A randomized phase II study of gemcitabine with vinorelbine (GV) vs. sequential gemcitabine and vinorelbine (G/V) in metastatic breast cancer (MBC): An interim analysis.

5268 Background: It is not clear whether the activity of the GV combination regimen would translate into better progression-free or overall survival (OS) when compared with the sequential therapy of Gemcitabine (G) and Vinorelbine (V) especially during toward the late phases of management in MBC. This randomized phase II study was conducted to evaluate the overall response rate (RR) of GV vs. G/V. Secondary objectives included individual responses of G and V, time to progression (TTP), time to treatment failure (TTF), OS, and toxicities. Patients and Methods: Patients(pts) with histologic or cytologic diagnosis of stage IV or recurrent breast cancer who had ECOG PS ≤2 and measurable disease were randomized to receive GV(G 1,000 mg /m 2 and V 25 mg/m 2 , D1 and D8 q3wk until PD) or G/V(G 1,000 mg/m 2 D1, D8, D15 q4wks until PD then V 30 mg/ m 2 D1 and D8 q3wks until PD). Randomization was performed according to number of prior metastatic chemotherapy ≥3 vs vs the rest. Pts received anthracycline and taxane and/or capecitabine chemotherapy in adjuvant and/or metastatic setting. Of total 82 patients to be accrued, 60 patients have been enrolled from 4/2004 to 10/2005. TTP of G/V arm was calculated from the day of randomization to the day of progression on V. Results: Of 60 pts enrolled, 32 pts were randomized to GV arm and 28 to G/V arm. 27% of pts were stage IV and 73% recurrent disease. 43% of pts received ≥3 previous chemotherapies. To date 58 pts were qualified for safety, TTF, TTP, and OS analysis, and 50 for response analysis. Baseline values were balanced between GV and G/V arms. For overall RR, TTF, TTP, and OS analysis, refer to Table 1. Hemtologic and non-hematologic toxicities were mild, and similar in each arm except for more G4 neutropenia in the GV arm (27%) than G/V arm (7%) without statistical significance (p=0.081). Conclusion: TTP was longer in G/V arm than GV arm (p=0.0195). RR, toxicity profiles and OS between two arms were not significantly different. This suggests that pts with MBC in the late phases of management would get more benefit by sequential administration of single agents.