Sanofi and Regeneron Pharmaceuticals have announced positive topline results from a pivotal phase 2 clinical study of cemiplimab in 82 patients with advanced cutaneous squamous cell carcinoma (CSCC), the second deadliest skin cancer after melanoma. Cemiplimab, an investigational human antibody targeting PD-1 (programmed cell death protein 1), demonstrated an overall response rate (ORR) of 46.3%, as determined by independent review. The median duration of response had not yet been reached at the data cut-off point (32 of 38 responses are ongoing). At the time of this analysis all patients had a minimum of 6 months of follow up.

The safety profile in this study was generally consistent with approved anti-PD-1 agents. These pivotal data will form the basis of a rolling Biologics License Application (BLA) submission to the US Food and Drug Administration (FDA), which has been initiated and is expected to be completed in the first quarter of 2018. A rolling BLA submission allows for portions of the regulatory application to be submitted to the FDA as they are completed. A submission to the European Medicines Agency (EMA) is also expected to be completed in the first quarter of 2018. These data confirm the positive phase 1 clinical trial expansion cohort results reported at ASCO 2017, which led to a Breakthrough Therapy Designation for cemiplimab in advanced CSCC in September 2017.

"EMPOWER-CSCC 1 was initiated in 2016 and has enrolled rapidly, underscoring the serious unmet need in advanced CSCC," said Elias Zerhouni, M.D., president, Global R&D, Sanofi. "We look forward to working with regulatory agencies globally to bring this important therapy to advanced CSCC patients as quickly as possible. We continue to rapidly advance a broad development program to evaluate cemiplimab both as monotherapy and combination across a number of solid tumor and blood cancers."

The efficacy data reported today include results from 82 patients in the phase 2 EMPOWER-CSCC 1 study. Approximately two-thirds of patients had progressed after prior systemic chemotherapy or radiation.

 "For patients with CSCC that cannot be cured by surgery or radiation, there are no FDA-approved treatment options, and advanced CSCC is responsible for 3,900 to 8,800 deaths per year in the US" said Israel Lowy, MD, PhD, vice president of Global Clinical Development and Head of Translational Science and Clinical Oncology, Regeneron. "This is the largest prospective study ever conducted in this disease, and we are pleased that many people were able to achieve deep and durable responses with cemiplimab monotherapy. The high and durable response rates seen in this study are particularly notable given that the study enrolled patients regardless of biomarker status."

EMPOWER-CSCC 1 is a single-arm, open-label clinical trial and remains active. Enrollment is complete in the study arm of patients with metastatic CSCC receiving a 3 mg/kg dose of cemiplimab every two weeks. Enrollment continues in the remaining two study arms of patients with metastatic CSCC receiving a 350 mg flat dose of cemiplimab every three weeks and patients with locally advanced and unresectable CSCC receiving a 3 mg/kg dose of cemiplimab every two weeks.

Updated results from both the EMPOWER-CSCC 1 phase 2 trial and the phase 1 clinical trial will be submitted for presentation at a 2018 medical congress.

Cemiplimab is being jointly developed by Regeneron and Sanofi under a global collaboration agreement. Cemiplimab is currently under clinical development, and its safety and efficacy has not been fully evaluated by any regulatory authority.