Imatinib Therapeutic Drug Monitoring

ARUP now offers a therapeutic drug monitoring (TDM) test for chronic myelogenous leukemia (CML) and gastrointestinal stromal tumor (GIST) patients being treated with the tyrosine kinase inhibitor (TKI) imatinib. Imatinib is a first-line treatment for CML and GIST.

Why Is This Testing Important?

Imatinib, when dosed according to TDM, yields similar major molecular response (MMR) as second generation TKIs.1

TDM Can Improve Dose Optimization

Optimization Table

Figure 1. In a study of 1,910 CML samples, imatinib trough plasma concentration levels are shown according to total daily dose. At each dose, mean concentrations are stated and indicated by a horizontal line. The top and bottom of each box represent the 25th and 75th percentiles, and vertical lines indicate the standard deviation. The dotted line corresponds to the imatinib Cmin threshold (1002 ng/mL).2

Imatinib Testing

Imatinib Ordering Information

To standardize lab test ordering in your clinical practice, Imatinib testing can be ordered through your existing laboratory provider. Please reference ARUP test code 3000539.

Cost Savings

Imatinib TDM helps you meet goals of improving population health, patient treatment, and reducing the cost of treating of CML and GIST. With the introduction of generic imatinib for the treatment of CML the price is expected to drop.3

A payor perspective analysis over 5 years demonstrated the potential of IM TDM to save hundreds of thousands of dollars.

Clinical Trials Support the Use of TDM For Imatinib Treatment of CML

OPTIM Imatinib Study1 (133 CML Patients)

  • Two-thirds (2/3) of patients did not have optimal imatinib exposure and would benefit from individualized TDM 
  • Major molecular response (MMR) at 12 months was achieved in 63 percent of patients in arm 1 dosed by TDM, compared to 37 percent of patients in arm 2 (no TDM; p=0.031) 

TOPS Imatinib Trial4 (476 CML patients)

  • Imatinib trough levels >1165 ng/mL were associated with a faster time to MMR (p=0.0304)
  • Trough levels above 3180 ng/mL were associated with a higher frequency of all grade neutropenia, anemia, and leukopenia. but not thrombocytopenia

Selected References

Efficacy in CML
Efficacy in GIST
Health Economic Model - CML

General Overviews

CML and imatinib
Adherence to imatinib
Pharmacogenetics of imatinib in GIST