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

• Ven/FluBu2 transplant with Tac/Mtx followed by Ven/Dec-c maintenance was safe, feasible and associated with a 2-year OS of 77%.

• Serial NGS-MRD revealed favorable outcomes with non-TP53 MRD pre-HCT and the possibility of TP53-MRD clearance on maintenance.

To improve the tolerability of post-transplant maintenance and outcomes despite poor risk disease genetics, we conducted a phase 1 study of venetoclax/FluBu2 RIC transplantation with tacrolimus/methotrexate GVHD prophylaxis followed by all-oral venetoclax/decitabine-cedazuridine (ven/dec-c) maintenance in poor-risk MDS/AML patients (N=30). 58% had prior venetoclax exposure and 63% were TP53-mutated; 15/19 had TP53 multi-hit state. At a median of +55 days, pre-emptive maintenance therapy with venetoclax (400 mg on days 1-14) and dec-c (decitabine 35 mg/cedazuridine 100 mg on days 1,3,5 or 1,2,3) was initiated for eight 42-day cycles in 26/30 (87%) patients (remaining 3 relapsed early, 1 withdrew). On maintenance, grade 3-4 neutropenia (96%) occurred though infections were rare (N=2). No DLTs occurred. 6-month acute GVHD grade II-IV rate was 13%. 1-year moderate/severe chronic GVHD rate was 31%. At a median follow up of 25.1-months (range,15-33), median OS and PFS were not reached. On maintenance, 2-year OS was 77% (95%CI,55-89), PFS 62% (95%CI,38-79), NRM 0%, and cumulative incidence of relapse 38% (95%CI,18-59). Exploratory studies identified 96% had pre-transplant NGS-MRD+, favorable survival in those with non-TP53 MRD+, and delayed conversion on maintenance in 11/18 (61%) in those with TP53 MRD+. PROs assessed in first 6-months of maintenance were stable except for emotional function, which improved (P=0.008). Trial is registered at clinicaltrials.gov/NCT03613532.