5 Conclusion
In our study, a UPLC-MS/MS method for analysis of imatinib was established. Under the optimized experimental conditions, this method showed good selectivity and reliability and has been used for routine imatinib monitoring for patients receiving adjuvant and neoadjuvant therapy for GIST. We found that gender may be the affecting factor of imatinib Cssmin. Whether the imatinib Cssmin threshold of 1100 ng/mL could be contributed to oncotherapy for patients with adjuvant and neoadjuvant therapy for GIST should be further studied.