Real-world data from the Royal Marsden Hospital show that the side effect profile of ado-trastuzumab emtansine (T-DM1) in the treatment of advanced human epidermal growth factor receptor 2 (HER2)-positive breast cancer is similar to that shown in clinical trials. However, there are a number of differences.
A study published in Cancer Treatment and Research Communications identified 128 patients with advanced HER2-positive breast cancer (median age, 55 years) on T-DM1 from 1 January 2014 to 12 March 2018.
Among participants, 89.8 per cent had Eastern Cooperative Oncology Group performance status 0-1 and 21.1 per cent had presented with de novo metastatic disease. More than half (57.8%) had estrogen receptor-positive disease, and 38.3 per cent had central nervous system involvement.
A total of 88.3 per cent of patients had received trastuzumab for advanced disease (with pertuzumab in 28.9%), and 11.7 per cent had only received trastuzumab in the adjuvant setting.
Grade ≥3 adverse events occurred in 35.9 per cent of patients - liver toxicity (19.5%), anaemia (6.2%) and thrombocytopenia (4.7%). Peripheral neuropathy of any grade was reported in 21.9 per cent of cases, bleeding in 9.4 per cent and ejection fraction decline in five patients.
Median progression-free survival was 8.7 months, and overall survival was 20.4 months. Prior pertuzumab did not influence survival outcomes.
The safety of T-DM1 in the Royal Marsden population is similar to that reported in clinical trials; however, this study found higher rates of peripheral neuropathy and deranged liver function.