FDA Grants Zanubrutinib an Accelerated Approval in Marginal Zone Lymphoma

Nick Mulcahy

September 15, 2021

The US Food and Drug Administration (FDA) has granted an accelerated approval to zanubrutinib (Brukinsa) for the treatment of adult patients with relapsed or refractory (R/R) marginal zone lymphoma (MZL) who have received at least one anti-CD20-based regimen, the drug's maker BeiGene announced in a press statement.  

The drug works as an inhibitor of Bruton's tyrosine kinase (BTK), which plays a critical role in B-cell receptor signaling, a driver in the development of marginal zone lymphoma, according to the company.

The new approval comes just 2 weeks after the oral drug received an accelerated approval for the treatment of adult patients with Waldenström's macroglobulinemia, a rare non-Hodgkin lymphoma. The drug also has an accelerated approval for treating mantle cell lymphoma in patients who have received at least one prior therapy and is being studied in the treatment of chronic lymphocytic leukemia.

The latest indication is based on results from two single-arm clinical trials, with overall response rate (ORR) as the primary endpoint.

In the multicenter, phase 2 MAGNOLIA trial, zanubrutinib "demonstrated impressive overall response and complete remission rates, with responses observed in all MZL subtypes," said Stephen Opat, MBBS, of Monash University in Melbourne, Australia and lead principal investigator of the study. "In addition, this next-generation BTK inhibitor was well-tolerated in these patients, with low rate of discontinuation due to adverse reactions."

In the MAGNOLIA trial, 66 patients with R/R MZL who had received at least one anti-CD20-based regimen were treated with zanubrutinib. Among the patients were 26 with extranodal subtype, 26 with nodal subtype, 12 with splenic subtype, and 4 with unknown subtype.

The ORR was 56% with a complete response rate of 20%, based on CT scan assessment.

In addition, the ORR was 67% with a complete response rate of 26%, based on PET-CT scan assessment.

The median duration of response (DoR) was not reached at the median follow-up time of 8.3 months, with 85% of responders still in remission at 12 months. Responses were observed in all MZL subtypes.

In an earlier, phase 1/2 trial of the agent, 20 patients were evaluated, including 9 with extranodal subtype, 5 with nodal subtype, and 6 with splenic subtype. Based on CT scan assessment, the ORR was 80% with a complete remission rate of 20%. The median DoR was not reached at the median follow-up time of 31.4 months, with 72% of responders still in remission at 12 months.

The most common (≥30%) adverse reactions, including laboratory abnormalities, in the pooled safety population of 847 patients were decreased neutrophil count, upper respiratory tract infection, decreased platelet count, hemorrhage, decreased lymphocyte count, rash, and musculoskeletal pain, said the company.

Nick Mulcahy is an  award-winning  senior journalist for Medscape, focusing on oncology, and can be reached at  nmulcahy@medscape.net  and on Twitter:  @MulcahyNick

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