First-line treatment of metastatic HER2-positive breast cancer with dual anti-HER2 therapy and docetaxel: a case report

Abstract

We report a 50-year-old woman with prior left mastectomy for HER2-positive breast cancer who declined adjuvant therapy and presented in October 2023 with chest wall nodules, left arm lymphedema, and multifocal metastatic disease on FDG-PET/CT involving regional lymph nodes, chest wall, skeleton, and liver (cT4cN3cM1). Biopsy confirmed invasive ductal carcinoma, ER-negative/PR-negative, HER2 IHC 3+, with Ki-67 30%. She received first-line pertuzumab, trastuzumab, and docetaxel for six cycles, followed by maintenance pertuzumab and trastuzumab; treatment was well tolerated. Interim PET-CT after six cycles showed near-complete metabolic resolution of chest wall, nodal, and hepatic lesions, with only residual blastic bone metastases of low FDG uptake, consistent with a partial response. Serial imaging over more than 18 months demonstrated sustained disease control without new lesions while on continued dual HER2 blockade. This case illustrates the effectiveness and tolerability of guideline-recommended first-line dual HER2 blockade plus a taxane in metastatic HER2- positive breast cancer and highlights access issues under national insurance where pertuzumab is not routinely reimbursed, necessitating private funding in this patient.