Treatment of metastatic cutaneous squamous cell carcinoma in a solid organ transplant recipient with programmed death-1 checkpoint inhibitor therapy.

Limited data exist on the use of immune checkpoint inhibitors (ICI) for the treatment of metastatic cutaneous squamous cell carcinoma (CSCC) in solid organ transplant recipients (SOTR). We report a case of a SOTR who developed metastatic disease following multiple surgeries, three cycles of adjuvant radiotherapy, and minimization of immunosuppression. He was subsequently treated with pembrolizumab and achieved a complete response. However, the patient developed ICI-induced allograft rejection requiring therapy discontinuation. The allograft was salvaged following IVIg and steroids. The patient developed recurrent disease which failed rechallenge with pembrolizumab but achieved a partial response following cemiplimab administration. This case illustrates the potential to treat metastatic CSCC in a SOTR with anti-programmed death-1 therapy and preserve graft function despite allograft rejection.