Neoadjuvant Treatment of HER2 Positive Early High-risk and Locally Advanced Breast Cancer

Dual targeting of HER2 with trastuzumab and pertuzumab in HER2-positive breast cancer is linked to clinical evidence of reversal of initial resistance to trastuzumab (Baselga J et al, J Clin Oncol 2010) in cases progressing on trastuzumab therapy, and in dramatic improvement in progression free and overall survival when the two monoclonal antibodies are used in combination with docetaxel (THP regimen) as first line therapy of metastatic disease as shown in the CLEOPATRA study (Swain S et al, ESMO abstract 2014). The randomized NeoSphere study showed that the same THP regimen given for 4 cycles as neoadjuvant treatment increased the rate of pathologic complete response (pCR) over that with conventional docetaxel and trastuzumab or docetaxel and pertuzumab (Gianni L et al, Lancet Oncol 2012). Encouraging clinical data emerging in the field of tumor immunotherapy have demonstrated that therapies focused on enhancing T cell responses against cancer can result in a significant survival benefit in patients with advanced malignancies (Hodi FS and Dranoff G, J Cutan Pathol 2010; Kantoff PW et al, New Engl J Med 2010; Chen DS et al, Clin Cancer Res 2012). Many human tumors have been found to overexpress PD L1, which acts to suppress anti tumor immunity. PD 1 is an inhibitory receptor expressed on T cells following T cell activation, which is sustained in states of chronic stimulation, such as in chronic infection or canc Atezolizumab is a human monoclonal antibody containing an engineered Fc-domain to optimize efficacy and safety that targets PD-L1 and blocks binding of its receptors, including PD-1 and B7.1. In addition to being involved in the natural progression of cancer, immunity can affect the activity of various anticancer agents. Accordingly, recent evidence suggests that some chemotherapeutic drugs, such as anthracyclines and oxaliplatin, rely on the induction of anticancer immune responses. Immune responses also play a major role in the efficacy of targeted therapies with monoclonal antibodies (Stagg J et al, Breast Care 2012). Studies have shown monoclonal antibodies such as trastuzumab and rituximab rely in part on immunemediated killing through antibody-dependent cellular cytotoxicity (ADCC). While innate immune responses appear to be important for tumor antigen-targeted monoclonal antibody therapies, recent studies in mice and correlative clinical evidence suggest that trastuzumab may also stimulate adaptive antitumor immunity. These studies raise the possibility that combination strategies may be used to capitalize on the adaptive tumor-specific immunity generated by anti-HER2 monoclonal antibodies. Based on these considerations, we plan to conduct a randomized neoadjuvant study of the combination of trastuzumab, pertuzumab, carboplatin and paclitaxel with or without atezolizumab in women with early high-risk and locally advanced HER2-positive suitable for neoadjuvant therapy. One study arm will also include anthracycline and cyclophosphamide.