Pharmacophore-Modeled Screening for HbF-Inducing Agents

DESCRIPTION (provided by applicant): Induction of endogenous fetal globin (HbF) can ameliorate the clinical severity of the beta globin disorders. Many short chain fatty acids and derivatives (SCFADs) stimulate activity from the fetal globin gene promoter, and some create an accessible chromatin structure through HDAC inhibition and histone hyperacetylation. However, the available SCFA drugs require high doses or intravenous infusions, which are difficult for many patients to tolerate. A HbF inducer which is effective orally at lower doses, through higher potency or persistence in plasma for a longer duration of time, is still needed for an optimal therapeutic. Our laboratory initially identified active SCFAs using medicinal chemistry methods, and found several additional actions which inhibit or stimulate cell growth, altering therapeutic potential negatively or positively. These SCFADs were used to create and then refine a 3-D molecular model, or pharmacophore of chemical structures which are essential for and some of which inhibit HbF-inducing activity. This pharmacophore was used to virtually screen a chemical library of 13,000 compounds by molecular modeling, and identified 28 potential candidate compounds. 20 of the 28 pharmacophore-predicted candidates were found to induce HbF (a 70 percent success rate). While some predicted compounds have higher potency in vitro over prior generations, many still do not have optimal pharmacokinetic profiles in vivo. Additional candidates are needed for development of an optimal therapy. We propose here to use our validated pharmacophore for high-throughput virtual screening of chemical libraries containing 2 million compounds for additional HbF-inducers. The resulting candidates will be evaluated for functional activity in reporter gene assays and for specific activity in inhibiting class I HDACs, which induces HbF without causing cellular toxicity. This virtual screening using molecular modeling with confirmation by reporter assay and selection of a specific HDAC activity should generate additional compounds for development of an optimal HbF inducer for an effective life-long treatment