Long-time Response with Ado-trastuzumab Emtansine in a Recurrent Metastatic Breast Cancer

Breast cancer is the most common cancer in a woman with a five-year survival of patients with metastatic disease is estimated at 23%. Ado-trastuzumab emtansine (T-DM1) is a HER2-antibody drug conjugate currently approved for the treatment of HER2-positive pre-treated metastatic breast cancer (BC). We report a case of recurrent metastatic breast cancer with unusually lengthy progression-free survival (PFS) on T-DM1 chemotherapy. She was diagnosed with Triple Positive Stage IIIC multifocal invasive ductal carcinoma of the left breast. After completing neoadjuvant chemotherapy, she underwent a bilateral mastectomy. Final pathology showed partial response. Postoperatively, she received adjuvant chemotherapy and radiation therapy. She was started on Q21 days trastuzumab following completion of adjuvant chemotherapy. Systemic imaging showed liver lesions and biopsy confirmed recurrence. She was started on T-DM1, endocrine therapy with anastrozole was continued. She is currently status post 45 cycles. T-DM1 was approved for the treatment (single-agent) of HER2-positive, metastatic BC based on phase III data from the EMILIA and TH3RESA study. Median PFS in the T-DM1 arm was 9.6 months. Herein, we present a case of a woman with recurrent triple positive metastatic BC with a lengthy progression-free survival on T-DM1 chemotherapy.