Cancer Treatment with Immune Checkpoint Inhibition in Solid Organ Transplant Recipients in Switzerland.

Background/Objectives: There is limited data on treatment outcomes under immune checkpoint inhibitor (ICI) administration in solid organ transplant recipients (sOTRs). This study aims to evaluate cancer outcome and allograft rejection risk in sOTRs receiving ICI. Methods: This is a retrospective multicenter study. The data had been collected within the Swiss Transplant Cohort Study (STCS) database. We searched for matching individuals from May 2008 up to the end of 2024. The primary outcomes were treatment response and survival; the secondary outcome was allograft rejection. Additional analyses included associated factors such as tumor, transplant, and treatment characteristics. Results: We identified ten patients, six of whom received a kidney allograft, while the remaining four received a liver, lung, pancreas, or combined kidney-pancreas transplant. Treatment response was achieved in half of the sOTRs, with a complete response (CR) in three and prolonged stable disease (SD) in two patients. CR was achieved in all three patients after only a few infusions. At the time of data analysis, four out of ten patients were still alive. Graft rejection occurred in six out of ten cases, five of which occurred after the first cycle of ICI administration. Conclusions: Data is limited and definitive conclusions from this study cannot be drawn given the limited sample size. However, ICI displays promising effects on cancer outcomes in sOTRs with advanced malignancies. The study's findings demonstrate an overall response in half of sOTRs, but with graft rejection occurring in a similar number of patients. We propose initiating immunotherapy as early as possible, given the promising results, particularly in patients with kidney transplants. We further suggest that in sOTRs, a few ICI infusions could potentially be a cautious option, pending further evidence.