Impact of cemiplimab treatment duration on clinical outcomes in advanced cutaneous squamous cell carcinoma

Treatment duration with checkpoint inhibitors must be optimized to prevent unjustified toxicity, but evidence for the management of cutaneous squamous cell carcinoma is lacking. A retrospective study was performed to evaluate the survival of patients with cutaneous squamous cell carcinoma (CSCC) who discontinued cemiplimab due to different causes and without progression. Among 95 patients with CSCC who received cemiplimab, 22 (23%) patients discontinued immunotherapy due to causes other than progression, such as comorbidities, toxicity, complete response or lack of compliance (group that discontinued before censoring [DBC]), then 73 patients had standard treatment scheduled (STS). The overall survival was 25.2 months (95% CI: 8.9-29.4) in STS group and 28.3 months (95% CI: 12.7-28.3) in the DBC group; deaths for all causes were 11/22 (50%) in the DBC group and 34/73 (46.6%) in the STS group (p = 0.32). 10/22 (45.4%) subjects died due to CSCC in the DBC after discontinuation and 34/73 (46.6%) in the STS group, and the difference between groups was not significant (p = 0.230). Duration of treatment was significantly lower in subjects with stable disease versus those with complete or partial response (16.9, 30.6 and 34.9 months, respectively; p = 0.004). Among the 22 STS patients, 12 received cemiplimab for less than 12 months (10 [83%] died) and 10 for at least 12 months (1 [10%] died). Our observation, finding no outcome difference between DBC and STS groups, suggests that ICI treatment after one year might expose patients to further treatment related events without efficacy advantages.