Immune Checkpoint Inhibitor Therapy of Malignancy in Kidney Transplant Recipients: Analysis of Real-world Outcomes

Background. The use of immune checkpoint inhibitors (ICIs) in kidney transplant recipients (KTR) for cancer treatment is limited by concerns of allograft rejection and uncertain oncologic efficacy. Methods. We conducted a single-center retrospective study of KTR with unresectable or metastatic malignancies treated between 2018 and 2025. The primary study cohort included 33 patients treated with ICI, whose outcomes were compared with 20 matched KTR treated with non-ICI systemic chemotherapy (SC). Results. KTR treated with ICI achieved an objective response rate of 36.4% (12/33) versus 30.0% (6/20) with SC, and a clinical benefit rate of 54.5% (18/33) versus 35.0% (7/20); neither difference was statistically significant (objective response rate P = 0.77; clinical benefit rate P = 0.27). Disease progression occurred in 81.8% of ICI-treated patients and 95.0% of SC-treated patients ( P = 0.23), and death because of cancer progression occurred in 63.6% and 75.0%, respectively ( P = 0.58). Median progression-free survival was 7.3 mo (95% confidence interval [CI], 4.3-10.8 mo) in the ICI group versus 4.1 mo (95% CI, 2.8-6.3 mo) in the SC group (log-rank P = 0.156). Median overall survival was 15.1 mo (95% CI, 7.6-37.3 mo) with ICI versus 8.7 mo (95% CI, 4.9-14.8 mo) with SC (log-rank P = 0.079). Posttreatment allograft rejection occurred in 12.1% of ICI-treated patients and 0.0% of SC-treated patients ( P = 0.29), with irreversible graft loss in 3.0%. Grade ≥2 immune-related adverse events occurred in 12.1% of ICI-treated patients, and no treatment-related deaths were observed. Conclusions. ICI therapy was associated with a trend toward longer overall survival when compared with SC and with a low rate of rejection and allograft loss.