Systemic retinoids for the chemoprevention of cutaneous squamous cell carcinoma and verrucal keratosis in a cohort of patients on BRAF inhibitors

Summary Background The treatment of metastatic melanoma has changed greatly with the development of inhibitors targeted at the mutated BRAF kinase present in up to 50% of metastatic melanoma cases. These agents, vemurafenib and dabrafenib, have been shown to increase median survival. Unfortunately, they have also been associated with the development of verrucal keratosis (VK) and cutaneous squamous cell carcinoma (cuSCC). These lesions require surgical excision, and when a large number of these lesions need to be treated, it can significantly affect the patient's quality of life. Objectives To determine if acitretin is suitable as a chemopreventative agent against the development of verrucal keratosis and cuSCC, in patients on BRAF inhibitors. Methods Patients treated with a BRAF inhibitor, vemurafenib or dabrafenib, for stage IV metastatic melanoma, who had undergone more than five surgical excisions to remove lesions suggestive of cuSCC, were offered the opportunity to commence acitretin as a chemopreventative agent. Patients were evaluated every 4 weeks. Clinical and histological data were collected. Results Eight patients, who had a total of 24 cuSCC removed, were included in the study. After commencement of acitretin, only five cuSCC were excised from two patients. The most significant reduction was in a patient who had developed 13 cuSCC over 10 months and only two cuSCC 3 months after commencing acitretin. No modifications in the dose of the BRAF inhibitor were made as a result of cuSCC in any of these patients. Conclusions Acitretin should be considered as a chemopreventative agent for VK and cuSCC in patients taking BRAF inhibitors, before considering dosage reductions. What's already known about the topic? The BRAF inhibitors vemurafenib and dabrafenib trigger the development of verrucal keratosis (VK) and cutaneous squamous cell carcinomas (cuSCC), requiring multiple surgical interventions and, in some cases, dose reduction. What does this study add? Acitretin may be a useful agent in the prevention of VK and cuSCC in patients on BRAF inhibitors. Acitretin may help avoid dose reduction due to the development of VK and cuSCC in patients on BRAF inhibitors. The patient's quality of life is improved as the number of surgical procedures required is reduced.