Water-soluble PDE4 inhibitors for the treatment of dry eye.

PDE4 inhibitors have the potential to alleviate the symptoms and underlying inflammation associated with dry eye. Disclosed herein is the development of a novel series of water-soluble PDE4 inhibitors. Our studies led to the discovery of coumarin 18, which is effective in a rabbit model of dry eye and a tear secretion test in rats.

Identification of KD5170: a novel mercaptoketone-based histone deacetylase inhibitor.

We report the identification of KD5170, a potent mercaptoketone-based Class I and II-histone deacetylase inhibitor that demonstrates broad spectrum cytotoxic activity against a range of human tumor-derived cell lines. KD5170 exhibits robust and sustained histone H3 hyperacetylation in HCT-116 xenograft tumors following single oral or i.v. dose and inhibition of tumor growth following chronic dosing.

Alpha-mercaptoketone based histone deacetylase inhibitors.

In an effort to discover novel non-hydroxamic acid histone deacetylase (HDAC) inhibitors, a novel alpha-mercaptoketone was identified in a high-throughput screen. Lead optimization of the screening hit, led to a number of potent HDAC inhibitors. In particular, alpha-mercaptoketone 19y (KD5150) exhibited nanomolar in vitro activity and inhibition of tumor growth in vivo.

KD5170, a novel mercaptoketone-based histone deacetylase inhibitor that exhibits broad spectrum antitumor activity in vitro and in vivo.

Histone deacetylase (HDAC) inhibitors have garnered significant attention as cancer drugs. These therapeutic agents have recently been clinically validated with the market approval of vorinostat (SAHA, Zolinza) for treatment of cutaneous T-cell lymphoma. Like vorinostat, most of the small-molecule HDAC inhibitors in clinical development are hydroxamic acids, whose inhibitory activity stems from their ability to coordinate the catalytic Zn2+ in the active site of HDACs. We sought to identify novel, nonhydroxamate-based HDAC inhibitors with potentially distinct pharmaceutical properties via an ultra-high throughput small molecule biochemical screen against the HDAC activity in a HeLa cell nuclear extract. An alpha-mercaptoketone series was identified and chemically optimized. The lead compound, KD5170, exhibits HDAC inhibitory activity with an IC50 of 0.045 micromol/L in the screening biochemical assay and an EC50 of 0.025 micromol/L in HeLa cell-based assays that monitor histone H3 acetylation. KD5170 also exhibits broad spectrum classes I and II HDAC inhibition in assays using purified recombinant human isoforms. KD5170 shows significant antiproliferative activity against a variety of human tumor cell lines, including the NCI-60 panel. Significant tumor growth inhibition was observed after p.o. dosing in human HCT-116 (colorectal cancer), NCI-H460 (non-small cell lung carcinoma), and PC-3 (prostate cancer) s.c. xenografts in nude mice. In addition, a significant increase in antitumor activity and time to end-point occurred when KD5170 was combined with docetaxel in xenografts of the PC-3 prostate cancer cell line. The biological and pharmaceutical profile of KD5170 supports its continued preclinical and clinical development as a broad spectrum anticancer agent.

R-isomers of Arg-Gly-Asp (RGD) mimics as potent alphavbeta3 inhibitors.

The integrin alpha(v)beta(3), vitronectin receptor, is expressed in a number of cell types and has been shown to mediate adhesion of osteoclasts to bone matrix, vascular smooth muscle cell migration, and angiogenesis. We recently disclosed the discovery of a tripeptide Arg-Gly-Asp (RGD) mimic, which has been shown to be a potent inhibitor of the integrin alpha(v)beta(3) and has excellent anti-angiogenic properties including its suppression of tumor growth in animal models. In other investigations involving RGD mimics, only compounds containing the S-isomers of the beta-amino acids have been shown to be potent. We were surprised to find the potencies of analogs containing enantiomerically pure S-isomers of beta-amino acids which were only marginally better than the corresponding racemic mixtures. We therefore synthesized RGD mimics containing R-isomers of beta-amino acids and found them to be relatively potent inhibitors of alpha(v)beta(3). One of the compounds was examined in tumor models in mice and has been shown to significantly reduce the rate of growth and the size of tumors.

Synthesis of cinnamic acids and related isosteres as potent and selective alpha v beta 3 receptor antagonists.

We describe a series of conformationally-restricted cinnamic acid peptidomimetics as well as several cinnamic acid isosteres, including 3-phenylpropionic acids, 2-amino-3-phenylpropionic acids, phenoxyacetic acids and 2-phenylcyclopropylcarboxylic acids. Several analogues demonstrated low to sub-nanomolar potencies against alpha(v)beta(3) and greater than 200-fold selectivity against the other beta(3) integrin alpha(IIb)beta(3). In whole 293 cells, many of these analogues also showed modest selectivity against other alpha(v) integrins such as alpha(v)beta(1) and alpha(v)beta(5). These compounds were synthesized from readily available starting materials using either Heck or Mitsunobu coupling conditions.

Synthesis of imidazopyridines and purines as potent inhibitors of leukotriene A4 hydrolase.

The synthesis and biological evaluation of a series of heterocyclic analogues of the previously reported LTA(4) hydrolase inhibitor 1b are described. Imidazopyridine and purine analogues are specifically highlighted with several demonstrating excellent potency in our in vitro assays, as well as good oral activity in a mouse ex vivo assay.

Synthesis of potent leukotriene A(4) hydrolase inhibitors. Identification of 3-[methyl[3-[4-(phenylmethyl)phenoxy]propyl]amino]propanoic acid.

Leukotriene B(4) (LTB(4)) is a potent, proinflammatory mediator involved in the pathogenesis of a number of diseases including inflammatory bowel disease, psoriasis, rheumatoid arthritis, and asthma. The enzyme LTA(4) hydrolase represents an attractive target for pharmacological intervention in these disease states, since the action of this enzyme is the rate-limiting step in the production of LTB(4). Our previous efforts focused on the exploration of a series of analogues related to screening hit SC-22716 (1, 1-[2-(4-phenylphenoxy)ethyl]pyrrolidine) and resulted in the identification of potent, orally active inhibitors such as 2. Additional structure-activity relationship studies around this structural class resulted in the identification of a series of alpha-, beta-, and gamma-amino acid analogues that are potent inhibitors of the LTA(4) hydrolase enzyme and demonstrated good oral activity in a mouse ex vivo whole blood LTB(4) production assay. The efforts leading to the identification of clinical candidate SC-57461A (8d, 3-[methyl[3-[4-(phenylmethyl)phenoxy]propyl]amino]propanoic acid) are described.