Friendly fire? A case of inadvertent reactivation and progression of chronic lymphocytic leukemia following the treatment of cutaneous squamous cell carcinoma with Cemiplimab – case report

Over the past decade, immune checkpoint inhibitors (ICIs) have revolutionized oncology care, resulting in sustained clinical remissions and prolonged overall survival. With this remarkable success comes the challenge of managing adverse events. We present a case of a patient with chronic lymphocytic leukemia (CLL) and cutaneous squamous cell carcinoma (cSCC) who received treatment for the advanced cSCC with Cemiplimab. This intervention led to a rapid progression of her hitherto quiescent CLL, and she began treatment for it. Understanding the complex mechanism of action of ICIs and the pathophysiology of lymphoid malignancies is important for the safe use of ICIs.