Journal: bioRxiv

Article Title: OKN4395, a first-in-class EP2/EP4/DP1 triple antagonist reprograms prostanoid-driven immunosuppression to restore antitumor immunity

doi: 10.64898/2026.02.08.704632

Figure Lengend Snippet: ( A ) Compound 1: lead compound from [29] with moderate dual inhibition; Compound 2. lead compound from [30] with potent EP2 inhibition; Compound 3. lead compound from [31] with potent dual EP2/EP4 inhibition. The OKN4395 series is derived from [31]. Most of the diversity in the series comes from the exploration of the right hand aryl system bearing the carboxylic acid. Compound 3 is an example of that series. ( B ) cAMP production after stimulation with PGE2 (EC80, 2nM) measured on HEK293 stable clones expressing human EP2 (hEP2). Values represent mean of n=10 technical replicates ± SEM. ( C ) cAMP production after stimulation with PGE2 (EC80, 6nM) measured on HEK293 stable clones expressing human EP4 (hEP4). Values represent mean of n=10 technical replicates ± SEM. ( D ) cAMP production after stimulation with PGD2 (EC80, 300pM) measured on CHO-K1 cells stable clone transfected for human DP1 (hDP1). Values represent mean of n=4 technical replicates ± SEM. ( E ) Visualization of OKN4395 antagonist activity at 1µM screened with gpcrMAX GPCR LeadHunter Panel (Eurofins) obtained with the plotrender spatial data mapper tool developed by gpcrdb. ( F ) Summary table of OKN4395 IC50 on human prostanoid receptors. ( G ) Plausible binding mode of a representative of OKN4395 series in DP1 (DP1: orange, ligand: green). Hydrogen bonds are yellow dashed lines.

Article Snippet: For experiment controls, the following inhibitors were used across several experiments: PF-04418948 (S7211, Selleckchem) is a selective EP2 receptor antagonist .

Techniques: Inhibition, Derivative Assay, Clone Assay, Expressing, Stable Transfection, Transfection, Activity Assay, Binding Assay

Journal: bioRxiv

Article Title: OKN4395, a first-in-class EP2/EP4/DP1 triple antagonist reprograms prostanoid-driven immunosuppression to restore antitumor immunity

doi: 10.64898/2026.02.08.704632

Figure Lengend Snippet: ( A ) cAMP production after stimulation with PGE2 (EC80) measured on HEK293 stable clones expressing EP2 or EP4 from different species or stimulation with PGD2 (EC80) measured on transfected HEK293 cells transiently expressing DP1 from different species. EC80 PGE2 concentrations are mouse EP2 (mEP2) 300pM, mouse EP4 (mEP4) 200pM, rat EP2 (rEP2) 35-45pM, rat EP4 (rEP4) 5.8-7.8pM, monkey EP2 (mkEP2) 35-40pM, monkey EP4 (mkEP4) 4.2-7.8pM, dog EP2 (dEP2) 65-80pM and dog EP4 (dEP4) 17.8-22.7pM. EC80 PGD2 concentrations are mouse DP1 (mDP1) 2.5nM, rat DP1 (rDP1) 4.4nM and monkey DP1 (mkDP1) 0.75nM. Values represent mean of n=4 (mEP2), n=6 (mEP4), n=10 (rEP2, rEP4, mkEP2, mkEP4, dEP2, dEP4), n=2 (mDP1, rDP1, mkDP1) technical replicates ± SEM. ( B ) cAMP production after stimulation with different PGE2 concentrations measured on SF295 cells (left) or BT549 cells (right) naturally expressing EP2 and EP4 receptor respectively. Values represent mean of n=2 technical replicates ± SEM. ( C ) Activation of (left) hEP1 and (middle) hEP3 after stimulation with PGE2 (EC80, 45nM and 15nM respectively) was measurement on U2OS cells and CHO-K1 cells expressing human EP1 and human EP3 respectively. (Right) cAMP production after stimulation with iloprost (EC80, 60pM) measured on HEK293 stable clones expressing hIP. Values represent mean of n=8 (hEP1, hEP3) and n=4 (hIP) technical replicates ± SEM. ( D ) Selectivity of OKN4395 (top 1µM; bottom 10µM) across 166 G protein-coupled receptors. OKN4395 activity was quantified as the percentage of the natural ligand response, with reduced activity indicating inhibition. ( E ) Superimposition of EP4 (cyan), EP2 (purple) and DP1 (green) binding sites (left). Interactions made by a representative of OKN4395 series in DP1 (right). All the main residues essential for the interactions are conserved in the three proteins. ( F ) Evolution of the distance between the carboxylate of OKN4395 and the interacting arginine residue in EP3, EP4 and DP1, showing the gradual weakening of its strength through movement of the ligand in EP3 and the stability in EP4 and DP1 (solid line: averaged across the triplicates, shaded area: standard deviation).

Article Snippet: For experiment controls, the following inhibitors were used across several experiments: PF-04418948 (S7211, Selleckchem) is a selective EP2 receptor antagonist .

Techniques: Clone Assay, Expressing, Transfection, Activation Assay, Activity Assay, Inhibition, Binding Assay, Residue, Standard Deviation

Journal: Annual review of pharmacology and toxicology

Article Title: Neuroinflammation and Disease: Pathways and Opportunities

doi: 10.1146/annurev-pharmtox-062124-043519

Figure Lengend Snippet: Pathways to inflammation mediated by EP2 and CCR2. Activation of CCR2 and EP2 receptors by their respective ligands triggers multiple intersecting biochemical pathways that converge in both the cytoplasm and nucleus to drive inflammatory gene transcription. Abbreviations: Akt, protein kinase B; AP1, activator protein 1; CCL2, chemokine ligand 2; CCR2, C-C chemokine receptor type 2; COX-2, cyclooxygenase-2; CREB, cAMP response element–binding protein; EP2, prostaglandin E2 receptor; EPAC, exchange protein directly activated by cAMP; ERK, extracellular signal–regulated kinase; IκBα, nuclear factor of kappa light polypeptide gene enhancer in B cells inhibitor alpha; IKKβ, IκB kinase; JAK, Janus kinase; MAPK, mitogen-activated protein kinase; MEK, mitogen-activated protein kinase kinase; NF-κB, nuclear factor κB; PGE2, prostaglandin E2; PI3K, phosphoinositide 3-kinase; PKA, protein kinase A; RAF, rapidly accelerated fibrosarcoma; RAS, rat sarcoma virus; STAT, signal transducer and activator of transcription. Figure created in BioRender; Varvel N. 2025. https://BioRender.com/bzee9od .

Article Snippet: Currently, the only selective EP2 antagonist to have entered clinical trials is the Pfizer compound.

Techniques: Activation Assay, Binding Assay, Virus

Journal: Annual review of pharmacology and toxicology

Article Title: Neuroinflammation and Disease: Pathways and Opportunities

doi: 10.1146/annurev-pharmtox-062124-043519

Figure Lengend Snippet: Immediate and delayed inflammatory events after seizure activity. (①) Within 30 min of seizure initiation, neuronal COX-2 is induced, producing PGE2. (②) A defective BBB allows serum proteins, including albumin, to enter the brain. BBB leakage occurs as early as 5 h postseizure . (③) Vascular smooth muscle cells, perivascular macrophages, and microglia express CCL2. (④) Monocytes enter the brain in an EP2- and CCR2-dependent manner. (⑤) Astrocytes, microglia, and monocytes contribute to an inflammatory response typified by morphological changes and secretion of immune cytokines and chemokines. (⑥) Mural pericytes detach from the BBB endothelium, further eroding the integrity of the BBB . Abbreviations: BBB, blood-brain barrier; CCL2, chemokine ligand 2; CCR2, C-C chemokine receptor type 2; COX-2, cyclooxygenase-2; EP2, prostaglandin E2 receptor subtype 2; PGE2, prostaglandin E2; RBC, red blood cell. Figure created in BioRender; Varvel N. 2025. https://BioRender.com/h30r747 .

Article Snippet: Currently, the only selective EP2 antagonist to have entered clinical trials is the Pfizer compound.

Techniques: Activity Assay