Citations

Abstract Background: Genetics play an important role in late-onset Alzheimer’s Disease (AD) etiology and dozens of genetic variants have been implicated in AD risk through large-scale GWAS meta-analyses. However, the precise mechanistic effects of most of these variants have yet to be determined. Deeply phenotyped cohort data can reveal physiological changes associated with genetic risk for AD across an age spectrum that may provide clues to the biology of the disease.Methods: We utilized over 2000 high-quality quantitative measurements obtained from blood of 2831 cognitively normal adult clients of a consumer-based scientific wellness company, each with CLIA-certified whole-genome sequencing data. Measurements included: clinical laboratory blood tests, targeted chip-based proteomics, and metabolomics. We performed a phenome-wide association study utilizing this diverse blood marker data and 25 known AD genetic variants, adjusting for sex, age, vendor (for clinical labs), and the first four genetic principal components; sex-SNP interactions were also assessed.Results: We observed statistically significant SNP-analyte associations for five genetic variants after correction for multiple testing (for SNPs in or near NYAP1, ABCA7, INPP5D, and APOE), with effects detectable from early adulthood. The ABCA7 SNP and the APOE2 and APOE4 encoding alleles were associated with lipid variability, as seen in previous studies; in addition, six novel proteins were associated with the e2 allele. The most statistically significant finding was between the NYAP1 variant and PILRA and PILRB protein levels, supporting previous functional genomic studies in the identification of a putative causal variant within the PILRA gene. Sex modified the effects of four genetic variants, with multiple interrelated immune-modulating effects associated with the PICALM variant. In post-hoc analysis, sex-stratified GWAS results from an independent AD case-control meta-analysis supported sex-specific disease effects of the PICALM variant, highlighting the importance of sex as a biological variable.Conclusions: Known AD genetic variation influenced lipid metabolism and immune response systems in a population of non-AD individuals, with associations observed from early adulthood onward. Further research is needed to determine whether and how these effects are implicated in early-stage biological pathways to AD. These analyses aim to complement ongoing work on the functional interpretation of AD-associated genetic variants.

Background: Osteochondritis dissecans (OCD) occurs most commonly in the knees of young individuals. This condition is known to cause pain and discomfort in the knee and can lead to disability and early knee osteoarthritis. The cause is not well understood, and treatment plans are not well delineated. The Research in Osteochondritis Dissecans of the Knee (ROCK) group established a multicenter, prospective cohort to better understand this disease. Purpose: To provide a baseline report of the ROCK multicenter prospective cohort and present a descriptive analysis of baseline data for patient characteristics, lesion characteristics, and clinical findings of the first 1000 cases enrolled into the prospective cohort. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Patients were recruited from centers throughout the United States. Baseline data were obtained for patient characteristics, sports participation, patient-reported measures of functional capabilities and limitations, physical examination, diagnostic imaging results, and initial treatment plan. Descriptive statistics were completed for all outcomes of interest. Results: As of November 2020, a total of 27 orthopaedic surgeons from 17 institutions had enrolled 1004 knees with OCD, representing 903 patients (68.9% males; median age, 13.1 years; range, 6.3-25.4 years), into the prospective cohort. Lesions were located on the medial femoral condyle (66.2%), lateral femoral condyle (18.1%), trochlea (9.5%), patella (6.0%), and tibial plateau (0.2%). Most cases involved multisport athletes (68.1%), with the most common primary sport being basketball for males (27.3% of cases) and soccer for females (27.6% of cases). The median Pediatric International Knee Documentation Committee (Pedi-IKCD) score was 59.9 (IQR, 45.6-73.9), and the median Pediatric Functional Activity Brief Scale (Pedi-FABS) score was 21.0 (IQR, 5.0-28.0). Initial treatments were surgical intervention (55.4%) and activity restriction (44.0%). When surgery was performed, surgeons deemed the lesion to be stable at intraoperative assessment in 48.1% of cases. Conclusion: The multicenter ROCK group has been able to enroll the largest knee OCD cohort to date. This information is being used to further understand the pathology of OCD, including its cause, associated comorbidities, and initial presentation and symptoms. The cohort having been established is now being followed longitudinally to better define and elucidate the best treatment algorithms based on these presenting signs and symptoms.

Abstract Background The National Institutes of Health define African Americans or Blacks, American Indians, Alaska Natives, Hispanics or Latinos, Native Hawaiians, and other Pacific Islanders as being underrepresented in medicine. A number of studies have demonstrated that improving diversity of such underrepresented demographics within the medical profession improves patient outcomes, medical education and reduces health disparities in patients from vulnerable racial or socioeconomic groups. Despite this recognition, significant underrepresentation of various racial, ethnic, and sexual identities still exists within nearly all medical specialties. Aims The purpose of this study was to a gain a greater understanding of the current state of diversity, equity, and inclusion (DEI) efforts among U.S. hematology and medical oncology fellowship training programs. We explored the perspectives of adult and pediatric fellowship program directors regarding current recruitment strategies and suggestions for improvement to help mitigate the effects of implicit and explicit bias. Here, we present an interim analysis of the data using descriptive statistics. Methods: We convened a multi-institutional collaboration of fellowship program directors, teaching faculty, and staff members of the American Society of Hematology to develop a survey examining perceptions of DEI efforts among hematology and medical oncology fellowship program directors. The survey was pilot tested in a small group of program directors representing 6 different academic programs (5 adult, 1 pediatric). The final online survey was distributed via email to 224 fellowship program directors at U.S. adult and pediatric hematology and medical oncology fellowship programs. The survey included 29 questions regarding perspectives on bias within the fellowship selection process, current DEI initiatives, and current faculty and fellow demographics. Survey respondents were asked to rate the importance of numerous factors in determining which applicants to invite utilizing a scale of 0-10, with 0 and 10 representing lowest and highest importance, respectively. To measure program director perceptions of certain applicant groups, survey respondents were asked to rate applicant demographics as being advantaged/disadvantaged based on survey options ranging from 0-5, with 0 and 5 representing very disadvantaged and very advantaged, respectively. Results: At interim analysis, 41 of 224 program directors completed the survey for an interim response rate of 21%, including 25 adult program directors and 16 pediatric program directors, with representation from university and community programs. Of the program directors surveyed, 28 (68%) reported having access to a dedicated diversity committee or DEI policies in place to improve recruitment of underrepresented applicants. In determining which applicants to invite, respondents placed highest value on the applicant's program director letter (mean score ± standard deviation: 7.44±1.93), caliber of the applicant's residency program (7.28±2.06) and letters of recommendations (7.15±2.23). Survey respondents viewed white and male applicants as representing the most advantaged demographic group, while LGBTQI, age>40, and U.S. citizen and non-citizen international medical graduates were the most disadvantaged (Table 1). Suggestions regarding improving DEI in the fellowship selection process included implementing bias training, identifying potentially disadvantaged applicants in ERAS, increasing faculty diversity, and pairing underrepresented applicants with interviewers based on applicant preference. Conclusion: While the majority of hematology and medical oncology fellowship program directors report having DEI programs or policies to improve recruitment of underrepresented applicants, perceptions of advantaged/disadvantaged groups may extend beyond demographics traditionally viewed as being underrepresented in medicine. As our survey is ongoing, we plan to reanalyze our data when the survey has been finalized with a higher response rate utilizing multivariable regression to identify themes that may further improve DEI efforts within the fellowship selection process. Figure 1 Figure 1. Disclosures LaCasce: Bristol-Myers Squibb Company.: Other: Data Safetly and Monitoring. Murphy: North American Thrombosis Foundation: Honoraria. Naik: Rigel: Research Funding. Podoltsev: Pfizer: Honoraria; Blueprint Medicines: Honoraria; Incyte: Honoraria; Novartis: Honoraria; Celgene: Honoraria; PharmaEssentia: Honoraria; Bristol-Myers Squib: Honoraria; CTI BioPharma: Honoraria.

Abstract Introduction: Idecabtagene vicleucel (ide-cel, bb2121) is the first chimeric antigen receptor (CAR) T cell therapy approved for the treatment of relapsed or refractory multiple myeloma after four or more prior lines of therapy, including an immunomodulatory agent, a proteasome inhibitor, and an anti-CD38 monoclonal antibody. bb21217 is a B-cell maturation antigen (BCMA) directed CAR T cell therapy which uses the same CAR molecule as ide-cel, with the addition of a PI3K inhibitor (bb007) during ex vivo culture to enrich the drug product (DP) for memory-like T cells and decrease the proportion of highly differentiated or senescent T cells. We hypothesize that DPs enriched for memory like CAR T cells will persist and function longer than non-enriched DPs and this increased persistence will positively influence duration of response (DOR). We previously demonstrated patients with sustained response are more likely to have drug product enriched for naïve gene signatures and depleted of effector gene signatures compared to patients without a sustained response. Methods: CRB-402 (NCT03274219) is a multi-center phase 1 trial of bb21217 in RRMM patients who received ≥3 prior lines of antimyeloma therapy, including a proteasome inhibitor and an immunomodulatory agent, or are double-refractory to both classes. In expansion, patients were required to have prior exposure to an anti-CD38 antibody and were required to be refractory to their last line of therapy. Patients underwent lymphodepletion with fludarabine (30 mg/m 2) and cyclophosphamide (300 mg/m 2) daily for 3 days, then received a single infusion of bb21217 at 150, 300 or 450 x 10 6 CAR+ T cells. The primary outcome measure is incidence of adverse events (AEs), including dose-limiting toxicities (DLTs). Additional outcome measures include overall response rate and DOR by IMWG Uniform Response Criteria. Exploratory analyses include correlation of outcome with the molecular characteristics of materials collected temporally through the treatment course, including PBMCs at apheresis, CAR+ T cells from drug product and CAR+ T cells collected from patients around the time of peak expansion. Results: Asof Feb 16, 2021, 72 patients received bb21217, 12 at 150, 14 at 300 and 46 at 450 x 10 6 CAR+ T cells; median follow up for all patients is 9.0 (<1-36) months (M). Patients had a median of 6 (3-17) prior lines of therapy with 49/72 (68%) triple refractory. Cytokine release syndrome (CRS) developed in 54/72 (75%) patients and was predominately G1/2 (51 pts), with 1 G3 event and 2 deaths (previously reported). Median time to first onset of CRS was 2 days (1-20); tocilizumab (38 pts) + corticosteroids (12 pts) was used to manage CRS. Eleven (15%) patients developed neurotoxicity [8 G1/G2, 2 G3, 1 G4] with median time to first onset of 7 (2-24) days. Response was assessed per investigator for 72 patients treated with bb21217 (Table). CAR+ T cells remained detectable in 30/37 (81%) patients and 9/15 (60%) patients at 6 and 12 M respectively, post bb21217 infusion. Of the 15 patients evaluable for MRD with ≥CR, 14 (93%) were MRD negative at 10 -5 by NGS. Analysis of peripheral blood samples collected 15 days post bb21217 infusion demonstrated patients with higher than the median number of CD8+ CAR+ T cells expressing CD27 and CD28 had significantly longer DOR (p=0.0024), compared to patients with lower than the median values. This suggests less differentiated, more proliferative CAR+ T cells at peak expansion are associated with prolonged disease response (median DOR in high vs low: 27.2M (95% CI; 16.8, NE) vs 9.4M (95% CI; 5.1, NE). Conclusions: Adverse events are consistent with known toxicities of CAR T cell therapies. Efficacy results are encouraging with a median DOR estimate of 17M, CR rate continues to mature. Patients with higher levels of proliferative, less differentiated memory like CAR+ T cells at peak expansion are more likely to experience prolonged DOR, continuing to support the hypothesis that the memory like T cell phenotype associated with bb21217 results in prolonged DOR. Figure 1 Figure 1. Disclosures Raje: Caribou: Other; Janssen: Other; bluebird bio: Other; Amgen: Other; Celgene: Other; BMS: Other. Shah: Poseida: Research Funding; Precision Biosciences: Research Funding; Sanofi: Consultancy; Sutro Biopharma: Research Funding; Karyopharm: Consultancy; Janssen: Research Funding; Oncopeptides: Consultancy; Kite: Consultancy; Nektar: Research Funding; Indapta Therapeutics: Consultancy; GSK: Consultancy; CSL Behring: Consultancy; CareDx: Consultancy; BMS/Celgene: Research Funding; Bluebird Bio: Research Funding; Amgen: Consultancy; Teneobio: Research Funding. Kaufman: BMS: Consultancy, Research Funding; Tecnofarma SAS, AbbVie: Honoraria; Incyte, celgene: Consultancy; Janssen: Honoraria; Incyte, TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Heidelberg Pharma: Research Funding; Amgen: Research Funding; Fortis Therapeutics: Research Funding; Novartis: Research Funding; Roche/Genetech, Tecnopharma: Consultancy, Honoraria; Sutro, Takeda: Research Funding; Genentech, AbbVie, Janssen: Consultancy, Research Funding. Siegel: Celularity: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria, Speakers Bureau; Takeda: Honoraria; Bristol Myers Squibb: Honoraria, Speakers Bureau; Amgen Inc.: Honoraria; Karyopharm: Honoraria; Janssen: Honoraria, Speakers Bureau. Munshi: Janssen: Consultancy; Bristol-Myers Squibb: Consultancy; Legend: Consultancy; Adaptive Biotechnology: Consultancy; Amgen: Consultancy; Takeda: Consultancy; Abbvie: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Oncopep: Consultancy, Current equity holder in publicly-traded company, Other: scientific founder, Patents & Royalties; Karyopharm: Consultancy; Pfizer: Consultancy. Rosenblatt: Parexel: Consultancy; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Imaging Endpoints: Consultancy; Attivare: Consultancy; Wolters Kluwer Health Inc: Consultancy, Patents & Royalties. Lin: Sorrento: Consultancy; Takeda: Research Funding; Juno: Consultancy; Celgene: Consultancy, Research Funding; Merck: Research Funding; Vineti: Consultancy; Legend: Consultancy; Bluebird Bio: Consultancy, Research Funding; Novartis: Consultancy; Gamida Cell: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. Jakubowiak: BMS: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Gracell: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees. Timm: bluebird bio: Current Employment. Yeri: bluebird bio: Current Employment. Martin: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Campbell: Bristol Myers Squibb: Current Employment, Current holder of individual stocks in a privately-held company. Finney: bluebird bio: Current Employment, Current equity holder in publicly-traded company. Truppel-Hartmann: bluebird bio: Current Employment. Petrocca: blue bird bio: Ended employment in the past 24 months. Berdeja: Abbvie, Acetylon, Amgen: Research Funding; Celularity, CRISPR Therapeutics: Research Funding; Bluebird bio, BMS, Celgene, CRISPR Therapeutics, Janssen, Kite Pharma, Legend Biotech, SecuraBio, Takeda: Consultancy; EMD Sorono, Genentech: Research Funding; GSK, Ichnos Sciences, Incyte: Research Funding; Lilly, Novartis: Research Funding; Poseida, Sanofi, Teva: Research Funding.

Abstract Background: In the ELARA (E2202) trial (NCT03568461), tisagenlecleucel (tisa-cel) demonstrated high response rates in patients with relapsed/refractory follicular lymphoma (r/r FL), including those with high-risk disease, with an overall response rate (ORR) of 86% and complete response rate (CRR) of 66%. As ELARA did not include a comparator arm, an adjusted indirect treatment comparison (ITC) using patient-level data from a global retrospective cohort study was conducted. This study aimed to provide comparative, contextual evidence to the efficacy outcomes of tisa-cel from ELARA relative to standard of care (SOC) in routine practice. Methods: ELARA is an ongoing, single-arm, global, multicenter, phase II trial which evaluates the efficacy and safety of tisa-cel in adult patients with r/r FL. As of March 29, 2021, 98 patients were enrolled with a median follow-up of 15 months. SOC data were obtained from ReCORD-FL, a global retrospective cohort study of clinical outcomes in patients with r/r FL meeting the ELARA eligibility criteria who were treated per routine practice at 10 academic centers across North America and Europe; 7 ReCORD-FL sites are also participating in ELARA, but no patients are enrolled in both studies. In ReCORD-FL, with a data cutoff date of December 31, 2020, a total of 187 patients with ≥2 lines of previous treatment were identified for inclusion, with a median follow-up from third-line of 57 months. A complete-case comparison analysis was performed for 97 ELARA apheresed patients and 143 ReCORD-FL patients with complete data on all baseline variables and prognostic factors used for adjustment. For the comparative analysis, one line of therapy (LoT) per patient was selected using a propensity score model to identify the LoT which had the highest chance of being enrolled in ELARA conditional on baseline characteristics and prognostic factors available at the start of the LoT (i.e., the selected LoT was the one with the highest propensity score to be in ELARA). After selection of LoT, an adjusted ITC was performed to assess the effect of tisa-cel versus SOC by measuring CRR, ORR, progression-free survival (PFS), overall survival (OS), and time to next treatment (TTNT). A subgroup analysis of SOC patients with ≥1 eligible LoT initiated from 2014 on (coinciding with the introduction of the Lugano response criteria as well as regulatory approval of idelalisib) was performed for all endpoints. Results: Baseline characteristics for the tisa-cel and SOC cohorts are described in Table 1; after weighting, baseline variables, including number of previous lines of systemic therapy (median: 4 lines) were well balanced between the tisa-cel and SOC cohorts. Treatment regimens observed for ReCORD-FL patients at LoT selection were: anti-CD20 antibody plus alkylator (31.5% of patients), anti-CD20 antibody without alkylator (25.9%), alkylator without anti-CD20 antibody (17.5%), and regimens other than anti-CD20 antibody and alkylator (25.2%). After LoT selection and adjusting for differences in baseline variables, tisa-cel was associated with improvement over SOC in CRR (69.1% vs. 37.3%), ORR (85.6% vs. 63.6%), as well as PFS, TTNT and OS (Table 2, Figures 1-2), with a numerically higher 6-month PFS rate vs. SOC (85.3% vs. 66.5%), as well as higher 24-month OS rate (87.8% vs. 64.8%). Further, there was an estimated 80% reduction in death risk in favor of tisa-cel over SOC, a 40% reduction in risk of progression in favor of tisa-cel over SOC and a 69% reduction in risk of death or requiring a new anticancer therapy (Table 1). In the sub-analysis of SOC patients with lines of therapy initiated in or after 2014, the superiority of tisa-cel over SOC was confirmed in all the efficacy outcomes (CRR: 69.1% vs. 30.5%; ORR: 85.6% vs. 58.8%; hazard ratios substantially < 1 for OS, PFS, TTNT). Conclusion: The ITC results suggest that tisa-cel has superior efficacy over SOC in r/r FL for all evaluated endpoints. A key limitation of this study is that response assessment criteria and schedule was more heterogeneous in ReCORD-FL than in ELARA. However, the sub-analysis on SOC patients assessed with a LoT selected in 2014 or later (when more patients could have been assessed using the Lugano response criteria) showed similar favorability for tisa-cel over SOC in all the efficacy outcomes. Moreover, outcome parameters independent of response criteria, namely OS and TTNT, were also significantly better for tisa-cel vs. SOC. Figure 1 Figure 1. Disclosures Salles: Abbvie, Epizyme, Morphosys, Regeneron: Consultancy, Honoraria; Bayer: Honoraria; Beigene, BMS/Celgene, Debiopharm, Genentech/Roche, Genmab, Incyte, Ipsen, anssen, Novartis. Kite/Gilead, Loxo, Miltneiy, Rapt, TAKEDA, Velosbio, Allogene: Consultancy. Schuster: Acerta Pharma/AstraZeneca: Consultancy; Alimera Sciences: Consultancy; BeiGene: Consultancy; Juno Theraputics: Consultancy, Research Funding; Loxo Oncology: Consultancy; Tessa Theraputics: Consultancy; Genentech/Roche: Consultancy, Research Funding; Merck: Research Funding; Pharmacyclics: Research Funding; Adaptive Biotechnologies: Research Funding; Incyte: Research Funding; TG Theraputics: Research Funding; Novartis: Consultancy, Honoraria, Patents & Royalties, Research Funding; Abbvie: Consultancy, Research Funding; Nordic Nanovector: Consultancy; Celgene: Consultancy, Honoraria, Research Funding. Dreyling: BeiGene: Consultancy; Celgene: Consultancy, Research Funding, Speakers Bureau; Amgen: Speakers Bureau; Genmab: Consultancy; Gilead/Kite: Consultancy, Research Funding, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau; Abbvie: Research Funding; Astra Zeneca: Consultancy, Speakers Bureau; Bayer HealthCare Pharmaceuticals: Consultancy, Research Funding, Speakers Bureau. Kuruvilla: AbbVie: Honoraria; Amgen: Honoraria; AstraZeneca: Honoraria, Research Funding; Antengene: Honoraria; Roche: Honoraria, Research Funding; Incyte: Honoraria; BMS: Honoraria; Merck: Honoraria; Janssen: Honoraria, Research Funding; Karyopharm: Honoraria, Other: Data and Safety Monitoring Board; Novartis: Honoraria; Medison Ventures: Honoraria; Pfizer: Honoraria; Gilead: Honoraria; Seattle Genetics: Honoraria; TG Therapeutics: Honoraria. Patten: ROCHE: Research Funding; GILEAD SCIENCES: Honoraria, Research Funding; ABBVIE: Honoraria; NOVARTIS: Honoraria; ASTRA ZENECA: Honoraria; JANSSEN: Honoraria. Von Tresckow: AbbVie: Other: Congress and travel support; Amgen: Consultancy, Honoraria; AstraZeneca: Honoraria, Other: Congress and travel support; BMS-Celgene: Consultancy, Honoraria, Other: Congress and travel support; Kite-Gilead: Consultancy, Honoraria; MSD: Consultancy, Honoraria, Other: Congress and travel support, Research Funding; Novartis: Consultancy, Honoraria, Other: Congress and travel support, Research Funding; Pentixafarm: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Other, Research Funding. Smith: Alexion, AstraZeneca Rare Disease: Other: Study investigator; Celgene, Genetech, AbbVie: Consultancy. Davis: Novartis, Vertex Pharmaceuticals, Pfizer, Eisai, Eli Lilly, AstraZeneca: Research Funding. Anjos: Novartis: Current Employment. Chu: Novartis: Current Employment, Current equity holder in publicly-traded company. Zhang: Novartis: Current Employment, Current equity holder in publicly-traded company. Lobetti Bodoni: Spouse: Harlcok Healthcare: Current holder of individual stocks in a privately-held company; Spouse: Takeda: Consultancy, Honoraria, Speakers Bureau; Spouse: Celgene: Honoraria; Spouse: Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Spouse: Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Spouse: Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Spouse: NHS: Ended employment in the past 24 months; Spouse: F. Hoffmann-La Roche: Current Employment, Current equity holder in publicly-traded company; Gilead: Other: Travel sponsorship in June 2019; Novartis: Current Employment, Current equity holder in publicly-traded company. Thieblemont: Kyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Gilead Sciences: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses , Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Bristol Myers Squibb/Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Cellectis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Hospira: Research Funding; Bayer: Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses . Fowler: BostonGene, Corp: Current Employment, Current holder of stock options in a privately-held company; Bristol Myers Squibb, F. Hoffmann-La Roche Ltd, TG Therapeutics and Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding. Dickinson: Janssen: Consultancy, Honoraria; Takeda: Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria; MSD: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gilead Sciences: Consultancy, Honoraria, Speakers Bureau; Amgen: Honoraria; Celgene: Research Funding; Roche: Consultancy, Honoraria, Other: travel, accommodation, expenses, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau. Martinez-Lopez: Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Incyte: Consultancy, Research Funding, Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau; Astellas: Research Funding, Speakers Bureau. Wang: Eli Lilly: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding; InnoCare: Research Funding; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; MorphoSys: Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. Link: Genentech/Roche: Consultancy, Research Funding; MEI: Consultancy; Novartis, Jannsen: Research Funding.

Abstract Clinical significance of somatic gene variants needs to be comprehensively characterized for their diagnostic, prognostic and/or therapeutic actionability in patient management. However, challenges remain due to discrepancies in interpretation and reporting of these somatic variants among different testing labs. Therefore, standardized curation, clinical interpretation and reporting of somatic variants in hematologic cancers is critical. To address this issue, the Hematologic Cancer Taskforce (HCT), composed of 52 multi-disciplinary experts including oncologists, molecular pathologists, lab directors, genomic scientists and biocurators, was formed in January 2020 within the ClinGen Somatic Cancer Clinical Domain Working Group (CDWG) with a goal to undertake systematic curation and evidence-based clinical interpretation of genes/somatic variants associated with hematologic malignancies. In collaboration with the Clinical Interpretation of Variants in Cancer (CIViC) (civicdb.org) knowledgebase, HCT members curate, edit, and verify Evidence Items for each variant extracted from peer-reviewed publications. Monthly discussions based on these Evidence Items lead to the preparation of variant Assertions, which summarize the state of the field consensus variant interpretation and include tiering based on the AMP/ASCO/CAP guidelines (PMID: 27993330). FMS-like tyrosine kinase 3 (FLT3) encodes a class III receptor tyrosine kinase expressed in hematopoietic cells. FLT3 mutations, including both internal tandem duplication (ITD) and mutations in the tyrosine kinase domain (TKD), are the most common mutations in acute myeloid leukemia (AML), occurring in approximately 30% of all AML cases. Implementing FLT3 tyrosine kinase inhibitors (TKIs) in different treatment regimens for FLT3 mutated AML patients has led to significantly improved overall survival. Type I FLT3 inhibitors, including midostaurin, gilteritinib, sunitinib, lestaurtinib, and crenolanib, bind to the ATP-binding site when the receptor is in active conformation. Type II FLT3 inhibitors, including sorafenib, ponatinib, and quizartinib, interact with a hydrophobic region directly adjacent to the ATP-binding domain that is only accessible when the receptor is inactive, which prevents receptor activation. Generally in AML cells, type I FLT3 inhibitors prevent activity for both ITD and TKD mutations, while Type II inhibitors target ITD but lack efficiency against TKD mutations. The development of TKD mutations in AML cells with ITD have proved to be a mechanism of acquired, or secondary resistance to Type II FLT3 inhibitors. The HCT is piloting curation assessments of FLT3 alterations, including ITD, TKD and non-TKD variants, in AML. So far, the HCT has curated 75 evidence items for FLT3 somatic variants. FLT3-ITD, as well as D835 and I836 were asserted as tier 1 level A variants based on the prediction of response to gilteritinib in relapsed/refractory AML (PMIDs: 27993330, 31665578, 28645776, 28516360, 27908881). Recent curation activities are focused on FLT3 D839G and N676K, as clinical trials using large AML patient cohorts are lacking in their ability to validate drug response/resistance associations of these two TKD variants due to their low frequency. Functional studies showed both variants result in increased proliferation and protection from apoptosis, supporting the oncogenic potential of these two variants (PMIDs: 26891877, 2468088). FLT3 D839G combined with ITD confers resistance to pexidartinib and ponatinib, both Type II FLT3 inhibitors (PMIDs: 25847190, 23430109). FLT3 N676K predicts response to the Type I FLT3 inhibitor, gilteritinib, when N676K is present alone or in combination with ITD. Interestingly, FLT3 N676K in the absence of ITD predicts response to sorafenib, a Type II FLT3 inhibitor (PMIDs: 32040554, 32984009). However, these results are mostly derived from in vitro studies. Two separate Tier II, Level D Assertions have been submitted for FLT3-ITD&D839G for its response to pexidartinib and ponatinib, and more evidence is being collected to form an Assertion for FLT3 N676K. The complexity of the prediction of response/resistance associated with FLT3 D839G and N676K supports the importance of evidence-based curation and collection for these variants in the context of the overall mutation profile, disease context and specific FLT3 TKIs to clearly define their clinical impact. Disclosures Pullarkat: Stemline Therapeutics: Honoraria.

Abstract Background: Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative treatment for acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). While many factors influence the outcomes of allo-HCT in these leukemias, the independent impact of ABO mismatching between the patient and donor remains unclear. Methods: Using the CIBMTR database, we identified adults aged ≥18 years with AML or ALL who underwent allo-HCT from HLA-matched sibling donor (MSD) or 8/8 matched unrelated donor (MUD) between 2008-2018. We excluded patients who underwent transplant from a mismatched donor source or who received an ex-vivo T-cell depleted graft. Patients were stratified into cohorts based on ABO status (match, minor mismatch, major mismatch, bidirectional mismatch). Outcomes such as overall survival (OS), disease free survival (DFS), non-relapse mortality (NRM), relapse, incidence of acute graft versus host disease (GVHD), chronic GVHD, neutrophil engraftment, platelet engraftment and graft failure were evaluated. Survival analysis was done using Kaplan-Meier method and significant predictors were evaluated using Cox-proportional hazard regression method. Multivariate regression model included main effect (ABO status) and covariates (patient age, gender match, disease type, disease status, HCT-CI, Karnofsky performance status, donor type, conditioning intensity/use of TBI, stem cell source, GVHD prophylaxis, ATG/alemtuzumab use, transplant year). Results: Of 4946 patients who met the study criteria, 2741 patients (55.4%) were ABO matched, 1030 patients (20.8%) had minor ABO mismatch, 899 patients (18.1%) had major ABO mismatch and 276 patients (5.6%) had bidirectional ABO mismatch. Graft manipulation for ABO incompatibility was performed in 900 patients (minor ABO mismatch=532; major ABO mismatch=226; bidirectional mismatch=142), however, the information on individual graft manipulation techniques was limited. In multivariable analysis (table 1), major ABO mismatch significantly affected the OS, platelet engraftment and primary graft failure. Compared to ABO matched allo-HCT, major ABO mismatched allo-HCT was associated with worse OS (major mismatch - HR 1.16, 95% CI 1.05-1.29; p=0.005), inferior platelet engraftment (HR 0.83, 95% CI 0.77-0.90; p=<0.001), and higher risk of primary graft failure [4.5% (major mismatch) vs. 3.2% (ABO matched) - HR 1.60, 95% CI 1.12-2.30, p=0.01]. There was a significant interaction between the ABO status and graft type (peripheral blood vs. bone marrow) for the acute GVHD grades 2-4 model, and they are presented separately (table 1). Bidirectional ABO mismatch also significantly impacted the outcomes such as acute GVHD grades 2-4 (in bone marrow stem cell subgroup, HR 0.50, 95%CI 0.27-0.93, p=0.02) in addition to a trend towards inferior survival and NRM (p-value not significant). Other outcomes such as relapse (p=0.41), acute GVHD grades 3-4 (p=0.13), and chronic GVHD (p=0.30) were not significantly influenced by the ABO status. Conclusions: Our study demonstrates that pre-transplant ABO status is an independent predictor of survival and other post-transplant outcomes in a large cohort of patients with AML and ALL undergoing allo-HCT in the recent era. This demonstrates the importance of considering ABO status in the donor selection algorithms and potential strategies to mitigate its adverse impact. Due to the limited information available on graft manipulation strategies, the impact of graft manipulation techniques on the outcomes could not be evaluated and needs to be investigated in future studies. Figure 1 Figure 1. Disclosures Guru Murthy: Techspert: Consultancy; Guidepoint: Consultancy; Cancerexpertnow: Honoraria; Qessential: Consultancy; TG therapeutics: Other: Advisory board; Cardinal Health Inc.: Honoraria. Devine: Magenta Therapeutics: Current Employment, Research Funding; Tmunity: Current Employment, Research Funding; Sanofi: Consultancy, Research Funding; Johnsonand Johnson: Consultancy, Research Funding; Orca Bio: Consultancy, Research Funding; Be the Match: Current Employment; Vor Bio: Research Funding; Kiadis: Consultancy, Research Funding. Farhadfar: Incyte: Consultancy. Sharma: Vertex Pharmaceuticals/CRISPR Therapeutics: Other: Salary support paid to institution; Novartis: Other: Salary support paid to institution; Spotlight Therapeutics: Consultancy; Medexus Inc: Consultancy; CRISPR Therapeutics: Other, Research Funding; Vindico Medical Education: Honoraria. Stefanski: Novartis: Honoraria. Pulsipher: Equillium: Membership on an entity's Board of Directors or advisory committees; Adaptive: Research Funding; Jasper Therapeutics: Honoraria. Shaw: mallinkrodt: Other: payments; Orca bio: Consultancy.