Identifying Risk Factors Associated with Survival and Drug-Related Toxicities in Imatinib-Resistant Gastrointestinal Stromal Tumor (GIST) Patients Treated with Sunitinib

Objectives: Sunitinib is the preferred second-line treatment option to imatinib escalation in patients with imatinib-resistant advanced gastrointestinal stromal tumors. In this study, we aimed to determine the risk factors affecting survival and sunitinib-related toxicities in imatinib-resistance GIST patients. Methods: Clinical characteristics of 40 imatinib-resistant GIST patients who received second-line sunitinib were evaluated. Statistical analysis was performed to determine risk factors associated with survival and sunitinib-related toxicities. Results: The median age was 53 and the male to female ratio was 24/16. The most common of the primary tumor location was small bowel (25; 62.5%). There were 17 (42.5%) patients who developed resistance to imatinib within the first 24 months. Median overall survival (OS) and progression-free survival were 31.6 months and 19.6 months, respectively. Among many risk factors, best response to sunitinib (Hazard ratio [HR]: 2.34) and imatinib resistance (HR: 0.43 were independent prognostics for OS. The only risk factor for sunitinib-related grade 3 or 4 toxicity was advanced age (Odds ratio: 1.90). Conclusion: Long-term use of imatinib and best response to sunitinib are the most important clinical parameters to evaluate the efficacy of sunitinib. Sunitinib-related toxicity is frequently observed and has a high potential for toxicity in elderly patients. Abstract Drug-Relat-