ESTRO 2025 - Abstract Book

S1698

Clinical - Sarcoma & skin cancer & malignant melanoma

ESTRO 2025

2751

Digital Poster Cemiplimab-Radiotherapy combination in cutaneous squamous cell carcinoma(cSCC) inoperable-locally advanced or metastatic: safety and efficacy profile. Alessia Reali 1 , Simone Baroni 1 , Claudio Scaffidi 1,2 , Rachele Petrucci 1 , Luca Frassinelli 1 , Anna Merlotti 3 , Paola Queirolo 4 , Marcella Occelli 5 1 SSD Radioterapia, Michele e Pietro Ferrero Hospital-ASLCN2, Verduno, Italy. 2 SSC Radioterapia, Università degli Studi di Genova, Genova, Italy. 3 SSC Radioterapia, Santa Croce e Carle Hospital, Cuneo, Italy. 4 Divisione Oncologia Medica del Melanoma e Sarcomi, Istituto Europeo di Oncologia, Milano, Italy. 5 SSC Oncologia, Santa Croce e Carle Hospital, Cuneo, Italy Purpose/Objective: Cemiplimab - a programmed cell death protein-1 (PD-1) inhibitor - has been approved as first line treatment for patients with metastatic or inoperable-locally advanced cSCC. Radiotherapy (RT) has been shown to modulate the immunogenicity of tumour cells and potentially may improve efficacy of PD-1 inhibitors when delivered concurrently. To our knowledge, there is a lack of literature data among Cemiplimab and RT association and we report our experience. Material/Methods: Between September 2020 and December 2023, 8 patients with metastatic or inoperable-locally advanced inoperable cSCC were treated with Cemiplimab in association to RT at our 2 different Hospitals. Radiotherapy was administered to the site of inadequate therapeutic response both in the case of metastatic and locally advanced disease (5 patients) or immediately before or during Cemiplimab infusion (3 patients). Skin toxicity was reported according to the Radiation Morbidity Scoring Criteria for skin reaction developed by Radiation Therapy Oncology Group (RTOG). Results: All patients had an ECOG PS 0-2, sex distribution was 4 men and 4 women, others characteristics were summarizes in table 1. RT treatment doses varied from 12.5 Gy /5 fractions to 62.5 Gy/25 fractions, but the most used schedules were 20 Gy / 5 fractions and 30 Gy / 10 fractions. RT was delivered with electrons, MV and KV-X ray and during RT treatment Cemiplimab was not administrated. All patients completed RT, 25% of patients developed a cutaneous G2-3 RTOG acute toxicity while for the others no significant cutaneous acute toxicity was reported. 1 patient was lost at follow-up , instead 7 patients were alive without late toxicity and with controlled disease.

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