Randomized Phase II Trial of weekly paclitaxel alone versus trastuzumab plus weekly paclitaxel as first-line therapy of patients with Her-2 positive advanced breast cancer

Background: A randomized Phase II study evaluated the activity of weekly paclitaxel versus its combination with trastuzumab for treatment of patients with advanced breast cancer overexpressing HER-2. Patients and methods: Among 124 patients randomized, 123 are assessable for toxicity and 118 for response. Patients received weekly paclitaxel single agent (80 mg/m²) or combined with trastuzumab (4 mg/kg loading dose, then weekly 2 mg/kg). HER-2 overexpression was determined by immunohistochemistry (IHC). Patients with 2+/3+ IHC scores were eligible. IHC was compared with HER-2 serum extracellular domain (ECD). Results: Patient characteristics were similar in the two arms. Both treatments were feasible and well tolerated with no grade 4 hematologic toxicity. No patient developed cardiac toxicity. The combined treatment was statistically significant superior for overall response rate (ORR) (75% vs. 56.9%; P = 0.037), particularly in the subset of IHC 3+ patients (84.5% vs. 47.5%; P = 0.00050). A statistically significant better median time to progression was seen in the subgroup with IHC 3+ (369 vs. 272 days; P = 0.030) and visceral disease (301 vs. 183 days; P = 0.0080) treated with combination. Multivariable analysis of predictive factors showed that only IHC score retained statistically significant value for ORR (P = 0.0035). Conclusion: Weekly paclitaxel plus trastuzumab is highly active and safe and it is superior to paclitaxel alone in patients with IHC score of 3+.