Simple and Rapid Quantification of the Multi-Enzyme Targeting Antifolate Pemetrexed in Human Plasma

Our plain-English summary of Simple and Rapid Quantification of the Multi-Enzyme Targeting Antifolate Pemetrexed in Human Plasma, by E. van den Hombergh, N. de Rouw, M. van den Heuvel, et al (Therapeutic Drug Monitoring, 2020).

The study

• Authors: E. van den Hombergh, N. de Rouw, M. van den Heuvel, S. Croes, D.M. Burger, J. Derijks, N.P. van Erp, R. Ter Heine
• Journal: Therapeutic Drug Monitoring
• Published: 2020;42(1):146-150
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Pemetrexed is an antifolate cytostatic drug that targets multiple enzymes involved in folate biosynthesis and is indicated for treatment of non-small-cell lung cancer and malignant pleural mesothelioma. As evidence for an exposure-response/toxicity relationship is accumulating, dose individualization using therapeutic drug monitoring may be a feasible strategy to optimize treatment. The purpose of this study was to develop a simple, sensitive, high-performance liquid chromatography method with UV detection for quantification of pemetrexed levels in human plasma.

Method: The method involves a simple protein precipitation, followed by ultra-performance liquid chromatography with ultraviolet detection at a wavelength of 254 nm. Pemetrexed was separated using a mobile phase with a linear gradient and a run time of only 7 minutes.

Results: The assay has been validated over the concentration range 0.25-500 mg/L of pemetrexed. Accuracy for this assay ranged from -4.50% to 1.78%, and the within- and between-run coefficients of variation were <3.57%. Pemetrexed in plasma was proven to be stable for 8 months at -40°C.

Conclusions: The bioanalytical method we developed proved to be simple, accurate, precise, and fast. This analytical method is successfully in use for therapeutic drug monitoring and will be used for pharmacokinetic studies.

In plain English

This short communication described a laboratory test for measuring the cancer drug pemetrexed in human blood plasma. Pemetrexed is used to treat non-small cell lung cancer and malignant pleural mesothelioma. The study did not examine asbestos exposure. The authors' method removes proteins from plasma, then separates and measures the drug by liquid chromatography with ultraviolet detection, taking 7 minutes per run. The test measured pemetrexed reliably between 0.25 and 500 mg/L. Average accuracy ranged from -4.50% to 1.78%. Within-run variation ranged from 1.41% to 3.57%, and between-run variation was at most 2.44%. Blank plasma from six people and 108 drugs frequently used by the target patients caused no interfering peaks. Under all storage conditions tested, samples kept at least 96.1% of their starting concentration, including after 8 months at -40 °C. The test was used for one patient with impaired kidney function. The authors concluded that the method was simple, robust, accurate and rapid, and that it is in routine use at their hospital.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory development and validation of an analytical method (short communication)
• Who was studied: No patient group was studied. Testing used drug-free human plasma, including blank plasma from six individuals who did not use pemetrexed, plus one patient's samples as a clinical example. The work was done at Dutch hospitals.
• Exposure: No asbestos or other environmental exposure was studied. The substance measured was the drug pemetrexed in plasma, over 0.25 to 500 mg/L.
• Main results:
  • The test was linear, meaning it measured reliably, over pemetrexed concentrations from 0.25 to 500 mg/L.
  • Average accuracy ranged from -4.50% to 1.78%. Within-run coefficient of variation ranged from 1.41% to 3.57%.
  • Between-run coefficient of variation was at most 2.44%. This value was reached at the QC High level in Table 1. The text itself describes it as below 2.44%.
  • The lowest concentration the test could reliably measure was 0.25 mg/L.
  • Blank plasma from six individuals and 108 drugs frequently used in the target patient population (tested at 50 mg/L) showed no interference.
  • Under all conditions tested, pemetrexed stayed at no less than 96.1% of its initial concentration. Plasma samples were stable for 8 months at -40 °C.
  • Average extraction recovery across the three quality-control levels was 55%.
  • The test was used to measure pemetrexed levels over time in one patient with impaired renal function who received 755 mg.
• The authors' conclusion: The authors concluded that they had developed a simple, robust, accurate and rapid method for measuring pemetrexed in plasma. They reported it is in routine use at their hospital and in pharmacokinetic studies.
• Limitations the authors state:
  • The method measures pemetrexed in plasma, not its active polyglutamate metabolites. The authors said these metabolites are probably a better indicator of toxicity and efficacy, but no therapeutic ranges for them are known.

Topics

Medical terms in this study, explained in our Lexicon: Antifolate, Pemetrexed (Alimta), Lung Cancer, Pleural Mesothelioma.

Related studies

• Pemetrexed disodium: a novel antifolate clinically active against multiple solid tumors — A.R. Hanauske, V. Chen, et al. (2001)
• Therapeutic targeting malignant mesothelioma with a novel 6-substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolate via its selective uptake by the proton-coupled folate transporter — C. Cherian, S. Kugel Desmoulin, et al. (2013)
• Safety of Same-Day Vitamin B12 Supplementation in Patients Receiving Pemetrexed for the Treatment of Non-Small-Cell Lung Cancer or Pleural Mesothelioma: A Retrospective Analysis — Z. Schlei, W. Tan, et al. (2018)
• Clinical and pharmacokinetic phase I study of multitargeted antifolate (LY231514) in combination with cisplatin — R. Thödtmann, H. Depenbrock, et al. (1999)
• AMPK activation induced in pemetrexed-treated cells is associated with development of drug resistance independently of target enzyme expression — Y. Qin, I. Sekine, et al. (2019)
• Development of an enzyme-linked immunosorbent assay for the detection of human calretinin in plasma and serum of mesothelioma patients — I. Raiko, I. Sander, et al. (2010)

Browse return to medical research.