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Spectroscopic blood test tipped for brain tumor triage

15 Oct 2019

University of Strathclyde spin-out looking to launch commercial blood serum technique from 2022.

A simple blood test based on infrared spectroscopy could help speed up the diagnosis of brain tumors, say researchers developing the technology at the University of Strathclyde in Glasgow, UK.

Led by spin-out company ClinSpec Diagnostics and working with neurosurgeons at a hospital in Edinburgh, the team has just published a paper describing results on a prospective cohort of 104 patients - the first clinical validation study for such a technique.

Writing in the journal Nature Communications, ClinSpec founder and CTO Matthew Baker and colleagues report that their blood serum test - based on attenuated total reflection (ATR) Fourier transform (FTIR) spectroscopy - shows the potential for rapid patient triage, and faster access to diagnostic brain imaging for those more likely to have a brain tumor.

That is seen as critically important for assessing patients with vague symptoms such as headaches or dizziness, which might be the result of a brain tumor but are so common in the wider population that the disease is often left undiagnosed until patients begin to suffer from more serious symptoms such as seizures.

Diagnostic challenge
Co-author Paul Brennan, a consultant neurosurgeon at the University of Edinburgh, explained: "Diagnosing brain tumours is difficult, leading to delays and frustration for lots of patients.

"The problem is that symptoms of brain tumor are quite non-specific, such as headache, or memory problems. It can be difficult for doctors to tell which people are most likely to have a brain tumor.

"With this new test, we have shown that we can help doctors quickly identify which patients with these non-specific symptoms should be prioritized for urgent brain imaging. This means a more rapid diagnosis for people with a brain tumor, and quicker access to treatment."

While the blood test is not able to detect brain tumors directly - this still requires a computed tomography (CT) X-ray or MRI scan - previous studies have shown that there are subtle differences in infrared biosignatures of patients with and without cancer, as well as those with high-grade tumors originating in the brain versus metastatic tumors that have spread from elsewhere in the body.

"The diagnostic output is generated by machine learning algorithms, which learn the differences in infrared signatures that are indicative and exclusive to cancer," reports the team.

Critically, they have now found a way to carry out the triage-level blood analysis with the kind of high sample throughput and batch processing needed for clinical utility.

Etched sample slides
The work is centered on the development of disposable sample analysis slides based on silicon internal reflection elements (IREs). These can be produced at a fraction of the cost of conventional IREs that use a high refractive index optical material like diamond, germanium, or zinc selenide.

Silicon IREs are not normally used for biological fingerprinting, because lattice vibrations in the silicon crystal can obscure biochemically critical wavelengths. However, that effect can be minimized by reducing the pathlength of the infrared beam through the IRE, and by using microfabricated designs that allow only a single internal reflection.

The 75 x 25 mm optical slides developed by the Strathclyde team feature four separate sample areas: one for a background measurement, and three for repeat measurements of blood serum from an individual patient.

"This device is developed for the triplicate measurement of patient samples with optimized spectral throughput and performance," writes the team.

Baker and colleagues define the optically active region of the silicon IREs with an array of microfabricated v-grooves, where blood serum is deposited and then analyzed. The etched surface of the IRE faces the infrared beam, so that light is coupled through the IRE, and parallel to the direction of the grooves.

Patient cohorts
First, they used the technology to carry out a retrospective analysis of blood from a cohort of 724 patients, including a large number diagnosed with "gliobastoma" primary brain tumors.

On a per-patient basis, those results showed a diagnostic sensitivity and specificity of more than 90 per cent, indicating that patients with and without cancer could be identified very effectively.

Next, the team looked to assess the triage system in a more realistic and blinded clinical setting, analyzing the blood serum of 104 patients who had either been referred by their local doctor for brain imaging, or had recently been diagnosed with a brain tumor and admitted for surgery.

Those results showed significanty lower specificity and sensitivity of just over 80 per cent, although this is still sufficient to provide clinically useful information and cost savings when deciding which patients to send for follow-up brain imaging.

'Huge clinical potential'
Summing up the work, Baker and colleagues stated: "A sensitivity of 83.3 per cent shows the huge clinical potential of this test, effectively identifying those patients who desperately need brain scans.

"From a patient perspective, higher sensitivity has the greatest impact on quality of life due to the opportunity to identify and treat cancers early."

Baker added: "This is the first publication of data from our clinical feasibility study and it is the first demonstration that our blood test works in the clinic. Earlier detection of brain tumors in the diagnostic pathway brings the potential to significantly improve patient quality of life and survival, whilst also providing savings to the health services."

He and colleague Holly Butler, who is the director of research and development at ClinSpec, are now looking to carry out further clinical studies, with a roadmap that envisions regulatory approvals and a commercial launch in 2022.

Although their initial focus is on brain cancer, they say that the technology can provide a platform to test for other cancers and chronic diseases, as well as non-clinical applications.

According to the firm's web site, Baker, Butler, and CEO Mark Hegarty are currently looking to engage with equity investors, mentors, and other industry partners with experience in international counter diagnostics at scale, particularly in the US.

Spun out from Strathclyde earlier this year, ClinSpec has so far been supported with £0.6 million from Scottish Enterprise, and raised £1.6 million from investors EOS and Mercia Fund Managers, alongside the Scottish Investment Bank, Scottish Edge and Innovate UK.

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