The Efficacy and Safety of Additional Anti-HER2-Targeting Drugs in the Treatment of HER2-Positive Advanced Breast Cancer: A Meta-Analysis

Background: HER2-positive breast cancer patients account for one-fifth of the total breast cancer population. Besides, more anti-HER2-targeting drugs have appeared clinically. Objective: This study aimed to analyze the efficacy and safety of additional anti-HER2 (Human Epidermal growth Factor Receptor 2)-targeting drugs in the treatment of HER2-positive advanced breast cancers. Methods: The following databases were searched for published articles containing data on the efficacy and safety of additional anti-HER2-targeting drugs in HER2-positive advanced breast cancer from the time of their inception until December 2019: PubMed, Web of Science, EBSCO, and Cochrane library. The primary outcomes were Progression-Free Survival (PFS) and Overall Survival (OS). Results: The additional anti-HER2-targeting drugs significantly improved the PFS (HR: 0.66, p<0.001) and OS (HR: 0.77, p<0.001) of HER2-positive advanced breast cancer patients. Regarding drug types, lapatinib was the most effective (HR: 0.53, 95% Cl: 0.39-0.67, p<0.001), followed by pertuzumab (HR: 0.72, 95% Cl: 0.55-0.89, p=0.001). Trastuzumab was the least beneficial (HR: 0.87, 95% Cl: 0.31-1.44, p=0.594). Concerning treatment regimen, first-line treatment (HR: 0.67, 95% Cl: 0.52-0.82, p<0.001) was more effective than non-first-line treatment (HR: 0.82, 95% Cl: 0.71-0.94, p=0.004). The main Adverse Events (AEs) observed were diarrhea and decreased ejection fraction. Conclusion: Additional anti-HER2-targeting drugs can improve long-term prognosis in HER2-positive advanced breast cancers. Besides, they are associated with fewer AEs and are tolerable. Lapatinib is the most effective drug, followed by pertuzumab, whereas trastuzumab is the least effective. Concerning treatment, we recommend the use of anti-HER2-targeting drugs in first-line therapy of HER2-positive advanced breast cancers.