Highly sensitive quantification of pemetrexed in human plasma using UPLC-MS/MS to support microdosing studies

Our plain-English summary of Highly sensitive quantification of pemetrexed in human plasma using UPLC-MS/MS to support microdosing studies, by E.W.J. van Ewijk-Beneken Kolmer, M.J.A. Teulen, R.J. Boosman, et al (Biomedical Chromatography, 2022).

The study

• Authors: E.W.J. van Ewijk-Beneken Kolmer, M.J.A. Teulen, R.J. Boosman, N. de Rouw, J.A. Burgers, R. Ter Heine
• Journal: Biomedical Chromatography
• Published: 2022;36(2):e5277
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Pemetrexed is an antifolate drug approved for the treatment of non-small-cell lung cancer and mesothelioma. Assessing pemetrexed pharmacokinetics after administration of a microdose (100 μg) may facilitate drug-drug interaction and dose individualization studies with cytotoxic drugs, without causing harm to patients. Therefore, a highly sensitive bioanalytical assay is required. A reversed-phase ultra-high performance liquid chromatography method was developed to determine pemetrexed concentrations in human ethylenediaminetetraacetic acid-plasma after microdosing. [13 C5 ]-Pemetrexed was used as the internal standard. The sample preparation involved solid-phase extraction from plasma. Detection was performed using MS/MS in a total run time of 9.5 min. The assay was validated over the concentration range of 0.0250-25.0 μg/L pemetrexed. The average accuracies for the assay in plasma were 96.5 and 96.5%, and the within-day and between-day precision in coefficients of variations was <8.8%. Extraction recovery was 59 ± 1 and 55 ± 5% for pemetrexed and its internal standard. Processed plasma samples were stable for 2 days in a cooled autosampler at 10°C. The assay was successfully applied in a pharmacokinetic curve, which was obtained as a part of an ongoing clinical microdosing study.

© 2021 The Authors. Biomedical Chromatography published by John Wiley & Sons Ltd.

In plain English

This laboratory study from the Netherlands did not examine asbestos exposure. It described how the authors developed and checked a test that measures very low levels of pemetrexed in human blood plasma. Pemetrexed is a drug approved for non-small-cell lung cancer and mesothelioma. The test was meant to support microdosing studies, in which patients receive a 100 μg dose, which the authors called about 10,000-fold lower than a therapeutic dose. The test was validated from 0.0250 to 25.0 μg/L. Between 0.0600 and 25.0 μg/L, the authors reported that it was accurate and precise, with a maximum coefficient of variation of 8.80%. At the lowest level, 0.0250 μg/L, accuracy was 77%, below the preset requirement of 80 to 120%, and the authors chose to accept this. Recovery of pemetrexed from plasma was 59 plus or minus 1%. The test was then used in one patient given a 100 μg dose. All of that patient's measured concentrations fell within the validated range, although some samples had to be diluted. The authors concluded that they had successfully developed a highly sensitive test for pemetrexed after microdosing.

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 a bioanalytical assay (UPLC-MS/MS), applied to samples from one patient in an ongoing clinical microdosing study
• Who was studied: Drug-free EDTA plasma from a blood bank (Sanquin, Nijmegen); blank plasma from six oncological patients who did not receive pemetrexed (used to check for interference); and one patient given a 100 μg microdose in an ongoing clinical study (NCT03655834)
• Exposure: Not an asbestos exposure. The substance measured was the drug pemetrexed after a single 100 μg microdose, which the authors describe as about 10,000-fold lower than a therapeutic dose
• Main results:
  • The assay's concentration range for pemetrexed in plasma was set at 0.0250 to 25.0 μg/L
  • In the range 0.0600 to 25.0 μg/L, the method was accurate and precise, with a maximum coefficient of variation of 8.80%
  • Average accuracy in plasma was 96.5% (within-day) and 96.5% (between-day)
  • At the lowest level (LLOQ, 0.0250 μg/L), accuracy was 77%, which did not meet the preset requirement of 80 to 120%
  • Extraction recovery was 59 plus or minus 1% for pemetrexed (at QC low and QC high) and 55 plus or minus 5% for the internal standard
  • Processed plasma samples kept in the cooled autosampler (10 degrees C) were stable after 2 days, with mean concentrations of 102 plus or minus 7.41% of the initial concentrations
  • In the one patient given a microdose, all measured concentrations were within the validated range, though some samples had to be diluted before measurement
• The authors' conclusion: The authors concluded that they had successfully developed a highly sensitive UPLC-MS/MS assay for pemetrexed in EDTA plasma after microdosing, and that, to their knowledge, it was the first assay to quantify such low concentrations
• Limitations the authors state:
  • Accuracy at the lowest validated level (0.0250 μg/L) fell short of the preset requirement. The authors accepted this because such low concentrations were expected only at the end of the concentration-time curve and would contribute little to calculating cumulative exposure

Topics

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

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