Cost-Effectiveness of Lapatinib plus Letrozole in Post-Menopausal Women with Hormone Receptor- and HER2-Positive Metastatic Breast Cancer

Background: In the EGF30008 and TAnDEM (TrAstuzumab in Dual HER2 ER-positive Metastatic breast cancer) trials, anti-HER2 therapy plus an aromatase inhibitor (lapatinib + letrozole (LAP + LET) and trastuzumb + anastrozole (TZ + ANA), respectively) improved time to progression versus aromatase inhibitor monotherapy (LET and ANA, respectively) in post-menopausal women with previously untreated hormone receptor-positive (HR+) and HER2-positive (HER2+) metastatic breast cancer. Methods: A partitioned-survival analysis model using data from EGF30008 and published results of TAnDEM and other literature was used to evaluate the incremental direct medical cost per quality-adjusted life year (QALY) gained with LAP + LET versus LET, ANA, and TZ + ANA in post-menopausal women with previously untreated HR+ and HER2+ metastatic breast cancer from the UK National Health Service (NHS) perspective. Results: Incremental costs for LAP + LET are pound 34,737 versus LET, pound 35,995 versus ANA, and pound 5,513 versus TZ + ANA. Corresponding QALYs gained are 0.467, 0.601, and 0.252 years. Cost/QALY gained with LAP + LET is pound 74,448 versus LET, pound 59,895 versus ANA, and pound 21,836 versus TZ + ANA. Given a threshold of pound 30,000/QALY, the estimated probability that LAP + LET is cost-effective is 1.4% versus LET, 9.2% versus ANA, and 51% versus TZ + ANA. Conclusions: Based on criteria for the evaluation of health technologies in the UK ( pound 30,000/QALY), LAP + LET is not likely to be cost-effective versus aromatase inhibitor monotherapy but may be cost-effective versus TZ + ANA, although the latter comparison is associated with substantial uncertainty.