Real-World Evaluation of Trastuzumab Emtansine Biosimilar in Early-Stage HER2-Positive Breast Cancer: Results from a Single-Centre retrospective Study in India Real-World outcomes of T-DM1 Biosimilar
Abstract
Background: Trastuzumab emtansine (T-DM1), an antibody–drug conjugate targeting HER2, is an established adjuvant therapy for residual invasive HER2-positive breast cancer after neoadjuvant treatment. Real-world evidence on trastuzumab emtansine biosimilars in early-stage disease is limited. This study evaluated invasive disease-free survival (IDFS) and safety outcomes with a trastuzumab emtansine biosimilar in routine practice.
Methods: This retrospective, single-centre observational study include 24 women with stage II/III HER2-positive breast cancer who received adjuvant trastuzumab emtansine biosimilar (3.6 mg/kg every 21 days) after neoadjuvant chemotherapy and surgery. The primary endpoint was IDFS; secondary endpoints were relapse patterns and treatment-emergent adverse events.
Results: Median age was 60.3 years; 83.3% were postmenopausal. At diagnosis, 20.8% had stage II and 79.2% had stage III disease. With a median follow-up of 14 months, five IDFS events occurred and no deaths were reported. Median IDFS was 14 months (95% CI: 13–15) and should be interpreted descriptively due to few events and short follow-up. Relapse occurred in 20.8%, most commonly in bone, brain, and liver. Common adverse events were thrombocytopenia (95.8%), neutropenia (79.2%), and anaemia (41.7%), predominantly grade 1–2. Left ventricular ejection fraction declined to <50% in 20.8%.
Conclusion: Adjuvant trastuzumab emtansine biosimilar use was feasible with a manageable safety profile in this single-centre real-world cohort. Efficacy findings are exploratory and require confirmation in larger prospective studies.
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