The search for new TB drugs has finally caught up with the pharmaceutical revolution of the last half of this century: solid-matrix-based methods of chemical synthesis now create combinatorial chemistry libraries of pharmaceuticals that contain millions of unique compounds. Using robotics and sophisticated assay instrumentation, these libraries can be screened with high throughput to identify compounds which are lethal to specific organisms, or which affect specific pathways know to be critical for bacterial survival. A year-old CRADA between the NIAID and Sequella, Inc. to develop combinatorial chemistry and a high throughput screening assay succeeded in synthesizing and screening approximately 100,000 analogues of the TB drug ethambutol in a very short period of time. The gene- based screen used in these studies identified compounds that affect specific regions of the M. tuberculosis genome that are activated in response to ethambutol therapy, and are involved in the cellular response to cell wall damage. The Sequella, Inc./NIH collaboration had impressive momentum (100,000 compounds screened, 200 hits, 4 lead compounds in 9 months). The Foundation intends to provide several gene-based and whole-cell high throughput screening assays to interested pharmaceutical companies to screen their chemical libraries in a similar timeframe. One company, for example, has 500,000 well- characterized chemicals taht have never been tested for TB. They are interested in providing the Foundation with these chemicals to test in a specific whole cell-screening assay as an initial screen for hits. Setting up the high throughput screen in-house, while not that expensive, represents an opportunity cost for that company and would require a BL3 facility. In addition, a validated whole-bacteria high throughput screening assay would be of benefit to the current NIAID/DAIDS drug screening program. The Foundation would be interested in transferring the screen to the NIH program over the course of this challenge grant. The Foundation goal is to reduce the barriers to entry that the major pharmaceutical companies face when considering the market for new TB drugs. Thus, providing tailored screening programs that support the specific needs of pharmaceutical partners is a relatively inexpensive endeavor that may improve the likelihood that medicines will emerge to improve the treatment of this neglected disease.
