Prognostic Factors Related to Clinical Response in Patients with Metastatic Melanoma Treated by CTL-Associated Antigen-4 Blockade

Three patients achieved complete responses (CR; ongoing at 29+, 52+, and 53+ months); an additional 20 patients achieved partial responses (PR) for an overall objective response rate of 17%. The majority of patients (62%, 86 of 139) developed some form of IRAE, which was associated with a greater probability of objective antitumor response (P = 0.0004); all patients with CR had more severe IRAEs. Prior therapy with IFNalpha-2b was a negative prognostic factor, whereas prior high-dose interleukin-2 did not significantly affect the probability of response. There were no significant differences in the rate of clinical response or development of IRAEs between the two trials. The duration of tumor response was not affected by the use of high-dose steroids for abrogation of treatment-related toxicities (P = 0.23). There were no treatment-related deaths.

In patients with metastatic melanoma, ipilimumab can induce durable objective clinical responses, which are related to the induction of IRAEs.