PD1 inhibitors with concomitant palliative radiotherapy for treatment of older patients with locally advanced or metastatic cutaneous squamous cell carcinoma: Experience from a single centre in the United Kingdom.

e21569 Background: Cutaneous squamous cell carcinoma (cSCC), a common disease among older individuals, is particularly challenging to manage with traditional treatments such as surgery and radiotherapy. The introduction of immunotherapeutic agents such as cemiplimab has shown promise in clinical trials, with an overall objective response rate (ORR) of ~50%. In this analysis, we share our real-world experience of managing cSCC with cemiplimab and concomitant palliative radiotherapy. Methods: Electronic health records identified thirty non-selected patients diagnosed with cSCC who received cemiplimab treatment between June 2021 and August 2024. We retrospectively reviewed the clinical records and radiological imaging of these patients. We gathered information on baseline demographic and clinical characteristics, including comorbidities (Charlson Comorbidity Index) and frailty (Rockwood Frailty Score), clinical and radiological outcomes, and adverse events. Results: The patient cohort was 93.3% male with a median age of 80 years; multiple comorbidities were common, and frailty scores indicated a vulnerable population. Most tumours (86.7%) were in the head and neck area; 70% were locally advanced and 30% were metastatic. Two-thirds of the cohort (66.6%) received a palliative dose of radiotherapy concomitant with cemiplimab. Overall ORR was 80% (60% complete and 20% partial response) with a median overall survival of 25.4 months and a progression-free survival of 28.9 months. Clinical response was generally observed after two cycles. Ten patients died, five from progressive disease and five not related to cancer or its treatment. Patients who didn’t respond had early disease progression. Treatment was well tolerated; adverse events were mainly of low grade, and the most common were fatigue (30.0%) and dermatitis (16.7%). Conclusions: Our experience with concomitant cemiplimab and palliative radiotherapy for LA/M cSCC in an older, vulnerable population suggests a good response to these treatments, with an 80% ORR (30% increase with previous studies). While this hypothesis needs to be confirmed in future trials, our data appear consistent with increased antitumor activity in the combination of both therapies. Best response rate. Best Response Rate Complete Response 18 (60%) ORR=80% Partial Response 6 (20%) Stable Disease 1 ( 3.33) Progressive Disease 5 ( 16.7%) ORR: Overrated response ( CR+PR).