The Food and Drug Administration has approved ibrutinib for the treatment of patients with relapsed or refractory marginal zone lymphoma (MZL), the drug’s manufacturers report.

The approval marks the fifth indication for ibrutinib (Imbruvica) in just over 4 years, and ibrutinib is the first agent specifically approved for relapsed/refractory MZL, according to press releases issued by Janssen Biotech and Pharmacyclics, the two manufacturers that jointly developed and marketed the Bruton tyrosine kinase inhibitor.

Patients with marginal zone lymphoma – who comprise about 12% of all non-Hodgkin lymphoma cases – must require systemic therapy and have failed a previous anti-CD20–based therapy to be eligible for ibrutinib treatment.

After receiving various fast-track, breakthrough therapy, priority review, and accelerated approval designations from the FDA, ibrutinib was previously approved to treat mantle cell lymphoma; refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL); CLL/SLL with 17p deletion; and Waldenstrom’s macroglobulinemia, another rare form of non-Hodgkin lymphoma. The MCL and MZL approvals are based on overall response rates, and full approval is likely to require additional confirmatory data.

The new indication is based on data from a phase II, open-label, single-arm manufacturer-sponsored study that showed a 46% overall response rate (95% confidence interval, 33.4-59.1) in a cohort of 63 MZL patients who had failed one or more prior therapies. Of these, 3.2% had a complete response and 42.9% had a partial response. The median duration of response was not reached (NR) (range, 16.7 months–NR), with median follow-up of 19.4 months. The median time to initial response was 4.5 months (2.3-16.4 months).

All three MZL subtypes were represented in the cohort, and ibrutinib appeared to be effective across subtypes. Thrombocytopenia, fatigue, anemia, diarrhea, bruising, and musculoskeletal pain were commonly reported adverse events.

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