Nearly Half of Patients With Metastatic CSCC Respond to Cemiplimab, on Fast Track at FDA

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FDA has fast-tracked the Biologics License Application for cemiplimab, with a decision expected October 28, 2018.

After taking the programmed-death-1 (PD-1) inhibitor cemiplimab for an average of nearly 8 months, nearly half of patients with metastatic cutaneous squamous cell carcinoma (mCSCC) responded to treatment in a phase 2 study. A median duration of response had not been reached, according to results presented Monday at the annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago, Illinois.

The results were simultaneously published in the New England Journal of Medicine.1 The journal abstract featured both reports of the expansion cohort from phase 1, which saw a response from 13 of 26 patients (50%, 95% confidence interval [CI], 30-70); as well as results from phase 2, which reported responses from 28 of 59 patients.

"The study of cemiplimab for the treatment of advanced cutaneous squamous-cell carcimona was underpinned by the recognition that a high mutation burden may render these tumors sensitive to effector T cells in the context of immune checkpoint blockade," the authors write.

The study of 54 men and 5 women, average age 71 years (range, 38-93 years), involved a 3-mg/kg dose given intravenously every 2 weeks. Tumor measurements were performed every 8 weeks. Overall response rate (ORR) was the primary endpoint, and duration of response (DOR) was the key secondary endpoint.


FDA has already granted priority review status to cemiplimab, which is being developed by Regeneron and Sanofi. A decision on the Biologics License Application is expected by October 28, 2018.

Cutaneous squamous cell carcinoma, or skin cancer, is very common in the United States, and most often, it is treatable. But in 5% of the cases, it becomes metastatic, and there is no standard of care for this form of the disease. Thus, cemiplimab would fill a significant unmet need for patients with mCSCC. At ASCO 2017, Regeneron presented promising phase 1 results that resulted in the FDA’s action. Results presented this year include data through October 27, 2017, according to the abstract presented Monday.

At the time of data cutoff, patients had been followed up for an average of 7.9 months (range, 1.1-15.6 months). ORR, as measured by an independent review team examining patient scans, was 47% (95% CI, 34-61). The rate of durable disease control was 61% (95% CI, 47-74), with 4 complete responses and 24 partial responses. The average time to initial response was 1.9 months.

Of the 28 patients who had a response, the duration of response exceeded 6 months for 57%, and 82% still had a response and were taking cemiplimab at the time of the data cutoff.

The most common adverse events (AEs) were diarrhea (27%), fatigue (24%), and nausea (17%). The paper reported 25 AEs of grade 3 or higher, including 17 that were serious and 3 that led to discontinuation of treatment; 3 were associated with an outcome of death. The study's authors said the side effects observed were typical among patients treated with checkpoint inhibitors.2

"The strong results seen with cemiplimab are noteworthy given that advanced CSCC is a very serious condition that currently has no approved treatments once surgery is no longer an option," Michael R. Migden, MD, co-lead author and associate professor in the Departments of Dermatology and Head and Neck Surgery at The University of Texas MD Anderson Cancer Center, said in a statement. "Advanced CSCC tumors were shown to be responsive to cemiplimab in both metastatic and locally advanced patients, with the results being clinically meaningful and consistent between the phase 1 and phase 2 trials."


1. Migden MR, Rischin D, Schmults CD, et al. PD-1 blockade with cemiplimab in advanced cutaneous squamous-cell carcinoma. N Engl J Med 2018; doi:10.1056/NEJMoa1805131.

2. Rischin D, Migden MR, Chang A, et al. Primary analysis of phase 2 results for cemiplimab, a human monoclonal anti-PD-1, in patients with metastatic cutaneous squamous cell carcinoma (mCSCC). J Clin Oncol 2018;36(suppl; abstr 9519).