Case report: sinusoidal obstruction syndrome post-treatment with trastuzumab emtansine in breast cancer

Resumo

Objective: Trastuzumab emtansine (T-DM1) is an anti-HER2 antibody-drug conjugate indicated for the treatment of HER2-
positive breast cancer. One of the most severe adverse events reported with T-DM1 is hepatotoxicity. More recently, some
cases of noncirrhotic portal hypertension have been described in patients with long-term T-DM1. The underlying liver condition is usually sinusoidal obstruction syndrome. Methodology: Here, we present the case of a patient with early-stage
HER2-positive breast cancer who received adjuvant T-DM1 and developed hepatotoxicity due to this condition. Results: We
report a case of a 46-year-old woman with early-stage (stage III) HER2-positive breast cancer who started adjuvant T-DM1
therapy for residual disease after HER2-directed therapy. After 3 cycles of T-DM1, the patient started a new-onset elevation of liver tests and there was focal hepatic steatosis on abdominal CT. A reduction in platelet count was also apparent
during the T-DM1 therapy. Liver elastography was performed and showed signs of moderate liver fibrosis. The patient
underwent a liver biopsy which revealed sinusoidal obstruction, and so T-DM1 has been suspended. Thereafter, the patient
had normalization of liver tests and platelet count. After discussion with a Hepatologist, we opted to definitively suspend
T-DM1 therapy due to the risk of progression to noncirrhotic portal hypertension. Conclusion: We presented a rare case
of sinusoidal obstruction syndrome induced by T-DM1 in a patient with breast cancer. Hepatotoxicity is one of the main
adverse events of T-DM1. A high index of suspicion for liver injury must be maintained for patients who develop liver test
abnormalities and/or signs of portal hypertension during treatment with T-DM1. This shows the usual complexity in treating patients with new drugs for breast cancer and the importance of multidisciplinary monitoring