Ipilimumab is a human monoclonal antibody that blocks the activity of CTLA-4, blocking the function of CTLA-4 as a down regulator of T-cell activation. It is approved for the treatment of unresectable or metastatic melanoma and supported by two prospective, randomized, international trials, one each in previously untreated and treated patients.[6,19]
Previously treated patients. A total of 676 patients with previously treated, unresectable stage III or stage IV disease, who were HLA-A*0201-positive patients, were entered into a three-arm, multinational, randomized, double-blind trial comparing ipilimumab with or without glycoprotein 100 (gp100) peptide vaccine to the gp100 vaccine plus placebo. Patients were stratified by baseline metastases and prior receipt or nonreceipt of IL-2 therapy. Of the patients, 82 had metastases to the brain at baseline. The median OS was 10 months and 10.1 months among patients receiving ipilimumab alone or with the gp100 vaccine, respectively, versus 6.4 months for patients receiving the vaccine alone (hazard ratio [HR], 0.68; P < .001; HR, 0.66; P < .003).
An analysis at 1 year showed that among those patients treated with ipilimumab, 44% and 45% of them were alive compared with 25% of the patients who received vaccine only. Grade 3 to grade 4 immune-related adverse events (AEs) occurred in 10% to 15% of patients treated with ipilimumab. These immune-related AEs most often included diarrhea or colitis, and endocrine-related events (i.e., inflammation of the pituitary) that required cessation of therapy and institution of anti-inflammatory agents, such as corticosteroids or in four cases, infliximab (i.e., an anti-tumor necrosis factor-alpha antibody). There were 14 deaths related to study drugs (2.1%), and seven were associated with immune-related AEs.[Level of evidence: 1iA]
Previously untreated patients. A multicenter, international trial randomly assigned 502 patients untreated for metastatic disease (adjuvant treatment was allowed) in a 1:1 ratio to ipilimumab (10 mg/kg) plus dacarbazine (850 mg/m2) or placebo plus dacarbazine (850 mg/m2) at weeks 1, 4, 7, and 10 followed by dacarbazine alone every 3 weeks through week 22. Patients with stable disease or an objective response and no dose-limiting toxic effects received ipilimumab or placebo every 12 weeks thereafter as maintenance therapy. The primary endpoint was survival.
Patients were stratified according to Eastern Cooperative Oncology Group (ECOG) performance status (PS) and metastatic stage. Approximately 70% of the patients had an ECOG PS of 0, and the remainder of the patients had an ECOG PS of 1. Approximately 55% of the patients had stage M1c disease. The median OS was 11.2 months (95% confidence interval [CI], 9.4–13.6) versus 9.1 months (95% CI, 7.8–10.5). Estimated survival rates in the two groups respectively were 47.3% and 36.3% at 1 year; 28.5% and 17.9% at 2 years; and 20.9% and 12.2% at 3 years (HR for death with ipilimumab-dacarbazine, 0.72; P < .001). The most common study-drug–related AEs were those classified as immune related. Grade 3 to 4, immune-related AEs were seen in 38.1% of patients treated with ipilimumab plus dacarbazine versus 4.4% in patients treated with placebo plus dacarbazine, the most common being hepatitis and enterocolitis. No drug-related deaths occurred.[Level of evidence: 1iA]