Systematic review of programmed cell death-1 inhibitor therapy for advanced-stage cutaneous squamous cell carcinoma in solid-organ transplant recipients.

Background: Programmed cell death-1 (PD-1) inhibitors represent an effective treatment option for advanced cutaneous squamous cell carcinoma (cSCC). However, solid organ transplant (SOT) recipients with cSCC have traditionally been excluded from clinical trials.

Objective: To assess the safety and efficacy of PD-1 inhibitors for stage III-IV cSCC in SOT recipients.

Materials & methods: A systematic review was performed using the PubMed, EMBASE, and Scopus databases.

Results: We identified 21 articles describing 33 SOT recipients (26 kidney, four liver, two lung, and one heart) with stage III-IV cSCC treated with PD-1 inhibitors. Eleven patients (33.3%) experienced allograft rejection. Of the 25 cases with iRECIST scores, twelve patients (48.0%) had a complete response (CR), eight (32.0%) showed a partial response (PR), three (12.0%) progressive disease, and two (8.0%) stable disease (SD). Including patients without available iRECIST scores, 21 patients (63.6%) showed tumor response. Eleven patients died, with six (54.5%) due to tumor progression and one (9.1%) due to allograft rejection after foregoing dialysis.

Conclusion: PD-1 inhibitors demonstrate efficacy for advanced cSCC and confer a risk of allograft rejection in SOT recipients, requiring careful assessment of risks and benefits. If anti-PD-1 therapy is pursued, use of mTOR inhibitors, prophylactic steroids, and donor-derived cell-free DNA monitoring may mitigate the risk of rejection.