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.