T-DM1 for advanced breast cancer after multi-anti-HER2-target therapy: a case report

Abstract

We report a case of human epidermal growth factor receptor 2 positive (HER2+) breast cancer progressing to multiple metastases during several lines of anti-Her2 targeted therapy and chemotherapy, showing responses to TDM-1 and receiving clinical complete remission. The patient was diagnosed with HER2+ stage IIA invasive carcinoma of the left breast. The tumor progressed with skin invasion after neoadjuvant chemotherapy and continued progressing with sternum metastasis after trastuzumab-contained salvage treatment and dual-targeted therapy combined with chemotherapy. Afterward, the next-generation sequencing (NGS) test detected a PIK3CA mutation and the amplification of ERBB2. A third-line salvage therapy using everolimus and trastuzumab combined with chemotherapy consequently resulted in stable disease. After the therapy of TDM-1, the tumor received a durable complete clinical remission (cCR) that was maintained for 30 months. The regimen was initially TDM1 once 3 weeks for 19 months, then modified to once 4 weeks after the cCR statement lasted for 1year, and discontinued after another 10 months. During the medication, the patient regularly underwent the PET-CT every 3 to 4 months and was still disease-free until this report. This case delivers a view that keeping anti-HER2 therapy and adjusting regimens precisely according to gene sequencing can bring advanced HER2+ breast cancer to cCR.