Molecular Responses Are Observed across Mutational Spectrum in Treatment-Naïve Higher-Risk Myelodysplastic Syndrome Patients Treated with Venetoclax Plus Azacitidine

▪ Introduction: Patients (pts) with higher-risk myelodysplastic syndromes (MDS) are typically treated with azacitidine (Aza). Venetoclax (Ven) is a selective, potent, oral BCL-2 inhibitor that has demonstrated synergy with Aza in preclinical studies of myeloid malignancies. Higher-risk MDS is associated with mutations in genes involved in RNA splicing, epigenetic regulation, transcription, and cellular signaling. Assessing the dynamics of genetic variants during treatment of higher-risk MDS enables understanding of the molecular determinants of response. This phase 1b study (NCT02942290) evaluates Ven + Aza for treatment-naïve higher-risk MDS, and we report efficacy among mutationally defined subgroups as well as the depth of molecular response. Methods: Pts (≥18 years) with higher-risk MDS enrolled in the study had International Prognostic Scoring System intermediate-2 or high-risk MDS, bone marrow (BM) blasts 5 to ≤10%, n=21; >10 to ≤20%, n=49; >20%, n=1). For the entire population, mORR was 80% (CR 40% and mCR 40%; no PR)