Immune Checkpoint Inhibitor Therapy Use in Kidney Transplant Recipients: A Single-Center Study

Background: Immune checkpoint inhibitors (ICI) have radically improved cancer outcomes. Due to concerns regarding graft rejection, ICI's were infrequently offered to KTR's despite significant cancer related mortality. We report the cancer and allograft outcomes of patients receiving ICI therapy at our center. Methods: We retrospectively reviewed all KTR's undergoing ICI therapy at our center that were referred to our transplant clinic for immunosuppression (IS) management from December 1, 2018 to May 1, 2024. All patients continue to be followed, unless deceased. Indication biopsies were performed for acute kidney injuries. Results: 21 patients met inclusion criteria. Patient characteristics and outcomes are described in Table 1. No acute rejection was noted. 1 patient had biopsy evidence of chronic antibody mediated rejection and recurrent PLA2R positive membranous nephropathy after 11 months of Pembrolizumab. This patient had a complete response with a stable creatinine of 1.5-1.8 mg/dL 2 years post therapy completion. Of 16 evaluable patients, 1 had complete response, 3 had partial response, and 2 had stable disease. Therapy limiting extra-renal immune related adverse events were noted in 1 patient with colitis. Conclusion: The absence of acute rejection or frequently recurrent native disease in our cohort is encouraging, though objective response is low. Many patients were frail with advanced disease at the time of ICI initiation, likely contributing to the poor objective response, though degree and type of IS may also have influenced outcomes. Additional prospective studies comparing IS regimens while controlling for disease burden are needed. Table 1 - Total Patients (n=21) Median Age at ICI Therapy Initiation (years) 65 (range 52-78) ESRD Secondary to Glomerulopathy (%) 43 Advanced Cutaneous Squamous Cell Carcinoma (%) 57 Metastatic Melanoma (%) 19 Patients on PD1 Inhibitor (%) 95 Maintenance Post ICI (Calcineurin Inhibitor/Pred) (%) 67 Maintenance Post ICI (Mammalian Target of Rapamycin Inhibitor/Pred) (%) 28 Rejection (%) 4.8 Median Follow Up (months) 3 (range 0.25 - 44) Objective Response in 16 evaluable patients (%) 25 Stable Disease in 16 Evaluable Patients (%) 12.5 Median Overall Survival For Patients with Progressive Disease (months) 3 (range 0.25-8) Median Time from Transplant to ICI Initiation (years) 8 (range 1-29)