A REGISTRY-BASED, OBSERVATIONAL SAFETY STUDY OF INOTUZUMAB OZOGAMICIN (INO) IN PATIENTS WITH B-CELL PRECURSOR ACUTE LYMPHOBLASTIC LEUKEMIA (ALL) PROCEEDING TO HEMATOPOIETIC STEM CELL TRANSPLANT (HSCT)

Objective: InO is a CD22-directed antibody-drug conjugate indicated for treatment of relapsed/refractory (R/R) ALL. InO has been associated with hepatotoxicity and hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS), particularly post-HSCT. Registry data from the Center for International Blood and Marrow Transplant Research (CIBMTR) was analyzed to assess toxicity in patients (pts) with ALL who received InO prior to HSCT. Methodology: CIBMTR patient data are being collected from 2017-2022 after US approval of InO. Data accrued from 2017–2020 from 131 US adult pts (median age 40 y) treated with InO who proceeded to allogeneic HSCT were included. Using interim data at 3 y, we evaluated post-HSCT outcomes, including clinical status, overall survival (OS), non-relapse mortality (NRM), relapse, death after relapse, and investigator-defined adverse events, including hepatic VOD/SOS. All statistical analyses are descriptive. Results: Before HSCT, 36% of pts received 1 InO cycle, 46% had 2 cycles, 17% had ≥3 cycles. Median time from last InO dose to HSCT was 2.0 mos (range: 0.4–26.2). At data lock (Nov 2020, n=131), VOD/SOS incidence within 100 d post-HSCT was 13% (18% of R/R ALL pts, n=91). Post-HSCT 12 mo OS was 55%; post-HSCT 12 mo NRM was 21%; post-HSCT 12 mo relapse was 36%; non-HSCT-related 12 mo mortality was 25%. Most pts (89%) who underwent HSCT during complete remission (CR) experienced continued CR post-HSCT. Conclusion: Incidence of VOD/SOS after first HSCT in InO-treated pts with R/R ALL in this study was similar to the 18-19% reported in pooled analyses of 2 clinical trials among InO-treated pts with R/R ALL and in the INO-VATE study. The NRM at 1 y of 21% (23% R/R ALL) is lower than the NRM at 1 y of 38% reported in the pooled analyses of R/R ALL InO recipients. © 2021 American Society of Clinical Oncology, Inc. Reused with permission. Accepted/presented at the 2021 ASCO Annual Meeting. All rights reserved.