UCBG 2-04: Long-term results of the PACS 04 trial evaluating adjuvant epirubicin plus docetaxel in node-positive breast cancer and trastuzumab in the human epidermal growth factor receptor 2–positive subgroup

Abstract Purpose We conducted a double-randomised phase III trial to evaluate a concomitant taxane-anthracycline regimen in node-positive breast cancer and the efficacy of trastuzumab in the human epidermal growth factor receptor 2 (HER2)–positive subpopulation. Methods A total of 3010 patients with node-positive breast cancer were randomly assigned to receive 6 cycles of 500 mg/m2 of fluorouracil, 100 mg/m2 of epirubicin and 500 mg/m2 of cyclophosphamide (FEC) or 75 mg/m2 of epirubicin and 75 mg/m2 of docetaxel (ED). Patients with HER2-positive tumours were secondary randomly assigned to either trastuzumab or observation. The primary end-point was disease-free survival (DFS) in the two chemotherapy arms. Results After a 115-month median follow-up, DFS was not significantly better in the ED arm (DFS: 70%, 95% confidence interval [CI]: 67–72) than in the FEC arm (DFS: 68%, 95% CI: 65–70; hazard ratio [HR] = 0.88, 95% CI: 0.77–1.01; p = 0.064). The OS was not different between FEC (OS: 80%, 95% CI: 78–83) and ED (OS: 81%, 95% CI: 79–83); HR = 0.97, 95% CI: 0.81–1.16; p = 0.729). ED appeared more toxic. In the 528 HER2-positive subset, there was trend for a higher DFS, in the intention-to-treat population, in the trastuzumab arm (DFS: 68%, 95% CI: 61–74) than in the observation arm (DFS: 60%, 95% CI: 54–66; HR = 0.77, 95% CI: 0.57–1.03; p = 0.079). In the per-protocol population, DFS was significantly higher in the trastuzumab arm (DFS: 70%, 95% CI: 63–76) than in the observation arm (DFS: 59%, 95% CI: 53–65; HR = 0.69, 95% CI: 0.51–0.94; p = 0.0156). The OS was not different between these 2 arms. Conclusion This study did not show superiority of the concomitant anthracycline-taxane arm which was more toxic in high-risk node-positive breast cancer patients. Long-term results of the HER2-positive subpopulation are in line with those of the other adjuvant trastuzumab trials but quantitatively less pronounced mostly because of lack of power.