14 October 2024

Tandem mass spectrometry-based assay for heparan-N-sulphatase in paediatric CSF: A potential pharmacodynamic biomarker for mucopolysaccharidosis type IIIA therapy

Speziale, R., Hocquemiller, M., Mei, X., Fabbrini, D., Malancona, S., Aiach, K., Laufer, R., & Orsatti, L. (2025).
Clinica Chimica Acta, 565, 119987. https://doi.org/10.1016/j.cca.2024.119987

Ultra-sensitive tandem mass spectrometry-based assay development and validation

The article, “LC-MS/MS Assay for Heparan-N-Sulphatase in Pediatric CSF: A Potential Pharmacodynamic Biomarker for Mucopolysaccharidosis Type IIIA Therapy,” published in Clinica Chimica Acta, covers the development, optimization, and qualification of a highly sensitive methodology using UHPLC-MS/MS to determine Heparan-N-Sulphatase (SGSH) activity in Mucopolysaccharidosis Type IIIA (MPS IIIA) patients. This method has demonstrated sensitivity in detecting the decrease in SGSH enzyme activity levels in patients affected by the disease, compared to traditional methods.

Understanding MPS IIIA and the Need for Better Diagnostics

MPS IIIA, also known as Sanfilippo Syndrome, is a lysosomal storage disorder caused by mutations affecting heparan-N-sulphatase production. This leads to heparan sulfate accumulation in lysosomes, particularly in the brain, resulting in progressive neurodegeneration. The disease typically begins between the ages of 2 and 6 and is characterized by grave consequences, including premature death.

Currently, there are no approved treatments for MPS IIIA, though clinical trials are exploring various therapeutic approaches. A significant challenge has been the lack of accurate methods to monitor disease progression and treatment efficacy in real-time.

The LC-MS/MS Assay: A Step Forward

Our newly developed LC-MS/MS assay offers a method to measure SGSH activity in CSF, which has been notoriously difficult due to long incubation times and the need for secondary enzymatic steps. However, our tandem mass spectrometry (MS) method offers several advantages over traditional fluorometric assays including:

Direct measurement of the enzymatic reaction product via mass spectrometry.
Higher sensitivity, resulting in a lower limit of quantification (LLOQ) in CSF samples
Reduction in total assay time, increasing throughput without compromising accuracy or sensitivity

This assay could potentially serve as a pharmacodynamic biomarker for evaluating therapies aimed at patients with MPS IIIA.

Broader Implications in Drug Discovery

Thanks to the state-of-the-art technology available at IRBM, a wide range of applications can be covered, from small molecules to peptides and proteins. Our high level of technological know-how and experience allows us to develop highly customizable assays, capable of addressing the challenges of the drug discovery field and supporting the advancement of programs across various therapeutic areas and drug modalities. Cutting-edge mass spectrometry techniques such as LC-MS/MS and HRMS play a pivotal role in mass elucidation, offering an unparalleled combination of sensitivity, specificity, and versatility. These technologies are indispensable from the early stages of compound screening, all the way through to advanced pharmacokinetics, metabolism, and toxicology studies.

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What’s Next?

While further studies are needed to fully validate and assess the long-term clinical utility of the assay, we are hopeful that this research will contribute to the development of new therapies for patients with MPS IIIA. We look forward to continuing our efforts to develop additional tools that will ultimately benefit patients with neurodegenerative disorders like this.

Unlock the Potential of Bespoke biomarker assays

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