Pharmacoeconomic analysis for K-Ras status–based decisions for first-line therapy of metastatic colorectal cancer (mCRC) in Spain.

Abstract

438 Background: Personalized medicine is a challenge for current oncology practice. Nowadays there are no pharmacoeconomic analyses in Spain dealing with the clinical and financial impact secondary to K-Ras based decisions for first-line therapy in mCRC patients. So, this study was aimed to assess the cost- effectiveness of K-Ras status based decisions in first- line therapy of mCRC patients in comparison with non- K-Ras based selection of available therapies. Methods: K-Ras mutation prevalence and efficacy of available therapies (measured as response rate and progression free survival) were extracted from randomized clinical trials (RCT) that allowed on-label use of accessible drugs in Spain. Then, we have simulated all possibilities of combination therapies for first-line mCRC based on K-Ras status (wild- type vs mutated) and confronted with all therapies that could be chosen in absence of K-Ras analysis. Prices for all drugs in Spain were used to assume the best- value for each drug including all possibilities to reduce pharmacy costs. For first line, median duration of therapy reported by RCT was used to calculate the final budget. 70 kg and 1.7 m were used as reference for patients dose calculations. Results: First-line therapy that includes a biological drug in absence of K-Ras status based decisions implies an incremental cost per 1% of increased response rate of 1,237 euros for irinotecan based doublets and 3,193 euros for oxaliplatin based doublets. On the opposite, K-Ras based decisions reduce costs per objective response by 69% and 35% for irinotecan and oxaliplatin- based schedules in K-Ras wild-type population incorporating cetuximab as biological agent. These data mimic all calculi based on incremental costs secondary to improved progression free survival measured as HR when all scenarios without prior determination of K-Ras status were confronted with K-Ras based decisions. Conclusions: K-Ras based decisions reduces costs per objective response as well as per improved progression free survival. The most cost- effective scenario among all simulated was cetuximab in combination with chemotherapy for patients that harbor wt K-Ras mCRC.