Safety and efficacy of T-DM1 in patients with advanced HER2-positive breast cancer The Royal Marsden experience.

Abstract

BACKGROUND: Ado-trastuzumab emtansine (T-DM1) is standard of care for patients with advanced HER2+ breast cancer who relapse within 6 months of adjuvant trastuzumab or progress on first-line anti-HER2 therapy. We evaluated its safety and efficacy in our real-world population. METHODS: We identified patients on T-DM1 from 01/01/2014 to 12/03/2018 from our electronic records. Patients', tumour characteristics, safety and efficacy outcomes were recorded. Chi-squared/Fishers exact test and Kaplan-Meier methods were utilised. RESULTS: 128 patients receiving T-DM1 were included in the analysis with a median age of 55 years (26-85). 89.8% of patients had ECOG PS 0-1 and 21.1% had presented with de novo metastatic disease. 57.8% had ER-positive disease and 38.3% central nervous system involvement. 88.3% of patients had received trastuzumab for advanced disease (with pertuzumab in 28.9%) and 11.7% had only received trastuzumab in the adjuvant setting. Grade ≥3 adverse events occurred in 35.9% of patients. These were liver toxicity (19.5%), anaemia (6.2%) and thrombocytopenia (4.7%). Peripheral neuropathy of any grade was reported in 21.9% of cases, bleeding in 9.4% and ejection fraction decline in 5 patients. Median progression-free survival was 8.7 months and overall survival 20.4 months. Prior pertuzumab did not influence survival outcomes. CONCLUSIONS: The safety of T-DM1 in our population is similar to available literature, although we observed higher rates of peripheral neuropathy and deranged liver function. These findings are relevant for the potential role of TDM-1 in the curative setting.