The FDA has granted accelerated approval to zanubrutinib, an inhibitor of Bruton tyrosine kinase (BTK), to treat adults with mantle cell lymphoma who have received at least one prior therapy. Zanubrutinib is the third BTK inhibitor to be approved by the FDA for treatment of a hematologic malignancy, after ibrutinib in 2013 and acalabrutinib in 2017.
The zanubrutinib approval was based on results from a single-arm clinical trial, which measured overall response rate (complete or partial shrinkage of tumors after treatment) in 86 patients. Eighty-four percent of patients’ tumors shrunk, and the median duration of response was 19.5 months (range not provided). An additional single-arm trial, in which 84% of 32 patients had tumor shrinkage with a median duration of response of 18.5 months (range not provided), supported these findings.
Notably, these trials were conducted outside the U.S., and this approval is the first based on efficacy data predominantly collected from Chinese research, according to zanubrutinib’s manufacturer, BeiGene.
AEs associated with zanubrutinib include neutropenia, thrombocytopenia, leukopenia, anemia, upper respiratory tract infection, bruising, rash, diarrhea, and cough. The FDA’s approval notes that patients should be monitored for bleeding, infection, cardiac arrhythmias, and cytopenias. Women of reproductive age and men with female partners of reproductive age should use contraception during treatment, and pregnant or breastfeeding women should not take zanubrutinib because of potential harm to a fetus or newborn.