Daiichi Sankyo Company, Limited announced that the primary endpoint has been achieved from ESAX-HTN study (phase 3 pivotal study of non-steroidal, selective novel mineralocorticoid receptor (MR) blocker, esaxerenone (INN; code name: CS-3150), for patients with essential hypertension in Japan.

ESAX-HTN study is a double blind study of esaxerenone to evaluate efficacy and safety compared to eplerenone in patients with essential hypertension in Japan. Preliminary and ongoing analyses indicated no significant safety concerns in the ESAX-HTN study. The detailed study results will be disclosed at a future scientific meeting.

In March 2006, Daiichi Sankyo and Exelixis entered into a research collaboration agreement to discover, develop and commercialize novel therapies targeted for MR. Under the terms of the agreement, Daiichi Sankyo has exclusive development, manufacturing and commercialization rights for the compounds worldwide.

Esaxerenone is one of the in-licensed compounds identified during the research collaboration with Exelixis, and has subsequently been developed by Daiichi Sankyo.

The phase 3 pivotal study, ESAX-HTN is, a randomized, double-blind, 3-arm, parallel group comparison study with eplerenone as active control in patients with essential hypertension in Japan. The primary endpoint is sitting systolic blood pressure (SBP) / diastolic blood pressure (DBP) change from baseline after 12-week treatment, and the secondary endpoint is mean 24 hour SBP/DBP change from baseline after 12-week treatment. 1,001 patients were randomized at 44 clinical sites in Japan.

Esaxerenone is an orally administered, non steroidal, selective blocker of MR. Binding of aldosterone to MR plays a central role in the regulation of plasma sodium (Na+), extracellular potassium (K+) and arterial blood pressure by acting on the collecting ducts in nephrons. In the phase 2, double blind, placebo-controlled dose finding study with essential hypertension patients in Japan, 2.5mg/day and 5mg/day of esaxerenone showed significant reduction compared to placebo in sitting SBP/DBP. As recently reported, aldosterone is regarded as a potent mediator of organ damage. Esaxerenone may have a role in preventing these organ damaging effects.