Efficacy and safety of fixed-duration venetoclax plus obinutuzumab in untreated Japanese CLL and SLL: a phase 2 study

This phase 2 study (NCT05105841) evaluated the safety and efficacy of a fixed-duration 12-cycle regimen of venetoclax plus obinutuzumab in Japanese patients with previously untreated chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL). The primary efficacy endpoint was the complete remission (CR)/complete remission with incomplete marrow recovery (CRi) rate, assessed by an independent review committee (IRC) according to the 2008 International Workshop on CLL criteria. Ten patients (6 male, 4 female; 9 CLL, 1 SLL) with a median age of 69.5 years (range 52-76) received venetoclax for a median duration of 11.3 months (range 9.2-12.4). The IRC-assessed CR/CRi rate based on the best overall response was 90.0% (95% confidence interval 55.5%, 99.7%). All patients experienced at least one treatment-emergent adverse event (TEAE), and three patients (30.0%) experienced at least one serious TEAE. The most common TEAEs included infusion-related reactions (60.0%), decreased neutrophil count (50.0%), and nausea (40.0%). Nine patients (90.0%) experienced TEAEs related to venetoclax, while all ten patients (100.0%) had TEAEs related to obinutuzumab. One patient (10.0%) developed COVID-19 pneumonia, necessitating the discontinuation of venetoclax. These findings demonstrate the high efficacy and manageable safety profile of venetoclax plus obinutuzumab in this patient population.