Drug-Induced Liver Injury (DILI) in Luminal B/Her2-Enriched Breast Cancer Patient during Adjuvant Trastuzumab: Case Report and Literature Review

Trastuzumab is a humanized monoclonal antibody used to treat some types of Breast Cancer (BC), including advanced, relapsing or metastatic, specifically in BCs in which the Human-Epidermal Growth Factor Receptor2 (HER2/neu) protein is overexpressed. The anti-HER2 therapy with Trastuzumab is generally well tolerated and the most frequent adverse effects are hypersensitivity reactions and cardiotoxicity, whereas liver toxicity is reported occasionally in literature, being mainly related to Antibody Drug Conjugates (ADCs), like Trastuzumab Emtansine. We present here a case report and the correlated literature review of a Luminal B/HER2+ BC patient who experienced an important liver toxicity due to Trastuzumab in the adjuvant setting. The cause-effect relationship has been analyzed and demonstrated by the time correlation, AST/ALT trend, exclusion of other causes of liver damage and reappearance of hepatotoxicity at Trastuzumab rechallenge. The hepatotoxicity led to permanent treatment discontinuation. Careful monitoring of liver function during Trastuzumab therapy is so far needed to identify early hepatotoxicity that can be severe for the patient.