High dose (HD) IL-2 for metastatic renal cell carcinoma (mRCC) in the targeted therapy era: Extension of OS benefits beyond complete response (CR) and partial response (PR).

423 Background: HD IL-2 has been reported to have a overall response rate (ORR) for mRCC of 15% and a median OS of 19 months (Fyfe, 1995), however, the studies that led to its regulatory approval are >15 years old and were performed in an era preceding targeted therapies. Methods: The PROCLAIM registry (www.proclaimregistry.com), a HD IL-2 observational database currently with over 30 participating sites, consists of a retrospective cohort (treated between 2007 and 2012) informing an ongoing prospective cohort (~600 patients). We report on the retrospective mRCC subjects (n=97, 13 sites) with survival status determined as of November 2013 and a median follow-up of 32 months. Sites were encouraged to enroll patients sequentially. Inclusion criteria required that patients have received at least one dose of HD IL-2. Results: The ORR was 22% (8% CR and 14% PR). Of 97 subjects, 36 were confirmed deceased and 61 were known to be alive, none were lost to follow-up. The median OS was 51 months, compared to a medi...