Exelixis, Inc., a biopharmaceutical company, announced that its partner Daiichi Sankyo Company, Limited has initiated a phase 3 pivotal trial to evaluate CS-3150 (esaxerenone (r-INN)), an oral, non-steroidal, selective mineralocorticoid receptor antagonist, as a treatment for essential hypertension in Japanese patients. As a result of Daiichi Sankyo enrolling the first patient in the programme’s phase 3 pivotal trial, Exelixis is eligible for a $15 million milestone payment, which it expects to receive in the fourth quarter of 2016.

In March 2006, Daiichi Sankyo and Exelixis entered into a research collaboration agreement to discover, develop and commercialize novel therapies targeting the mineralocorticoid receptor. Under the terms of the agreement, Daiichi Sankyo has exclusive global development, manufacturing, and commercialization rights for the compounds. CS-3150 is one of the compounds identified during the research collaboration, and has subsequently been developed by Daiichi Sankyo.

The ESAX-HTN phase 3 pivotal trial is a randomized study of CS-3150 versus eplerenone in Japanese hypertensive patients. The trial will enroll an estimated 930 patients into three treatment arms: 2.5 mg and 5 mg doses of CS-3150, and 50 mg of eplerenone. The eighteen-week trial includes a four week washout period, twelve week study period and two week follow-up period. Among other inclusion criteria, to participate in the trial patients must be classified as hypertensive with systolic blood pressure between 140-180 mmHg, diastolic blood pressure between 90-110 mmHg and a mean 24-hour blood pressure reading greater than 130/80 mmHg. The primary objective is to evaluate the antihypertensive effect and safety of CS-3150 2.5 mg once daily compared to eplerenone; a secondary objective is to evaluate the effectiveness of the 2.5 and 5 mg doses of CS-3150.

In addition to ESAX-HTN, Daiichi Sankyo is sponsoring six smaller phase 3 clinical trials of CS-3150 in specific populations of patients with hypertension, either as monotherapy or in combination with other therapies used to treat the condition. The largest of these trials, Study J302, has been active since March 2016 and is a long-term, open-label study to evaluate the efficacy and safety of CS-3150 in 360 patients with essential hypertension, including forms that cannot be controlled by angiotensin II receptor blockers (ARB) or angiotensin converting enzyme (ACE) inhibitors. Another study in the programme, J306, will evaluate the efficacy and safety of CS-3150 as an add-on to ARB or ACE inhibitor therapy in patients with hypertension and type 2 diabetes with albuminuria, a population for whom eplerenone is contraindicated.

“We are pleased to see our partner Daiichi Sankyo continue to advance CS-3150 through clinical development and into a well designed phase 3 pivotal trial in Japanese patients with essential hypertension,” said Michael M. Morrissey, Ph.D., president and chief executive officer of Exelixis. “While our strategic partners devote their time and resources to progressing out-licensed Exelixis-discovered compounds, our internal team is focused on continuing to build a global franchise for cabozantinib and participating meaningfully in the commercialization of cobimetinib in the United States.”

Daiichi Sankyo’s decision to take CS-3150 into phase 3 clinical development was guided by results from multiple phase 2 trials, including data from a randomized, placebo-controlled double-blind trial evaluating doses of CS-3150, and open-label eplerenone in 400 patients with hypertension. Daiichi Sankyo is currently reviewing those data in advance of potential submission for publication or presentation at a scientific forum later this year.

CS-3150 (esaxerenone (r-INN)) is an oral, non-steroidal, selective antagonist of the mineralocorticoid receptor (MR), a nuclear hormone receptor implicated in a variety of cardiovascular and metabolic diseases. MR antagonists can be used to treat hypertension and congestive heart failure due to their vascular protective effects. Recent studies have also shown beneficial effects of adding MR antagonists to the treatment regimen for Type 2 diabetic patients with nephropathy. As a non-steroidal, selective MR antagonist, CS-3150 may have potential for the treatment of hypertension, diabetic nephropathy and congestive heart failure, and may provide protection from end organ damage due to vascular complications.

CS-3150 is one of the compounds identified during Exelixis’ research collaboration with Daiichi Sankyo, which the companies entered into in March 2006. Under the terms of the agreement, Exelixis granted Daiichi Sankyo an exclusive, worldwide license to certain intellectual property primarily relating to compounds that modulate MR. In exchange, Exelixis received a $20 million upfront payment, research funding for a joint research period, and the potential for substantial clinical development, regulatory and commercialization milestone payments, as well as double-digit royalties on sales. Since the conclusion of the joint research period in November 2007, Daiichi Sankyo has been responsible for all subsequent preclinical and clinical development, and will also oversee regulatory, manufacturing and commercialization activities for the compound.

Exelixis, Inc. is a biopharmaceutical company committed to the discovery, development and commercialization of new medicines with the potential to improve care and outcomes for people with cancer.