Zanubrutinib, Obinutuzumab, and Venetoclax for First-Line Treatment of Mantle Cell Lymphoma with a TP53 Mutation

• Zanubrutinib, obinutuzumab, and venetoclax was safe and effective for the frontline treatment of TP53-mutant mantle cell lymphoma.

• The 2-year PFS of 72% compares favorably with previously reported outcomes with chemoimmunotherapy in TP53-mutant MCL.

Background: TP53-mutant mantle cell lymphoma (MCL) is associated with poor survival outcomes with standard chemoimmunotherapy. Dual BTK and BCL2-inhibition with or without anti-CD20 monoclonal antibody therapy has shown promising activity in TP53-mutant MCL. We conducted a multi-center phase 2 study of zanubrutinib, obinutuzumab, and venetoclax (BOVen) in untreated MCL patients with TP53 mutation. Patients initially received zanubrutinib 160mg twice daily and obinutuzumab. Obinutuzumab 1000mg was given on cycle 1 day 1, 8, 15 and day 1 of cycles 2-8. After 2 cycles, venetoclax was added with weekly dose-ramp up to 400mg daily. After 24 cycles, if patients were in complete remission with undetectable minimal residual disease using an immunosequencing assay, treatment was discontinued. The primary endpoint was met if ³11 patients were progression free at 2 years. The study included 25 patients with untreated MCL with TP53 mutation. The best overall response rate was 96% (24/25) and the complete response rate was 88% (22/25). Frequency of uMRD5 and uMRD6 at cycle 13 was 95% (18/19) and 84% (16/19). With median follow up of 28.2 months, the primary endpoint was met with a 2-year progression-free survival of 72%, and the 2-year disease-specific and overall survival were 91% and 76%, respectively. Common side effects were generally low grade and included diarrhea (64%), neutropenia (32%), and infusion-related reactions (24%). BOVen was well tolerated and met its primary efficacy endpoint in TP53-mutant mantle cell lymphoma. These data support its use and further evaluation of the BOVen regimen in this high-risk population. NCT03824483