Grant support and Acknowledgements: This work has been supported by funding from EU H2020 Research & Innovation programme, No. 731875 (LIVERHOPE).We acknowledge Nicola Van Berckel for her administrative support and her valuable collaboration with the development of the Liverhope Project.

5019 Background: Chemotherapeutic options for HRPC are limited. S is a novel oral platinum compound. Methods: The SPARC trial is a multinational randomized double blind study comparing S 80 mg/m2/day x 5 q5weeks po + prednisone (P) vs placebo + P in HRPC patients (pts) who failed prior chemotherapy. In this analysis, progression-free survival (PFS) was the primary endpoint, defined as a composite endpoint of radiologic progression, symptomatic progression, skeletal events or death. All cases were blindly adjudicated for progression by an independent review committee (IRC). Results: 950 pts were accrued between Sept 2004 and Jan 2006. Baseline characteristics were well balanced between treatment arms. 51% of the pts had received prior docetaxel. 68% were ≥ 65 yrs old and 27% were ≥ 75 yrs old. Pts received a median of 4 courses in the S arm (range:1–28) vs 2 courses in the placebo arm (range 1–16). 802 pts had an IRC defined progression-free (PFS) event consisting in 80% of the cases of radiologic progression, pain progression or death. All analyses were conducted on an intent-to-treat basis. S was associated with a 31% reduction in the risk of PFS events (HR=0.69; 95% CI: 0.60–0.80; p<0.00001) and a 33% reduction in the risk of pain progression (HR=0.67; 95% CI: 0.54 - 0.83; p=0.00028). Consistent results in favor of S were found for PFS and time to pain progression in all subsets examined, including pts treated with prior docetaxel. Superior PSA response (25% vs.12%, p=0.00007), objective tumor response (7% vs. 1%, p<0.002), pain response (24% vs. 14%, p<0.005), and duration of pain response (HR=0.59; 95%CI: 0.35–1.00; p=0.049) were observed for S. Final analysis of overall survival awaits the occurrence of the pre-specified number of events. S was generally well tolerated - myelosuppression was the most frequent side effect, but grade 4 neutropenia was uncommon (4%) and a single patient had grade 4 thrombocytopenia. Grade 3/4 non-hematologic side effects included infection (4%), vomiting (2%) and diarrhea (2%). Conclusions: S is well tolerated and significantly reduces the risk of disease progression for HRPC pts who have failed prior chemotherapy. Supported by GPC Biotech and Pharmion No significant financial relationships to disclose.