Novel Blood Test a Potential 'Game Changer' in Ovarian Cancer

Pam Harrison

November 28, 2018

A novel test engineered from a bacterial toxin has been shown to detect significant levels of a specific biomarker released into the blood by ovarian cancer cells at all stages of the disease, including the early stages, distinguishing patients with ovarian cancer from healthy unaffected controls, research indicates.

"Ovarian cancer is notoriously difficult to detect in its early stages, when there are more options for treatment and survival rates are better," James Paton, PhD, director, Research Centre for Infectious Diseases, University of Adelaide, Australia, said in a statement by his institution.

"Our new test is therefore a potential game changer," he added.

The research was published online November 19 in Biochemical and Biophysical Research Communications.

Diagnostic Markers for Detection of Early Stage Ovarian Cancer

The Australian team obtained serum samples from patients with stage I through IV ovarian cancer, along with samples from healthy unaffected women as controls.

They then engineered a subunit of the Shiga toxigenic Escherichia coli, which can recognize N-glycolylneuraminic acid (Neu5Gc)-containing glycans found in human tumor tissues and cells.

In earlier work, the same researchers had engineered a Neu5Gc-specific lectin, SubB2M, to enhance recognition of Neu5Gc-containing glycans.

They then used a technique known a surface plasmon resonance (SPR) to detect binding of the glycans to SubB2M, which was immobilized on a sensor chip.

"Using our engineered Neu5Gc-specific lectin, SubB2M, we showed via SPR that Neu5Gc levels are significantly elevated in serum samples from ovarian cancer patients at stages I, II, IIIC, and IV," the investigators report.

They also showed that Neu5Gc levels are elevated in most stage I and II ovarian cancer serum samples, and that levels from all patients with stage IIIC and IV far exceeded those in age-matched healthy controls.

These findings suggest that Neu5Gc-containing tumor antigens have the potential to serve as diagnostic markers for the detection of both early and later-stage ovarian cancer, the researchers emphasize.

Test 2 Years Away From Clinical Application?

Asked by Medscape Medical News how far away the test might be from clinical application, Paton noted that they are perhaps 2 years away from the test being available.

This timescale will depend on investment from a commercial partner to fund validation studies using larger numbers of serum samples, as well as adaption of the test to high throughput screening technology platforms used in diagnostic pathology laboratories.

"But I am very hopeful that this can be achieved," he said in an email.

It is established that serum CA125 levels are elevated in approximately 80% of patients with ovarian cancer at the time of diagnosis.

However, CA125 levels are very low in the early stages of ovarian cancer and rarely detectable at this stage, as Paton observed.

This is why the CA125 test is approved only for monitoring response to treatment as well as disease recurrence.

Paton and other coauthors have reported that they are named inventors on a patent on matter contained in their manuscript.

Biochem Biophys Res Commun. Published online November 19, 2018. Full text

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