Astellas Discontinues Development Of Factor Xa Inhibitor Darexaban

TOKYO - There is one less oral Factor Xa inhibitor vying for approval after Astellas Pharma Inc. announced it discontinued global development of darexaban for all indications. Unable to find a partner to co-develop the compound, Astellas is bowing out of the anticoagulant space.

The compound has been in limbo since Japan's Pharmaceuticals and Medical Devices Agency requested additional data for an NDA for prevention of venous thromboembolism in February. Astellas withdrew the application and announced it would seek a development and commercialization partner for the drug. The company said PMDA's request for additional data was related to the scope of patient registration rather than a concern about safety data.

But later in the year, trial results were posted that put the drug's risk-benefit profile into question. Results of a Phase II RUBY-1 trial disclosed in August showed increased bleeding in acute coronary syndrome patients compared to placebo.

With 9,000 patients already enrolled in darexaban trials, Astellas indicated to analysts in May that the company was in discussions with at least two potential collaborators (Also see "Astellas Fortifies Vesicare And Mirabegron; Looks For Organic Growth In Emerging Markets" - Scrip, 13 May, 2011.).

But there is already a crowded field of Factor Xa inhibitors either already approved or nearing approval, and Astellas could not find a partner willing to commit to the compound, which was in various Phase IIB or Phase III studies, and at least five years away from approval for the indication of stroke prevention.

The company acknowledged the "intensified competition" for darexaban in the novel anticoagulant space, which includes Bristol-Myers Squibb Co.'s apixaban, Boehringer Ingelheim GMBH's Pradaxa (daigatran) and Bayer AG's Xarelto (rivaroxaban).

Fellow Japanese company Daiichi Sankyo Co. Ltd. launched its own oral Factor Xa inhibitor edoxaban in Japan in July for prevention of post-surgery thromboembolism, a marginal market, with 10-year peak sales of $6.5 million. The company is currently conducting a 21,000-patient Phase III trial for the much larger market of stroke prevention in atrial fibrillation patients (Also see "Daiichi Sankyo's Edoxaban Enters Its First Market; Eisai "Very Pleased" With Eribulin Japanese Price Listing" - Scrip, 20 Jul, 2011.).

Astellas indicated to PharmAsia News that it has no further intentions to pursue anticoagulants, saying it is "very much unlikely" that the company will develop another compound or look for in-licensing opportunities for anticoagulants. The company has no other cardiovascular compounds in its development pipeline.

Instead, the company will continue its focus on its three core therapeutic areas: urology, oncology, and transplantation/immunology/infectious diseases.

Astellas launched overactive bladder treatment Betanis (mirabegron) in Japan in September, the first market for the drug, which the company forecasts to have blockbuster potential.

Daniel Poppy ([email protected])

[Editor's note: This article appears courtesy of PharmAsiaNews.com, Elsevier Business Intelligence's source for Asian biotech and pharmaceutical news. Register for a 30-day risk free trial - no credit card required.]