[Relationship between ripretinib concentration and the prognosis of advanced gastrointestinal stromal tumors in China: a multicenter study].

<b>Objective:</b> To investigate the prognosis and safety of ripretinib in the treatment of patients with advanced gastrointestinal mesenchymal stromal tumors (GISTs) and to analyze the relationship between blood concentrations of this drug and prognosis. <b>Methods:</b> In this retrospective study, we investigated the effects of ripretinib in patients with advanced GISTs. The inclusion criteria comprised: (1) daily oral administration of ripretinib scheduled; and (2) uninterrupted treatment for at least 1month, with a stable and relatively fixed daily dosage maintained for a minimum of 2 weeks. Exclusion criteria comprised concurrent use of other tyrosine kinase inhibitors and presence of significant organ dysfunction. We retrospectively identified 79 patients with advanced GISTs who had received ripretinib across seven medical centers, namely Jiangsu Provincial Hospital, Jiangsu Cancer Hospital, Nanjing Drum Tower Hospital Affiliated to Nanjing University, Sir Run Run Shaw Hospital of Zhejiang University, Renji Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, and the General Hospital of the People's Liberation Army, from 1 June 2021 to 31 March 2024. The cohort included 48 men and 31 women, 19 of whom had received ripretinib as second-line, 13 as third-line, and 47 as fourth-line therapy. Two peripheral venous blood samples were obtained from each participant and high-performance liquid chromatography-tandem mass spectrometry used to determine peak (Cmax) and trough (Cmin) concentrations of ripretinib. Machine learning methodologies, specifically the K-nearest neighbor algorithm combined with the Gridsearch CV strategy, were employed to establish the threshold for Cmin. We analyzed adverse reactions, treatment efficacy, median progression-free survival (mPFS), and the relationship between drug blood concentration and selected clinical parameters. <b>Results:</b> In the entire cohort, the Cmin and Cmax of ripretinib were 467 ± 360 μg/L and 986 ± 493 μg/L, respectively. Notably, female patients and individuals in the high-dose group exhibited significantly higher values for both Cmin and Cmax (both <i>P</i><0.05). However, variations in drug concentrations associated with the line of ripretinib therapy, treatment efficacy, disease progression, and presence of selected specific genetic mutations were not significantly associated with values of Cmin and Cmax (<i>P</i>>0.05). Among the 79 patients with advanced GISTs receiving ripretinib, reported adverse reactions included alopecia (53, 67.09%), hand-foot syndrome (24, 30.38%), fatigue (22, 27.85%), and myalgia (21, 26.58%). Two patients (2.53%) had grade III complications, both classified as hand-foot syndrome. The correlation between Cmax and adverse reactions was not statistically significant (<i>P</i> > 0.05). By the time of the latest follow-up, five deaths (6.3%) had occurred within the cohort. The mPFS for the group was 16.3 months, with a mPFS of 14.4 months for those receiving standard dosage and 7.0 months for those receiving escalating dosage. Among the 65 patients treated with standard doses of ripretinib, those with Cmin exceeding a threshold of 450 μg/L exhibited a significantly longer mPFS (18.0 months vs.13.7 months; <i>P</i> < 0.05). <b>Conclusion:</b> In China, patients with advanced GISTs exhibit a notable tolerance to ripretinib, with no evidence for a correlation between adverse reactions and Cmax for the drug. Additionally, a Cmin exceeding 450 μg/L may be associated with an extended mPFS.