15-Day Duration of Venetoclax Combined with Azacitidine in Treatment-Naive Higher-Risk Myelodysplastic Syndromes: A Prospective Multicenter Study

BACKGROUND: Higher-risk myelodysplastic syndromes (HR-MDS) carry a high risk of progression to acute myeloid leukemia and poor overall survival. Hypomethylating agents (HMAs), such as azacitidine, remain the standard of care but have limited efficacy. A 15-day venetoclax-azacitidine regimen has shown promising objective response rates (ORR) and potential as a bridge to allogeneic hematopoietic stem cell transplantation (HSCT) in relapsed/refractory HR-MDS. We conducted a prospective multicenter trial to evaluate its efficacy and safety in previously untreated patients. METHODS: ) on days 1-7 of each 28-day cycle. The primary endpoint was ORR (2006 IWG criteria); secondary endpoints included complete remission (CR), overall survival (OS), and AML progression. RESULTS: Twenty-eight patients (median age: 63 years) were enrolled, with a median follow-up of 8.5 months. ORR was 85.7% per 2006 IWG (CR: 35.7%, marrow CR: 50.0%), and 78.6% per 2023 IWG (CR: 35.7%). Responses were consistent across molecular and IPSS-R subgroups. Median OS was not reached. High neutrophil count and high cytogenetic risk were favorable factors; TP53 mutation/deletion was an adverse prognostic marker. Grade 3-4 hematologic toxicities included neutropenia (96.4%), anemia (71.4%), and thrombocytopenia (64.3%). Serious adverse events (35.7%) were mainly infections. No dose-limiting or unexpected toxicities were observed. CONCLUSIONS: The 15-day venetoclax plus azacitidine regimen demonstrated high efficacy and manageable toxicity in treatment-naïve HR-MDS. It may be particularly beneficial for patients with high neutrophil counts, adverse cytogenetics, or those eligible for HSCT, supporting further investigation in larger trials.