Year-to-year impact budget analysis of biologic therapies for first-line metastatic colorectal cancer (mCRC) therapy in Spain.

Abstract

e14144 Background: Pharmacoeconomic studies deal with populations of patients as if they were admitted at the division of medical oncology in the same date. Real patients are treated along the entire year so that budget simulations should be adjusted to chronological patterns of oncological assistance. Deferred budget impact analysis is undergone in order to assess long-run economic implications of clinical decisions on first-line mCRC therapies in Spain. Methods: As metastatic colorectal cancer diagnosis is not affected by seasonal influences, we have created a mathematical model assuming that a single patient is diagnosed every month and this patient has a 53% possibility to harbor a native K-Ras sequence. Calculi were arranged based on median duration of therapy. For bevacizumab-based therapy, budget impact for year t+1 begins at month 5 and beyond. For patients that receive cetuximab-based therapy, budget impact for year t+1 begins at month 7. The same approach was performed for doublets without any monoclonal antibody. Prices for all drugs in Spain were assumed to represent the best-value for each drug including all possibilities to reduce pharmacy costs. For first line, median duration of therapy reported by randomized trials was used to calculate the final budget. 70kg and 1.7 m were used as reference for patient dose calculations. Results: When K-Ras status is not tested and bevacizumab-based schedules are administered to every patient, annual growth of budget increases by 55- 60%. If K-Ras status is analyzed and wild-type patients are treated with cetuximab combinations and mutated patients receive bevacizumab, yearly budget growth amounts to 39-41%. Annual budget growth is minimized (25%) when K-Ras wt patients are treated with cetuximab combinations whereas K-Ras mutated tumours received chemotherapy alone. Conclusions: Duration of therapy plays a key role on budget impact estimations from both overall and year to year perspectives. K-Ras based clinical decisions not only optimize outcomes as measured by response rates but also minimize economic implications on annual budget growths.