METHODS: In the TROIKA trial, patients with ERBB2-positive early breast cancer were randomized and treated with either HD201 or the referent trastuzumab. Eligible patients received 8 cycles of either HD201 or referent trastuzumab (loading dose, 8 mg/kg; maintenance dose, 6 mg/kg) every 3 weeks in combination with 8 cycles of chemotherapy (4 cycles of docetaxel, 75 mg/m2, followed by 4 cycles of epirubicin, 75 mg/m2, and cyclophosphamide, 500 mg/m2) in the neoadjuvant setting. The patients then underwent surgery followed by 10 cycles of adjuvant HD201 or referent trastuzumab according to their initial randomization to complete one year of trastuzumab-directed therapy. Event-free and overall survival rates were calculated using Kaplan-Meier analysis. The hazard ratio for event-free survival was estimated by Cox proportional hazards regression.

RESULTS: The final analysis was performed after all patients completed the study at a median follow-up of 37.7 months (Q1-Q3, 37.3-38.1 months). A total of 502 randomized patients received either HD201 or the referent trastuzumab, and 474 (94.2%) were eligible for inclusion in the per-protocol set. In this population, the 3-year event-free survival rates were 85.6% (95% CI: 80.28-89.52) and 84.9% (95% CI: 79.54-88.88) in the HD201 and referent trastuzumab groups, respectively (log rank p = 0.938) (HR 1.02, 95% CI: 0.63-1.63; p = 0.945). The 3-year overall survival rates were comparable between the HD201 (95.6%; 95% CI: 91.90-97.59) and referent trastuzumab treatment groups (96.0%, 95% CI: 92.45-97.90) (log rank p = 0.606). During the posttreatment follow-up period, adverse events were reported for 64 (27.4%) and 72 (29.8%) patients in the HD201 and the reference trastuzumab groups, respectively. Serious adverse events were rare and none of which were related to the study treatment.

CONCLUSIONS: This final analysis of the TROIKA trial further confirms the comparable efficacy and safety of HD201 and trastuzumab.