Trastuzumab-emtansine induced pleural and pericardial effusions

Introduction Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate which combine trastuzumab (T), a monoclonal antibody targeting the human epidermal growth factor receptor-2 (HER2), and a cytotoxic molecule derived from maytansine (DM1). Case report We report the first case of T-DM1-associated pleural and pericardial effusions three weeks after the second course of T-DM1 in a patient with breast cancer. Drug-induced pleural and pericardial effusions was implicated in the absence of other etiologies. The Naranjo Scale indicated a probable drug-induced adverse reaction. Management & outcome: The patient fully recovered after thoracentesis and discontinuation of T-DM1. The patient has reported no side effect after the sixth course of trastuzumab. Discussion To our knowledge, this is the first case in the literature of bilateral pleural and pericardial effusions in a patient treated with T-DM1. The successful initiation of treatment with trastuzumab following withdrawal of T-DM1 suggests that emtansine played a role in the development of bilateral pleural and pericardial effusions. We hypothesize that the patient's condition was a result of a local inflammatory reaction to emtansine by direct toxicity.