Pruritus and Melanoma and Cutaneous Carcinomas Treated With Immunotherapy

Immune checkpoint inhibitors (ICIs) are commonly used in the therapeutic arsenal of metastatic melanoma, Merkel cell carcinoma and cutaneous squamous cell carcinoma, thanks to their inhibiting effects on cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA4) and anti-programmed death-1 (anti-PD1) respectively. These treatments can induce numerous cutaneous and non-cutaneous adverse effects that are mainly due to their immunological action. Their most frequent adverse effects are dysthyroidism, autoimmune hepatitis, colitis and skin disorders. Among those, pruritus is frequently reported as a side effect of these treatments. Its incidence has been estimated between 11% and 47%. Pruritus can deeply affect the patient's quality of life and may lead to treatment discontinuation. Until now, ICI-related pruritus has been poorly studied and it is not understood. In the literature, data on the presence and characteristics of pruritus in patients treated by ICIs were provided, without analyzing the causes of this pruritus. Indeed, it is not known if the occurrence of pruritus is related to direct or indirect effects of ICIs. Some authors reported a correlation between the occurrence of cutaneous adverse events under ICIs and the survival. The principal aim of our study was to analyze the putative causes of pruritus occurring in patients treated with ICIs for melanomas and cutaneous carcinomas. The other objectives were to assess the association between the occurrence of pruritus and survival, and between the other adverse events and pruritus.