CTLA-4 (cytotoxic T lymphocyte–associated antigen 4) is a modulatory receptor on T cells involved in downregulating T cell activation. In animal models, CTLA-4 blockade abrogates tolerance to “self” antigens, resulting in the augmentation of antitumor immunity and induction of autoimmunity. CTLA-4 blockade by means of monoclonal antibodies (ipilimumab and tremelimumab) has been evaluated in multiple clinical trials in patients with metastatic cancer, mainly those with melanoma and renal cell cancer.

We examine available literature and ongoing clinical trials with ipilimumab and tremelimumab and review our own experience with patients treated with CTLA-4 blockade, with an emphasis on issues of direct relevance to surgical oncologists.

CTLA-4 blockade can cause durable tumor regression in patients with metastatic melanoma and other solid tumors. Grade III/IV autoimmune toxicity has been frequently encountered in clinical trials and includes enterocolitis, dermatitis, hypophysitis, uveitis, and hepatitis. Enterocolitis is the most common immune-related adverse event and may cause severe diarrhea requiring intravenous hydration, high-dose corticosteroids, and blockade of tumor necrosis factor alpha with infliximab. Most patients respond to medical treatment, but up to 12% with grade III/IV enterocolitis develop perforation or bleeding that requires colectomy.

As more patients are enrolled onto clinical trials involving ipilimumab and tremelimumab, an increasing number of surgeons may be involved in the care of these patients who develop treatment-related complications. In this report, we review the rationale for CTLA-4 blockade and review selected clinical studies published so far with ipilimumab and tremelimumab. We offer guidelines on the management of patients who develop enterocolitis.