Scientific Poster Session III - Original Research

Original Research
  Monday, October 14, 2024
  01:00 PM–02:30 PM

Abstract

Introduction:

Therapeutic drug monitoring (TDM) is a powerful tool to individualise imatinib dosing. Few studies have investigated the relationship between medication adherence and plasma imatinib levels in postoperative Gastrointestinal stromal tumors (GIST) patients.

Research Question or Hypothesis:

It is whether the level of imatinb plasma can be as a key predictor for medication adherence in patients with GIST.

Study Design:

The study was conducted in the First Affiliated Hospital of Ningbo University, Zhejiang, China. Patients that visited the GIST specialty clinic between January 2021 and December 2023 were included, and prescribed imatinib for more than one month.

Methods:

Adherence was assessed by medication possession ratio and brief adherence rating scale. The steady-state plasma concentration of imatinib (C_min) was determined and compared between adherent and non-adherent groups.

Results:

A total of 110 patients were enrolled, of which 33 were considered non-adherent. The restricted mean survival time (RMST) at 5 year was measured for progression-free survival (PFS). Non-adherent patients had RMST of 32.47 months, while adherent patients had RMST of 54.59 months (P < 0.05). C_min was lower in non-adherent patients compared with adherent patients (750.35 vs. 1396.65 ng/mL, P < 0.05). Using TDM as an objective measurement to assess adherence, C_min of 919 ng/mL could be the cutoff value to predict the risk of non-adherence. Patients with C_min = 919 ng/mL had median PFS of 68.79 months compared to 31.03 months for patients with C_min < 919 ng/mL (P < 0.05).

Conclusion:

Poor adherence to imatinib was a notable problem in the postoperative adjuvant treatment and appeared to be associated with shorter PFS. Monitoring imatinb plasma levels gives physicians an objective measurement to assess individual adherence and can support treatment decisions.

Presenting Author

Hong-Bin Xu PhD in Pharmacology
the First Affiliated Hospital of Ningbo University

Authors

Tao Xu Master's degree in Pharmacology
the First Affiliated Hospital of Ningbo University

Suyan Zhu Master's degree in Applied Chemistry
the First Affiliated Hospital of Ningbo University