940P - Overall survival benefit with sipuleucel-T by baseline prostate-specific antigen (PSA): an exploratory analysis from three phase 3 trials
|Date||29 September 2012|
|Event||ESMO Congress 2012|
|Session||Poster presentation I|
|Topics|| Prostate Cancer
Cancer Immunology and Immunotherapy
P. Kantoff1, G. Chodak2, R. Sims3, J.B. Whitmore4, P. Schellhammer5
AbstractIntroduction and objective
Sipuleucel-T is an autologous cellular immunotherapy approved for the treatment of asymptomatic or minimally symptomatic metastatic castrate-resistant prostate cancer (mCRPC) based on improved overall survival (OS) in the pivotal phase 3 IMPACT trial (NCT00065442). In a subgroup analysis of pooled data from three Phase 3 trials of sipuleucel-T in mCRPC, baseline PSA was found to be the most significant predictive factor for OS. To further investigate the impact of baseline PSA levels on outcomes following sipuleucel-T, we conducted an exploratory analysis of patients (pts) from three Phase 3 trials.Methods
The analysis included all 737 randomized pts from three Phase 3 trials (D9901, D9902A and IMPACT). Pts were categorized by baseline PSA quartile (Table), as well as by ECOG PS, and median for other baseline prognostic variables (i.e. lactate dehydrogenase [LDH], alkaline phosphatase [ALP], and hemoglobin [Hgb]). Median OS and hazard ratio (HR) were estimated using Kaplan-Meier and Cox models, respectively.Results
HR values suggest consistent treatment effect in all subsets, although there is inadequate power to show statistical significance within each quartile. There was a trend toward an increased magnitude of treatment benefit in pts with a lower baseline PSA (Table). Results for other baseline prognostic variables also suggest a trend toward greater benefit with better prognostic features. However, results for baseline Hgb indicated an opposite trendConclusions
Although not powered for statistical significance, this analysis supports a consistent OS benefit with sipuleucel-T across PSA quartiles in patients enrolled in Phase 3 trials. The greater benefit with lower baseline PSA suggests that pts with less advanced disease may benefit more from sipuleucel-T.
|Baseline PSA (ng/mL)|
|≤22.3||>22.3– ≤ 49.9||>49.9– ≤ 137.8||>137.8|
|Median OS, mos|
|HR; 95% CI||0.48; 0.32–0.73||0.76; 0.53–1.11||0.67; 0.47–0.95||0.88; 0.62–1.25|
P. Kantoff: Advisory boards for Dendreon Corporation
G. Chodak: Stock ownership in Amgen; Advisory boards for Dendreon Corporation and Janssen; Honoraria for Dendreon Corporation and Amgen.
R.B. Sims: Stock ownership and employee of Dendreon Corporation.
J.B. Whitmore: Employee of Dendreon Corporation; Stock ownership in Dendreon Corporation and Amgen,
P. Schellhammer: Honoraria for Dendreon Corporation