HER2-TARGETED THERAPIES

Presentation and Diagnosis

LL is a 45-year-old woman who was diagnosed with invasive ductal carcinoma of the right breast (HR-, HER2+). The breast mass was measured at 2 cm based on mammogram and confirmed by PET/CT. The workup PET/CT also showed increased uptake in a right axilla node, which was confirmed on biopsy to be positive for ductal carcinoma. 

Treatment

LL was treated with dose-dense doxorubicin and cyclophosphamide followed by paclitaxel and trastuzumab. Her pretreatment echocardiogram reported a left ventricular ejection fraction (LVEF) of 55%. Thereafter, she underwent a mastectomy and lymph node dissection. She was noted to have remaining disease in the lymph node as well as an additional node in the right axilla that was positive for disease. She was then treated with ado-trastuzumab emtansine (T-DM1). Her repeat echocardiogram was reported at 50%.

Cardiovascular Toxicity Mitigation and Management

After five cycles of T-DM1, LL reported swelling of her lower extremities and shortness of breath when she walked up stairs. An echocardiogram indicated an LVEF of 35%. The T-DM1 was held and she was referred to cardiology. She was started on metoprolol and lisinopril. 

At this time, she was noted to have a negative PET/CT without evidence of active breast cancer. She was closely monitored by cardiology, and approximately 5 months after her T-DM1 was stopped, she reported having back pain. A repeat echocardiogram indicated her LVEF was 48%. On MRI she was noted to have evidence of bone metastasis. LL was started on trastuzumab and docetaxel along with denosumab. She continues close follow-up by cardiology.