MAP2K1 and retinal vein occlusion: Central serous-like retinopathy and serous retinal detachment, retinal vein occlusion, blurred vision, transient visual disturbance, and retinal pigment epithelial detachment have all been reported as DLTs with other MEK1/2 inhibitors in phase I clinical trials [16], with transient drug-related retinopathies reported with MEK inhibitors in patients with metastatic melanoma [37, 44] and MEK inhibitor treatment associated with other ocular adverse events [45].