Design of LFA-1 antagonists based on a 2,3-dihydro-1H-pyrrolizin-5(7aH)-one scaffold

Insights into the chemistry and therapeutic potential of acrylonitrile derivatives

Acrylonitrile is a fascinating scaffold widely found in many natural products, drugs, and drug candidates with various biological activities. Several drug molecules such as entacapone, rilpivirine, teriflunomide, and so forth, bearing an acrylonitrile moiety have been marketed. In this review, diverse synthetic strategies for constructing desired acrylonitriles are discussed, and the different biological activities and medicinal significance of various acrylonitrile derivatives are critically evaluated. The information gathered is expected to provide rational guidance for the development of clinically useful agents from acrylonitriles.

Dynamics of allosteric modulation of lymphocyte function associated antigen-1 closure-open switch: unveiling the structural mechanisms associated with outside-in signaling activation

OBJECTIVES

To provide insight into the dynamics of the shape-shifting mechanistic events associated with the opening (activation) of Lymphocyte Function Associated Antigen-1 upon allosteric modulation by an activator, ICAM Binding Enhancer-667 (IBE-667), using molecular dynamics simulation.

RESULTS

Various parameters were used to appropriately describe and understand the sequence of events that characterized its activation across the simulation period such as residual distances, TriCα angles; as well as the dihedral angle. Our findings revealed a significant residual fluctuation and stability difference between both systems. Also, there was a synergistic coordination of the active MIDAS site by the downward pull of the α7 helix upon ligand binding, which appeared to be directly proportional to each other.

CONCLUSION

Allosteric binding of IBE-667, activated LFA-1 integrin as evidenced by residual motion at the MIDAS region which appears to be synergistically coordinated by the downward pull of the α7 helix.

Protein-protein interactions as drug targets

Modulation of protein-protein interactions (PPIs) is becoming increasingly important in drug discovery and chemical biology. While a few years ago this 'target class' was deemed to be largely undruggable an impressing number of publications and success stories now show that targeting PPIs with small, drug-like molecules indeed is a feasible approach. Here, we summarize the current state of small-molecule inhibition and stabilization of PPIs and review the active molecules from a structural and medicinal chemistry angle, especially focusing on the key examples of iNOS, LFA-1 and 14-3-3.

The therapeutic potential of I-domain integrins

Due to their role in processes central to cancer and autoimmune disease I-domain integrins are an attractive drug target. Both antibodies and small molecule antagonists have been discovered and tested in the clinic. Much of the effort has focused on αLβ2 antagonists. Maybe the most successful was the monoclonal antibody efalizumab, which was approved for the treatment of psoriasis but subsequently withdrawn from the market due to the occurrence of a serious adverse effect (progressive multifocal leukoencephalopathy). Other monoclonal antibodies were tested for the treatment of reperfusion injury, post-myocardial infarction, but failed to progress due to lack of efficacy. New potent small molecule inhibitors of αv integrins are promising reagents for treating fibrotic disease. Small molecule inhibitors targeting collagen-binding integrins have been discovered and future work will focus on identifying molecules selectively targeting each of the collagen receptors and identifying appropriate target diseases for future clinical studies.

Integrins as therapeutic targets: lessons and opportunities

The integrins are a large family of cell adhesion molecules that are essential for the regulation of cell growth and function. The identification of key roles for integrins in a diverse range of diseases, including cancer, infection, thrombosis and autoimmune disorders, has revealed their substantial potential as therapeutic targets. However, so far, pharmacological inhibitors for only three integrins have received marketing approval. This article discusses the structure and function of integrins, their roles in disease and the chequered history of the approved integrin antagonists. Recent advances in the understanding of integrin function, ligand interaction and signalling pathways suggest novel strategies for inhibiting integrin function that could help harness their full potential as therapeutic targets.

Discovery of tetrahydroisoquinoline (THIQ) derivatives as potent and orally bioavailable LFA-1/ICAM-1 antagonists

This letter describes the discovery of a novel series of tetrahydroisoquinoline (THIQ)-derived small molecules that potently inhibit both human T-cell migration and super-antigen induced T-cell activation through disruption of the binding of integrin LFA-1 to its receptor, ICAM-1. In addition to excellent in vitro potency, 6q shows good pharmacokinetic properties and its ethyl ester (6t) demonstrates good oral bioavailability in both mouse and rat. Either intravenous administration of 6q or oral administration of its ethyl ester (6t) produced a significant reduction of neutrophil migration in a thioglycollate-induced murine peritonitis model.

Small molecule antagonist of leukocyte function associated antigen-1 (LFA-1): structure-activity relationships leading to the identification of 6-((5S,9R)-9-(4-cyanophenyl)-3-(3,5-dichlorophenyl)-1-methyl-2,4-dioxo-1,3,7-triazaspiro[4.4]nonan-7-yl)nicotinic acid (BMS-688521)

Leukocyte function-associated antigen-1 (LFA-1), also known as CD11a/CD18 or alpha(L)beta(2), belongs to the beta(2) integrin subfamily and is constitutively expressed on all leukocytes. The major ligands of LFA-1 include three intercellular adhesion molecules 1, 2, and 3 (ICAM 1, 2, and 3). The interactions between LFA-1 and the ICAMs are critical for cell adhesion, and preclinical animal studies and clinical data from the humanized anti-LFA-1 antibody efalizumab have provided proof-of-concept for LFA-1 as an immunological target. This article will detail the structure-activity relationships (SAR) leading to a novel second generation series of highly potent spirocyclic hydantoin antagonists of LFA-1. With significantly enhanced in vitro and ex vivo potency relative to our first clinical compound (1), as well as demonstrated in vivo activity and an acceptable pharmacokinetic and safety profile, 6-((5S,9R)-9-(4-cyanophenyl)-3-(3,5-dichlorophenyl)-1-methyl-2,4-dioxo-1,3,7-triazaspiro-[4.4]nonan-7-yl)nicotinic acid (2e) was selected to advance into clinical trials.