FDA approves zanubrutinib for Waldenström macroglobulinemia
The FDA approved zanubrutinib for adults with Waldenström macroglobulinemia.
Zanubrutinib (Brukinsa, BeiGene) is a small-molecule inhibitor of Bruton tyrosine kinase in development as monotherapy or part of combination therapy for treatment of various B-cell malignancies. It previously had been approved in the United States for treatment of adults with mantle cell lymphoma who received at least one prior therapy.
The randomized ASPEN trial compared zanubrutinib vs. ibrutinib (Imbruvica; Janssen, Pharmacyclics) for patients with Waldenström macroglobulinemia.
One cohort included 201 patients with MYD88 L265P mutation-positive disease. Researchers randomly assigned 102 patients to 160 mg zanubrutinib twice daily. The other 99 patients received 420 mg ibrutinib once daily. Treatment continued until disease progression or unacceptable toxicity.
A second cohort included 26 patients with MYD88 wild-type disease and two patients with unknown MYD88 mutation status. These patients received 160 mg zanubrutinib twice daily.
Response rate assessed by independent review committee served as the major efficacy outcome. Duration of response served as an additional efficacy outcome.
The FDA based approval on results of a noncomparative assessment of zanubrutinib-treated patients.
In the first cohort, researchers reported a response rate of 77.5% (95% CI, 68.1-85.1) with zanubrutinib, and 94.4% (95% CI, 85.8-97.9) achieved event-free responses that lasted at least 12 months.
In the second cohort, 13 (50%) of 26 evaluable patients achieved response.
The most common adverse events among zanubrutinib-treated patients included decreased neutrophil count, upper respiratory tract infection, decreased platelet count, rash, hemorrhage, musculoskeletal pain, decreased hemoglobin, bruising, diarrhea, pneumonia and cough.
The FDA previously granted zanubrutinib fast track and orphan drug designation for this indication.