Experience of using pertuzumab in anticancer therapy for HER2-positive breast cancer

Background. Breast cancer is one of the most common malignancies and one of the leading causes of cancer deaths among women in the Russian Federation. The prognosis of the disease is largely determined by the biological subtype of the tumor. Her2-positive breast cancer is characterized by an aggressive course and unfavorable prognosis. The use of pertuzumab, a recombinant humanized monoclonal antibody to the human epidermal growth factor receptor 2, significantly improved immediate and long-term treatment outcomes. The aim of the study was to evaluate treatment outcomes in patients with Her2-positive molecular subtype of breast cancer receiving chemotherapy combined with a dual anti-Her2 blockade, and to assess the intensity and incidence of side effects. Material and methods. Between 2015 and 2018, 37 patients with Her2-positive breast cancer received chemotherapy combined with a dual anti-HER2 blockade (docetaxel 75 mg/m2 i/v on day 1 + trastuzumab 6 mg/kg (loading dose 8 mg/kg) i/v on day 1 + pertuzumab 420 mg (loading dose 840 mg) i/v on day 1 once every 3 weeks). The mean age of the patients was 45.6 ± 11.6 years. Results. Neoadjuvant pertuzumab in combination with trastuzumab and docetaxel resulted in pathological complete response in 12 % of patients and pathological partial response in 36 % of patients. Among patients who received the above neoadjuvant therapy regimen, disease progression was observed in 4 % of patients. The most common side effects were weakness and fatigue (5.4 % of cases) and grade I-II leukopenia (5.4 %). Conclusion. The study demonstrated the efficacy of antitumor therapy with pertuzumab in combination with trastuzumab and docetaxel as well as the absence of severe side effects associated with this treatment regimen in patients with Her2-positive breast cancer.