A 59-Year-Old Woman With HER2+ De Novo Metastatic Breast Cancer

Case: A 59-Year-Old Woman WithHER2+ De Novo Metastatic Breast Cancer

Initial presentation

• A 59-year-old, postmenopausal woman presented to her PCP for an annual physical exam, she was referred to undergo screening mammography; she reported back and hip pain along with occasional headaches
• PMHx: diabetes, medically controlled
• OB/GYNHx: nulliparous
• FHx: no family history of cancer
• PE: obese, palpable left breast mass with axillary adenopathy

Clinical workup

• Labs: alkaline phosphatase 230 IU/L (normal range 20-140 IU/L); otherwise WNL
• Breast imaging revealed a 2.1 cm irregular appearing mass in the left breast with suspicious axillary adenopathy
• Ultrasound-guided core biopsy of the left breast mass and axillary node confirmed high-grade infiltrative ductal carcinoma; ER-, PR-,HER2,3+ by IHC
• Brain MRI was negative
• PET/CT and bone scan revealed multiple lesions in the spine and pelvis; and several pulmonary nodules; pulmonary nodule biopsy revealed invasive ductal carcinoma; ER-,HER2+
• ECOG PS 1

Treatment and Follow-Up

• She was started on paclitaxel + trastuzumab + pertuzumab and completed 6 months of chemotherapy at which point paclitaxel was discontinued due to worsening neuropathy; trastuzumab and pertuzumab were continued
• Follow-up imaging at 3 months showed no FDG activity in the bones or lungs; bone pain resolved
  • Denosumab was started to reduce skeletal related events
• Further follow-up imaging showed stable disease until 18 months when she developed worsening cough; imaging showed progressive bone disease and multiple new pulmonary nodules
  • Trastuzumab emtansine (T-DM1) was started
• Follow-up imaging showed response to treatment which lasted for ~ 9 months
  • She developed headaches, and increasing bone pain
• Brain MRI at that time showed 3 lesions, all < 2-cm; she was treated with SRS (stereotactic radio surgery)
  • Bone scan showed progressive bone metastases
• Initiated neratinib 240 mg (6 tablets) PO QD + capecitabine
  • She was started on prophylactic loperamide