Pertuzumab–Docetaxel–Trastuzumab regimen in HER2-positive metastatic breast cancer: Real-world data from India

PURPOSE: Dual human epidermal growth factor receptor 2 (HER2) blockade with pertuzumab and trastuzumab plus chemotherapy is the standard first-line treatment for HER2-positive metastatic breast cancer (BC), as per the CLEOPATRA trial. However, real-world data from low- and middle-income countries (LMICs), including India, remains limited. This study evaluated the efficacy and safety of the pertuzumab-trastuzumab-docetaxel (PTH) regimen in Indian patients with HER2-positive metastatic breast cancer. METHODS: A retrospective analysis of 134 patients with HER2-positive metastatic BC treated with first-line PTH between August 2016 and December 2024 was conducted. Patients received six cycles of pertuzumab (loading dose: 840 mg; maintenance: 420 mg every three weeks), trastuzumab (loading dose: 8 mg/kg; maintenance: 6 mg/kg every three weeks), and docetaxel (75 mg/m² every three weeks), followed by maintenance trastuzumab and pertuzumab with or without endocrine therapy. The primary endpoint was overall survival and secondary endpoints included progression-free survival;, overall response rate, and treatment-related toxicities graded using Common Terminology Criteria for Adverse Events version 4.0. Kaplan-Meier curves and Cox proportional hazards models were used for survival and prognostic analyses. RESULTS: At a median follow-up of 42 months, the median overall survival was 49.3 months and the median progression free survival was 29.3 months. The overall response rate was 72.4%. Grade 3-4 adverse events were infrequent (anemia: 7.5%, neutropenia: 3.0%), with no treatment-related deaths. No baseline clinical or pathological factors were significantly associated with survival outcomes except hormonal profile. Hormone positivity (estrogen and or progesterone) were associated with poor survival CONCLUSION: First-line PTH demonstrated prolonged survival and high response rates in this Indian cohort, with manageable toxicity. These real-world findings support its feasibility and effectiveness in LMIC settings.