Verification of imatinib cost-effectiveness in advanced gastrointestinal stromal tumor in British Columbia (VINCE-BC study)

Background. This cost-effectiveness analysis of imatinib in British Columbia Cancer Agency (BCCA) patients with advanced gastrointestinal stromal tumors (GIST) was performed to justify funding. Patients and Methods. A pragmatic, retrospective review identified BCCA patients with advanced GIST who received imatinib or historical treatment during successive, pre-specified time periods. Primary outcome was the cost-effectiveness (CE) of imatinib based on median overall survival (MOS). Secondary outcomes were cost-effectiveness based on median progression-free survival (PFS) and comparison to literature efficacy. This study took the BCCA perspective. Sensitivity analyses varying effectiveness over the 95% confidence interval (CI), cost to its extremes, discounting level at 0, 3, and 5%, and substituting life expectancy for MOS were performed. Results. Forty-six and 47 patients in the imatinib and historical groups respectively showed MOS with imatinib to be 66.7 months (95%CI 61.7— infinity) compared to 7.7 (95%CI 6.0—12.6) in the historical group. Median-PFS were 45.3 months (95%CI 24.4—infinity) and 5.6 (95%CI 3.5—8.5) respectively. Imatinib effectiveness was similar to literature reports. The annual incremental CE ratio for imatinib was $15,882 CDN per median life year gained and $23,603 CDN per median year of PFS. Conclusions. Imatinib for advanced GIST seems cost-effective in BC. Results were robust across a range of sensitivity analyses. J Oncol Pharm Practice (2008) 14: 105—112.