A Review of Margetuximab-Based Therapies in Patients with HER2-Positive Metastatic Breast Cancer

SIMPLE SUMMARY: HER2+ metastatic breast cancer (MBC) is a highly prevalent type of breast cancer owing to its resistance to conventional anti-HER2 drugs. Therefore, novel agents that can arrest tumor progression and enhance the overall survival rates of HER2+ breast cancer patients, which would represent a major advancement toward the treatment of HER2 + MBC, need to be developed. This review provides insights into the clinical implication and utility of margetuximab, an anti-HER2 drug, in HER2 + MBC treatment, focusing on studies on the efficacy of margetuximab. Margetuximab is indeed an excellent addition to the arsenal of anti-HER2 mAb drugs that can be used for treating HER2 + MBC. ABSTRACT: Breast cancer (BC) is the most commonly diagnosed cancer globally, with high mortality rates. Targeted drug therapies have revolutionized cancer treatment. For example, treatment with human epidermal receptor 2 (HER2) antagonists has markedly improved the prognosis of patients with HER2-positive BC (HER2 + BC). However, HER2+ metastatic BC (MBC) remains prevalent owing to its resistance to conventional anti-HER2 drugs. Therefore, novel agents are needed to overcome the limitations of existing cancer treatments and to enhance the progression-free and overall survival rates. Progress has been made by optimizing the fragment crystallizable (Fc) domain of trastuzumab, an IgG1 monoclonal, chimeric anti-HER2 antibody, to develop margetuximab. The modified Fc domain of margetuximab enhances its binding affinity to CD16A and decreases its binding affinity to CD32B, thereby promoting its antitumor activity. This review summarizes studies on the efficacy of margetuximab, discusses its utility as an anti-HER2 monoclonal antibody drug for the treatment of HER2 + BC, and presents the latest advances in the treatment of BC. This review provides insights into the clinical implication of margetuximab in HER2 + MBC treatment.