Donor-transmitted squamous cell carcinoma in kidney transplant recipient successfully treated with checkpoint inhibitors: a case report.

We report a case of suspected donor-transmitted squamous cell carcinoma (SCC) in a kidney transplant recipient who received an organ from a deceased donor with no evidence of malignancy at the time of procurement. Approximately one year after transplantation, the recipient developed metastatic SCC with bone and lung involvement. Molecular genotyping was inconclusive regarding donor origin, as tumor cells lacked human leukocyte antigen (HLA) expression. Notably, a second recipient who received the liver from the same donor also developed SCC and subsequently died, raising suspicion of donor transmission. Allograft nephrectomy and complete withdrawal of immunosuppression were initially considered; however, the patient declined due to concerns regarding quality of life associated with dialysis. Systemic chemotherapy was initiated but resulted in disease progression after two months. Treatment was subsequently switched to the checkpoint inhibitor cemiplimab, with concurrent discontinuation of all immunosuppressive therapy except prednisone. Acute graft rejection occurred after two cycles, and the patient resumed dialysis. Subsequent imaging demonstrated findings consistent with pseudoprogression before achieving near-complete remission. The patient completed two years of immunotherapy, after which treatment was discontinued, and remains under surveillance with ongoing near-complete remission. This case highlights the potential role of checkpoint inhibition combined with immunosuppression withdrawal as a therapeutic strategy in in selected patients with donor-transmitted SCC following kidney transplantation.