Mass Spectrometry for the Analysis of Metabolites and Proteins

Experts at the 2024 Analytica conference in Munich, Germany presented a two-part session focused on clinical mass spectrometry; the first session dealt with metabolites, and the second with proteins. The sessions were chaired by Uta Ceglarek of the Institute of Laboratory Medicine, Clinical Mass Spectrometry Section at the University of Leipzig Medical Center, in Germany and Christoph Seger of Labordiagnostic St. Gallen West AG in Switzerland.

The first part of the session began with “LC–MS³ Yields Unparalleled Diagnostic Specificity in Primary Newborn Screening for Congenital Adrenal Hyperplasia,” presented by Alexander Gaudl of the University of Leipzig in Germany. Gaudl discussed how newborn screening for the disease state by immunoassay (IA) suffers from analytical limitations such as cross reactivity and matrix effects. As alternative tandem-mass spectrometric approaches are not suitable for high throughput screening due to long analysis times, Gaudl and colleagues applied, for the first time, a rapid one-minute LC–MS/MS/MS (LC–MS³) assay and compared the diagnostic efficiency with IA for primary screening of congenital adrenal hyperplasia in newborns.

That presentation was followed by Anne K. Bendt of the National University of Singapore and her discussion, “Lipidomics Biomarker Discovery – A Case Study.” To successfully evolve from the current research-grade methods to assays suitable for routine clinical applications, Bendt argued that a harmonization, or standardization, of these mass spectrometry-based workflows is necessary. Her presentation intended to provide an overview of international efforts to tackle the issues of workflow harmonization, and to serve as an open invitation for others to join this growing community.

Katharina Habler of the Institute of Laboratory Medicine, University Hospital, LMU Munich, Germany, presented “Therapeutic Drug Monitoring of Orphan Drugs.” Designed to treat rare diseases affecting a small population, orphan drugs pose unique challenges in terms of therapeutic drug monitoring (TDM) due to limited patient data and variability in drug response. Habler discussed how liquid chromatography-tandem mass spectrometry (LC–MS/MS) has emerged as a powerful tool for precise and sensitive drug quantification, and can support therapeutic interventions for orphan drug-treated patients. Habler’s presentation focused on cystic fibrosis transmembrane conductance regulator (CFTR) modulators.

The first session concluded with moderator Christoph Seger’s presentation “CE-Certified and LDT Assays in Laboratory Medicine: Instrumental Analysis Facing Scylla and Charybdis.” Guidance for assay use provided by industry tend to be non-transparent and astonishingly forbidding. In the usually accredited environments of laboratory medicine an academic culture has been developed in the past decades to override such flaws and limitation of the methods offered. With this premise in mind, the current regulatory situation in analytical laboratory medicine services were discussed, based on examples of Labordiagnostic St. Gallen West AG’s daily work.

The second part of the session began with Lydia Kollhoff’s presentation, “Development of a Rapid and Specific MALDI-TOF Mass Spectrometric Assay for SARS-CoV-2 Detection.” Kollhoff, from the Department of Pharmaceutical Chemistry and Bioanalytics at Martin Luther University Halle-Wittenberg, in Germany, discussed how her team’s new method allows the detection of SARS-CoV-2 nucleoprotein as low as 8 amol/μl, and discriminates SARS-CoV-2 delta (B.1.617.2) variant from all other variants in patients’ samples, thus making their method highly valuable to monitor the emergence of new virus variants.

Christa Cobbaert of Leiden University Medical Centre in the Netherlands presented “On the Way to Precision Cardiovascular Diagnostics with a Next Generation Lipoprotein(a) Reference Measurement System Based on Quantitative Protein Mass Spectrometry and Molar Units.” During her lecture, the state-of-the-science regarding the clinical utility of the genetically determined apolipoprotein (a) in Lipoprotein(a) was explained, as well as the challenges that current Lipoprotein(a) measurement procedures bring.

Philippe Massonnet, of Liège University Hospital in Belgium introduced “Quantification of 1-84 Parathyroid Hormone: From Immunoassays to LC–MS/MS Candidate Reference Measurement.” Massonnet and his group have developed and validated the first LC–MS/MS method with antibody-free sample preparation to become a candidate reference assay for 1-84 parathyroid hormone (TH). This method was also used to recalibrate the results obtained from the IA. The results of this recalibration, ongoing work within the group, and future perspectives were all discussed.

The session concluded for the afternoon with the presentation “A combined Newborn Screening Method for Sickle Cell Disease, Biotinidase Deficiency, and Tyrosinemia Type I by Flow-Injection Tandem Mass Spectrometry (FIA-MS/MS)” led by Jeanette Klein of Charité Universitätsmedizin in Berlin, Germany. SpotOn Clinical Diagnostics developed a dried blood spot (DBS) FIA-MS/MS method for sickle cell disease (SCD) screening, based on extraction and tryptic digestion of hemoglobin from DBS and detection of disease-specific peptides by FIA-MS/MS. The method was used in pilot studies to demonstrate its potential from technical point of view and to provide epidemiological data about the prevalence of SCD in Germany. Klein pointed out that, besides capillary electrophoresis and HPLC, the method she discussed was recommended by the legal regulation body.