Real‐World Response of Cemiplimab Immunotherapy for Treating Locally Advanced or Metastatic Cutaneous Squamous Cell Carcinoma in a Tertiary UK Oncology Centre

Introduction Cemiplimab has been licensed for use in the United Kingdom as the sole immunotherapy agent for first‐line use in advanced cutaneous squamous cell carcinoma (a‐cSCC). Given that previous clinical trials leading to the approval of cemiplimab had relatively small patient cohorts with relatively short follow‐up periods, with a large proportion of patients who had received prior systemic treatment, this retrospective real‐world study sought to add further insight into survival and toxicity in patients who exclusively had received first‐line use of cemiplimab, as well as comparing response rates (RRs) based on primary site location. Methods This retrospective study identified patients diagnosed with a‐cSCC between 01/08/2019 and 31/03/2024 who received cemiplimab as first‐line treatment at our institution. Data to enable response assessment and toxicity were collected and analyzed. Results 50 patients were identified with a mean age of 75 years (range: 44–94). 78% ( n = 39) of the patients’ primary lesion originated from the head and neck (H&N) region, whilst the remaining 22% ( n = 11) had a primary lesion from other areas. No patients had received prior systemic treatment for a‐cSCC. Overall, the disease control rate (DCR) was 74%, and the RR was 55.8% with complete response in 35% ( n = 15), partial response in 21% ( n = 9), and stable disease in 19% ( n = 8). In patients with H&N primary site of disease, RR was 58.9% versus 27.2% in patients with non‐H&N primary site of disease, with a p value of 0.027. The overall mean PFS for the study population was 27.3 months (95% CI: 21.2–33.5 months), with the median PFS not reached for the study duration. The median PFS for patients with H&N primary site of disease was not reached as compared to the median PFS of 4 months (95% CI: 2.2–5.7 months) for patients with non‐H&N primary site of disease, with a p value of 0.049. The median OS for the study population was 34 months (95% CI: 15.4–52.5 months). Grade 3 toxicities were reported in 22% ( n = 11) with no Grade 4 toxicites. Discussion The use of cemiplimab as first‐line treatment in a‐cSCC demonstrates high efficacy and low rates of serious toxicity, which is especially reassuring in a patient cohort comprising of more elderly patients. The high complete RR seen in our patient cohort may reflect the exclusive first‐line use of cemiplimab in our study, as per now established real‐world practice in a‐cSCC. Higher RRs and PFS are seen in patients with head/neck primary site of disease vs. non head/neck primary site, which should be evaluated further in future clinical trials.