Zanubrutinib-rituximab followed by shortened chemoimmunotherapy as frontline treatment for mantle cell lymphoma (CHESS): a phase II trial

A combination of Bruton's tyrosine kinase (BTK) inhibitor ibrutinib and rituximab has shown promising efficacy in mantle cell lymphoma (MCL). This phase II trial evaluated the second-generation BTK inhibitor zanubrutinib plus rituximab as induction, followed by shortened chemoimmunotherapy as frontline treatment for MCL (NCT04624958). Eligible patients had histologically confirmed stage II-IV disease requiring immediate therapy and no prior MCL-related systemic treatment. Patients received zanubrutinib-rituximab for up to 12 cycles (part A); those achieving a complete response (CR) or experiencing disease progression proceeded to four cycles of R-DHAOx (rituximab, dexamethasone, cytarabine, and oxaliplatin) (part B). Patients with CR after part B received zanubrutinib maintenance for one year. The primary endpoint was the CR rate at part A completion. Forty-two patients were enrolled. The CR rate at part A completion was 88% (95% confidence interval [CI], 74-96), and 86% (95% CI, 72-95) at part B completion. Hematologic toxicities predominated: the most common grade 3-4 adverse events were neutropenia (7%) in part A, and thrombocytopenia (77%) and neutropenia (49%) in part B. In conclusion, zanubrutinib-rituximab induction followed by shortened R-DHAOx is efficacious with manageable safety as frontline therapy for MCL. This strategy allows for a reduction in chemotherapy cycles and warrants validation in randomized controlled trials.