Improving treatment outcomes for patients with HER2‑positive breast cancer using neoadjuvant double HER2 blockade

Background. Dual anti-HER2-targeted therapy in breast cancer (BC) significantly increased the rate of pathological complete response (pCR) compared to single blockade when added to chemotherapy. However, limited data exist on the long-term impact on survival of the additional increase in pCR.Aim. To improve recommendations regarding HER2-targeted agents and chemotherapy in the neoadjuvant treatment of BC.Materials and methods. N.N. Petrov National Medical Research Oncology Center, Ministry of Health of Russia took participation in some clinical trials of neoadjuvant treatment of HER2-positive breast cancer, including NeoSphere and NeoALTTO. In multicenter, open-label, phase 2 randomised NeoSphere trial, patients with locally advanced, inflammatory, or early-stage HER2-positive BC were randomly assigned to receive four neoadjuvant cycles of trastuzumab (8 mg/kg loading dose, followed by 6 mg/kg every 3 weeks) plus docetaxel (75 mg/m2 from every 3 weeks, increasing to 100 mg/m2 from cycle 2 if tolerated) (group A), pertuzumab (420 mg every 3 weeks) and trastuzumab plus docetaxel (group B), pertuzumab and trastuzumab (group C), or pertuzumab and docetaxel (group D). After surgery, patients received three cycles of FEC. Рatients in group C received four cycles of docetaxel prior to FEC, and trastuzumab 6 mg/kg every 3 weeks to complete 1 years treatment. In NeoALTTO trial from 455 patients 154 patients received lapatinib, 149 – trastuzumab, 152 – combination of lapatinib and trastuzumab.Results. Between 2007, and 2009, 417 patients were randomly assigned to group A (107 patients), group B (n = 107), group C (n = 107), or group D (n = 96). At clinical cutoff, 87 patients had disease progression or died. 5-year progressionfree survival rates were 81 % (95 % confidence interval (CI) 71–87) for group A, 86 % (95 % CI 72–91) for group B, 73 % for group C, and 73 % for group D (95 % CI 0.34–1.40). Disease-free survival rates were consistent with progressionfree survival rates and were 81 % (95 % CI 72–88) for group A, 84 % (95 % CI 72–91) for group B, 80 % (95 % CI 70–86) for group C, and 75 % (95 % CI 64–83) for group D. In NeoALTTO trial patients who achieved pCR had longer progressionfree survival (85 % (95 % CI 76–91)) compared with patients who did not achieve pCR (76 % (95 % CI 71–81)).Conclusion. High levels of progression-free survival and disease-free survival at 5–10-years follow-up show large and overlapping CI, but support the primary endpoint (pCR) and suggest that neoadjuvant pertuzumab is beneficial when combined with trastuzumab and docetaxel. Additionally, they suggest that pCR could be an early indicator of long-term outcome in early-stage HER2-positive BC.