MEK inhibitors: a new class of chemotherapeutic agents with ocular toxicity

A new class of chemotherapeutic agents, MEK inhibitors, has recently been developed and is proving to be an effective treatment for a number of cancers. A pattern of ocular adverse events has followed these drugs through clinical trials and their association with retinopathy is only just beginning to be recognized. We present two cases of MEK inhibitor-associated retinopathy followed by a review of the current literature on ocular toxicity associated with MEK inhibitors. Patients undergoing treatment with MEK inhibitors appear to have high rates of multifocal serous retinal detachments as well as retinal vein occlusions. We present the first report of cystoid macular edema associated with MEK inhibitor use. The mechanism of these adverse events is still unclear though they seem to be related to oxidative stress and blood retinal barrier breakdown. Management of the ocular toxicity can range from observation to topical treatments or intravitreal injections. Fortunately most ocular adverse events appear to be self-limited and do not require discontinuing the MEK inhibitor. Discontinuation or decreased dosing of MEK inhibitors may be reserved for cases of severe sight-threatening ocular toxicity.