The U.S. Food and Drug Administration (FDA) has approved Brukinsa (zanubrutinib) for treating adults with mantle cell lymphoma (MCL) who have received at least one prior therapy. This is the first drug to be FDA approved by the Chinese based company, BeiGene Ltd.
The drug was also fast tracked for approval based on a single-arm Phase II study. The FDA’s Accelerated Approval process is for drugs to treat serious conditions that fill an unmet medical need based on a result that is reasonably likely to predict a clinical benefit to patients. Since it was approved on a phase II study, it is likely that further clinical trials to verify and describe zanubrutinib’s clinical benefit – either by the FDA and/or by insurance companies – will be necessary.
In the Phase II, single-arm study, 86 MCL patients who had received at least one prior treatment were given zanubrutinib. The study found the drug to be highly effective in reducing tumor size. The overall response rate (ORR) was 84% (50% of patients had a complete response and 24% had a partial response). The median duration of response (time between the initial response to therapy and subsequent disease progression or relapse) was 19.5 months. Similar results were observed in a smaller Phase I/II study involving 32 patients.
The most common adverse reactions (> 10%) were decreased neutrophil count, decreased platelet count, upper respiratory tract infection, decreased white blood cell count, decreased hemoglobin, rash, bruising, diarrhea, cough, musculoskeletal pain, pneumonia, urinary tract infection, blood in the urine (hematuria), fatigue, constipation, and hemorrhage. The most frequent serious adverse reactions were pneumonia (11%) and hemorrhage (5%).
Zanubrutinib is a Bruton’s tyrosine kinase (BTK) inhibitor. In a news release, Luhua (Michael) Wang, MD, Professor at The University of Texas MD Anderson Cancer Center said, “BTK inhibition is an established mode of treatment for patients with MCL, but many patients treated with previously approved BTK inhibitors do not fully respond to BTK therapy or are forced to discontinue treatment early due to side effects. Today we have a new option for our adult patients who have received one prior systemic or targeted therapy and are living with MCL, an aggressive blood cancer that’s often diagnosed at a more advanced stage.”
MCL is a type of non-Hodgkin’s lymphoma that accounts for 3-10% of all non-Hodgkin’s lymphomas in the United States. In most cases, a diagnosis is not made until the cancer has metastasized to the lymph nodes, bone marrow and other organs. The lymphoma is treatable, but many patients will relapse and some will not respond to first line therapies. As such, additional treatment options are needed.
Zanubrutinib tablets (80 mg) can be taken with or without food at a recommended dose of 320 mg/day.