Posterior reversible encephalopathy syndrome induced by enzalutamide in a patient with castration-resistant prostate cancer.

Posterior reversible encephalopathy syndrome (PRES) is a clinical/radiological syndrome characterized by symptoms that can include seizure, headache, impaired vision and hypertension, and can be confirmed by magnetic resonance imaging. Numerous reports have emerged that describe PRES in cancer patients. The list of medications linked to PRES can include traditional cytotoxic chemotherapeutics (e.g., cisplatin, cyclophosphamide, and high-dose corticosteroids), newer agents that target the vascular endothelial growth factor pathway (e.g., bevacizumab, sunitinib, and pazopanib), and supportive care mediations (e.g., granulocyte colony stimulating factors and erythropoietin). We report, for the first time, a case of PRES that is secondary to treatment with enzalutamide, a potent androgen receptor antagonist used in the treatment of metastatic castration-resistant prostate cancer. Enzalutamide is approved for the treatment of both docetaxel-pretreated and chemotherapy-naïve metastatic castration-resistant prostate cancer. Enzalutamide has been previously linked to the increased risk of seizures. Clinicians should be aware that, in rare cases, patients treated with enzalutamide could potentially be at risk for PRES. If symptoms suggestive of PRES arise in patients receiving enzalutamide, the drug should be discontinued immediately and the diagnostic process should be initiated.