How cost effective trastuzumab is for human epidermal growth factor receptor 2 (HER2)-positive breast cancer depends largely on patients’ age and hormone receptor status, according to a review published in PLOS Medicine.
Early stage HER2-positive breast cancer tends to be more aggressive and resistant to standard chemotherapy, resulting in a poorer prognosis for many patients. Trastuzumab, a monoclonal antibody that binds the HER2 protein, was the first agent approved as a targeted therapy for HER2-positive disease. However, while the treatment has been highly effective in this patient group, it is also a high-cost pharmaceutical. Indeed, incremental cost-effectiveness ratios (ICERs) reported in a number of studies have found that treatment with trastuzumab typically costs more than $100,000 per quality-adjusted life year (QALY).
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Still, despite a greater emphasis being placed on cost management in recent years, there has been little research conducted on how the drug has been used in patients of differing age and hormone receptor status. Thus, researchers led by William Leung, University of Otago (Wellington, New Zealand), conducted a study estimating the cost effectiveness of a 12-month trastuzumab regimen compared with standard chemotherapy alone, by four estrogen receptor (ER) and progesterone receptor (PR) subtypes and then by age at treatment initiation.
A utility analysis using a Markov macrosimulation model with a lifetime horizon was then created comparing the two treatment regimens utilizing the latest effectiveness measures from landmark randomized trials. A New Zealand health system perspective was adopted and, in a hypothetical cohort, 37% of patients were ER+/PR+, 15% of patients were ER+/PR−, 3% of patients were ER−/PR+, and 45% of patients were ER−/PR−.
Results showed that adjuvant treatment with trastuzumab improved 20-year overall survival from 65% to 73%, and 10-year overall survival from 74% to 82.5% among all patients aged 50 to 54 years. Additionally, QALYs for trastuzumab versus standard chemotherapy were more than 2 times greater for patients with ER−/PR− disease compared with those who had ER+/PR+ subtype. These results were fairly consistent across most age groups in the study.
“Our findings suggest that incremental QALYs for trastuzumab versus chemotherapy alone are between 2.1 to 2.3 times higher for the worst prognosis (ER−/PR−) subtype compared to the best prognosis (ER+/PR+) subtype, causing ICERs for the former to be less than half those of the latter,” said the researchers.
These findings led the researchers to conclude that the cost-effectiveness of trastuzumab for patients with HER2-positive breast cancer can vary significantly based on the age and the hormone receptor subtype of the patient.
Future studies will be needed to expand on this data by exploring other heterogenetic factors such as number of involved nodes, tumor size/grade, and cardiovascular risk. The authors note that the results from several new studies will soon be reported; meta-analyses that include data from these trials will help to better inform treatment decisions regarding the optimal use and duration of trastuzumab therapy.—Sean McGuire
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