Kidney transplant recipients (KTR) are at increased risk of cancer due to chronic immunosuppression. The cumulative incidence ratio of non-melanoma skin cancer has been estimated to be>60% compared to the general population. Cemiplimab, a human monoclonal IgG4 antibody against programmed cell death (PD-1) has shown considerable clinical activity in metastatic and locally advanced cutaneous squamous cell carcinoma (cSCC) in patients for whom no widely accepted standard of care exists. Data regarding the use of cemiplimab in SOTR and particularly in KTR are scarce. In this study, we report on the real-life outcome of cemiplimab use in a Belgian cohort of seven KTR suffering from advanced cSCC.

To report on the overall response rate (ORR) and safety of cemiplimab in KTR in Belgium.

Retrospective study of kidney transplant recipients, suffering from advanced cSCC treated with cemiplimab.

Sept patients suffering from advanced cSCC, treated with cemiplimab, between 2018 and 2022, in Belgium were identified. 3 patients were on corticosteroid monotherapy, 1 patient on tacrolimus monotherapy and 3 patients were on at least 2 immunosuppressive treatments at start of cemiplimab. The ORR was 42.8%, SD was seen in 14.3% and PD was found in 42.8% of the patients, respectively. Biopsy-proven acute renal allograft rejection was observed in 1 patient, who eventually lost his graft function but showed a complete tumor response to treatment. Low grade skin toxicity was seen in 1 patient of the cohort (Fig. 1).

The present case series shows that the use of cemiplimab in KTR with advanced cSCC who failed to respond to conventional treatment is associated with an ORR of 42.8% with minimal risk of graft rejection (14.3%) and good tolerance. Cemiplimab may therefore be a feasible treatment for KTR with advanced cSCC and this treatment should therefore not be withheld in this difficult to treat patient population.