Abstract

Rational design of glycomimetic inhibitors based on the bioactive conformation of functional carbohydrates provides new therapeutic opportunities for the development of small molecule drugs with improved activity, pharmacokinetics, and bioavailability relative to native ligands. In designing more active glycomimetic selectin inhibitors, the low enthalpy (ΔH0) of the reaction is compensated by pre-forming the bioactive conformation thereby improving the entropy (ΔS0), known as S/H compensation. Modifications of the molecule that also stabilize the core structure, further improve ΔS0 and binding activity. To improve ΔH0, second site interactions were explored. To address the requirements for P and L-selectins, interactions were combined for both carbohydrate and sulfate-binding domains to produce heterobifunctional molecules. By stabilizing the bioactive core and exploring second site molecular interactions, we have produced a family of pan-selectin antagonists, one of which (GMI-1070) is now in development and scale-up synthesis as a lead compound. GMI-1070 is a potent inhibitor of E, P, and L-selectins in vitro and inhibits E and P-selectin-mediated leukocyte adhesion to endothelial monolayers under flow conditions. More importantly, GMI-1070 is active in several animal models of diseases requiring leukocyte adhesion and migration such as: a delayed-type hypersensitivity (DTH) response, cardiac ischemia/reperfusion injury, and vaso-occlusive crisis in sickle cell disease. GMI-1070 significantly inhibited infarct size in an ischemia/reperfusion cardiac injury model in rats. A single dose at 10mg/kg gave maximal inhibition. The effects of GMI-1070 on T-cell migration was studied in a DTH model. Mice were sensitized with oxazolone on the abdomen and then, 7 days later challenged on the ear. Donors T-cells from a different cohort of similarly sensitized mice were fluorescently labeled and injected into the test cohorts at the time of administration of GMI-1070. Three hours following injection, migration of fluorescent T-cells to the challenged area was determined. Selectin-dependent T-cell migration in the DTH response was completely eliminated with a dose of 10mg/kg of GMI-1070, suggesting the potential clinical application in diseases involving skin homing T-cells such as graft vs. host disease (GVHD) after bone marrow transplantation, and other inflammatory skin diseases. We have also shown that acute myelogenous leukemia (AML) cells adhere to endothelial cells under flow in a selectin-dependent mechanism suggesting that graft vs. leukemia as well as graft vs. host may be affected by treatment with GMI-1070. GMI-1070 was also tested in a model of vaso-occlusive crisis in sickle cell disease using Berkeley sickle cell mice. Blood flow was restored to normal values and adhesion of sickle red blood cells to adherent leukocytes was essentially eliminated as determined intravital microscopy using a dose of 20mg/kg administered at the time of elicitation of the vaso-occlusive challenge (TNFα) and at the start of intravital microscopy (70 minutes later). Based on the encouraging results in disease models, we are advancing the clinical development of GMI-1070 into Phase 1 studies to support indications which include the treatment of sickle cell patients in vaso-occlusive crisis.

Author notes

Disclosure:Employment: All authors under address 1 are employed by GlycoMimetics Inc. Consultancy: Both Paul Frenette and Beat Ernst are consultants to GlycoMimetics Inc. Ownership Interests: All authors under address 1 own stock in GlycoMimetics Inc. Beat Ernst also owns stock in GlycoMimetics Inc. Research Funding: Research funding is supplied to address’s 2 and 3 by GlycoMimetics Inc. Membership Information: John Magnani is a member of the Board of Directors of GlycoMimetics Inc.