Cost-effectiveness (CE) of lapatinib plus capecitabine (L+C) in women with HER2+ metastatic breast cancer (MBC) who received prior therapy with trastuzumab (TZ) based on updated survival data from EGF100151

Abstract

6559 Background: Lapatinib, an oral small molecule dual tyrosine kinase inhibitor binds intracellularly to the ATP site of the EGFR and HER2 receptors. In EGF100151, L+C improved time to progression (TTP) and progression free survival (PFS) vs capecitabine alone (C- only) in women with HER2+ MBC who received prior therapy with TZ. Methods: We evaluated the CE (ΔCosts/ΔQuality Adjusted Life Years [QALYs]) of L+C vs C-only in women with HER2+ MBC who have received prior therapy with TZ from the UK NHS (National Health Service) perspective using an assumed acquisition cost and updated survival data (March 2007 EGF100151 data-cutoff). Because many patients in clinical practice receive monotherapy with vinorelbine (V-only) or TZ-only or combination therapy with TZ and C (TZ+C) or TZ and V (TZ+V), we also assessed the CE of L+C vs these treatment strategies. PFS and overall survival (OS) with L+C and C-only were based on Weibull survival functions estimated from data in EGF100151. Post-progression survival (PPS) for L+C and C-only were calculated as OS minus PFS. Since data from comparative trials in this population are lacking, PFS with TZ+C, TZ+V and TZ-only were estimated from published cohort studies of continued TZ±chemotherapy (TZ±CT) following progression; PPS was assumed to equal that of L+C. PFS and OS with V-only were assumed equal to that of C-only. Drug costs were from the British National Formulary; other costs were from NHS reference costs and published studies. Utility values for PFS were from EQ-5D data in EGF100151; for PPS, from a UK community-based preference study in MBC. Costs and QALYs were discounted at 3.5% annually. Results: L+C is dominant (provides more QALYs at a lower cost) vs TZ+V, TZ+C, and TZ-only. Conclusions: Using updated survival data from EGF100151 and indirect comparisons in the absence of head-to-head data, suggests that L+C is a cost effective therapy vs TZ±CT from the UK NHS perspective. L+C C-only V- only TZ+V TZ+C TZ-only Total costs (£) 26,489 12,745 15,034 30,997 28,906 27,619 Total QALYs 0.901 0.738 0.738 0.762 0.762 0.762 CE L+C vs (£/QALY) 83,999 70,011 dominant dominant dominant Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration GlaxoSmithKline GlaxoSmithKline GlaxoSmithKline