Multiplex Protein Biomarker Profiling
Multiplex Biosciences (www.multiplexbiosciences.com) recently merged with Rules-Based Medicine (www.rbmmaps.com) and plans to expand its immunoassay panel for testing biomarkers in plasma. “Rules-Based Medicine can test up to 130 human analytes and wants to expand that up to 200 new assays over the next 18 months,” says Dominic Eisinger, Ph.D., president, Multiplex Biosciences. The protein biomarkers are from various sources, hormones, cytokines, or anything that provides a good indication of response to disease, disease diagnosis, and drug response.
“Multiplexing is much more cost-effective than single assays,” explains Dr. Eisinger. “Mass spectrometry is a great technique for discovery, but it doesn’t have the sensitivity to detect low abundant proteins.”
However, he says for plasma protein biomarker analysis, the quantitative sensitivity of the miniaturized multiplex immunoassays is in the single femtomole range from just a few microliters of raw unfractionated plasma. This high sensitivity is required for low-abundant tissue leakage factors, a promising biomarker candidate.
The company has reagents that prevent immunoassay interference. “There can be a lot of interference when you multiplex and have around 40 antibodies in a single well all working in concert. We work our permutations to make the assay as sensitive as possible,” says Dr. Eisinger. The company’s focus over the next year will be to build more multiplex miniaturized immunoassays for screening services. There have already been several novel biomarker discoveries made out of the company’s 130-analyte panel.
Current technologies allow for profiling thousands of proteins in plasma and discovering ones modulated by disease or drugs. Researchers at Caprion Pharmaceuticals (www.caprion.com) have developed CellCarta®, a platform for profiling proteins in plasma, other bodily fluids, or tissue.
“We use a combination of global proteomics and the reductionist approach,” says Paul Kearney, Ph.D., executive director, bioinformatics. “We try not to reduce the data set of proteins modulated by disease or drugs, but do try to keep all the modulated proteins for several reasons. We can perform a global assessment of not just the protein being modulated, but the biological processes that are modulated by disease or a drug. This allows you to study mechanism of action.”
Furthermore, he says, this enables a robust panel of biomarkers. “The global approach allows a much deeper understanding of what’s happening biologically to your proteins.”
It also allows quantification of disease severity and drug effects and provides information on pharmacodynamic questions like dose response and compound efficacy, as well as eliminates the need to develop an ELISA test. “You get answers to these questions immediately, without going into the additional 15 months of ELISA development and validation and taking the risk of failure,” adds Dr. Kearney.
The company has its own internal plasma biomarker discovery program on human plasma clinical samples in Alzheimer’s disease and hypertension. “Our proteomic assay correlates highly with the current diagnostic test used by most clinics to assess Alzheimer’s, the Mini Mental State Exam.”