Comprehensive analysis of adverse event profile changes with pertuzumab addition to trastuzumab‐based breast cancer therapy: Disproportionality analysis using VigiBase

Abstract Aims Pertuzumab is used in combination with trastuzumab‐based therapy for HER2‐positive breast cancer. However, real‐world safety information on pertuzumab remains limited. This study assessed the safety of adding pertuzumab to trastuzumab‐based therapy for HER2‐positive breast cancer using real‐world data. Methods VigiBase, the World Health Organization's global database of adverse events (AEs), containing reports from November 1967 to December 2023, was used. Signals for pertuzumab‐associated AEs in breast cancer cases were detected using the reporting odds ratio (ROR). Results Signals of trastuzumab plus pertuzumab relative to trastuzumab alone were detected in gastrointestinal disorders (ROR: 1.45, 95% confidence interval: 1.26–1.67), including diarrhoea (3.49, 2.83–4.30); infections and infestations (1.54, 1.24–1.91); and skin and subcutaneous tissue disorders (ROR: 1.63, 1.40–1.90), including pruritus (1.96, 1.51–2.55) and rash (1.63, 1.20–2.23). Further, signals of trastuzumab plus docetaxel plus pertuzumab relative to those of trastuzumab plus docetaxel were detected in gastrointestinal disorders (1.63, 1.38–1.93), including nausea (1.72, 1.24–2.39) and vomiting (1.48, 1.01–2.17), and in nervous system disorders (1.50, 1.20–1.87), including paraesthesia (2.60, 1.33–5.08) and peripheral sensory neuropathy (5.94, 1.79–19.71). The frequency of AEs causing or prolonging hospitalization was increased with trastuzumab plus pertuzumab compared to that with trastuzumab alone (1.18, 1.00–1.38). Conclusions AE profiles after the addition of pertuzumab to trastuzumab‐based therapy were comprehensively identified. The findings in this study highlight the importance of considering these AEs when selecting pertuzumab combination therapy to ensure the safety of patients with breast cancer.