Astellas withdraws drug application in Japan

Astellas Pharma has withdrawn the marketing application for its venous thromboembolism preventative darexaban in Japan, the first market in which it had filed the drug.

The marketing application, which was submitted in late September 2010, had been seeking approval of the oral Factor Xa direct inhibitor for the prevention of venous thromboembolism (VTE) in patients at risk, such as those undergoing orthopaedic surgical procedures in the lower limbs.

Astellas said it was withdrawing the application based on feedback from Japanese regulators that additional clinical trials would be required before the drug could be approved. The marketing application contained two phase II/III studies that compared darexaban to placebo in patients who had elective total knee or hip replacement surgeries in Japan and other Asian countries.

In addition, a North American phase II study for VTE prevention in patients after elective primary knee arthroplasty demonstrated dose-dependent efficacy in VTE prevention, according to the company.

Astellas said it will seek a partner for the development and commercialisation of darexaban for the VTE indication in the US and Europe and for an indication of stroke prevention in atrial fibrillation globally. "Astellas expects to decide future plans, including the indication of VTE in Japan, based on the outcome of the partnership discussion," the company noted.

Darexaban, which was discovered and developed by Astellas, works by directly and selectively inhibiting activated Factor X in the cascade of blood coagulation.