The ABC-14 regimen (Azacitidine, Venetoclax, and Chidamide) as a bridge to allogeneic hematopoietic stem cell transplantation for Acute Myeloid Leukemia: A single-center experience

Abstract

Abstract Background: The combination of azacitidine, venetoclax, and chidamide (ABC-14 regimen) has demonstrated efficacy comparable to “3+7” intensive chemotherapy (IC) with a favorable tolerability profile in newly diagnosed AML. However, its role as a bridging strategy to allogeneic hematopoietic stem cell transplantation (allo-HSCT) is not fully established. Aim: This study aimed to evaluate the post-transplant outcomes of AML patients who received the ABC-14 regimen as a bridging therapy to allo-HSCT. Methods: This retrospective study analyzed 51 patients with newly diagnosed, secondary, or relapsed/refractory (R/R) AML who underwent allo-HSCT between December 2022 and June 2024. Patients received either the ABC-14 regimen (n=16) or intensive chemotherapy (IC) (n=35) as bridging therapy prior to a modified busulfan/cyclophosphamide-based conditioning. The ABC-14 regimen consisted of azacitidine (75 mg/m² on days 1-7), venetoclax (daily ramp-up to 400 mg on days 1-14), and Chidamide (5 mg on days 1-6 and 8-13) in a 28-day cycle. We compared key post-transplant outcomes including engraftment, viral infections, cumulative incidence (CI) of GVHD, relapse, non-relapse mortality (NRM), and survival. Results:The analysis was conducted with a data cutoff of July 30, 2025. All patients achieved successful engraftment, with no significant differences in the median time to neutrophil (13.5 vs. 12 days; p=0.178) or platelet engraftment (16 vs. 13 days; p=0.502) between the ABC-14 and IC cohorts. Rates of 100-day and overall CMV/EBV infection were similar between the groups. The cumulative incidence (CI) of grade II-IV aGVHD (p=0.470) and chronic GVHD (p=0.674) was also comparable. While the rate of non-relapse mortality (NRM) was similar (12.5% vs. 14.3%; p=0.965). No relapses were observed in the ABC-14 cohort, compared to an incidence of 11.4% in the IC cohort(p=0.325). Accordingly, Leukemia-Free Survival (87.5% vs. 88.6%; p=0.818) and Overall Survival rates did not differ significantly between the groups (p> 0.05 for all timepoints). Conclusions: As a bridge to allo-HSCT, the ABC-14 regimen did not impair engraftment kinetics and resulted in post-transplant outcomes—including GVHD, infections, and NRM—that were comparable to bridging with intensive chemotherapy. The absence of relapses observed in the ABC-14 cohort during the follow-up period is a noteworthy finding. These results position ABC-14 as a feasible and promising bridging strategy for AML, warranting further investigation in prospective, randomized trials. Disclosures: No relevant conflicts of interest to declare.