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. 2023 Mar;29(3):457-460.
doi: 10.1177/13524585221136448. Epub 2022 Nov 30.

Fingerprick blood samples to measure serum natalizumab concentrations

Alyssa A Toorop  1 , Maurice Steenhuis  2 , Floris C Loeff  3 , Suzanne S Weijers  4 , Joep Killestein  1 , Theo Rispens  5 , Zoé LE van Kempen  1
Affiliations

Fingerprick blood samples to measure serum natalizumab concentrations

Alyssa A Toorop et al. Mult Scler. 2023 Mar.

Abstract

Background: Natalizumab via subcutaneous administration was recently approved for patients with multiple sclerosis.

Objective: In light of personalized extended dosing, in which treatment intervals are prolonged to a concentration cut-off, it would be preferable to measure natalizumab drug concentrations in capillary blood.

Methods: In this cross-sectional study in patients treated with intravenous (IV) natalizumab, capillary blood samples by fingerprick and venous blood samples were collected in 30 participants prior to IV administration of natalizumab.

Results: Natalizumab concentrations were similar with a mean bias of -0.36 μg/mL (95% CI: 1.3 to -2 μg/mL).

Conclusions: This study shows that physicians can monitor natalizumab drug concentrations by a fingerprick, which could be used for personalized extended dosing.

Keywords: Multiple sclerosis; capillary; extended interval dosing; fingerprick; natalizumab.

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Conflict of interest statement

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: A.A. Toorop reports no disclosures relevant to the manuscript; M. Steenhuis reports no disclosures relevant to the manuscript; F.C. Loeff reports no disclosures relevant to the manuscript; S.S. Weijers reports no disclosures relevant to the manuscript; J. Killestein received research grants for multicentre investigator initiated trials (DOT-MS trial, ClinicalTrials.gov Identifier: NCT04260711 (ZonMW) and BLOOMS trial (ZonMW and Treatmeds), ClinicalTrials.gov Identifier: NCT05296161), received consulting fees for F. Hoffmann-La Roche Ltd, Biogen, Teva, Merck, Novartis and Sanofi/Genzyme (all payments to institution), reports speaker relationships with F. Hoffmann-La Roche Ltd, Biogen, Immunic, Teva, Merck, Novartis and Sanofi/Genzyme (all payments to institution) apart from multi-sponsored events, adjudication committee of MS clinical trial of Immunic (payments to institution only); T. Rispens received funding for research from Genmab, received consulting fees from Novartis; Z.L.E. van Kempen reports no disclosures relevant to the manuscript.

Figures

Figure 1.
Figure 1.
Capillary versus venous blood samples for measurement of serum natalizumab concentrations. (a) Scatterplot of natalizumab concentrations (µg/mL) for capillary (x-axis) versus venous (y-axis) blood samples as analyzed with a Spearman correlation. (b) Bland-Altman plot showing the mean bias and upper- and lower limit of the 95% agreement range of natalizumab concentrations in µg/mL.
See this image and copyright information in PMC

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