271P Target therapy treatment patterns on advanced gastrointestinal stromal tumor (GIST) patients: a nation-wide cohort study in Taiwan

Abstract

Background Imatinib and sunitinib are two reimbursed targeted therapies for advanced GIST in Taiwan. A national-wide study was performed to evaluate the targeted therapies in GIST treatment among Taiwanese population. Methods We conducted a nationwide retrospective cohort study based on data from the National Health Insurance Research Database (NHIRD) between January 2005 and December 2010. All 1186 patients enrolled had histology-confirmed GIST with first-line imatinib (400mg qd) and follow-up more than one year. We estimated recurrence-free survival (RFS), progression-free survival (PFS), and overall survival (OS) probabilities with the Kaplan-Meier method. The proportional hazards assumption was verified by tests of correlations with time and examination of residual plots, and only variables that were deemed statistically significant were included in the final Cox model. Results With a median follow-up for surviving patients of 42 months, the median PFS of the cohort was 31 months since first-line imatinib. Cox proportional hazards multivariate analysis demonstrated directly switching to sunitnib was significant (hazard ratio: 0.77; 95% CI: 0.55-1.08; p < 0.001) prognostic factor for post-imatinib OS (59 months vs. 47 months). The whole cohort was divided into three groups. Group A (n = 585) had complete surgical resection and began imatinib treatment once recurrence confirmed. Group B(n = 419) received imatinib therapy within 3 months after operation. Group C (n = 182) was patients who were considered as unsuitable for operation.ThemedianRFSofGroupAwas16months(95%CI15-18) andthemedian OS after complete resection was 84 months. The cohort also demonstrated that PFS and OS of switching to sunitinib were longer than that with imatinib dose escalation after switching. Conclusions Taiwanese advanced GIST patients who failed first-line treatment still gained benefit from either imatinib dose escalation or a switch to sunitinib. Significant improvement in PFS using sunitnib directly as switch maintenance in advanced GIST. Clinical trial indentification In 1995, Taiwan launched a single-payer National Health Insuranceprogram,andasof2007,22.60millionofTaiwan's22.96millionpopulation were enrolled in this program. Each year, the Bureau of National Health Insurance, Taiwan, collects data, including registration files and original claim data for reimbursement, from the National Health Insurance, and sorts it into data files. These data files are de-identified by scrambling the identification codes of patients, medical institutions and physicians and sent to the National Health Research Institutes, Taiwan, to form the original files of the NHIRD. Therefore, these files contain all the records of individuals enrolled in the National Health Insurance program, and theyare available for research purposes only. Legal entity responsible for the study Taipei Medical University Funding Pfizer Limited, Taiwan Division Disclosure All authors have declared no conflicts of interest.