Abstract Introduction: Imatinib definitively contribute to improve prognosis for high-risk or unresectable GISTs. Due to therapeutic efficacy is limited by imatinib chemoresistance and toxicity, the exploration of predictive markers of imatinib therapeutic efficacy that early enable patients to utilize more effective therapeutic strategies remains urgent. Here, we evaluate that the ability of FBXW7 acts as a predictor of imatinib therapeutic effect in preclinical models, and the potential of FBXW7-MCL1 axis promote imatinib-induced apoptosis response. Methods: The cellular and in vivo correlation between FBXW7 and imatinib chemoresistance via FBXW7-MCL1 axis were evaluated by detecting IC50 value, apoptosis assay, and GIST xenograft studies. The clinical significance of FBXW7 as a predictor of imatinib treatment efficacy was examined in 140 high-risk patients with GISTs by immunohistochemical staining and multivariate analyses. Results: FBXW7 affects imatinib chemoresistance through regulating cellular apoptosis in GIST-T1 cells. FBXW7 targets MCL1 to regulate cellular apoptosis. MCL1 involves in the regulation of imatinib chemoresistance through inhibiting apoptosis of GIST-T1 cells. FBXW7 regulates imatinib chemoresistance via down-regulating MCL1 for enhancing imatinib-induced apoptosis in vitro. FBXW7 regulates imatinib sensitivity of GIST cells via targeting MCL1 to predict therapeutic efficacy of imatinib treatment in vivo. Through 5-year RFS rates analysis and multivariate analysis, the ability of FBXW7 predicting therapeutic efficacy of high-risk GIST patients with adjuvant imatinib was proved. Conclusions: FBXW7 regulates imatinib chemoresistance through inhibiting MCL1 for enhancing imatinib-induced apoptosis in GIST and acted as a reliable predictor of imatinib treatment efficacy in high-risk GIST patients treated imatinib. Citation Format: Xiyu Wu, Masaaki Iwatsuki, Meiyue Lou, Takatsugu Ishimoto, Yoshifumi Baba, Yuji Miyamoto, Hideo Baba. FBXW7 regulates imatinib chemoresistance through targeting MCL1 for apoptotic regulation in gastrointestinal stromal tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 956.