An Incyte drug developed to treat a rare type of anal cancer still has a shot at FDA approval, but the company needs to produce more clinical data from a larger study to support its application.
The regulator on Friday rejected Incyte’s submission, which was based on data from a Phase 2 study. The complete response letters that the FDA sends to companies are not public. According to Wilmington, Delaware-based Incyte, the correspondence states that the regulator needs to see additional data to demonstrate the drug’s clinical benefit treating patients with squamous cell carcinoma of the anal canal (SCAC) that has advanced or spread. The company said it is reviewing the letter and will discuss the next steps for the drug with the agency.
Retifanlimab is an antibody drug that blocks PD-1, a protein on the surface of T cells that keeps them from killing tumors. Blocking this so-called checkpoint protein clears the way for a patient’s immune cells to go after the cancer. The Incyte drug is an intravenous infusion given every four weeks.
Anal cancer is much rarer than cancer affecting the rectum or colon. According to the American Cancer Society, the greatest risk factor for anal cancer is infection by the human papillomavirus. SCAC has no FDA-approved therapies for patients whose disease progresses after treatment with chemotherapy.
The Phase 2 clinical trial evaluating retifanlimab was an open-label, single arm study. The 94 patients in the study had anal cancer that had progressed while under treatment with chemotherapy, or the patients were ineligible for or intolerant of chemotherapy. The main goal was to measure the objective response rate to the treatment.
According to data presented last September during the 2020 meeting of European Society for Medical Oncology, an independent review confirmed one patient had a complete response to treatment with the drug, 12 had partial responses, and 33 patients had stable disease. Those results translated to an objective response rate of 14% and a disease control rate of 49%.
FDA rejection of retifanlimab follows the 13 to 4 advisory committee vote last month recommending that a regulatory decision on the drug be deferred until more data are available from the drug’s confirmatory study. That study is underway with a targeted enrollment of 300 patients. The double-blind clinical trial is testing the Incyte drug plus chemotherapy against chemotherapy and a placebo.
“Patients with SCAC who have progressed after first-line chemotherapy currently do not have approved treatment options,” Incyte CEO Hervé Hoppenot said in a prepared statement. “While we are not surprised with the FDA decision given the [advisory committee] recommendation, we are disappointed. We remain committed to advancing science to find solutions for patients with unmet medical needs, and we will ensure close coordination with the FDA in order to address feedback and determine next steps for the review of retifanlimab.”
Incyte licensed retifanlimab from MaroGenics in 2017, paying the biotech $150 million up front for global rights. In addition to anal cancer, Incyte is evaluating the drug as a monotherapy for microsatellite instability-high endometrial cancer and Merkel cell carcinoma. The company is also testing the drug in combination with chemotherapy in non-small cell lung cancer.
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