P1-041 - Hepatotoxicity caused by Trastuzumab for adjuvant therapy of Breast Cancer in a Filipino Woman: a case report

Abstract

Trastuzumab is a humanized monoclonal immunoglobulin G1 (IgG1) kappa antibody that binds to the extracellular domain of HER2 which is overexpressed on breast cancer cells. It is a well tolerated drug compared to most standard chemotherapy but recently, there have been cases on hepatotoxicity induced by trastuzumab. There are currently only four reported cases in literature regarding trastuzumab induced hepatotoxicity. This report will present a rare case of hepatotoxicity in a Filipino woman taking trastuzumab as an adjuvant therapy for breast cancer. The patient is a 53-year-old woman with an unremarkable medical history and no social history of smoking or drinking alcohol who was diagnosed with Stage IIIB breast cancer and initially underwent neodjuvant chemotherapy with four cycles of doxorubicin (60 mg/m2) and cyclophosphamide (600 mg/m2) and then two cycles of docetaxel (75 mg/m2). Her baseline AST and ALT levels (33 IU/L and 26 IU/L, respectively) as well as her liver ultrasound were unremarkable. Prior to the second cycle, the patient's AST increased to 239 U/L (Grade 3) and ALT to 118 (Grade 2), hence chemotherapy was deferred. The levels eventually went down and her neoadjuvant therapy was completed. Trastuzumab was given as adjuvant therapy but after her seventh cycle, her AST rose again to 191 U/L (Grade 3) and ALT to 172 U/L (Grade 3). Laboratory work-ups to rule out other causes of hepatotoxicity like liver ultrasound and hepatitis profile were all normal. The treatment was deferred until her AST and ALT (30 U/L and 46 U/L, respectively) levels declined to normal levels. The plan is to complete the 18 cycles of trastuzumab therapy with periodic evaluation of liver enzymes. Although trastuzumab is a highly safe drug and tolerated by patients well, the authors still propose that liver enzymes be monitored in patients receiving this drug, especially those with previous history of liver injury.