Clinical characteristics and treatment outcomes of non-V600 E/K BRAF mutant melanoma patients: a single-institution experience.

ABSTRACT

The widespread use of more sensitive detection tools, such as next-generation sequencing, has increased the identification of a variety of BRAF mutations other than V600E/K in melanoma patients. However, there is a lack of established data regarding the efficacy of BRAF/MEK inhibitors and immune-checkpoint immune inhibitors (ICI) for these patients. We performed a retrospective study, including all the patients diagnosed with stage III or IV melanoma that were referred to the University Hospital of Bologna from 2011 to 2021, carrying a non-V600E or V600K mutation of BRAF and who were started on systemic treatment. We found 14 patients with stage III or IV melanoma harboring the following BRAF mutations V600R, V600_K601delinsE, K601E, p.T599_V600insT, L597V, G466R, S467L, and A598T. Of note, G466R and A598T BRAF mutations have never been previously reported in melanoma. Four patients received combined BRAF/MEK inhibitors, two patients BRAF inhibitor monotherapy, and six patients were treated with ICI for advanced melanoma; four patients received adjuvant treatment with nivolumab. Given the few cases and the absence of randomized clinical trials, it is important to report clinical experiences, which can guide physicians in the treatment of melanomas harboring rare BRAF mutations.