Complete metabolic response in HER2-positive metastatic breast cancer treated with subcutaneous Pertuzumab + Trastuzumab and Docetaxel: a case report

Christian Jonatan; Wulyo Rajabto

doi:10.22146/inajbcs.v57i3.Supplement.24236

Christian Jonatan Surabaya General Hospital, Surabaya, East Java, Indonesia
Wulyo Rajabto Dr. Cipto Mangunkusumo Hospital, Central Jakarta, Jakarta, Indonesia

DOI: https://doi.org/10.22146/inajbcs.v57i3.Supplement.24236

Keywords: metastatic breast cancer, HER2, pertuzumab, trastuzumab, docetaxel, subcutaneous, complete metabolic response

Abstract

Metastatic breast cancer (MBC) remains an incurable disease and a major cause of cancer-related death in women. The CLEOPATRA trial (2012) established that adding pertuzumab to trastuzumab and docetaxel significantly improved outcomes in HER2-positive MBC, leading to its recommendation as the standard
first-line regimen by NCCN and ESMO. We present a case of a 41-year-old woman with a six-month history of a right breast mass who initially declined biopsy. Ultrasonography revealed a 4.3 × 2.8 cm irregular hypoechoic lesion with axillary lymphadenopathy. Core biopsy confirmed invasive carcinoma of no special type, ER-/PR-, HER2-positive (IHC 3+). PET-CT demonstrated chest wall invasion and bone metastases, consistent with HER2-positive MBC, stage T4N3M1. The patient received six cycles of subcutaneous fixed-dose pertuzumab-trastuzumab and intravenous docetaxel every three weeks, along with zoledronic acid for bone
metastases. A follow-up PET-CT revealed a complete metabolic response (CMR). Maintenance of subcutaneous pertuzumab-trastuzumab was continued, and the patient remained clinically stable without disease progression. The pertuzumab-trastuzumab-taxane combination has demonstrated significant clinical benefit,
improving median progression-free survival by more than 6 months and overall survival by 16.3 months compared to trastuzumab and docetaxel alone. The fixeddose subcutaneous formulation, approved by the FDA in 2020, has shown noninferior efficacy and safety compared to intravenous administration in FeDeriCa
and PHranceSCa trials, with improved convenience and potential adherence benefits. This case highlights the effectiveness of subcutaneous pertuzumab-trastuzumab plus docetaxel in achieving CMR in HER2-positive MBC, reinforcing its role as guideline-recommended therapy and demonstrating the practical benefits of subcutaneous administration in real-world clinical practice.