Neoadjuvant Immunotherapy Shows Promise for Resectable CSCC

Jim Kling

September 27, 2022

Neoadjuvant immunotherapy for stage II-IV cutaneous squamous cell carcinoma (CSCC) led to a strong pathological complete response rate, according to results from a stage 2 clinical trial.

CSCC hasn't received much attention from pharmaceutical companies, in part because it so often responds well to surgery or local therapy. Still, some patients develop more advanced cancer that requires surgery, often on exposed surfaces like the scalp, face, or neck. That can lead to cosmetic and functional impairment.

"Having witnessed the toxicity of treatments over time has really kind of kind of pushed me for a long time to seek better ways to treat this," lead author Neil Gross, MD, said in an interview. Gross is director of clinical research in the department of head and neck surgery at the University of Texas MD Anderson Cancer Center, Houston. The study was presented at the annual meeting of the European Society for Medical Oncology and published simultaneously in the New England Journal of Medicine.

Gross and colleagues conducted a pilot study that examined neoadjuvant immunotherapy with cemiplimab (Libtayo, Regeneron). It received Food and Drug Administration approval in 2018 for metastatic cutaneous squamous cell carcinoma. The aim of the study was to determine how cells responded to the therapy and learn more about the biology, but the results turned heads. "We were surprised to learn just how well the patients responded, Over half of the patients had a complete pathologic response to treatment, and another 4 patients out of 20 had a near-complete pathological response. It prompted a multicenter trial to confirm whether or not what we're seeing was real," Gross said.

The new phase 2 study, conducted in 79 patients at centers in Australia, Germany, and the United States, was encouraging. "The results were very, very similar. About 63% overall had this really impressive pathologic response to treatment. And, it may even be an underestimation of the responses because there were several patients in the trial who responded so well that they refused surgery. Those patients were counted as nonresponders just to be most conservative," Gross said.

"I think it will change practice. The results are just so dramatic that it's hard to imagine it's not going to influence how patients are treated," he said.

Dramatic Results and an Attractive Option

Among 79 patients in the new trial, the median age was 73 years, 85% were male, and 87% were White. About 91% of primary tumors were head and neck; 6% were stage II, 48% stage III, and 46% stage IV. All patients received four doses of 350 mg cemiplimab at 3-week intervals.

After a median follow-up of 9.7 months (range, 1.3-19.6 months), 51% achieved a pathological complete response (95% confidence interval, 39%-62%). The null hypothesis was that 25% would achieve a pathologic response. An additional 13% had a pathological major response (95% CI, 6%-22%). 25% did not achieve a pathological complete or pathological major response, which was defined as viable tumor cells representing at least 10% of the surgical specimen.

72% of patients experienced an adverse event considered by the investigator to be related to treatment, most commonly fatigue (28%), maculopapular rash (14%), and diarrhea (11%). 15% of patients experienced immune-related adverse events. 4% experienced a grade 3 immune-related adverse event.

Despite the encouraging results, more research needs to be done. One key question is the optimal number of treatments prior to surgery. The pilot study used two doses while the phase 2 study used four doses. Another is whether the surgical excision can be safely reduced after treatment to reduce morbidity, and still another is whether some patients can avoid radiation. "There are lots of unanswered questions that are really important to how this gets rolled out into clinical practice, but I do think that there's no turning back. The results are so dramatic that it's a very attractive option to patients and providers. We will have to figure out how to learn the best way to use this in practice while it's being used," Gross said.

Additional studies are in the planning phase, though the results are so encouraging that they might hinder future research. "Will patients be willing in the future to be randomized to the current standard of care, which would be upfront surgery and radiation for advanced disease? I don't know. There's a lot of thought being put into the best way to design these studies moving forward that are really advantageous to patients, but still answer these some of these fundamental questions," Gross said.

He also noted that these studies looked at pathological responses, not overall survival or clinical outcomes. "We believe that these responses will be durable, but this has to be borne out as the data matures."

The study was funded by Regeneron. Gross has consulted for DragonFly Therapeutics, Intuitive Surgical, Regeneron, and Sanofi/Genzyme. He has been on scientific advisory boards for PDS Biotechnology and Shattuck Labs.

This article originally appeared on, part of the Medscape Professional Network.


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