Subgroup analysis of a phase III trial of doxorubicin vs doxorubicin plus tesmilifene in advanced breast cancer (ABC): Tesmilifene survival benefit focused on patients with more aggressive disease

756 Background: Tesmilifene (DPPE), a novel chemopotentiating small molecule, conferred a substantial (50%+) increase in median survival in MA.19, a 305 patient randomized trial in ABC (doxorubicin alone, 15.6 m; doxorubicin + DPPE, 23.6 m; p<0.03; J Clin Oncol 22: 269–276, 2004). Response rates and median progression free survival (PFS) were not different, however. Methods: YM Biosciences conducted an unplanned subgroup analysis of the MA.19 database to determine whether some subsets of patients might benefit differentially from the addition of DPPE. Results: Tally of post-trial treatments revealed minimal differences in exposure to a range of chemotherapy (CT) including taxanes; therefore, post-trial treatments do not explain the large survival (OS) difference. The only important prognostic factor maldistribution was the disease free interval (DFI) from original diagnosis to entry on trial, median 20 m (doxorubicin) vs 26 m (doxorubicin + DPPE). Although independently prognostic this DFI difference coul...