The Role of Biomarkers in Drug Development
- One use of biomarkers is to help drug developers make early "go or no go" decisions about whether to pursue a drug candidate. For example, a biomarker might show whether a drug compound can successfully pass through the cell wall or attach to a receptor on a target molecule. The results of these types of experiments can stop further, more expensive research on a potentially ineffective compound or may point to different approaches.
- In the later stages of drug development, biomarkers can help determine dosage rates---how often the drug should be administered and how much should be given each time---needed to produce the desired affect. Biomarkers can also determine how much is too much, resulting in toxicity. Additionally, different bodies have different metabolisms that may affect how the body responds to a drug. The correct biomarker could show whether or not metabolic differences affect dosage rates.
- Once a drug candidate reaches clinical trails, biomarkers can show whether a drug has a clinically significant effect. During clinical trials, a "clinical endpoint"--defined by the FDA as "a characteristic that reflects how a patient feels, functions, or survives"--predicts a drug's efficacy. Biomarkers, however, can predict efficacy more quickly then conventional clinical endpoints. Biomarkers accepted for this use are called established surrogate endpoints. For example, a measurably smaller tumor is an established surrogate endpoint that predicts that a given drug effectively attacks a cancer.
- Biomarkers have shown great potential in the developing field of individualized therapies. Individuals respond differently to the same medicine due in part to differences in their DNA. A drug that benefits one patient may have little or no effect in another or, worse, may have serious side effects. Biomarkers can predict how an individual will react to a drug before it is administered. Biomarkers also offer hope for speeding up new drug development by proving earlier in the drug development process that a compound will have the necessary activity, safety and metabolic profile.
- Biomarker development is evolving and, like any new tool, has issues. Some of the issues are regulatory--researchers must discover biomarkers and assemble evidence of their significance while government regulators, notably the Food and Drug Administration, must define what signifies evidence and how to validate a biomarker. This effort requires significant collaboration between government, academics and industry. Some issues are scientific and, simply put, require a better understanding of disease processes to discover biomarkers for those disease pathways.
