Ipilimumab is a fully human monoclonal antibody registered in Australia for the treatment of patients with unresectable or metastatic melanoma who have failed or are intolerant to prior therapy. Delayed response kinetics, while a hallmark of this immunotherapy, complicates the early assessment of ipilimumab’s anti-tumor effect. A double-blind multicenter parallel phase III clinical trial (MDX010-020) comparing ipilimumab to an active placebo with overall survival as primary endpoint reported a hazard ratio (HR) of 0.66 (95%-CI: 0.51, 0.87)¹. The treatment regimen for ipilimumab in MDX010-020 consisted of four infusions over a 9 week period with re-staging at 12 weeks. In the event of a prolonged delay or multiple delays in treatment, the treatment regimen could be extended up to week 16. Eighteen percent of the patients in the trial were withdrawn, censored or died prior to the 12 week time point, with this figure increasing to 21% by week 16. A post-hoc analysis was performed exploring the survival of those patients who survived beyond the treatment regimen timeframe of weeks 12 or weeks 16. Kaplan-Meier estimates were calculated with a resulting HR=0.57 (95% CI: 0.43, 0.77) for patients surviving beyond the week 12 landmark time point and a HR=0.58 (95% CI: 0.42, 0.79) for patients surviving beyond the week 16 landmark time point. This study demonstrates that ipilimumab treated patients surviving beyond 3-4 months in study MDX010-020 demonstrated enhanced overall survival when compared to the overall patient population (HR=0.66).