Outcomes And Clinical Markers Associated With Benefit From Ipilimumab (Ipi) In Patients With Advanced Melanoma: A Retrospective Single-Institution Study

e20048 Background: Ipi (anti-CTLA4 antibody) is associated with improved survival and durable responses in a subset of melanoma pts. However, the optimal dose and schedule remain unclear and an unmet need to identify predictors of clinical benefit exists. This retrospective study of pts at the University of Washington aims at gaining further insight into these questions. Methods: Efficacy and safety outcomes and baseline characteristics of 126 pts receiving single agent Ipi from 2006-2012 were subjected to univariate analysis. Efficacy endpoints included OS, PFS, ORR and Duration of Clinical Benefit (DCB) defined as the time from Ipi initiation until documented progression or change in therapy (to capture outcomes on non-trial pts). Immune-related adverse events (IRAEs), absolute lymphocyte count (ALC), concordance of disease response by metastatic site, and use of radiation therapy (RT) were also analyzed. Results: The median age was 57.7 yrs. The 3 mg/kg (N=84; 67%) and 10 mg/kg (N=42; 33%) cohorts matched well for standard prognostic criteria. The efficacy endpoints, including OS, PFS, DCB, and ORR (see table) were not significantly different for the 3 mg/kg and 10 mg/kg cohorts. However, grade III/IV IRAEs were more frequent in the 10 mg/kg group (33% vs 17%, p=0.04). There was a significant correlation between efficacy outcomes and development of IRAEs (see table). Baseline ALC or changes in ALC at 7 weeks post-therapy and concurrent RT administration did not significantly correlate with improved outcomes. Responses were concordant between CNS and non-CNS sites. Conclusions: Our data supports the currently approved dose of 3mg/kg. The development of IRAEs was significantly associated with clinical benefit and further confirmation of this association is warranted. Results of other exploratory analyses will be presented at the meeting. [Table: see text]