Quantification Using LC-MS/MS
Dr. Houghton and his co-workers have developed an LC-MS/MS method for the measurement of seven steroids in human urine and validated for use in a regulated bioanalytical arena as a biomarker for 11b-hydroxy steroid dehydrogenase enzyme activity. This project drew upon a surrogate matrix calibration strategy for the quantification of endogenous analytes.
“Data generated using this method in support of two Phase I studies, with two different drugs, showed the power of pharmacodynamic data in supporting proof of concept, drug potency and kinetics, and evaluation of food-effect, said Dr. Houghton.
While there is a particular focus on protein and peptides as pharmacodynamic biomarkers of therapeutic effect or disease indicators, in some instances, there may be endogenous small molecules that are appropriate, he reported.
“By measuring changes in the ratio of these endogenous metabolites, all within a single multiplex LC-MS/MS assay, it was possible to both prove the efficacy of the drug, as well as the potency. Steroids, by their very nature and diverse action around the body, may prove in some disease state to be excellent biomarkers and are relatively cheap and easy to measure.”
One of the main challenges in the field, Dr. Houghton noted, is regulatory acceptance of biomarkers with clear guidance on validation and application in clinical trials and as diagnostics. “The FDA has recognized and is actively supporting this process, which should lead to more rapid acceptance of specific markers to particular disease states in the future.
“The pharmaceutical industry needs to continue to work hand-in-hand with regulators to ensure biomarkers become an integral part of the drug-development process. However, regulators around the world also need to recognize the cost implications to pharma companies of companion diagnostics and ensure there is adequate return-on-investment opportunity for drug companies for the added R&D spend.”