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Proteomics International Developing Protein Biomarker-Based Diagnostic for Diabetic Nephropathy


By Adam Bonislawski

Australian biotech company Proteomics International has identified a panel of 13 protein biomarkers for the detection of diabetic nephropathy.

The company, which presented the biomarkers at last month's Human Proteome Organization annual meeting in Sydney, is now looking for partners and funding to help it develop the panel as a commercial diagnostic and to explore the potential of some of the markers as drug targets, managing director Richard Lipscombe told ProteoMonitor.

The biomarkers were identified in the course of Proteomics International's work on Australia's Busselton Health Study, a landmark epidemiological research program launched in 1966 to study diseases common in the Australian population, and the Fremantle Diabetes Study, a longitudinal study coordinated by the University of Western Australia.

The company began work on the project in January 2009, in what then marked the first instance of proteomics being applied to the BHS (PM 08/13/2009). The biomarker panel was developed with samples from a total of 180 subjects from the two studies: 60 healthy controls, 60 with mild diabetic nephropathy, and 60 with severe cases of the disease.

Using iTRAQ labeling and MALDI TOF/TOF mass spectrometry on an AB Sciex 4800 TOF/TOF instrument, the researchers identified roughly 150 candidate protein biomarkers. In the study's validation phase they narrowed down those candidates to the current panel of 13 by using selected and multiple reaction-monitoring assays developed on an AB Sciex 4000 QTRAP machine.

According to Lipscombe, the company now plans to proceed with the work on two parallel tracks: developing an algorithm combining the 13 markers into a diagnostic for diabetic nephropathy, and expanding the number of subjects in the study in an effort to improve the panel.

"The numbers that we've looked at are still on the low side, and part of our current objective is to expand that, which will improve the statistics around it," he said. "We would expect that as we do more analysis, the number [of markers in the panel] will come down slightly from the number we have at the moment.

"Nonetheless, we have good statistics on the ones that we have, so in parallel we're looking to develop a diagnostic on that signature," he said.

Lipscombe said he envisions the work leading to a test that physicians can use to determine diabetes patients' risk status for developing nephropathy. With roughly 250 million people with diabetes worldwide, doctors need ways to predict which ones will progress to kidney disease.

"What [doctors] want is a better way of managing their patients," he said. "They don't want to be wasting time giving drugs to patients who are never going to get sick. So we're looking to narrow down the at-risk category and diagnose these people much earlier."

Proteomics International isn't alone in working on diabetes-related biomarkers. For instance, in May, the National Institute of Diabetes and Digestive and Kidney Diseases awarded a team of researchers led by Randall Nelson at Arizona State University's Biodesign Institute $3.1 million to validate 11 protein biomarkers linked to diabetes and cardiovascular disease (PM 05/07/2010). Lipscombe said, however, that he was unaware of any other groups working on protein biomarkers for diabetic nephropathy specifically.

He said that the company doesn't yet have specificity or sensitivity data regarding the biomarker panel's ability to diagnose diabetic nephropathy, but claimed that the researchers would "get a better handle" on those statistics as they expanded the size of the study.

Proteomics International is actively pursuing additional funding and commercial partners to help it do this, Lipscombe said.

"The resources we've had to this date have been great, but we know that to do this on the scale that is now required will require some extra partners with more capacity than we have," he said. "The work has gone well. These are exciting results and in our minds they've validated our approach and the strength of our cohorts. Now we need bigger partners to be able to do this more efficiently."

Provided the right partner, Proteomics International could get a protein biomarker-based diagnostic for diabetic nephropathy to market within a year, Lipscombe said. He noted that the company has been approached by several biotech firms about collaborating on developing a diagnostic kit and would be meeting with them within the next several weeks.

The company is partial to MALDI TOF/TOF MS followed by MRM and SRM assays for the discovery and validation phases of its biomarker work, but it is "currently weighing the advantages of switching to an immunoassay system" for the diagnostic itself, Lipscombe said.

"In my mind 13 [biomarkers] is just about the tipping point where it's too many for an immunoassay approach," he said. "So we'll either need to narrow that panel down if we go with immunoassays, or if we stay with 13 we'll need another mass spectrometer or two."

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Longer term, Proteomics International hopes through its biomarker research to identify potential new targets for pharmaceutical companies developing drugs for diabetes and, Lipscombe said, is currently in discussions with several large pharmaceutical firms. It is part of the Western Australian Institute for Medical Research's Centre for Food and Genomic Medicine, which has as one of its objectives to "look for new [drug] targets and potential therapies for diabetes and obesity," he noted.

"We were envisioning that we could find molecules that could be new drug targets in the future, but obviously going down that route is a long one, so the first objective was to try to find some diagnostic markers and the interim step is to use those markers to allow you to personalize therapy," he said.

Lipscombe also observed that, while the company's research has focused specifically on protein biomarkers for diabetic nephropathy, these biomarkers could also help detect kidney disease more generally.

"That's an area we're now looking to explore," he said. "Obviously the overlap between diabetic kidney disease and kidney disease generally is clear, so now we need to move back in the other direction and focus on the fact that we have kidney disease [markers] as well as diabetic kidney disease [markers]."

Regarding money to finance these various initiatives, Lipscombe noted that, while it is still "probably too early for venture capital funding," the company is "moving towards that path." It also may pursue state and federal funding, as well as "more traditional grant funding," he added.

The company is also investigating protein biomarkers for respiratory diseases and Alzheimer's disease using similar mass spec-based approaches, Lipscombe said.