Kinase experiment:

CHO-hCX3CR1 membranes together with different concentrations of AZD8797 are incubated in 50 mM HEPES, 100 mM NaCl, 5 mM MgCl2, 10 μM GDP and 0.01% gelatin in a MicroWell 96-well plate. 0.56 μCi/mL [35S]GTPγS and EC80 of CX3CL1 are then added. The plate is incubated at 30℃ for 1 h and subsequently unbound [35S]GTPγS is separated from bound by vacuum filtration to a Printed Filtermat B. The different AZD8797 concentrations are achieved by stepwise dilution in DMSO to achieve a final DMSO concentration of 1% in all wells after addition of assay buffer, regardless of AZD8797 concentration[1].

Animal experiment:

Rats: AZD8797 is formulated in 30–35% (wt/wt) hydroxy-propyl-beta-cyklodextrin and administered s.c. through osmotic minipumps. Treatment is blinded to the operator. The plasma concentration of AZD8797 is analyzed twice from each rat[2].

AZD8797 is an allosteric non-competitive modulator of the human CX3CR1 receptor; antagonizes CX3CR1 and CXCR2 with Kis of 3.9 and 2800 nM, respectively.

In a flow adhesion assay, AZD8797 antagonizes the natural ligand, fractalkine (CX3CL1), in both human whole blood (hWB) and in a B-lymphocyte cell line with IC50 values of 300 and 6 nM respectively. AZD8797 also prevents G-protein activation in a [35S]GTPγS accumulation assay. AZD8797 positively modulates the CX3CL1 response at sub-micromolar concentrations in a β-arrestin recruitment assay. In equilibrium saturation binding experiments, AZD8797 reduces the maximal binding of 125I-CX3CL1 without affecting Kd[1]. AZD8797 binds selectively with high affinity to human and rat CX3CR1 (Ki of hCX3CR1, 4 nM; Ki of rCX3CR1, 7 nM, respectively). The equilibrium dissociation constant, KB, demonstrates that AZD8797 is a very potent inhibitor for human CX3CR1 (10 nM). The potency is threefold lower for rat CX3CR1 (29 nM) and decreases even further at mouse CX3CR1 (54 nM)[2].

AZD8797 treatment in Dark Agouti rats with myelin oligodendrocyte glycoprotein-induced EAE results in reduced paralysis, CNS pathology, and incidence of relapses. The compound is effective when starting treatment before onset, as well as after the acute phase[2].

[1]. Cederblad L, et al. AZD8797 is an allosteric non-competitive modulator of the human CX3CR1 receptor. Biochem J. 2016 Mar 1;473(5):641-9. [2]. Ridderstad Wollberg A, et al. Pharmacological inhibition of the chemokine receptor CX3CR1 attenuates disease in a chronic-relapsing rat model for multiple sclerosis. Proc Natl Acad Sci U S A. 2014 Apr 8;111(14):5409-14. [3]. Sofia Karlstro?, et al. Substituted 7-amino-5-thio-thiazolo[4,5-d]pyrimidines as potent and selective antagonists of the fractalkine receptor (CX3CR1). J Med Chem. 2013 Apr 25;56(8):3177-90.