SITC 2021: Phase II Study Results of Retifanlimab in Advanced Merkel Cell Carcinoma
Posted: Wednesday, November 24, 2021
Giovanni Grignani, MD, of Candiolo Cancer Institute, FPO-IRCCS, Italy, and colleagues presented the results of their POD1UM-201 study at the 2021 Society for Immunotherapy of Cancer (SITC) Annual Meeting (Abstract 545). This phase II trial, which evaluated the efficacy and safety of the anti–PD-1 monoclonal antibody retifanlimab, concluded that this monotherapy “continues to demonstrate promising clinical activity and safety in patients with advanced or metastatic, chemotherapy-naive Merkel cell carcinoma.”
A total of 87 patients with chemotherapy-naive, advanced or metastatic Merkel cell carcinoma were administered 500 mg of intravenous retifanlimab every 4 weeks for up to 2 years. Eligibility requirements included an Eastern Cooperative Oncology Group performance status of at most 1, measurable disease, and no prior systemic therapy.
Primary efficacy analysis utilized data on the first 65 patients assessed. At data cutoff, just over half (52.3%) of participants remained on treatment, 41.5% discontinued treatment, and 6.2% had completed therapy; treatment was discontinued because of disease progression (27.7%), adverse events (10.8%), physician decision, or death (1.5% each). The objective response rate was 46.2%, including 22 and 8 partial and complete responses, respectively, and the disease control rate was 53.8%.
Treatment-emergent adverse events affected the majority (75.9%) of patients, with 25 treatment-emergent and 12 treatment-related events of grade 3 or higher. Immune-related adverse events were detected in 23 individuals, including 8 events of grade 3 or higher. Notably, four participants discontinued therapy because of immune-related events, and one patient had a grade 3 infusion reaction.
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