Ibrutinib is active in patients with previously treated marginal zone lymphoma (MZL) and has a good safety profile, the results of a multicenter, open-label phase II trial published in Blood suggest.
Nearly half of 63 patients responded to monotherapy with the once-daily oral inhibitor of Bruton tyrosine kinase, and ibrutinib was generally well tolerated, according to the study (). The results prompted the U.S. Food and Drug Administration to grant accelerated approval of ibrutinib for patients with MZL who were previously treated with at least one prior anti-CD20–based therapy.
“MZL is frequently linked to chronic infection, which may induce B-cell receptor (BCR) signaling, resulting in aberrant B-cell survival and proliferation,” note the investigators, who were led by, a hematologic oncologist with the Lymphoma Service at the Memorial Sloan-Kettering Cancer Center, New York. “Single-agent ibrutinib induced durable responses with a favorable benefit–risk profile in patients with previously treated MZL, confirming the role of BCR signaling in this malignancy.”
“As the only approved therapy, ibrutinib provides a treatment option without chemotherapy for MZL,” they maintain. “Future studies will investigate ibrutinib in treatment-naive patients or as combination strategies in relapsed/refractory MZL.”
In the trial, which was funded by Pharmacyclics, an AbbVie Company, patients with MZL of all subtypes who had received at least one prior therapy with an anti-CD20 antibody–containing regimen were treated with 560 mg ibrutinib (Imbruvica) orally once daily. The median number of prior systemic therapies was two, and 63% had received prior chemoimmunotherapy.
The overall response rate, as assessed by an independent review committee using 2007 International Working Group criteria – the trial’s primary endpoint – was 48%, according to the published results. Benefit was similar across patients who differed regarding MZL subtype, number of prior regimen, and previous receipt of chemoimmunotherapy
After a 19.4-month median follow-up, the median duration of response was not reached, and median progression-free survival was 14.2 months.
The most common grade 3 or worse adverse events were anemia (14%), pneumonia (8%), and fatigue (6%). Serious adverse events of any grade affected 44% of patients. The most common was grade 3 or 4 pneumonia. Adverse events led to treatment discontinuation in 17% of patients and dose reductions in 10%.
“Due to evidence of pseudoprogression in our trial … biopsies may be warranted to differentiate between true lymphoma progression and immune-mediated antitumor response,” the investigators note.
Dr. Noy disclosed that she has received research funding from Pharmacyclics.