Efficacy of pertuzumab and trastuzumab as first line treatment in patients with HER2-Positive Metastatic Breast Cancer

Abstract

Background: Pertuzumab, a humanized monoclonal antibody, binds the HER2 extracellular domain (subdomain II), and has a complementary action to trastuzumab that binds to different HER2 domains. These two antibodies, when given together, provide a dual inhibition of receptor dimerization and greater anti-tumor activity. This study is the first to report results of these two antibodies as first line in HER2+ MBC, at Albairouni university hospital.

Patients and methods: Patients with HER2+ locally advanced or metastatic breast cancer received pertuzumab plus trastuzumab plus chemotherapy (either docetaxel or vinorelbine) as first-line treatment until the time of disease progression or the development of unmanageable toxicity. The primary end point assessed the objective response and clinical benefit.

Results: In the intention-to-treat population of 65 evaluable patients, clinical benefit rate and objective response rate were 95% and 81.4%, respectively. In the subgroups, patients had similar clinical benefit with first-line treatment of docetaxel or vinorelbine combined with trastuzumab and pertuzumab (96.7% vs. 94%, respectively).

Conclusion: Our results show a pronounced improvement in objective response and clinical benefit when adding pertuzumab to trastuzumab, and chemotherapy in patients with HER2-positive metastatic breast cancer. Oral vinorelbine should be highly considered for this combination.

Key words: Breast cancer; HER-2 positive; Metastatic; Pertuzumab; Docetaxel; Trastuzumab; Vinorelbine.