Promising SPG4 biomarker in blood samples

Biomarker matches drug levels in mouse brain tissue

Building on earlier work using stem cell cultures and skin samples from people with SPG4, Dr Gautam Wali now reports that the promising SPG4 biomarker, acetylated α-tubulin, is similarly found in blood samples. This has positive implications for drug discovery, testing and in clinical trial measurements, with significant advantages in convenience, time and cost.

In another study, the same biomarker was measured in the brains of healthy laboratory mice that showed increasing levels with increasing doses of candidate drug noscapine.

The Foundation facilitated and funded both these studies.


Gautam Wali

HSP-SPAST (SPG4) is the most common form of hereditary spastic paraplegia (HSP), a neurodegenerative disease-causing lower limb spasticity. Previous studies using HSP-SPAST patient-derived induced pluripotent stem cell cortical neurons have shown that patient neurons have reduced levels of acetylated α-tubulin, a form of stabilized microtubules, leading to a chain of downstream effects eventuating in increased vulnerability to axonal degeneration. Noscapine treatment rescued these downstream effects by restoring the levels of acetylated α-tubulin in patient neurons.

Here we show that HSP-SPAST patient non-neuronal cells, peripheral blood mononuclear cells (PBMCs), also have the disease-associated effect of reduced levels of acetylated α-tubulin. Evaluation of multiple PBMC subtypes showed that patient T cell lymphocytes had reduced levels of acetylated α-tubulin. T cells make up to 80% of all PBMCs and likely contributed to the effect of reduced acetylated α-tubulin levels seen in overall PBMCs.

Carolyn Sue

We further showed that mouse administered orally with increasing concentrations of noscapine exhibited a dose-dependent increase of noscapine levels and acetylated α-tubulin in the brain. A similar effect of noscapine treatment is anticipated in HSP-SPAST patients. To measure acetylated α-tubulin levels, we used a homogeneous time resolved fluorescence technology-based assay. This assay was sensitive to noscapine-induced changes in acetylated α-tubulin levels in multiple sample types. The assay is high throughput and uses nano-molar protein concentrations, making it an ideal assay for evaluation of noscapine-induced changes in acetylated α-tubulin levels.

This study shows that HSP-SPAST patient PBMCs exhibit disease-associated effects. This finding can help expedite the drug discovery and testing process.

SOURCE:  Front Neurosci. 2023 Mar 28;17:1073516. doi: 10.3389/fnins.2023.1073516. eCollection 2023. PMID: 37144097 Copyright © 2023 Wali, Siow, Liyanage, Kumar, Mackay-Sim and Sue.

Reduced acetylated α-tubulin in SPAST hereditary spastic paraplegia patient PBMCs

Gautam Wali  1   2   3 Sue-Faye Siow  2   3 Erandhi Liyanage  1   2 Kishore R Kumar  2   4   5 Alan Mackay-Sim  3   6 Carolyn M Sue  1   2   3

1. Neuroscience Research Australia and University of New South Wales, Sydney, NSW, Australia.

2. Kolling Institute for Medical Research and Department of Medicine, University of Sydney, Sydney, NSW, Australia.

3. Northern Clinical School, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.

4. Molecular Medicine Laboratory and Department of Neurology, Concord Repatriation General Hospital, Concord Clinical School, University of Sydney, Concord, NSW, Australia.

5. Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.

6. Griffith Institute for Drug Discovery, Griffith University, Brisbane, QLD, Australia.


    1. Editor’s note:There have been no clinical trials to answer that question. There are big challenges with rare diseases like HSP. Once candidate drugs are identified, finding sufficient numbers of participants with the confirmed genetic type; developing reliable tests and measures of effectiveness; and financing clinical trials of sufficient power and scale to provide definitive evidence and satisfy regulatory authorities … are all big challenges that need to be overcome in order to be successful. As yet, no one anywhere has put all the pieces together to run successful clinical trials (apart from a couple of instances of single person gene therapy trials for very rare forms of HSP, and even there, assessments of effectiveness are not yet forthcoming).

  1. This study talks about the use of Noscapine to rescue downstream effects of degeneration to the neuron. This is big. Noscapine used to be a topic of conversation but last I heard we were awaiting clinical trials and needing more money for this. Where are we with this drug? Is any of the money we raised this year going towards these trials so more of us can start using Noscapine?

    1. Editor’s note: Current status on Noscapine: The research/clinical trial team was unsuccessful on two occasions with applications for major grant funding. Since the COVID pandemic, the combined cost of a phase 1 (safety) + phase 2a (preliminary effectiveness) clinical trial is around the $2 million mark, more than double the pricetag pre-pandemic. The opportunity window to do these trials relatively cheaply is gone. The only evidence of effectiveness is with stem cells and their derivatives in a lab dish. This is not a showstopper, but the lack of evidence of effectiveness in some sort of SPG4 animal is a limitation. Another important limitation is the lack of a sufficiently sensitive and widely accepted biomarker of disease status that would be suitable for use in a clinical trial. With the much higher pricetag now on phase 1 + 2a, the risk of failure of the trials given the known limitations is now more substantial – $2 million is a lot of money to lose – which may be why the applications for grant funding were rejected in the first place. The willingness to undertake these trials would be significantly strengthened with effectiveness data in animal trials and/or a good outcome measure (biomarker). So, for now, work on the biomarker is progressing. If preliminary effectiveness is shown in a phase 2a trial, then it is on to (a number of) phase 2b trials as a minimum requirement to get market approval for the drug. The Foundation is ready to provide support or matching funding for clinical trials when the time comes.

  2. Are you working with any other doctors/scientists worldwide? People are now talking about NU9. They need SPG4 biomarkers to proceed. Dr. Ozdinler is making some breakthroughs. Could you work with her or share important information? We need a team to find a medication or cure!

    1. Editor’s note: We have been in touch with Dr Ozdinler since 2019 as well as other leading HSP clinicians and researchers globally. In general, collaboration is improving but there is still a long way to go to achieve open and timely sharing – researchers are historically and culturally, structurally and systematically incentivised not to share or collaborate with each other. However this is probably a lesser challenge than having adequate funding to implement research studies and accelerate the path towards a cure.

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