Saber, Wael

7006 Background: Measurable residual disease (MRD) prior to allogeneic hematopoietic cell transplantation (alloHCT) is associated with increased relapse and death in patients with acute myeloid leukemia (AML) in cytomorphological complete remission (CR). We recently demonstrated AML MRD detected in pre-alloHCT blood by DNA-sequencing was associated with increased relapse and decreased overall survival in patients randomized to reduced intensity conditioning (RIC) versus myeloablative conditioning (MAC). The clinical utility of such ultra-deep next-generation sequencing (NGS-MRD) had not yet been reported in a large multi-center cohort. Methods: Patients aged 18 or older who underwent first alloHCT between 2013-2017 for AML in first CR (CR1), reported to be FLT3, NPM1, IDH1, IDH2 and/or Kit mutated at diagnosis, with a pre-conditioning remission blood sample available in the CIBMTR biobank were eligible for this study. Ultra-deep anchored multiplex PCR-based NGS-MRD for the above mutations was performed on 500ng gDNA with error-corrected variant calling as previously described. The pre-specified statistical analysis plan was registered on OSF. Results: Of 457 patients with a sample available, 448 had sufficient clinical annotation and DNA for analysis. 147 of these 448 patients (33%) experienced relapse at a median of 5.6 months post-alloHCT. NGS-MRD was positive in 129 pre-alloHCT patient samples (29%), averaging 1.35 mutation(s)/patient (range: 1-4). 173 mutations were detected with a median VAF of 0.18% (range: 0.0054-62%), most frequently FLT3-ITD (n = 43 patients), NPM1 (n = 48), and IDH2 (n = 46). Testing positive by NGS-MRD prior to alloHCT was associated with a 3yr RFS of 36% (95% CI: 28-45%) compared with 56% (51-62%) in those testing negative (p < 0.001). Detection of NPM1 and/or FLT3-ITD mutations prior to alloHCT was associated with a 3yr relapse probability of 55% (43-67%) and RFS of 26% (16-37%). NGS-MRD impact was modified by conditioning intensity: positive patients receiving RIC/NMA had the highest relapse of 57% at 3yr, testing negative followed by RIC/NMA had the same relapse rate at 3yr (35%) as those who tested positive but received MAC (p < 0.001). At three years, those positive for FLT3-ITD and/or NPM1 mutations prior to RIC/NMA alloHCT had a relapse probability of 67% (50-83%) with a RFS of 19% (8-33%). HR for relapse if NGS-MRD positive pre-alloHCT in CR1 was 2.3 (p < 0.001, 95% CI 1.6-3.1) when adjusting for conditioning intensity and age group. Conclusions: In this largest cohort of NGS-MRD testing prior to alloHCT for AML reported to date, we confirm the ability to identify patients in CR1 but at high-risk of subsequent relapse. This evidence provides the foundation for future precision medicine approaches to reduce post-transplant AML relapse.

Abstract Background There has been an increase in overall utilization as well as improvement in overall survival (OS) after hematopoietic cell transplantation (HCT) for most hematologic disorders over time. It is not known if these changes have impacted racial/ethnic minorities equally. In this study, we describe changes in the volume and rate of autologous (auto) and allogeneic (allo) HCT and examine trends in survival in different racial/ethnic groups from 2009 to 2018. Methods Data were obtained from the Center for International Blood and Marrow Transplant Research (CIBMTR) which collects patient data on most autologous and allogeneic HCT recipients in the US. We compared the number of auto and allo transplants in 4 different racial/ethnic groups: Non-Hispanic Whites (NHWs), African Americans (AAs), Hispanics and 'Others' across five 2-year cohorts from 2009 to 2018. 'Others' included Asians, Pacific Islanders and Native Americans as well as non-US residents. Since numbers in individual categories were too low to be meaningful, they were grouped together as 'Others'. Multi race individuals and those with either race or ethnicity missing were excluded. Cox proportional hazards models were used to examine trends in overall mortality after auto HCT in adult patients (for NHL, HD, and MM), and allo HCT among adult and pediatric patients (for AML, ALL, lymphoma including chronic lymphocytic leukemia, and MDS/MPD) in the 4 different racial ethnic groups over 5 study time periods. These models were adjusted for sociodemographic and clinical variables (age, sex, Karnofsky/Lansky score, HCT-comorbidity index, disease, disease status, geographic region, insurance, marital status, education, distance to the transplant center, median income derived from patient's ZIP code). Graft type, donor, conditioning, GVHD prophylaxis, donor-recipient CMV match and donor-recipient sex match were included for allo HCT models. Results A total of 80,080 (59,666 NHWs, 10,683 AAs, 7,110 Hispanics) patients received an auto HCT and 60,412 (44,272 NHWs, 4,964 AAs, 7,826 Hispanics) received an allo HCTs from 2009 to 2018. The volume of auto and allo transplants increased overall, as well as within each race/ethnicity group, over the study periods. In addition, there was a significant change in the proportion of patients in each racial/ethnic group undergoing an auto HCT, with a lower proportion of NHWs and increased proportion of minorities over time (from 78%, 12% and 8% in 2009 -2010 to 71%, 15% and 10% in 2017-2018 for NHWs, AAs and Hispanics respectively; p&lt;0.001). Similar trends were observed for allo HCT: from 76%, 8% and 12% in 2009-2010 to 71%, 9% and 14% in 2017-2018 of all allo HCTs for NHWs, AAs and Hispanics respectively; p&lt;0.001. While there was an increase in the rate of transplants over the years across all racial/ethnic groups, the rate was higher in AAs and Hispanics as compared to NHWs (Table 1). There was no significant difference in overall mortality amongst the three main racial ethnic groups, though there was decrease in mortality over time for auto HCT and adult allo HCT patients. In the allo HCT pediatric group, AAs had higher overall mortality as compared to NHWs across all time periods. (Table 2) Figure 1 shows temporal trends in two-year survival by race and ethnicity. Conclusions This large population-based study shows an improvement in the rates and survival of auto and allo HCT in adults over time. Changes in the proportion of different racial/ethnic groups undergoing HCT are higher than rate of change of population growth (3% decline for NHWs, no change in AAs and 2% increase in Hispanics from 2010 to 2019 per William H. Frey analysis of census population estimates released June 25, 2020). Progress is reflected in higher rates of increase in racial/ ethnic minority groups and comparable survival across the racial ethnic groups in our cohort as compared to two prior registry studies (Baker et al. JCO 2005 and Baker et al. BBMT 2009) for most HCT patients. However, in pediatric patients undergoing allo HCT, the gap in survival between NHWs and AAs has continued to persist over the years. With increasing diversity of the US population, we need to strengthen our efforts for improving access to, and outcomes of HCT to narrow the gap for all patients requiring HCT, irrespective of their sociodemographic characteristics. Figure 1 Figure 1. Disclosures Wood: Koneksa Health: Consultancy, Current equity holder in publicly-traded company; Teladoc: Consultancy; Pfizer: Research Funding. Ailawadhi: Karyopharm: Consultancy; AbbVie: Consultancy; Genentech: Consultancy; Takeda: Consultancy; GSK: Consultancy, Research Funding; Xencor: Research Funding; Cellectar: Research Funding; Medimmune: Research Funding; Ascentage: Research Funding; Pharmacyclics: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; BeiGene, Ltd.: Consultancy; Sanofi: Consultancy; Oncopeptides: Consultancy. Saber: Govt. COI: Other.

Abstract Leukemia relapse and treatment related mortality (TRM) remain major obstacles for successful allogeneic hematopoietic cell transplantation (allo-HCT). The number of induction cycles using intensive chemotherapy at AML diagnosis to achieve complete remission (CR) and the number of consolidation cycles and disease status at the time of allo-HCT for patients with acute myeloid leukemia (AML) may each affect TRM and relapse rates. We investigated the impact of the number of induction/consolidation cycles and disease status on the success of allo-HCT in 3113 AML patients reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) (2008-2019). They received allo-HCT in first CR or with persistent leukemia (primary induction failure-PIF) receiving myeloablative (MA) or reduced-intensity (RIC) conditioning. 1473 AML patients (median age, 47 years) in CR received MAC; 862 (58%) achieved CR after 1 cycle of intensive induction chemotherapy and 74% of these had no evidence of measurable residual disease (MRD). 454 (31%) patients required 2 cycles to CR (72 % MRD negative) and 157 (11%) patients (69% MRD negative) after ≥ 3 cycles. The overall survival (OS), relapse and TRM by induction cycle number is shown in Table 1. Multivariate analysis demonstrated that CR after 1 cycle led to higher OS vs. 2 cycles (HR 1.32 95%CI 1.11-1.56, p&lt; 0.01) or ≥ 3 cycles (HR 1.47 95%CI 1.16-1.87, p&lt; 0.01), while OS after 2 cycles or ≥ 3 cycles were similar (HR 1.2 95%CI 0.87-1.4, p=0.38). Higher TRM was observed in patients receiving 2 or ≥ 3 cycles vs. only 1 induction cycles (HR 1.34 95%CI 1.05-1.72, p&lt; 0.02). Relapse risk was greater in those needing ≥ 3 cycles to achieve CR. Consolidation therapy after CR was associated with improved OS vs. no consolidation therapy (HR 1.57 95%CI 1.24-1.99, p&lt; 0.01). The need for ≥2 induction cycles plus consolidation therapy was associated with higher TRM (HR 1.34 95%CI 1.05-1.72, p&lt; 0.02). 1162 AML patients (median age, 63 years) in CR received allo-HCT after RIC; 714 (61%) achieved CR after 1 cycle of induction chemotherapy (72% MRD negative); 310 (27%) patients after 2 cycles (67% MRD negative) and 138 (12%) patients (58% MRD negative) after ≥ 3 cycles (Table 1). Multivariate analysis demonstrated that the number of induction cycles did not affect the OS or TRM. Relapse risk was greater in patients requiring ≥2 cycles to achieve CR. The use of consolidation therapy did not affect OS or TRM. MRD status at the time of allo-HCT did not have a significant impact on OS, TRM and relapse rates after either MA or RIC conditioning. 478 AML patients received allo-HCT after PIF (328 patients with MAC [median age, 51 years], 150 patients RIC [median age, 61 years], Table 1). After MAC, OS and relapse were significantly worse in PIF patients compared to any CR patients (p&lt;0.01). After RIC, relapse was significantly more frequent in PIF patients vs. CR patients after 1 or more induction cycles (p&lt;0.01). TRM was similar for PIF vs CR patients after MAC or RIC allo-HCT. These data demonstrate that among patients eligible for allo-HCT, the need for only one induction cycle to achieve CR, particularly when combined with consolidation therapy is associated with better outcomes after MA conditioning. Achieving CR prior to allo-HCT needing one or more induction cycles is associated with lower relapse rates and improved OS compared to patients with PIF that receive allo-HCT. Figure 1 Figure 1. Disclosures de Lima: BMS: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Miltenyi Biotec: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees. Hourigan: Govt. COI: Other. Litzow: Omeros: Other: Advisory Board; Pluristem: Research Funding; Jazz: Other: Advisory Board; AbbVie: Research Funding; Amgen: Research Funding; Actinium: Research Funding; Astellas: Research Funding; Biosight: Other: Data monitoring committee. Saber: Govt. COI: Other. Weisdorf: Incyte: Research Funding; Fate Therapeutics: Research Funding.

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 Introduction: Allogeneic hematopoietic cell transplantation (alloHCT) is the only potentially curative treatment available for acute myelogenous leukemia (AML). It is a medically complicated and resource intensive procedure for which there are patient-, provider- and system-related factors that may impact its utilization. While Medicare coverage for alloHCT may help address a major financial barrier to access, there is still an unmet need due to other factors. This study intended to examine trends and factors associated with utilization of alloHCT and to estimate unmet need for alloHCT among Medicare beneficiaries with AML. Methods: This retrospective cohort study included all patients with a diagnosis of AML identified in the Medicare claims data from 2010 through 2016. Primary patient selection criteria included: primary or secondary diagnosis of AML, age limit (65-74), and continuous enrollment (for at least 180 days after AML diagnosis in Part A and Part B fee-for-service programs). To study trends in utilization, the transplant rates were calculated as the number of patients who received an alloHCT within 180 days and one year of diagnosis (numerator) divided by the total number of patients diagnosed with AML within each diagnosis year (denominator). Transplant rates within one year of diagnosis were further adjusted by patient characteristics, including age group, sex, race, residential region, and Elixhauser Comorbidity Index (ECI). A multivariable logistic regression was utilized to identify factors associated with the likelihood of receiving alloHCT within one year of diagnosis. Two approaches were applied to estimate unmet need for alloHCT. The first approach (Approach 1) used claims data to identify the potential need for alloHCT among patients who achieved complete remission for at least 90 days; patients who achieved 90-day remission but did not receive alloHCT at any time point were considered to have unmet need. In the second approach (Approach 2), the total number of patients diagnosed with AML in the claims data was run through the National Marrow Donor Program (NMDP) methodology , which takes estimates of risk level, response to treatment, comorbidity, and early mortality into consideration. Overall estimated need and unmet need from 2010-2015 and over different time periods were evaluated for both approaches. Results: Among the 5,974 patients diagnosed with AML from March 1, 2010 through June 30 th, 2016, 1226 patients (21%) received an alloHCT by the end of 2016. Trend analysis results suggest that utilization of alloHCT increased from 2010 to 2016 (P &lt; 0.0001) (Figure 1). The likelihood of receiving alloHCT within one year of diagnosis was found to be associated with diagnosis year, age, race, geographic region, ECI, and population-level median household income (Table 1). Both approaches estimated that approximately 36% of the diagnosed patients were in need of alloHCT between 2010 and 2015. The overall unmet need was estimated as 59% and 43% based on the claims data approach and the NMDP methodology, respectively. Despite the differences in estimated unmet need between the two approaches, the unmet need for alloHCT was found to trend down over time (Figures 2 & 3). Discussion and Conclusions: Medicare coverage facilitates access to the health care system and receipt of health services when a need for treatment or care is recognized. Utilization of alloHCT has increased over time among Medicare beneficiaries with AML. However, there are persistent differences in utilization of alloHCT by age, race, geographic region, comorbidity, and socioeconomic status, indicating disparities in access to alloHCT among this population. The results of estimated need and unmet need for alloHCT may be affected by the lack of cytogenetics and molecular information in administrative claims. To minimize this limitation, we used NMDP methodology for validation and found a similar estimation of potential need for alloHCT and downward trend in unmet need. Although the unmet need for alloHCT for AML has improved over time, policy efforts, research, and continued education are needed to close the gap between the actual utilization of alloHCT and unmet need for this potentially curative treatment. Figure 1 Figure 1. Disclosures Saber: Govt. COI: Other.