A Rare Case of Pembrolizumab-Induced Uveitis in a Patient with Metastatic Melanoma

Pembrolizumab, a programmed cell death protein 1 (PD-1) inhibitor, is a humanized monoclonal antibody used in the treatment of metastatic or unresectable melanoma and advanced non-small cell lung cancer (NSCLC). We hereby report a case of pembrolizumab-induced uveitis to increase practitioner awareness. A 78-year-old woman presented with onset of panuveitis after initiation of pembrolizumab therapy for metastatic melanoma. The patient received three cycles of therapy every 21 days, during which her symptoms progressively worsened. She was treated with topical and systemic corticosteroids, and further pembrolizumab was discontinued despite a good response to therapy. Pembrolizumab has been associated with rapid onset of ocular inflammation and uveitis. PD-1 inhibitors mediate a T-cell response against cancer cells; however, autoimmune complications have been reported. Incidence of pembrolizumab-induced uveitis is reported to be < 1%. To date, three cases have been reported since its Food and Drug Administration approval in September 2014. Uveitis, if left untreated, may lead to permanent vision loss and ocular damage. Cases of immune-mediated uveitis have been reported with cancer immunotherapies. Oncologists and ophthalmologists should be aware of this complication. With the increasing targeted pharmaceuticals in oncology, effective management of adverse events is necessary to ensure patient safety and optimal outcomes.