OBJECTIVES: Treatment patterns for metastatic Colorectal Cancer (mCRC) patients have changed considerably with chemotherapies and targeted biologics often administered in various sequences but with limited cost-effectiveness evidence. The objective of the study was 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 common treatment sequences: 1) first-line oxaliplatin/irinotecan followed by second-line oxaliplatin/irinotecan + bevacizumab (OI-OIB), 2) first-line oxaliplatin/irinotecan + bevacizumab followed by second-line oxaliplatin/irinotecan + bevacizumab (OIB-OIB), 3) OI-OIB followed by a third-line targeted biologic (OI-OIB-TB), and 4) OIB-OIB followed by a third-line targeted biologic (OIB-OIB-TB). Input parameters were obtained from the Surveillance, Epidemiology and End Results – Medicare linked dataset for mCRC diagnosed from January 2004 through December 2009. Parameter uncertainty was accounted in a probabilistic sensitivity analysis. Costs (2014 U.S. dollars) and effectiveness were discounted annually at 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 OIB-OIB (versus OI-OIB) was not cost-effective with an incremental cost-effectiveness ratio (ICER) per patient of $119,007/QALY, OI-OIB-TB (versus OIB-OIB) was dominated and OIB-OIB-TB (versus OIB-OIB) was not cost-effective with an ICER of $405,857/QALY. Similar results were obtained assuming Log-normal distribution. Cost-effectiveness acceptability curves derived from probabilistic sensitivity analysis showed that at a WTP of $100,000/QALY gained; sequence OI-OIB was 34% cost-effective, followed by OIB-OIB (31%), OI-OIB-TB (20%), and OIB-OIB-TB (15%).
CONCLUSIONS: Treatment sequences with bevacizumab at first-line and targeted biologics at third-line may not be cost-effective at the commonly used threshold of $100,000/QALY gained but a marginal decrease in the cost of bevacizumab may make treatment sequences with first-line bevacizumab cost-effective. Future economic evaluations should validate the study results using parameters from ongoing clinical trials.
