Abstract: OBJECTIVE：TTo evaluate the blood concentrations and safety among gastrointestinal stromal tumor patients treated with the generic or branded domestic imatinib，and to provide recommendations for their use. METHODS：From December 2020 to December 2023，information on gastrointestinal stromal tumor patients who were treated with imatinib mesylate in the Fourth Hospital of Hebei Medical University were collected. The patients were divided into the original research drug imatinib mesylate tablets group，generic imatinib mesylate tablets group，and generic drug imatinib mesylate capsule group. Steady-state trough concentrations of imatinib and its active metabolite，N-desmethyl matinib，were measured by ultra-performance liquid chromatography with the Triple Quad 4500 Mass Spectrometry System. All the adverse reactions were collected and determined according to Common Adverse Event Evaluation Standard 5.0 (CTCAE 5.0). Differences in the plasma concentrations and adverse effects among the three groups were analyzed. RESULTS：There were no significance differences in trough concentrations of imatinib，N-desmethyl imatinib，the sum of imatinib and N-desmethyl imatinib，and side reaction grades among the generic and the two branded groups (all P>0.05). CONCLUSION：The branded and generic drugs of Imatinib mesylate had the same safety profile among treated patients.

Key words: imatinib, branded drug, generic drug, drug blood concentration, side reaction, cohort study