P11.52.A Peripheral neuropathies after BRAF and/or MEK inhibitors treatment: a pharmacovigilance study

Abstract Background BRAF (BRAFi) and MEK inhibitors (MEKi) demonstrated significant efficacy in the treatment of BRAF-activated tumours, firstly melanoma. Nevertheless, they are not devoid adverse events. Sparse reports literature suggest potential occurrence peripheral neuropathies (PN) under BRAFi/MEKi treatment, but their characteristics remain poorly defined. We aimed to characterize clinical phenotypes PN occurring using a national pharmacovigilance database. Material Methods queried French database for all cases toxicity attributed at least one BRAFi or MEKi compound. Only with symptoms description nerve conduction studies (NCS) conclusion were included. Results Sixteen occurred 15 patients identified. All had underlying Two main seen. Six (dabrafenib-trametinib, n=3; vemurafenib, n=2; vemurafenib-cobimetinib, n=1) presented length-dependent axonal polyneuropathy: mostly sensory lower limbs; NCS disclosed an neuropathy; management outcome variable. Nine n=5, encorafenib-binimetinib, n=3, developed demyelinating polyradiculoneuropathy: affected four limbs included hypoesthesia, weakness, ataxia; cranial nerves involved four; showed predominantly features; most received intravenous immunoglobulins (n=6) glucocorticoids (n=5), was variable; patient rechallenged different rapid relapse. Conclusion Patients may develop treatment-induced PN. seen: symmetric, axonal, polyneuropathy, polyradiculoneuropathy.