BRAF L597K mutation: an opportunity to treat

The outcomes of patients with metastatic melanoma (MM) have significantly improved after the introduction of BRAF-specific inhibitors. Herein is reported a patient with MM and non-V600-BRAF mutation who responded to iBRAF/iMEK therapy. In July 2014, a 63-year-old man presented with a 4.1mm-thick V600E-BRAF wild type melanoma on the back. Metastases were identified in one sentinel node and two of 11 subsequently excised lymph nodes, with no signs of distant metastatic disease. In September 2017, lung metastasis was observed and pembrolizumab was started. Progressive disease was apparent at cycle 10 and therapy was switched to ipilimumab. After four cycles, an asymmetric response was observed. In November 2017, next generation sequencing genomic profiling disclosed a rare L597K-BRAF mutation and vemurafenib plus cobimetinib therapy was initiated in January 2018. Seven days after treatment start, a remarkable clinical improvement was observed. In April 2018, the patient achieved partial response, which was sustained until October 2018. Cases of patients with non-V600-BRAF mutations responding to iBRAF/iMEK therapy have been reported over the last years. To the best of our knowledge, this is the first case reporting response to combined iBRAF/iMEK therapy in a patient with metastatic melanoma harboring L597K mutation.