ABSTRACT
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.
Subject(s)
Hydantoins/pharmacokinetics , Immunologic Factors/chemistry , Lymphocyte Function-Associated Antigen-1/drug effects , Nicotinic Acids/pharmacokinetics , Humans , Hydantoins/pharmacology , Lymphocyte Function-Associated Antigen-1/chemistry , Lymphocyte Function-Associated Antigen-1/immunology , Nicotinic Acids/toxicity , Structure-Activity RelationshipABSTRACT
LFA-1 appears to play a central role in normal immune responses to foreign Ags. In autoimmune or inflammatory diseases, there is increased expression of LFA-1 and/or its counterligand, ICAM-1. Others have demonstrated that the targeted disruption of LFA-1:ICAM interactions, either by gene deletion or Ab treatment in mice, results in reduced leukocyte trafficking, inflammatory responses, and inhibition of inflammatory arthritis in the K/BxN serum transfer model. However, there has been little success in finding a small-molecule LFA-1 antagonist that can similarly impact rodent models of arthritis. In this paper, we present the first reported example of an LFA-1 small-molecule antagonist, BMS-587101, that is efficacious in preclinical disease models. In vitro, BMS-587101 inhibited LFA-1-mediated adhesion of T cells to endothelial cells, T cell proliferation, and Th1 cytokine production. Because BMS-587101 exhibits in vitro potency, cross-reactivity, and oral bioavailability in rodents, we evaluated the impact of oral administration of this compound in two different models of arthritis: Ab-induced arthritis and collagen-induced arthritis. Significant impact of BMS-587101 on clinical score in both models was observed, with inhibition comparable or better than anti-mouse LFA-1 Ab. In addition, BMS-587101 significantly reduced cytokine mRNA levels in the joints of Ab-induced arthritis animals as compared with those receiving vehicle alone. In paws taken from the collagen-induced arthritis study, the bones of vehicle-treated mice had extensive inflammation and bone destruction, whereas treatment with BMS-587101 resulted in marked protection. These findings support the potential use of an LFA-1 small-molecule antagonist in rheumatoid arthritis, with the capacity for disease modification.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Arthritis, Experimental/drug therapy , Inflammation/drug therapy , Lymphocyte Function-Associated Antigen-1/metabolism , Spiro Compounds/pharmacology , Thiophenes/pharmacology , Animals , Arthritis, Experimental/immunology , Arthritis, Experimental/pathology , Cell Adhesion/drug effects , Cell Proliferation/drug effects , Cytokines/biosynthesis , Cytokines/drug effects , Disease Models, Animal , Enzyme-Linked Immunosorbent Assay , Humans , Inflammation/immunology , Inflammation/pathology , Lymphocyte Culture Test, Mixed , Lymphocyte Function-Associated Antigen-1/immunology , MiceABSTRACT
A new class of lymphocyte function-associated antigen-1 (LFA-1) antagonists is described. Elaboration of the 2,3-dihydro-1H-pyrrolizin-5(7aH)-one scaffold resulted in the synthesis of potent inhibitors of the LFA-1/ICAM-1 interaction. Along with the in vitro activity, we present the X-ray crystal structure of the complex of compound 9b, in a novel binding mode to the I-domain of LFA-1.
Subject(s)
Chemistry, Pharmaceutical/methods , Lymphocyte Function-Associated Antigen-1/chemistry , Pyrroles/chemistry , Crystallography, X-Ray , Drug Design , Drug Screening Assays, Antitumor , HeLa Cells , Humans , Inhibitory Concentration 50 , Models, Chemical , Molecular Conformation , Stereoisomerism , Temperature , X-RaysABSTRACT
LFA-1 (leukocyte function-associated antigen-1), is a member of the beta2-integrin family and is expressed on all leukocytes. This letter describes the discovery and preliminary SAR of spirocyclic hydantoin based LFA-1 antagonists that culminated in the identification of analog 8 as a clinical candidate. We also report the first example of the efficacy of a small molecule LFA-1 antagonist in combination with CTLA-4Ig in an animal model of transplant rejection.
Subject(s)
Lymphocyte Function-Associated Antigen-1/metabolism , Spiro Compounds/chemical synthesis , Thiophenes/chemical synthesis , Animals , Cell Adhesion/drug effects , Crystallography, X-Ray , Dogs , Graft Rejection/prevention & control , Humans , Lymphocyte Function-Associated Antigen-1/chemistry , Mice , Models, Molecular , Molecular Structure , Pneumonia/drug therapy , Pneumonia/immunology , Spiro Compounds/pharmacokinetics , Spiro Compounds/pharmacology , Stereoisomerism , Structure-Activity Relationship , Thiophenes/pharmacokinetics , Thiophenes/pharmacology , Transplantation, HomologousABSTRACT
LFA-1 (leukocyte function-associated antigen-1), is a member of the beta(2)-integrin family and is expressed on all leukocytes. The LFA-1/ICAM interaction promotes tight adhesion between activated leukocytes and the endothelium, as well as between T cells and antigen-presenting cells. Evidence from both animal models and clinical trials provides support for LFA-1 as a target in several different inflammatory diseases. This paper describes the de novo design, synthesis and in vitro activity of LFA-1 antagonists based on a bicyclic[5.5]hydantoin scaffold.
