A two-part, single-arm, multicentre, phase I study of zanubrutinib, a selective Bruton tyrosine kinase inhibitor, in Chinese patients with relapsed/refractory B-cell malignancies.

This single-arm, multicentre, phase I study is the first study of zanubrutinib, a potent, specific, irreversible Bruton tyrosine kinase (BTK) inhibitor, in Chinese patients with relapsed/refractory B-cell malignancies. The objectives were to evaluate safety and preliminary anti-tumour activity. Forty-four patients received zanubrutinib 320 mg once daily (QD) (n = 10) or 160 mg twice daily (BID) (n = 34) until disease progression or unacceptable toxicity. 29.5% of patients received zanubrutinib for at least two years. The most common adverse event (AE) and the most common grade 3 or higher AE was neutrophil count decreased (54.5% and 25.0% respectively). Two patients (4.5%) discontinued treatment due to AEs and one treatment-emergent AE led to death. All haemorrhagic events were grade 1-2 (except for one non-serious grade 3 purpura). No second primary malignancies, tumour lysis syndrome, or atrial fibrillation/flutter occurred. The overall response rate was 52.3% (complete response rate, 18.2%). Patients with all cancer subtypes benefited from treatment. BTK C481S/R or L528W mutations were found in zanubrutinib-progressive patients. The safety/efficacy profiles of patients treated with 320 mg QD and 160 mg BID were comparable and similar daily area under the curve (AUC) was achieved. Overall, zanubrutinib was well tolerated and either of these two regimens is clinically practical. Registered at ClinicalTrials.gov (NCT03189524, on 16 June 2017, https://clinicaltrials.gov/ct2/show/NCT03189524).

Pooled safety analysis of zanubrutinib monotherapy in patients with B-cell malignancies.

Zanubrutinib is a selective Bruton tyrosine kinase (BTK) inhibitor evaluated in multiple B-cell malignancy studies. We constructed a pooled safety analysis to better understand zanubrutinib-associated treatment-emergent adverse events (TEAEs) and identify treatment-limiting toxicities. Data were pooled from 6 studies (N = 779). Assessments included type, incidence, severity, and outcome of TEAEs. Median age was 65 years; 20% were ≥75 years old. Most patients had Waldenström macroglobulinemia (33%), chronic lymphocytic leukemia/small lymphocytic lymphoma (29%), or mantle-cell lymphoma (19%). Median treatment duration was 26 months (range, 0.1-65); 16% of patients were treated for ≥3 years. Common nonhematologic TEAEs were upper respiratory tract infection (URI, 39%), rash (27%), bruising (25%), musculoskeletal pain (24%), diarrhea (23%), cough (21%), pneumonia (21%), urinary tract infection (UTI), and fatigue (15% each). Most common grade ≥3 TEAEs were pneumonia (11%), hypertension (5%), URI, UTI, sepsis, diarrhea, and musculoskeletal pain (2% each). Atrial fibrillation and major hemorrhage occurred in 3% and 4% of patients, respectively. Atrial fibrillation, hypertension, and diarrhea occurred at lower rates than those reported historically for ibrutinib. Grade ≥3 adverse events included neutropenia (23%), thrombocytopenia (8%), and anemia (8%). Serious TEAEs included pneumonia (11%), sepsis (2%), and pyrexia (2%).Treatment discontinuations and dose reductions for adverse events occurred in 10% and 8% of patients, respectively. Thirty-nine patients (4%) had fatal TEAEs, including pneumonia (n = 9), sepsis (n = 4), unspecified cause (n = 4), and multiple organ dysfunction syndrome (n = 5). This analysis demonstrates that zanubrutinib is generally well tolerated with a safety profile consistent with known BTK inhibitor toxicities; these were manageable and mostly reversible.

A Phase II Trial of the Bruton Tyrosine-Kinase Inhibitor Zanubrutinib (BGB-3111) in Patients with Relapsed/Refractory Waldenström Macroglobulinemia.

PURPOSE: Although Bruton tyrosine kinase (BTK) inhibitors have demonstrated promising efficacy in patients with Waldenström macroglobulinemia (WM), data in Asian populations are scarce. This trial is the first to investigate the effect of a BTK inhibitor in Chinese patients with relapsed/refractory (R/R) WM. PATIENTS AND METHODS: Patients with R/R WM with at least one prior regimen were enrolled into this single-arm, multicenter, phase II study (NCT03332173) and received zanubrutinib 160 mg twice daily until disease progression or unacceptable toxicity. The primary endpoint was major response rate (MRR), as assessed by an independent review committee. Secondary endpoints included progression-free survival, overall response rate, duration of major response, and safety. RESULTS: Forty-four patients were enrolled. After a median follow-up of 33.0 (range, 3.2-36.5) months, MRR in all patients was 69.8%, with very good partial response or better in 32.6% of patients. All mutation groups benefited from zanubrutinib treatment (MRR in patients with MYD88 L265P mutation, 73%; MRR in patients with MYD88 wild type mutation, 50%). A higher response rate was seen in the MYD88 L265P/CXCR4 WT population, compared with the other populations. Median progression-free survival and median duration of major response were not reached. The most frequently reported grade ≥3 treatment-emergent adverse events (AEs) were neutrophil count decreased (31.8%), and platelet count decreased and pneumonia (20.5% each). No case of atrial fibrillation/flutter occurred. CONCLUSIONS: Zanubrutinib achieved a high rate of response that was durable and deep in patients with R/R WM across all subgroups, and potentially confers a positive benefit-risk profile for WM.