Cost-utility analysis of lapatinib in treatment of HER2-positive advanced breast cancer

Abstract

6553 Background: The EGF100151 clinical trial demonstrated that the addition of lapatinib to capecitabine in the treatment of HER2-positive advanced breast cancer increases median time to progression (TTP) by 8.5 weeks (18.6 weeks versus 27.1 weeks, p = 0.00013). A cost-utility analysis (CUA) was conducted to estimate projected lifetime clinical and economic effectiveness of this therapy from the U.S. societal perspective. Methods: We constructed a Markov model comprising of four health-states: metastatic breast-cancer (MBC) treatment with disease-free progression, respond-to-therapy, disease progression, and death. The model used Monte Carlo simulation to imitate the clinical course of a typical patient with MBC and is updated with response rates and major adverse effects. Transition probabilities were estimated based on the results from phase II (EGF20002) and phase III (EGF100151) of lapatinib clinical trials. Each cycle of the model was 6 weeks. The overall survival of the combined treatment was assumed to be approximately 2 months longer because the TTP was roughly 2 months longer when compared with the monotherapy. Direct costs of the therapy, major adverse events, laboratory tests, and disease progression; and indirect costs of patient time/travel were obtained from published sources. Health-state utilities were obtained from CUA study of Elkin et al (JCO, 2004). The model used 3% discount rate and reported in 2007 U.S. dollars. Results: Over a lifetime, the addition of lapatinib to capecitabine in the combination therapy is estimated to cost an additional $21,484, with an expected gain of 0.127 quality-adjusted life year (QALY) or incremental cost-utility ratio (ICUR) is $172,031/QALY. The 95% confidence limits of the base case ICUR ranged from $154,680 to $183,624/QALY. Cost-effectiveness acceptability curve indicated less than 10% probability that the base-case ICUR would be lower than $150,000/QALY. In sensitivity analyses, results ranged from $109,440 to $242,652/QALY; and were most sensitive to the cost of lapatinib. Conclusions: Compared with commonly accepted willingness to pay thresholds in oncology treatment the addition of lapatinib to capecitabine is not clearly cost effective, and is most likely to result in ICURs somewhat higher than threshold limits. No significant financial relationships to disclose.