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Investigational BTK Inhibitor Shows Promise in Waldenström Macroglobulinemia
Zanubrutinib is highly active and well-tolerated in patients with Waldenström macroglobulinemia (WM), according to updated results from a phase 1 clinical trial presented at the 10th International Workshop on WM.
Zanubrutinib is a small molecule Bruton’s tyrosine kinase (BTK) inhibitor currently being evaluated as monotherapy and in combination with other therapies for the treatment of patients with various lymphomas.
The study included 77 patients with treatment-naïve or relapsed/refractory WM, 73 of whom were evaluable for efficacy. The median follow-up time was 22.5 months, and 62 patients were still receiving the trial drug at the time of data cut off.
Updated results included an overall response rate of 92% and major response rate of 82%; roughly 40% of patients achieved a very good partial response. The 12-month progression-free survival was estimated at 89%.
The investigators noted an increased depth of response over time. In 46 patients with a follow-up of >1 year, only 4.3% achieved very good partial responses by week 14; however, this rate increased to 15.2% by week 26, and 32.6% by 1 year.
Zanubrutinib was well-tolerated, with the majority of adverse events of grade 1 or 2. The most frequently reported adverse events of any grade were petechia/purpura/contusion, upper respiratory tract infection, cough, diarrhea, constipation, back pain, and headache. Adverse events of grade 3-4 included neutropenia, anemia, hypertension, basal cell carcinoma, renal and urinary disorders, and pneumonia.
Serious adverse events were reported in 32 patients, and were attributed to zanubrutinib therapy in 5. A total of 9 patients discontinued therapy because of adverse events.
“We are hopeful that zanubrutinib, if approved, could potentially provide an important new treatment option to patients with WM and other hematologic malignancies,” said Constantine Tam, MD, Director of Hematology, St. Vincent’s Hospital, Melbourne, Australia, in a BeiGene press release.
BeiGene expects to file a new drug application with the FDA for zanubrutinib in 2019.—Janelle Bradley
