MS as a versatile metabolomics technology can serve as a stand-alone method for identifying compounds from complex mixtures or can create libraries identifying metabolic fragmentation patterns, useful for establishing a samples fingerprint.
Metabolon (www.metabolon. com) is focusing on the quantitative measurement and identification of the repertoire of biochemicals contained in biological samples. Mass spectrometry is a tremendous improvement over other methods, such as nuclear magnetic resonance, in that we can find hundreds of metabolites per sample and do so in the femtomolar range, points out Chris Beecher, Ph.D., vp biochemistry and technology. Also, you only need small amounts of sample. But we also have found that no single technology will provide the entire answer. We couple MS with LC and GC separations and merge all of this data using informatics to reveal novel metabolic fingerprints.
To prove its point, the company recently performed a study in collaboration with Massachusetts General Hospital to identify novel disease biomarkers for amyotrophic lateral sclerosis (ALS). It conducted a metabolomics analysis on blinded plasma samples from patients treated for motor neuron disease versus control patients.
We measured metabolites quantitatively and clearly saw that there were multiple populations within the ALS population, reports Dr. Beecher. We defined subsets as to whether patients were or were not taking the drug riluzole. We were able to identify physical subsets of disease and see the effect the drug had on patients. This drug was seriously altering patients blood chemistry.
This technology may provide answers as to whether specific drugs can revert patients to more normal conditions or if they cause significant side effects. This could identify which drugs are the best candidates to develop. Also, such information may tell us which pathways are impacted, and that would help identify mechanisms. The FDA has shown great interest in this area. They also feel it may provide insights into drug action that have never been possible before.
Metabolon is expanding its study to include hundreds of patients in a longitudinal investigation to follow disease progression and is initiating similar studies in Alzheimers and Parkinsons diseases.
So-called targeted approaches focus on preselected metabolites reflecting relevant metabolic pathways. This strategy has the advantage of honing in on specific metabolites that can be linked to a specific therapeutic area. In principle, this also could increase the analytical rigor and precision for identification and analysis.
Biocrates Life Sciences (www.biocrates. at) is pursuing targeted approaches utilizing tandem mass spectrometry (MS/MS) for metabolomic analysis.
MS/MS has a number of benefits, according to Armin Graber, Ph.D., CEO, including the ability to measure low nanomolar concentrations of metabolites in complex mixtures without needing chromatographic instruments. This allows high-throughput methods for accurate identification and quantification of arrays of metabolites in multiple pathways.
The company recently demonstrated the performance of its technology by identifying biomarkers characterizing a disease treated with an already approved therapeutic and a candidate drug class. It compiled comparative pharmacodynamic profiles for a PPAR-gamma agonist and the novel compound in a mouse model for diabetes mellitus type 2. PPAR (peroxisome proliferator-activated receptor) is an orphan nuclear receptor that plays a key role in regulating triglycerides, blood glucose homeostasis, and insulin resistance.
The results were so informative that the pharmaceutical company that asked us to perform this study launched a program for a new drug indication and will enter clinical development in 2006, says Dr. Graber. Furthermore, a joint research collaboration was initiated including several biomarker identification and validation projects.