Venetoclax/FluBu2 RIC transplant followed by all-oral venetoclax/decitabine maintenance for poor-risk MDS/AML

To improve the tolerability of posttransplant maintenance and outcomes despite poor-risk disease genetics, we conducted a phase 1 study of venetoclax (Ven) with FluBu2 (fludarabine/busulfan) reduced-intensity chemotherapy transplantation using tacrolimus/methotrexate graft-versus-host disease (GVHD) prophylaxis, followed by all-oral Ven/decitabine-cedazuridine (Ven/Dec-c) maintenance in patients with poor-risk MDS/AML (myelodysplastic syndrome/acute myeloid leukemia; N = 30). Overall, 58% had previous Ven exposure and 63% had TP53 mutation; 15/19 had TP53 multihit state. At a median of +55 days, prophylactic maintenance therapy with Ven (400 mg on days 1-14) and Dec-c (35 mg decitabine and 100 mg cedazuridine tablet on days 1, 3, and 5, or days 1, 2, and 3) was initiated for 8 cycles of 42 days each in 26 of 30 patients (87%; of the remaining patients, 3 relapsed early and 1 withdrew). On maintenance, grade 3/4 neutropenia (96%) occurred although infections were rare (n = 2). No dose-limiting toxicities occurred. The 6-month acute GVHD grade 2 to 4 rate was 13%. The 1-year moderate/severe chronic GVHD rate was 31%. At a median follow-up of 25.1 months (range, 15-33), median overall survival (OS) and progression-free survival (PFS) were not reached. On maintenance, 2-year OS was 77%, PFS was 62%, nonrelapse mortality was 0%, and cumulative incidence of relapse was 38%. Exploratory studies identified 96% of patients had pretransplant next-generation sequencing molecular residual disease (MRD) positivity, favorable survival in those with non-TP53 MRD positivity, and delayed conversion on maintenance in 11 of 18 (61%) with TP53-MRD positivity. Patient-reported outcomes assessed in the first 6 months of maintenance were stable except for emotional function, which significantly improved. This trial was registered at www.ClinicalTrials.gov as NCT03613532.