Purpose: Mantle-cell lymphoma (MCL) is an incurable mature B-cell neoplasm with high initial response rates followed almost invariably by relapse. Prognosis for patients following relapse is poor, and treatment choices are limited. We evaluated the efficacy and safety of zanubrutinib, an investigational selective Bruton's tyrosine kinase (BTK) inhibitor. Patients and Methods: Patients with relapsed/refractory MCL were enrolled in this ongoing phase II, single-arm, open-label study, and treated with oral zanubrutinib 160 mg twice daily. The primary endpoint is overall response rate (ORR) assessed by an independent review committee (per Lugano 2014 classification); secondary endpoints include duration of response (DOR), time to response, progression-free survival (PFS), and safety. Results: Eighty-six patients (median age, 60.5 years) were enrolled after a median of 2 prior lines of therapy, received ≥1 dose of the study drug, and were evaluable for safety and efficacy. After a median follow-up of 18.4 months, 72 (84%) patients achieved an objective response, with 59 (68.6%) achieving a complete response (CR). Median DOR and PFS were 19.5 and 22.1 months, respectively; 12-month event-free estimates for DOR and PFS are 78% and 76%, respectively. Most common grade ≥3 adverse events (AE) were neutropenia (19.8%) and lung infection/ pneumonia (9.3%). Three patients experienced major bleeding events, and there were no reports of atrial fibrillation. Eight (9.3%) patients discontinued zanubrutinib for AEs. Conclusions: These results demonstrate high and durable ORR and CR rates in patients with relapsed/refractory MCL. Zanubrutinib was generally well tolerated; grade ≥3 BTK inhibitorassociated toxicities (hemorrhage, rash, hypertension, diarrhea, atrial fibrillation) were uncommon.

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Background: Bruton tyrosine kinase (BTK) inhibitors have demonstrated a high degree of efficacy in the treatment of B cell malignancies characterized by constitutive B cell receptor activation, including chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Methods: The efficacy and safety of zanubrutinib, an investigational highly selective BTK inhibitor, was evaluated in this single-arm, phase 2 study of Chinese patients with relapsed/refractory CLL/SLL. The primary endpoint was overall response rate as assessed by an independent review committee. Results: Of the 91 evaluable patients, 77 (84.6%) achieved a response, with three (3.3%), 54 (59.3%), and 20 (22%) patients achieving a complete response, partial response, and partial response with lymphocytosis, respectively, after a median follow-up of 15.1 months. The estimated 12-month event-free rate for duration of response was 92.9%. The most commonly reported grade ≥ 3 adverse events (AEs) were neutropenia (44%), thrombocytopenia (15.4%), lung infection/pneumonia (13.2%), upper respiratory tract infection (9.9%), and anemia (8.8%). The 12month overall survival rate was 96%. Eight (9.0%) patients discontinued zanubrutinib due to AEs, and seven (8.0%) patients required at least one dose reduction. Conclusion: Treatment of patients with relapsed/refractory CLL/SLL with zanubrutinib was generally well tolerated and resulted in a high overall response rate, thereby conferring a favorable benefit-risk profile.