Fingerprick blood samples to measure serum natalizumab concentrations

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.

Diagnostic accuracy of dried blood spots for serology of vaccine-preventable diseases: a systematic review

INTRODUCTION

Venous serum and plasma are optimal specimens for serological testing but may be logistically infeasible. Dried blood spots (DBS) are a feasible alternative, provided results are adequately sensitive and specific. We aimed to assess the diagnostic accuracy of DBS to measure IgG and IgM antibodies for vaccine-preventable diseases and compare test validity of DBS with venous blood.

AREAS COVERED

In October 2020, we searched seven databases for peer-reviewed studies assessing the diagnostic accuracy of DBS specimens compared with serum in detecting antibodies to VPDs in humans. We extracted data and assessed risk of bias in all included studies. We calculated sensitivity and specificity with 95% confidence intervals for each index-reference test comparison. We narratively synthesized the identified evidence on diagnostic accuracy and blood collection and processing methods for DBS. Studies on measles and rubella IgG and IgM were the most frequently identified and reported generally high sensitivity and specificity.

EXPERT OPINION

Lack of standardization in collection, storage, and testing methods limited systematic comparison across studies. Our findings indicate a need for additional validation studies on the diagnostic accuracy of DBS to expand their use in serological surveillance. We recommend practical considerations to improve standardized reporting for DBS validation studies.

Have we got 'patient-centric sampling' right?

RA Koster currently works as Associate Director of Bioanalytical Science at the LC-MS/MS department at PRA Health Sciences in the Laboratory in Assen, The Netherlands. He is responsible for the LC-MS/MS analytical method development and leads a team of method development analysts and scientists. As global microsampling specialist within PRA he is interested in all developments regarding microsampling and aims to continuously improve microsampling techniques. He has been working in the field of bioanalysis for 19 years, in which he performed and supervised numerous analytical method developments using LC-MS/MS. He started his career in 2001 at Pharma Bio-Research (before it was acquired by PRA) as an LC-MS/MS analyst. In 2005, he moved to the University Medical Center Groningen where he focused on the development and validation of analytical methods for drugs and drugs of abuse in matrices like blood, plasma, hair, saliva, dried blood spots and volumetric absorptive microsampling with LC-MS/MS. In 2015 he obtained his PhD on the subject 'The influence of the sample matrix on LC-MS/MS method development and analytical performance'. In 2017, he started as Senior Scientist at PRA Health Sciences and in 2019, he accepted his current role of Associate Director of Bioanalytical Science. He is a (co-)author of more than 35 publications.