Myasthenia Gravis Exacerbation Following BRAF and MEK Inhibitor Therapy

Introduction While there is a well-known association of immune check point inhibitors and myasthenia gravis (MG), there has also been three previous cases of new onset MG being associated with B-Raf proto-oncogene serine/threonineprotein kinase (BRAF) and/or mitogen-activated protein kinase (MEK) inhibition treatment. The previously associated medications include binimetinib (MEK inhibitor) and the combination of dadrafenib (BRAF inhibitor) and trametinib (MEK inhibitor).1–3 We report a novel case of a patient with well controlled generalized MG who developed exacerbation after treatment for metastatic melanoma with vemurafenib, a BRAF inhibitor, and cobimetinib, a MEK inhibitor.