Suspected Abscopal-Pattern Response following Radiotherapy in a Patient Receiving Cemiplimab for Advanced Cutaneous Squamous Cell Carcinoma: A Case Report

Introduction

The abscopal effect is a rare phenomenon in which localized radiotherapy leads to regression of distant, nonirradiated tumors through systemic immune activation, often enhanced by immune checkpoint inhibitors. It is infrequently reported in cutaneous squamous cell carcinoma and even less so in immunocompromised patients. We report a case of head and neck cutaneous squamous cell carcinoma in an immunocompromised patient treated with PD-1 inhibition and localized radiotherapy, in which a distant untreated lesion regressed, consistent with a suspected abscopal response.