Real-World Evaluation of a Trastuzumab Emtansine Biosimilar (Ujvira®) in Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Metastatic Breast Cancer

BACKGROUND: Trastuzumab emtansine (T-DM1) is widely regarded as a standard treatment for human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC), but its cost puts it beyond the reach of many patients in low- and middle-income countries. Ujvira® (ZRC-3256; Zydus Lifesciences, India), a biosimilar version, could offer a more affordable alternative, although real-world experience with it is still limited. METHODS: This retrospective, single-center study evaluated the efficacy and safety of Ujvira® in patients with HER2-positive MBC treated at a tertiary cancer center in India. All patients had prior trastuzumab exposure and received Ujvira® 3.6 mg/kg intravenously every 21 days until progression or unacceptable toxicity. The primary endpoint was progression-free survival (PFS), estimated by the Kaplan-Meier method. Secondary endpoints included objective response rate (ORR), safety (graded per CTCAE v5.0), and exploratory subgroup analyses based on ECOG performance status, hormone receptor expression, comorbidities, and metastatic pattern. RESULTS: Fifty-one patients were included (mean age 58.0 ± 8.4 years; 47 (92.2%) postmenopausal). Median PFS was 6.9 months (95% CI 6.2-9.0) overall, 7.7 months in the second-line setting, and 9.1 months in the third-line setting. The ORR was 35.3%. Treatment was well tolerated; the most common adverse events were thrombocytopenia in 17 patients (33.3%) and anemia in 10 patients (19.6%). Dose reductions occurred in eight patients (15.7%), which did not affect efficacy (PFS 6.8 vs 6.9 months; p = 0.25). CONCLUSIONS: In this real-world Indian cohort, Ujvira® demonstrated efficacy and safety consistent with innovator T-DM1, with preserved outcomes even among heavily pretreated and comorbid patients. These results support Ujvira® as an effective, tolerable, and accessible therapeutic option for HER2-positive MBC in resource-limited settings.