Myasthenia gravis following dabrafenib and trametinib for metastatic melanoma.

In myasthenia gravis (MG), autoantibodies bind to postsynaptic acetylcholine (AChR) receptors or related proteins at the neuromuscular junction.(1) This impairs synaptic transmission, causing fatigable muscle weakness. MG has been reported in patients undergoing cancer treatment, specifically immunotherapy with immune checkpoint inhibitors.(2) In patients with metastatic melanoma carrying a BRAF V600 mutation, a different class of treatment, combined molecularly targeted therapy with the BRAF inhibitor dabrafenib and the MEK inhibitor trametinib, improves overall survival and is now the standard of care.(3) We report a case of AChR antibody-positive MG developing after exposure to dabrafenib and trametinib.