Data Extraction
Two investigators (YZQ and CZH) independently conducted the study selection in accordance with the inclusion and exclusion criteria above and extracted data from the included trials. The extracted information included first author’s name, year of publication, country, National Clinical Trials (NCT) registry number, phase, treatment regimen, sample size, basic patient characteristics (i.e., age, primary tumor type, HER2 expression status), efficacy outcomes (PFS, OS, ORR, DCR) and incidences of ang grade or grade≥3 AEs. Disputes during the process were resolved by discussion with a third investigator (WS).