Cardiotoxic Effects of Antibody Drug Conjugates vs Standard Chemotherapy in ERBB2-Positive Advanced Breast Cancer A Systematic Review and Meta-Analysis

IMPORTANCE Antibody-drug conjugates (ADCs), such as trastuzumab emtansine and trastuzumab deruxtecan, are effective in treating erb-b2 receptor tyrosine kinase 2 (ERBB2)–positive breast cancer (BC) that has progressed on prior ERBB2-targeted therapy, warranting evaluation of their cardiotoxic profiles. OBJECTIVE To compare the incidence of cardiotoxic effects of ADCs vs standard-of-care chemotherapy regimens for ERBB2-positive locally advanced or metastatic BC. DATA SOURCES PubMed, ScienceDirect, Cochrane Library, and ClinicalTrials.gov databases were searched in December 2024 for studies published between 2000 and 2024. STUDY SELECTION The included studies were (1) phase 3 clinical trials that investigated locally advanced or metastatic ERBB2-positive BC; (2) clearly defined left ventricular ejection fraction (LVEF) decrease or heart failure definitions; (3) clearly defined LVEF monitoring frequency by echocardiography or multigated acquisition scan; (4) included studies consisted solely of either trastuzumab emtansine, trastuzumab deruxtecan, or one of the first-line to fourth-line chemotherapy regimens for unresectable stage IV ERBB2-positive breast cancer per the 2025 National Comprehensive Cancer Network guidelines; and (5) clearly defined cardiovascular eligibility criteria. DATA EXTRACTION AND SYNTHESIS Data from eligible studies were extracted by 3 reviewers. A random-effects model was used for the pooled analysis. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was followed. MAIN OUTCOMES AND MEASURES The primary outcome was cardiotoxic effects, which were defined as the incidence of LVEF decrease. The pooled analysis was performed using logit-transformed proportions with the inverse variance method and a DerSimonian-Laird random-effects model for between-study variance, with Wilson score 95% CIs. RESULTS In this meta-analysis of 9538 patients, a pooled analysis demonstrated a 0.94% (95% CI, 0.56%-1.57%) incidence of LVEF decrease with trastuzumab emtansine, a 4.20% (95% CI, 2.91%-6.01%) incidence with trastuzumab deruxtecan, a 4.85% (95% CI, 3.73%-6.28%) incidence with trastuzumab plus chemotherapy, and a 5.52% (95% CI, 3.41%-8.83%) incidence with trastuzumab plus pertuzumab plus chemotherapy. A trim-and-fill analysis was used if evidence of publication bias was found. CONCLUSIONS AND RELEVANCE This meta-analysis found that trastuzumab emtansine was associated with the lowest incidence of LVEF decrease, and trastuzumab deruxtecan, trastuzumab plus chemotherapy, and trastuzumab plus pertuzumab plus chemotherapy had similar incidences. More research is needed into the cardiotoxic effects of these therapies.