The Application of Therapeutic Drug Monitoring of Imatinib in the
Patients with Gastrointestinal Stromal Tumors (GISTs): A Retrospective
Cross-Sectional Study
Abstract
Aims: The optimal dose of imatinib on survival in the adjuvant treatment
of patients with resected GISTs remains unsettled. Therefore, this study
aimed to assess the impact of the adjustment of dose based on imatinib
plasma trough concentrations (Cmin) on the prognosis of GIST based in
the adjuvant setting. Methods: We conducted a retrospective
cross-sectional study of GIST patients treated with imatinib.
Simultaneously, the blood samples at steady-state of the aforementioned
patients were obtained for the determination of imatinib Cmin. Inverse
probability of treatment weighting (IPTW) was used for reducing
selection bias in baseline characteristics. Kaplan–Meier analyses and
multivariate Cox proportional hazards were used to evaluate the
association of the different dosages of imatinib with recurrence-free
survival (RFS). Results: A total of 79 patients were identified in this
study. Of these patients treated with imatinib 200 mg/d (n=8), 300 mg/d
(n=33), 400 mg/d (n=37), and 600 mg/d (n=1)the mean±standard deviation
(SD) imatinib Cmin was 704±299ng/mL, 1153±473.3ng/mL, and
1246±491.3ng/mL, respectively. Additionally, imatinib Cmin of 200-mg/day
group was significantly lower than groups of 300- (P=0.036) and
400-mg/day (P=0.016), no significant difference in the Cmin of 300- and
400 -mg/day group (P=0.427) (Fig 3). Before and after adjustment by
propensity score-based IPTW, no significant difference in
recurrence-free survival between the Conclusions: Our findings provide a
new insight that imatinib Cmin may be used as a potential biomarker, to
assist in the evaluation of the safety, and efficacy of individualized
dosage adjustments in the adjuvant setting.