The UK Medicines and Healthcare products Regulatory Agency (MHRA) has approved retifanlimab, marketed as ZYNYZ, for adults with squamous cell carcinoma of the anal canal that cannot be removed by surgery and is either metastatic or has returned in the same area as the original cancer. The approval was granted on 5 November 2026 to Incyte Biosciences UK Ltd and announced by the regulator on 11 November 2026.

Retifanlimab is given by intravenous infusion over about 30 minutes once every four weeks. For the first six treatment cycles it is used alongside the chemotherapy medicines carboplatin and paclitaxel. The drug works by blocking a pathway cancer cells use to avoid immune detection, helping the immune system recognise and attack them. The MHRA previously approved it on 6 July 2026 for advanced Merkel cell carcinoma, a rare skin cancer.

The regulator said a study of 308 people with metastatic or locally advanced squamous cell carcinoma of the anal canal found retifanlimab with chemotherapy increased the time people lived without their cancer worsening compared with placebo plus chemotherapy. Julian Beach, the MHRA's Executive Director, Operations, said the approval offers a new option for adults whose cancer cannot be removed by surgery, has spread, or has returned, and that the agency will continue to monitor the medicine's safety and effectiveness. Side effects are listed in the patient information leaflet and product characteristics summary.