Daiichi upbeat on drug to prevent strokes and clots

TOKYO Feb 21 (Reuters) - Japan's Daiichi Sankyo Co Ltd (4568.T) said on Thursday it was highly satisfied with mid-stage results for a key drug to prevent strokes and clots, and would move on to late-stage trials despite fierce competition in the field.

It also said it would aim to seek approval for a diabetes drug candidate in 2011, hoping to prove its superiority to market leader Actos, but it offered little news on closely watched blood thinner prasugrel, which it recently submitted for approval with partner Eli Lilly (LLY.N).

Daiichi Sankyo is one of several drug makers racing to develop alternatives to warfarin, used for decades to prevent strokes in people with atrial fibrillation -- or irregular heartbeat -- and prevent blood clots after orthopaedic surgery.

Warfarin, sold by Bristol-Myers Squibb Co. (BMY.N) under the brand name Coumadin but now widely available as a generic medicine, is notoriously difficult to tolerate due to its interactions with food and other medicines, and needs constant monitoring.

The potential market size for the drug class, known as Factor Xa drugs, is by seen by some as $5 billion-plus, and Daiichi Sankyo global R&D head John Alexander believes the company is running third behind rivals in terms of clinical trial progress.

A once-daily pill called rivaroxaban, being developed jointly by Bayer AG BAYG.DE and Johnson & Johnson (JNJ.N), is believed to be the furthest along, followed by Bristol-Myers Squibb Co (BMY.N) and Pfizer's (PFE.N) apixaban.

Domestic rival Astellas Pharma (4503.T) is also developing a rival drug called YM150 and privately held Boehringer-Ingelheim is working on a drug with a different mechanism but which would compete in the same market.

"There is a lot of competition but it is a massive market and we expect the number of patients to increase. We're aiming to develop the best-in-class drug," said Kazunori Hirokawa, an R&D executive officer at Daiichi Sankyo.

The company has completed Phase IIb trials for the experimental medicine DU-176b for patients with total hip replacement and total knee replacement but has not disclosed a timetable for Phase III studies.

Phase IIb studies for patients with atrial fibrillation are ongoing and a Phase III study for those patients is due to begin around September.

Alexander at Daiichi Sankyo said its development lag behind Bayer and Johnson & Johnson could be partly explained by caution on finding the right dosing levels.

"The big question is have they got the dosing right?" he said, saying it was clear that doses for some drugs needed to be adjusted for different patients.

Daiichi Sankyo also revealed it was aiming to seek approval for diabetes drug candidate CS-011 in 2011 after it showed superior efficacy and a similar safety profile to market leader Actos, which is made by Takeda Pharmaceutical Co Ltd (4502.T).

Actos has benefited greatly since a U.S. analysis linked rival Avandia, made by GlaxoSmithKline (GSK.L) (GSK.N), to a higher risk of heart attack last year.

The development timeline means CS-011 would not reach the market before Actos loses its U.S. patent protection in 2011 but executives said that as they were aiming to achieve superior efficacy over Actos, there was still a significant market opportunity. (Editing by Michael Watson)