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Retifanlimab is a PD-1 antibody approved for Merkel cell carcinoma and, with chemotherapy, as the first immunotherapy standard for advanced anal cancer.
Retifanlimab is an IgG4 monoclonal antibody that blocks PD-1 binding to PD-L1 and PD-L2, restoring T-cell activity against tumours. It is used in metastatic or recurrent locally advanced Merkel cell carcinoma and in advanced anal squamous cell carcinoma. POD1UM-201 showed a 52% response rate in chemotherapy-naive metastatic Merkel cell carcinoma, supporting accelerated US approval in 2023 and EU approval in 2024. POD1UM-303/InterAACT-2 (Lancet 2025) randomised patients with first-line advanced anal SCC to carboplatin-paclitaxel with or without retifanlimab, and adding the antibody improved both progression-free and overall survival, leading to approval in 2025 for the combination and for monotherapy after platinum. It is the first immunotherapy standard for anal cancer. Retifanlimab shows that adding checkpoint blockade to chemotherapy can lengthen survival in a virus-driven cancer.
Backbone ribbon from PDB 9EHT. RCSB PDB 9EHT. The ribbon widens where the chain is folded into a regular pattern and narrows where it is a loose loop.
Blocks PD-1 binding to PD-L1/PD-L2, restoring T-cell activity. Connects to PD-1.
1.Retifanlimab binds PD-1.
Background: ADC sequencing, Antigen escape (antigen loss, lineage switch), BCG-unresponsive, Castration-resistant prostate cancer (CRPC), Circulating tumour DNA (ctDNA). Also on OnCo: Resistance: how tumours escape each drug class · Lines of therapy.
Given by infusion or injection in a clinic or hospital outpatient department, so it is a Part B drug: Medicare pays 80% after the Part B deductible and the patient owes 20% coinsurance, uncapped in Original Medicare unless a Medigap policy applies. FDA-approved for Merkel cell carcinoma and squamous anal cancer.
Covered under the medical benefit with prior authorisation confirming diagnosis, biomarker status and line of therapy; site-of-care policies may steer infusions away from hospital outpatient departments.
20% Part B coinsurance on a high-cost infusion adds up quickly: Medigap Plan G or N, Medicare Advantage maximum out-of-pocket, Medicaid dual eligibility, or a charity fund are the usual buffers.
Sources: Medicare.gov: Chemotherapy · Medicare.gov: Prescription drugs (outpatient, Part B). Not medical or financial advice; verify with your plan.
Sources: NICE search: retifanlimab. Funding decisions are indication-specific and change monthly; verify with NICE and your treating team.
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Adult patients with metastatic or recurrent locally advanced Merkel cell carcinoma (MCC)
Accelerated approval on a surrogate endpoint, with a confirmatory trial required. source
Adult patients with metastatic or recurrent locally advanced Merkel cell carcinoma (MCC)
Confirmed: the accelerated approval of 2023 converted to traditional approval 2.7 years after it was granted. source
| Region | Year | Indication |
|---|---|---|
| US | 2023 | Metastatic or recurrent locally advanced Merkel cell carcinoma |
| US | 2025 | Locally recurrent or metastatic anal SCC with carboplatin-paclitaxel; monotherapy after platinum |
| EU | 2024 | Merkel cell carcinoma |
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Query for this drug: (TITLE:"Retifanlimab" OR ABSTRACT:"Retifanlimab" OR TITLE:"Zynyz" OR ABSTRACT:"Zynyz") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Retifanlimab, not a curated reading list.
Shares Merkel cell polyomavirus (MCPyV) status, POD1UM-201 (retifanlimab in advanced Merkel cell carcinoma), Merkel cell carcinoma, Skin cancer (all types).
Shares POD1UM-201 (retifanlimab in advanced Merkel cell carcinoma), Oncogenic viruses, Merkel cell carcinoma, Skin cancer (all types).
Shares POD1UM-201 (retifanlimab in advanced Merkel cell carcinoma), Oncogenic viruses, Merkel cell carcinoma, Skin cancer (all types).
Shares POD1UM-201 (retifanlimab in advanced Merkel cell carcinoma), Merkel cell carcinoma, Skin cancer (all types), Immune checkpoint inhibitors.
Shares Metastatic and recurrent anal squamous cell carcinoma, Anal cancer (squamous cell carcinoma), Immune checkpoint inhibitors.
Shares Metastatic and recurrent anal squamous cell carcinoma, Oncogenic viruses, Anal cancer (squamous cell carcinoma).
Shares Metastatic and recurrent anal squamous cell carcinoma, Anal cancer (squamous cell carcinoma).