Multicenter, non-randomized phase II study with RPR109881 in taxane-exposed metastatic breast cancer (MBC) patients (pts): Final results

Abstract

565 Background: RPR109881 is a semisynthetic taxane with demonstrated broad spectrum of activity in in vivo tumor models, particularly in taxane-resistant models. Methods: This Phase II study with RPR109881 administered as 1-hour IV infusion every 3 weeks at 90 mg/m2 evaluated its efficacy in MBC pts previously treated with chemotherapy (CT) including paclitaxel or docetaxel. Pts were stratified in 2 strata: 1) taxane non-resistant (NRS) if they had demonstrated objective response (OR) to prior taxane or 2) taxane-resistant (RS) if DFI ≤ 12 months following adjuvant taxane CT or no OR for metastatic disease. Results: 62 pts were enrolled in NRS and 68 in RS. Median age: 54 years (33–76). 693 cycles were administered: median 6 (1–12) and 3 (1–21) in NRS and RS respectively. The most common and severe toxicities were: Table 1. 2 toxic deaths were reported in the RS (septic shock and sudden death at cycle 1). Ten additional pts (3 consent withdrawns, 2 lost to follow up, 1 non-measurable lesion, 1 incomplete tumor assessment, 3 discontinuations for toxicities) were not evaluable for response. Efficacy assessed by external reviewers in treated population per stratum. There was 41.9% OR (CI: 29.5–55.2%) in NRS and 19.4% (CI: 10.8–30.9%) in RS. TTP and survival will be presented. Conclusion: RPR109881 demonstrates promising activity in taxane-exposed MBC. A phase III study comparing RPR109881 versus capecitabine is underway. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration sanofi-aventis Aventis