Indirect comparison of the cost-effectiveness of letrozole plus lapatinib (LET+LAP) versus anastrozole plus trastuzumab (ANA+TZ) as first-line treatment for postmenopausal women with HER2+ and HR+ metastatic breast cancer (MBC) from the U.K. National Health Service (NHS) perspective.

Abstract

1035 Background: The EGF30008 trial assessed the efficacy of the combination of the anti-HER2 tyrosine kinase inhibitor LAP and the aromatase inhibitor (LET) compared with LET plus placebo in postmenopausal women with HER2+ and HR+ MBC. The TAnDEM study evaluated the benefits of adding TZ to the AI ANA in postmenopausal women with advanced HER2+ and HR+ MBC. Both studies demonstrated statistically significant improvements in progression-free survival (PFS) with the addition of anti-HER2 therapy. Methods: An economic model was used to evaluate the incremental cost per quality-adjusted life year (QALY) gained with LET+LAP versus ANA+TZ as first-line treatment in postmenopausal women with HR+ and HER2+ MBC from the U.K. NHS perspective. Expected PFS and overall survival (OS) with LET+LAP and ANA+TZ were based on adjusted indirect comparison using data from the TAnDEM and EGF30008 trials as well as the P025 trial of LET versus tamoxifen (TAM) and the TARGET and North American trials of ANA versus TAM. Costs and utility values were obtained from the literature. Results: Shown in the Table (all results are discounted). LET+LAP yields more progression-free life years (PFLYs), life years (LYs), and QALYs than ANA+TZ. Medication costs are greater with LET+LAP, partly due to longer PFS. These higher costs are offset by savings in costs of drug administration. LAP+LET is therefore dominant (less costly and more QALYs) versus ANA+TZ. Conclusions: Letrozole plus lapatinib has greater effectiveness and lower cost from the U.K. NHS perspective when indirectly compared with anastrozole plus trastuzumab. Measure LET+LAP ANA+TZ Difference Effectiveness PFLY 1.181 1.042 0.139 LY 3.399 3.021 0.378 QALYs 2.434 2.162 0.272 Costs (in £) Medication 29,568 21,031 8,537 Drug administration 520 13,753 -13,232 Other preprogression 8,285 7,307 978 Other postprogression 20,105 17,943 2,162 Total 58,479 60,033 -1,554 Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration GlaxoSmithKline GlaxoSmithKline GlaxoSmithKline GlaxoSmithKline GlaxoSmithKline, Royal Marsden NHS Foundation Trust & Institute of Cancer Research Research Fund