FDA approves pembrolizumab for relapsed/refractory PMBCL


The immune checkpoint inhibitor pembrolizumab (Keytruda) has been approved for the treatment of relapsed or refractory primary mediastinal large B-cell lymphoma in adult and pediatric patients.

The Food and Drug Administration based the accelerated approval on results from 53 patients with relapsed or refractory primary mediastinal large B-cell lymphoma in the KEYNOTE-170 trial. In the phase 2 trial, patients received 200 mg of pembrolizumab intravenously for 3 weeks until unacceptable toxicity or documented disease progression occurred. This continued for up to 24 months in patients who did not display progression. The overall response rate to pembrolizumab was 45% (95% CI, 32-60), which included both complete (11%) and partial (34%) responses. The median duration of response was not met within the follow-up period (median, 9.7 months) and the median time to first objective response was 2.8 months.

The recommended dose for pembrolizumab in adults is 200 mg every 3 weeks. It is recommended that pediatric patients receive 2 mg/kg every 3 weeks, with a maximum dose of 200 mg.

The most common adverse reactions to pembrolizumab were musculoskeletal pain, upper respiratory tract infection, pyrexia, fatigue, cough, dyspnea, diarrhea, nausea, arrhythmia, and headache. In total, a quarter of patients with adverse reactions required systemic treatment with a corticosteroid and 26% of patients had serious adverse reactions.

Pembrolizumab was approved via the FDA’s accelerated approval process, which allows for earlier approval of drugs that treat serious medical conditions and fulfill an unmet medical need. The drug was approved based on tumor response rate and durability of response, the FDA noted.

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