Cost-effectiveness of treatment sequences of chemotherapies and targeted biologics for elderly metastatic colorectal cancer patients

Abstract

BACKGROUND: Treatment patterns for metastatic colorectal cancer (mCRC) patients have changed considerably over the last decade with the introduction of new chemotherapies and targeted biologics. These treatments are often administered in various sequences with limited evidence regarding their cost-effectiveness. OBJECTIVE: To conduct a pharmacoeconomic evaluation of commonly administered treatment sequences among elderly mCRC patients. METHODS: A probabilistic discrete event simulation model assuming Weibull distribution was developed to evaluate the cost-effectiveness of the following common treatment sequences: (a) first-line oxaliplatin/ irinotecan followed by second-line oxaliplatin/irinotecan + bevacizumab (0I-0IB); (b) first-line oxaliplatin/irinotecan + bevacizumab followed by second-line oxaliplatin/irinotecan + bevacizumab (0IB-0IB); (c) 0I-0IB followed by a third-line targeted biologic (0I-0IB-TB); and (d) 0IB-0IB followed by a third-line targeted biologic (0IB-0IB-TB). Input parameters for the model were primarily obtained from the Surveillance, Epidemiology, and End Results-Medicare linked dataset for incident mCRC patients aged 65 years and older diagnosed from January 2004 through December 2009. A probabilistic sensitivity analysis was performed to account for parameter uncertainty. Costs (2014 U.S. dollars) and effectiveness were discounted at an annual rate of 3[%]. RESULTS: In the base case analyses, at the willingness-to-pay (WTP) threshold of $100,000/quality-adjusted life-year (QALY) gained, the treatment sequence 0IB-0IB (vs. 0I-0IB) was not cost-effective with an incremental cost-effectiveness ratio (ICER) per patient of $119,007/QALY; 0I-0IB-TB (vs. 0IB-0IB) was dominated; and 0IB-0IB-TB (vs. 0IB-0IB) was not cost-effective with an ICER of $405,857/QALY. Results similar to the base case analysis were obtained assuming log-normal distribution. Cost-effectiveness acceptability curves derived from a probabilistic sensitivity analysis showed that at a WTP of $100,000/QALY gained, sequence 0I-0IB was 34[%] cost-effective, followed by 0IB-0IB (31[%]), 0I-0IB-TB (20[%]), and 0IB-0IB-TB (15[%]).