the time of CAR T cell infusion included morphologic disease (≥5% bone marrow blasts) (65%), measurable residual disease (MRD) positive (16%) and negative CR (18%). CRS of all grades was observed in 57.6% and grade 3-4 CRS in 13%; neurotoxicity of all grades was observed in 25% and grade 3-4 in 8%. With a median follow-up of 12.7 months (range, 2.2-60.3), DFS at 3, 6 and 12 months following CAR T cell infusion was 80.9% % (95% CI: 76.6%-84.9%), 71.2% (95% CI: 66.1%-76.0%) and 57.6% (95% CI: 51.8%-63.3%), respectively. OS at 3, 6 and 12 months was 93.6% (95% CI: 90.8%-96.0%), 89.8% (95% CI: 86.4%-92.8%) and 79.4% (95% CI: 74.7%-83.6%), respectively. Incidences of relapse without censoring at subsequent HCT at month 3, 6 and 12 were 18.5% (95% CI: 14.5%-22.8%), 28.2% (95% CI: 23.5%-33.3%), and 40.6% (95% CI: 35.0%-46.3%), respectively. Of the 347 patients who received CD19 CAR therapy, 62 patients (18%) had subsequent HCT in CR as a consolidation post-CAR with a median time from CAR T to HCT of 4.7 months (range, 1.1-18.6). 36% had a prior HCT (i.e., pre-CAR), 87% received myeloablative regimen and among the 57 patients with MRD evaluation 56 were negative (98%). Frequencies of post-CAR HCT did not change during the 5-year study period. Overall, transplant related mortality (TRM) at month 6 was 8.9% (95% CI: 3.6-16.1), and grade 2-4 acute GvHD was observed in 38.0% (95% CI: 28.4-48.2) of patients at month 6. Post-CAR HCT used as a consolidation was associated with lower relapse (hazard ratio (HR) 0.37; p=0.037) but no significant impact on mortality (HR 0.75, p=0.51) or DFS (HR=0.46, p=0.057). When accounting for any HCT performed after CAR T cell, HCT was associated with higher mortality (Figure). Conclusions: This is the largest clinical series to date examining the impact of post-CAR HCT on clinical outcome of R/R B-ALL patients. We found that 18% of the patients had post-CAR HCT as a consolidation therapy with a favorable safety profile of 8.9% TRM rate despite a prior transplant rate of 36%. Consolidation HCT after CAR T cell resulted in significant reduction in leukemia relapse with a trend towards better DFS. Consolidation HCT seem safe and incurred a benefit by reducing disease relapse. Further studies in understanding the role of consolidation HCT as planned, or post-CAR T cell response-based strategy or treatment for early B-cell recovery are needed to further define the best candidates for HCT after tisagenlecleucel . Figure 1 Figure 1. Disclosures Park: BMS: Consultancy; Affyimmune: Consultancy; Kite Pharma: Consultancy; Curocel: Consultancy; Novartis: Consultancy; Minerva: Consultancy; Innate Pharma: Consultancy; PrecisionBio: Consultancy; Intellia: Consultancy; Amgen: Consultancy; Autolus: Consultancy; Servier: Consultancy; Artiva: Consultancy; Kura Oncology: Consultancy. Nikiforow: Kite/Gilead: Other: ad HOC Advisory Boards; Novartis: Other: ad Hoc Advisory Boards; Iovance: Other: ad Hoc Advisory Boards; Glaxo Smith Kline (GSK): Other: ad Hoc Advisory Boards. Hu: Kite/Gilead: Research Funding; Novartis: Research Funding; Celgene: Research Funding. Ahmed: Merck: Research Funding; Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Seagen: Research Funding; Xencor: Research Funding. Badar: Pfizer Hematology-Oncology: Membership on an entity's Board of Directors or advisory committees. Cairo: Servier: Speakers Bureau; Sanofi: Speakers Bureau; Amgen: Speakers Bureau; Jazz Pharmaceutical: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sobi: Speakers Bureau; Omeros: Membership on an entity's Board of Directors or advisory committees; Nektar: Membership on an entity's Board of Directors or advisory committees. Dholaria: Janssen: Research Funding; Takeda: Research Funding; Jazz: Speakers Bureau; MEI: Research Funding; Pfizer: Research Funding; Angiocrine: Research Funding; Poseida: Research Funding; Celgene: Speakers Bureau. Grover: Kite: Other: Advisory Board; Genentech: Research Funding; ADC: Other: Advisory Board; Tessa: Consultancy; Novartis: Consultancy. Locke: Gerson Lehrman Group: Consultancy; Emerging Therapy Solutions: Consultancy; Moffitt Cancer Center: Patents & Royalties: field of cellular immunotherapy; Calibr: Consultancy, Other: Scientific Advisory Role; BMS/Celgene: Consultancy, Other: Scientific Advisory Role; Wugen: Consultancy, Other; Legend Biotech: Consultancy, Other; Janssen: Consultancy, Other: Scientific Advisory Role; Iovance Biotherapeutics: Consultancy, Other: Scientific Advisory Role; Novartis: Consultancy, Other, Research Funding; GammaDelta Therapeutics: Consultancy, Other: Scientific Advisory Role; Takeda: Consultancy, Other; EcoR1: Consultancy; Cowen: Consultancy; Umoja: Consultancy, Other; Kite, a Gilead Company: Consultancy, Other: Scientific Advisory Role, Research Funding; Cellular Biomedicine Group: Consultancy, Other: Scientific Advisory Role; Bluebird Bio: Consultancy, Other: Scientific Advisory Role; Amgen: Consultancy, Other: Scientific Advisory Role; Allogene Therapeutics: Consultancy, Other: Scientific Advisory Role, Research Funding. Murthy: CRISPR Therapeutics: Research Funding. Mussetti: GILEAD: Other: Clinical trials participation, Research Funding; TAKEDA: Honoraria; NOVARTIS: Honoraria, Other: Clinical trials participation. Pulsipher: Jasper Therapeutics: Honoraria; Adaptive: Research Funding; Equillium: Membership on an entity's Board of Directors or advisory committees. Qayed: Novartis: Membership on an entity's Board of Directors or advisory committees; Medexus: Membership on an entity's Board of Directors or advisory committees; Mesoblast: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; BMS: Other. Reshef: Gilead, BMS, Precision, Immatics, Atara, Takeda, Shire, Pharmacyclics, Incyte: Research Funding; Gilead and Novartis: Honoraria; Bayer, BMS, Regeneron, TScan, Synthekine, Atara, Jasper: Consultancy. Rizzieri: Kite: Honoraria, Speakers Bureau; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Stemline: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Acrotech: Membership on an entity's Board of Directors or advisory committees; Teva: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; AROG: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Karyopharm: Honoraria, 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; Celltrion: Membership on an entity's Board of Directors or advisory committees; Mustang: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Honoraria; Pharmacyclics: Honoraria. Sharma: Vertex Pharmaceuticals/CRISPR Therapeutics: Other: Salary support paid to institution; Medexus Inc: Consultancy; CRISPR Therapeutics: Other, Research Funding; Vindico Medical Education: Honoraria; Spotlight Therapeutics: Consultancy; Novartis: Other: Salary support paid to institution. Schultz: BMS DSMB: Other: payment; Sobi: Membership on an entity's Board of Directors or advisory committees. Turtle: Century Therapeutics Ad hoc advisory boards (last 12 months): Nektar Therapeutics, Allogene, PACT Pharma, Astra Zeneca, Amgen: Membership on an entity's Board of Directors or advisory committees; Precision Biosciences: Membership on an entity's Board of Directors or advisory committees; Eureka Therapeutics: Membership on an entity's Board of Directors or advisory committees; Caribou Biosciences: Membership on an entity's Board of Directors or advisory committees; T-CURX: Membership on an entity's Board of Directors or advisory committees; Myeloid Therapeutics: Membership on an entity's Board of Directors or advisory committees; ArsenalBio: Membership on an entity's Board of Directors or advisory committees; Minerva: Other; Nektar Therapeutics: Other; Juno Therapeutics/BMS: Other: Payments, Patents & Royalties: Patent licensed to Juno Therapeutics.; Precision Biosciences, Eureka Therapeutics, Caribou Biosciences, Myeloid Therapeutics, ArsenalBio: Current holder of stock options in a privately-held company. Pasquini: Kite Pharma: Research Funding; Novartis: Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; GlaxoSmithKline: Research Funding. Perales: MorphoSys: Honoraria; Cidara: Honoraria; Bristol-Myers Squibb: Honoraria; Miltenyi Biotec: Honoraria, Other; Sellas Life Sciences: Honoraria; Takeda: Honoraria; Karyopharm: Honoraria; Celgene: Honoraria; Omeros: Honoraria; Nektar Therapeutics: Honoraria, Other; Equilium: Honoraria; Novartis: Honoraria, Other; NexImmune: Honoraria; Incyte: Honoraria, Other; Kite/Gilead: Honoraria, Other; Merck: Honoraria; Servier: Honoraria; Medigene: Honoraria.

Abstract There is a lack of large comparative study on the outcomes of reduced intensity conditioning (RIC) in acute myeloid leukemia (AML) transplantation using fludarabine/busulfan (FB) and fludarabine/melphalan (FM) regimens. Adult AML patients from Center for International Blood and Marrow Transplant Research who received first RIC allo-transplant between 2001 and 2015 were studied. Patients were excluded if they received cord blood or identical twin transplant, total body irradiation in conditioning, or graft-versus-host disease (GVHD) prophylaxis with in vitro T-cell depletion. Primary outcome was overall survival (OS), secondary end points were leukemia-free survival (LFS), nonrelapse mortality (NRM), relapse, and GVHD. Multivariate survival model was used with adjustment for patient, leukemia, and transplant-related factors. A total of 622 patients received FM and 791 received FB RIC. Compared with FB, the FM group had fewer transplant in complete remission (CR), fewer matched sibling donors, and less usage of anti-thymocyte globulin or alemtuzumab. More patients in the FM group received marrow grafts and had transplantation before 2005. OS was significantly lower within the first 3 months posttransplant in the FM group (hazard ratio [HR] = 1.82, P &lt; .001), but was marginally superior beyond 3 months (HR = 0.87, P = .05). LFS was better with FM compared with FB (HR = 0.89, P = .05). NRM was significantly increased in the FM group during the first 3 months of posttransplant (HR = 3.85, P &lt; .001). Long-term relapse was lower with FM (HR = 0.65, P &lt; .001). Analysis restricted to patients with CR showed comparable results. In conclusion, compared with FB, the FM RIC showed a marginally superior long-term OS and LFS and a lower relapse rate. A lower OS early posttransplant within 3 months was largely the result of a higher early NRM.