Clinical Data
An ongoing Phase 1 trial of zanubrutinib as a monotherapy in patients with different subtypes of B-cell malignancies, including Waldenström macroglobulinemia (WM), chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and other non-Hodgkin’s lymphomas (NHL), is being conducted in China. The trial is fully enrolled and comprised of two parts – a dose escalation phase involving 21 patients and a dose-expansion phase of 23 patients treated with zanubrutinib at the recommended Phase 2 dose of 160 mg taken orally twice daily.Preliminary findings suggested that there was no significant difference in the pharmacokinetic profile of zanubrutinib between Chinese and non-Chinese patients. Preliminary findings also showed complete or greater than 80 percent sustained BTK occupancy was achieved among these patients with both single- and multiple-dose administrations. As of June 15, 2018, after a median follow-up of 9.5 months (2.3 months--23.4 months), 21 patients (47%) remained on treatment. With 44 patients enrolled in the trial, 34 were evaluable for response. Of the nine patients with CLL/SLL, the overall response rate (ORR) was 100 percent, with two complete responses (CRs), six partial responses (PRs), and a PR with lymphocytosis (PR-L). Of the two patients with mantle cell lymphoma (MCL), there was one CR and one stable disease (SD). Of the two patients with WM, there was one PR and one SD. Of the 26 patients with follicular lymphoma (FL), the ORR was 42 percent with two CRs and nine PRs. There were three patients with FL who were not evaluable at the time of the data cutoff. Of the five patients with marginal zone lymphoma (MZL), there were three SDs and two patients who were not evaluable.At the time of data cutoff, no dose-limiting toxicities occurred during dose escalation portion of the trial and there were no unexpected safety signals identified in the trial. No deaths related to adverse events were observed in the trial. The most common adverse events (occurring in ≥ 20% of patients) of any attribution among all 44 patients were neutrophil count decreased (50%), anemia (32%), upper respiratory tract infection (25%), white blood cell count decreased (25%), platelet count decreased (23%), rash (23%), hematuria (20%), and hyperuricemia (20%).