Immune Checkpoint Inhibitor Use in Solid Organ Transplant Recipients: A Systematic Review.

Chronic immunosuppression in solid organ transplant recipients (SOTRs) leads to an increased risk of a wide variety of cancers. Immune checkpoint inhibitor (ICI) therapy is indicated for many of these; however, the risks and benefits of ICI use in the SOTR population have not been well characterized. We performed a systematic literature review identifying 119 reported cases of ICI use among SOTRs. Treatments used included PD-1 inhibition (75.6%), CTLA-4 inhibition (12.6%), PD-L1 inhibition (1.7%), and combination and/or sequential ICI therapy (10.1%). The most common cancers included cutaneous melanoma (35.3%), hepatocellular carcinoma (22.7%), and cutaneous squamous cell carcinoma (18.5%). The overall objective response rate (ORR) was 34.5%, with a median duration of response of 8.0 months. Ongoing response was seen in 21.0%. Cutaneous squamous cell carcinoma had significantly better ORR compared with other cancer types (68.2% vs 26.8%; odds ratio [OR], 5.85; P =.0006). Factors associated with improved ORR included increasing time from transplant to ICI (OR, 1.09; P =.008) and preemptive reduction in intensity of the graft maintenance immunosuppressive regimen (50.0% vs 18.5%; OR, 4.40; P =.0088). Rejection occurred in 41.2%, graft failure in 23.5%, and immune-related adverse events in 18.5%. Factors significantly associated with allograft rejection included allograft PD-L1 positivity (100% vs 0%; P<.0001) and absence of tacrolimus in the immunosuppressive regimen (48.7% vs 25.6%; OR, 0.36; P =.019). The most common cause of death was progressive malignancy (64.0%), followed by graft failure (24.0%). Our analysis provides current benchmark data to help inform management of SOTRs with advanced cancers that are reflected by our patient cohort. Biomarker development, more robust datasets, and prospective study of concomitant immunosuppression management may help refine decision-making in this complex scenario in the future. Close coordination of care between the medical oncologist and transplant specialist is encouraged to help optimize treatment outcomes.