Corneal transplant rejection after treatment with pembrolizumab: report of two cases

Introduction: Immune checkpoint inhibitors (ICIs) have transformed the management of advanced stage cancers but pose a risk for immune-mediated complications. This study describes 2 cases of corneal transplant rejection after pembrolizumab therapy. Patient and Clinical Findings: A 78-year-old man with prior penetrating keratoplasty (right eye) and deep anterior lamellar keratoplasty (left eye) received pembrolizumab and enfortumab vedotin for metastatic bladder cancer. After 2.5 months, he developed corneal neovascularization, edema, and stromal haze in the right eye. The second patient was a 64-year-old woman with advanced endometrial cancer treated with pembrolizumab in combination with paclitaxel and carboplatin. 5 months after starting treatment, she underwent Descemet membrane endothelial keratoplasty. She self-discontinued topical corticosteroids and developed keratic precipitates 3 months postoperatively. Diagnosis, Intervention, and Outcomes: Both patients were diagnosed with corneal graft rejection and treated with topical prednisolone acetate 1%. Rejection resolved after 5 months in the first patient and after 3 weeks in the second. Conclusions: This report highlights 2 rare instances of corneal transplant rejection associated with pembrolizumab. Prompt recognition and treatment can reverse rejection and preserve vision without interrupting systemic cancer therapy. Patients with corneal transplants should be counseled on this potential risk and closely monitored during ICI treatment.