On Saturday 16th June an oral abstract session took place at the 23rd Congress of the European Hematology Association (EHA). Abstract S854 was presented by Jorge Castillo, Dana-Farber Cancer Institute, Boston, US, on the phase II study outcomes of venetoclax in patients with previously treated Waldenström macroglobulinemia (WM).
- Eligible patients included in the study (N = 30) were treated with 200mg venetoclax orally once daily for a week up to 800mg once daily until disease progression or for a maximum of 2 years
- Median follow-up was 11 months
- The baseline median serum IgM was 3,543 mg/dl (range 642-7,970 mg/dl) and at 6 months, the median serum IgM had declined to 1,640 mg/dl (range 49-5,220 mg/dl)
- The overall response rate was of 87% and the major response rate was 74%
- 5 patients (17%) achieved very good partial response (VGPR) and a partial response was seen in 17 patients (57%)
- The major response rate was not statistically different based on relapsed or refractory disease, prior ibrutinib exposure or CXCR4 mutation status
- VGPR rate at best response was lower in patients with prior ibrutinib exposure (7% vs 27%), and in patients with CXCR4MUT compared with CXCR4WT (7% vs 29%)
- The most frequent Adverse Events (AEs) Grade ≥3 included: neutropenia (n = 9), anemia (n = 2) and upper respiratory infection (n = 1)
Dr Castillo concluded his talk by stating that the results of this study demonstrated that the use of venetoclax was safe and effective in patients with previously treated WM. It also showed venetoclax efficacy in patients with CXCR4 mutations and patients with previous exposure to BTK inhibitors.