SBIR-STTR Award

The overall goal of this SBIR proposal is the identification of small molecules capable of blocking the cytotoxic action of Bacillus anthracis lethal toxin by blocking the transmembrane pore formed by the protective antigen component of the toxin. Such molecules are envisioned for use as drugs for the treatment of anthrax. The strategy to identify such compounds involves developing an assay for testing the ability of compounds to inhibit the cytotoxic effect of anthrax toxin. A limited representative library of compounds will be designed and synthesized. The synthesized compounds will then be tested for inhibitory activity. The resulting baseline data will be used for computer-assisted design of compounds with improved affinity towards the transmembrane pore, followed by a second round of chemical synthesis and testing.

Results from our SBIR Phase I project demonstrated that beta-cyclodextrin derivatives designed to block the trans-membrane channel formed by B. anthracis protective antigen (PA) can inhibit the cytotoxic effects of anthrax toxin at low micromolar concentrations. Based on successful completion of the feasibility study, the overall goal of our Phase II project is to select the best drug candidates for anthrax treatment. To achieve this goal we will perform large-scale design, synthesis and screening of chemical libraries, and test the best candidates in small animal studies. The specific aims of this Phase II study are: (1) Utilize crystallographic coordinates and initial testing data in concert with computational chemistry to design additional beta-cyclodextrin derivatives with increased affinity to the PA pore. (2) Optimize a cell-based assay to screen the inhibition of the anthrax toxin cytotoxic effect, establish and validate cell-based and biochemical assays to test chemical compounds for the ability to block the PA channel. (3) Synthesize representative libraries of beta-cyclodextrin analogues, and screen them using biochemical and cell-based assays. (4) Perform toxicity and efficacy tests in mice using at least five compounds with inhibitory activity at nanomolar concentrations to select drug candidates. Long term goals include subsequent preclinical and clinical studies that will lead to the development of a new anti-anthrax treatment.

Thesaurus Terms:
Bacillus anthracis, bacterial antigen, bacterial toxin, molecular dynamics, technology /technique development bacteria infection mechanism, bacterial protein, chemical information system, chemical registry /resource, chemical synthesis, combinatorial chemistry, cyclodextrin, cytotoxicity, small molecule laboratory mouse