Background:

Ki : 13 and 20 nM for human and rat EP4, respectively

CJ-023423 is an EP4 receptor antagonist.

Prostaglandin E2 (PGE2) can activate 4 E prostanoid (EP) receptors, namded EP1-4. EP4, a Gs protein-coupled receptor, plays key roles in cancer, bone formation and resorption, as well as atherosclerosis by elevating the second messenger cAMP.

In vitro: In vitro, CJ-023,423 was able to inhibit [(3)H]PGE(2) binding to both human and rat EP(4) receptors. CJ-023,423 was found to be highly selective for the human EP(4) receptor over other human prostanoid receptor subtypes. CJ-023,423 also inhibited PGE(2)-evoked elevation in intracellular cAMP at the human and rat EP(4) receptors with pA(2) of 8.3 and 8.2 nM, respectively [1].

In vivo: In vivo, po administration of CJ-023,423 could significantly reduce the thermal hyperalgesia that was induced by i.p. injection of PGE(2). CJ-023,423 was also effective in models of acute and chronic inflammatory pain. In addition, CJ-023,423 was able to significantly reduce mechanical hyperalgesia in the carrageenan model. Furthermore, CJ-023,423 reversed complete Freund's adjuvant-induced chronic inflammatory pain response significantly [1].

Clinical trial: A study of the effect of CJ-023,423 on the incidence of stomach ulcers has been completed but no result is release. Another phase II trial of CJ-023,423 in advanced solid tumors is proposed [https://clinicaltrials.gov/ct2/results term=CJ-023423&Search=Search].

Reference:
[1] Nakao, K. ,Murase, A.,Ohshiro, H., et al. CJ-023,423, a novel, potent and selective prostaglandin EP4 receptor antagonist with antihyperalgesic properties. Journal of Pharmacology and Experimental Therapeutics 322(2), 686-694 (2007).