Bayer and partner Johnson & Johnson are to speed up the clinical development programme for their anticoagulant Xarelto, accelerating late-stage trials of the potential blockbuster as a treatment for acute coronary syndrome.

The firms say they are now planning to initiate Phase III trials earlier than the previously announced date of second half of 2009, now that Phase II results of a Xarelto (rivaroxaban) study in patients with ACS have been chosen for the late-breaking clinical trial session at the American Heart Association’s meeting in New Orleans in November. The data will report the results from the ATLAS ACS TIMI 46 trial, a 3,500-patient study investigating the safety and efficacy of rivaroxaban on top of aspirin, or aspirin plus a thienopyridine versus placebo.

Xarelto, an oral Factor Xa inhibitor taken once-daily, was recently recommended for approval by the European Committee for Medicinal Products for Human Use for the prevention of venous thromboembolism in patients undergoing elective hip or knee replacement surgery. It has also been filed in the USA for that indication.

However the big bucks would come from an eventual approval for ACS and in the prevention of stroke in atrial fibrillation. Xarelto is one of the drugs, along with Bristol-Myers Squibb/Pfizer’s investigational Factor Xa inhibitor and Boehringer Ingelheim’s already-approved Pradaxa (dabigatran etexilate), an oral direct thrombin inhibitor, that is looking to challenge the market-leading position of Sanofi-Aventis’ Lovenox (enoxaparin)

B-MS and Pfizer said last week that they will not be seeking approval for apixaban in 2009, as expected, after the drug failed in a late-stage trial for the prevention of VTE in patients undergoing total knee replacement. However, it is expected that they will present more promising data on the drug on its use in ACS at the European Society of Cardiology meeting in Munich on Tuesday.