FDA Grants Accelerated Approval to Retifanlimab-Dlwr for Metastatic or Recurrent Locally Advanced Merkel Cell Carcinoma
On March 22, 2023, the U.S. Food and Drug Administration (FDA) granted accelerated approval (https://www.fda.gov/drugs/resources-information-approved-drugs/fda-grants-accelerated-approval-retifanlimab-dlwr-metastatic-or-recurrent-locally-advanced-merkel) to retifanlimab-dlwr (Zynyz®) for adult patients with metastatic or recurrent locally advanced Merkel cell carcinoma (MCC).
The agent’s safety and efficacy were evaluated in PODIUM-201 (NCT03599713), an open-label, multiregional, single-arm study evaluating 65 patients with metastatic or recurrent locally advanced MCC who had not received prior systemic therapy for advanced disease.
Major efficacy outcome measures were objective response rate (ORR) and duration of response (DOR), as assessed by an independent central review committee according to RECIST v1.1. PODIUM-201’s ORR was 52% (95% CI = 40, 65) with an 18% complete response rate. Twenty-six patients (76%) had a DOR of at least 6 months, and 21 (62%) had a DOR of at least 12 months.
Among the safety population of 105 patients with MCC, the most common adverse reactions reported in at least 10% of those receiving retifanlimab-dlwr were fatigue, musculoskeletal pain, pruritus, diarrhea, rash, pyrexia, and nausea. Serious adverse reactions occurred in 22% of patients receiving retifanlimab-dlwr, including fatigue, arrhythmia, and pneumonitis (https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/761334s000lbl.pdf). Eleven percent of patients permanently discontinued (https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/761334s000lbl.pdf) retifanlimab-dlwr because of an adverse reaction. It included asthenia, atrial fibrillation, concomitant disease progression of chronic lymphocytic leukemia, demyelinating polyneuropathy, eosinophilic fasciitis, increased transaminases, infusion-related reaction, lung disorder, pancreatitis, polyarthritis, and radiculopathy (one patient each).
The recommended retifanlimab-dlwr dose is 500 mg administered via IV infusion over 30 minutes every four weeks for up to 24 months or until patients experience disease progression or unacceptable toxicity.
The review used the Assessment Aid (https://www.fda.gov/about-fda/oncology-center-excellence/assessment-aid), a voluntary submission from the applicant to facilitate the FDA’s assessment.
The application was granted priority review, fast track, and orphan drug designation. FDA expedited programs are described in the Guidance for Industry: Expedited Programs for Serious Conditions—Drugs and Biologics (https://www.fda.gov/regulatory-information/search-fda-guidance-documents/expedited-programs-serious-conditions-drugs-and-biologics).
Healthcare professionals should report all serious adverse events suspected to be associated with the use of any medicine and device to FDA’s MedWatch Reporting System (https://www.accessdata.fda.gov/scripts/medwatch/index.cfm) or by calling 800-FDA-1088.
For assistance with single-patient investigational new drug applications, contact OCE’s Project Facilitate (https://www.fda.gov/about-fda/oncology-center-excellence/project-facilitate) at 240-402-0004 or email OncProjectFacilitate@fda.hhs.gov (mailto:OncProjectFacilitate@fda.hhs.gov).