New Therapeutic Uses for Existing Drugs.

Eighty percent of drugs that enter human clinical testing are never approved for use. This means that for every five drugs that make it into the clinic, there are four that failed to show effectiveness for treating the disease or condition the drug was designed to treat.This high failure rate means there are many existing, partially developed therapeutic candidates with known pharmacology, formulation, and potential toxicity. Finding new uses for existing experimental drugs or biologics "repositioning" builds upon previous research and development efforts, so new candidate therapies can be advanced to clinical trials for a new use more quickly than starting from scratch.Federal funding initiatives in the U.S. and UK started to support pre-clinical /or early stage trials for repositioning existing experimental drugs or biologics (therapies). This chapter covers some of the process issues that have been solved and the remaining challenges that are still in need of solutions. The chapter is primarily written from a U.S. federal funding perspective. The general concepts could be applied more globally to benefit rare and neglected disease populations. The drug development and process bottlenecks are the same for both rare and common disease.