Evaluation of serum IL-17 levels during ipilimumab therapy: Correlation with colitis.

2505 Background: Ipilimumab is the first agent to demonstrate a survival benefit in patients with metastatic melanoma in a randomized phase III clinical trial. Immune-related adverse events (irAEs) are the most common side effects associated with ipilimumab. Grade III/IV irAEs occur in approximately 10-15% of patients, and colitis is the most common irAE within this group. Ipilimumab-associated colitis has been managed effectively with immunosuppressive medications in clinical trials. IL-17 is an important mediator of autoimmunity and inflammation that has been implicated in colitis. We evaluated serum IL-17 levels in patients treated with ipilimumab, comparing patients who developed colitis to those without irAEs. Methods: Patients with metastatic melanoma received 10 mg/kg of ipilimumab on an expanded access protocol (EAP) (CA184-045). We obtained serum samples from 52 serially accrued EAP patients. Samples were collected pre-treatment and at appointed intervals during treatment. The serum concentration...