Pattern of response of unresectable and metastatic cutaneous squamous cell carcinoma to programmed death-1 inhibitors: A review of the literature

Cutaneous squamous cell carcinoma (cSCC) is the second most frequent nonmelanoma skin cancer (NMSC). The majority of in situ cSCC [cSCC (Tis)] can be cured surgically, while local advanced and metastatic ones require other treatments, but there are no therapies approved by U.S. Food and Drug Administration (FDA). Available treatments for these stages included radiotherapy, chemotherapy as cisplatin, but responses to these treatments are usually of short duration. Programmed death-1 (PD-1) inhibitors (pembrolizumab, nivolumab, and cemiplimab) are an innovative immunologic treatment that now has been shown to be useful for the treatment of advanced cSCC. Nowadays, data about the response rate with the use of PD-1 inhibitors in cSCC are still few and, especially, the duration of the response after the start of treatment is short. Moreover, the number of cases is too small to express the beneficial effects of these treatments, although most data reported in the literature show quite good response rates. This review focused on some of the studies and associated results through an interesting research on search engines of all the cases about these systemic drugs, analyzing effects and side effects, and the research has been conducted considering published cases since March 2016 to October 2019.