Compound 43(Eshelman School of Pharmacy)

There is increasing interest in developing FPR2 agonists (compound 43, ACT‐389949 and BMS‐986235) as potential pro‐resolving therapeutics, with ACT‐389949 and BMS‐986235 having entered phase I clinical development. FPR2 activation leads to diverse downstream outputs. ACT‐389949 was observed to cause rapid tachyphylaxis, while BMS‐986235 and compound 43 induced cardioprotective effects in preclinical models. We aim to characterise the differences in ligand‐receptor engagement and downstream signalling and trafficking bias profile.

Concentration‐response curves to G protein dissociation, β‐arrestin recruitment, receptor trafficking and second messenger signalling were generated using FPR2 ligands (BMS‐986235, ACT‐389949, compound 43 and WKYMVm), in HEK293A cells. Log(τ/KA) was obtained from the operational model for bias analysis using WKYMVm as a reference ligand. Docking of FPR2 ligands into the active FPR2 cryoEM structure (PDBID: 7T6S) was performed using ICM pro software.

Bias analysis revealed that WKYMVm and ACT‐389949 shared a very similar bias profile. In comparison, BMS‐986235 and compound 43 displayed approximately 5‐ to 50‐fold bias away from β‐arrestin recruitment and trafficking pathways, while being 35‐ to 60‐fold biased towards cAMP inhibition and pERK1/2. Molecular docking predicted key amino acid interactions at the FPR2 shared between WKYMVm and ACT‐389949, but not with BMS‐986235 and compound 43.

In vitro characterisation demonstrated that WKYMVm and ACT‐389949 differ from BMS‐986235 and compound 43 in their signalling and protein coupling profile. This observation may be explained by differences in the ligand‐receptor interactions. In vitro characterisation provided significant insights into identifying the desired bias profile for FPR2‐based pharmacotherapy.