Discovery of novel dihydro-9,10-ethano-anthracene carboxamides as glucocorticoid receptor modulators

Design, Synthesis and Biochemical Evaluation of Novel Ethanoanthracenes and Related Compounds to Target Burkitt's Lymphoma

Lymphomas (cancers of the lymphatic system) account for 12% of malignant diseases worldwide. Burkitt’s lymphoma (BL) is a rare form of non-Hodgkin’s lymphoma in which the cancer starts in the immune B-cells. We report the synthesis and preliminary studies on the antiproliferative activity of a library of 9,10-dihydro-9,10-ethanoanthracene based compounds structurally related to the antidepressant drug maprotiline against BL cell lines MUTU-1 and DG-75. Structural modifications were achieved by Diels-Alder reaction of the core 9-(2-nitrovinyl)anthracene with number of dienophiles including maleic anhydride, maleimides, acrylonitrile and benzyne. The antiproliferative activity of these compounds was evaluated in BL cell lines EBV⁻ MUTU-1 and EBV⁺ DG-75 (chemoresistant). The most potent compounds 13j, 15, 16a, 16b, 16c, 16d and 19a displayed IC₅₀ values in the range 0.17–0.38 μM against the BL cell line EBV⁻ MUTU-1 and IC₅₀ values in the range 0.45–0.78 μM against the chemoresistant BL cell line EBV⁺ DG-75. Compounds 15, 16b and 16c demonstrated potent ROS dependent apoptotic effects on the BL cell lines which were superior to the control drug taxol and showed minimal cytotoxicity to peripheral blood mononuclear cells (PBMCs). The results suggest that this class of compounds merits further investigation as antiproliferative agents for BL.

Design of small molecules targeting transcriptional activation by NF-κB: overview of recent advances

BACKGROUND

The transcription factor NF-κB plays a central role in immune signaling and the inflammatory response. It also activates transcription of antiapoptotic factors in tumor cells, leading to enhanced cell survival. Because of the importance of NF-κB in inflammation and cancer, there is considerable interest in development of drugs that inhibit NF-κB activation or NF-κB-directed transcription. Recent elucidation of the intracellular pathways that activate NF-κB and mechanisms for transcriptional regulation by NF-κB has identified molecular targets for rational design of such drugs.

OBJECTIVE

This review provides an update on NF-κB signaling and an overview of three classes of NF-κB inhibitors: i) inhibitors of IκB kinase-β (also called IKK2), an essential link in the inflammatory response; ii) agents that react with NF-κB and prevent its binding to DNA; and iii) ligands for nuclear receptors such as the glucocorticoid receptor, PPARs and liver X receptor, which interfere with NF-κB-mediated transcription through a mechanism termed ligand-dependent transrepression. Recent progress in development of glucocorticoid receptor, PPAR and liver X receptor ligands with dissociated activity, which retain transrepression but have reduced transactivation potency, is also described.

CONCLUSIONS

NF-κB inhibitors have yielded promising results in rodent models of inflammatory disease and cancer. Some of these are currently advancing into clinical trials.

Non-steroidal Dissociated Glucocorticoid Receptor Agonists

Synthetic glucocorticoids, such as dexamethasone and prednisolone, are amongst the most commonly used drugs due to their potent and efficacious anti-inflammatory and immunosuppressive properties. However, their long-term and/or high-dose administration is limited by a number of deleterious side-effects, including glucocorticoid-induced diabetes and osteoporosis. Glucocorticoids exert their effects through binding to the glucocorticoid receptor. Since the discovery of multiple differentiated down-stream functions of the glucocorticoid-bound receptor, such as gene transrepression and transactivation, researchers in academia and industry have been on a quest to discover novel glucocorticoids that achieve functional selectivity, hence dissociating the desired anti-inflammatory from the undesired side-effects. This review describes the current state of discovery and development of non-steroidal glucocorticoid receptor agonists. Several small-molecule drug candidates have advanced into clinical trials, and have shown promising early biomarker data, as well as beneficial effects in topical applications. However, a clinically efficacious and systemically available glucocorticoid with significantly reduced side-effects as compared to current steroidal drugs, the “Holy Grail” in immunology, is still elusive.

Dimethyl-diphenyl-propanamide derivatives as nonsteroidal dissociated glucocorticoid receptor agonists

A series of 2,2-dimethyl-3,3-diphenyl-propanamides as novel glucocorticoid receptor modulators is reported. SAR exploration led to the identification of 4-hydroxyphenyl propanamide derivatives displaying good agonist activity in GR-mediated transrepression assays and reduced agonist activity in GR-mediated transactivation assays. Compounds 17 and 30 showed anti-inflammatory activity comparable to prednisolone in the rat carrageenan-induced paw edema model, with markedly decreased side effects with regard to increases in blood glucose and expression of hepatic tyrosine aminotransferase. A hypothetical binding mode accounting for the induction of the functional activity by a 4-hydroxyl group is proposed.

Recent advances in the development of novel glucocorticoid receptor modulators

IMPORTANCE OF THE FIELD

The glucocorticoid receptor plays a number of fundamental roles in human physiology. Glucocorticosteroids are the ultimate anti-inflammatory and immunosuppressive agents highly efficacious in the treatment of serious diseases, but also associated with serious side effects. Improvement in the therapeutic profiles of drugs, acting at the glucocorticoid receptor, is highly desired and may potentially arise from the separation of their gene transactivating and gene transrepressing properties.

AREAS COVERED IN THIS REVIEW

The review summarizes progress towards novel glucocorticoid drug candidates as indicated by the patent applications over the last 2 years (2008 - 2009). A brief discussion of glucocorticoid receptor biology and previous drug candidates is included.

WHAT THE READER WILL GAIN

The understanding of the structural scope and biological profiles of the glucocorticoid receptor modulators, currently in preclinical and clinical development, based on the review of approximately 180 composition-of-matter and method-of-use patent applications.

TAKE HOME MESSAGE

The information on the good chemotypical diversity of glucocorticoid receptor modulators needs to be supplemented by the clinical data - presumably, soon to become available - to allow a look into a possible improvement in therapeutic index over the classic glucocorticosteroids.

Structure guided design of 5-arylindazole glucocorticoid receptor agonists and antagonists

Glucocorticoid receptor (GR) agonists have been used for more than half a century as the most effective treatment of acute and chronic inflammatory conditions despite serious side effects that accompany their extended use that include glucose intolerance, muscle wasting, skin thinning, and osteoporosis. As a starting point for the identification of GR ligands with an improved therapeutic index, we wished to discover selective nonsteroidal GR agonists and antagonists with simplified structure compared to known GR ligands to serve as starting points for the optimization of dissociated GR modulators. To do so, we selected multiple chemical series by structure guided docking studies and evaluated GR agonist activity. From these efforts we identified 5-arylindazole compounds that showed moderate binding to the glucocorticoid receptor (GR) with clear opportunities for further development. Structure guided optimization was used to design arrays that led to potent GR agonists and antagonists. Several in vitro and in vivo experiments were utilized to demonstrate that GR agonist 23a (GSK9027) had a profile similar to that of a classical steroidal GR agonist.