Emerging Toxicities of Antibody-Drug Conjugates for Breast Cancer: Clinical Prioritization of Adverse Events from the FDA Adverse Event Reporting System

Antibody-drug conjugates (ADCs) are gaining widespread use in the treatment of breast cancer, although toxicity remains an underexplored issue in the real-world clinical setting. Individual case safety reports collected in large pharmacovigilance databases can advance our knowledge on their safety profile in routine clinical practice. We prioritized adverse events (AEs) reported with ADCs approved for breast cancer using the Food and Drug Administration Adverse Event Reporting System (FAERS). We assessed clinical priority of AEs reported in FAERS (February 2013–March 2022) for trastuzumab emtansine (T-DM1), trastuzumab deruxtecan (T-DXd), and sacituzumab govitecan (SG) by attributing a score to each AE disproportionally reported with ADCs. Four criteria were assessed: clinical relevance, reporting rate, reported case fatality rate, and stability of disproportionality signals (consistency of the reporting odds ratio across multiple analyses using three different comparators). We retained 6589 reports (77.4