Pfizer has decided to return the rights to an early-stage inhaled asthma treatment to Rigel Pharmaceuticals.

The latter company will now assume development of R343, its inhaled syk inhibitor for allergic asthma that recently completed several Phase I trials. Pfizer's departure is a result of the US giant's decision to exit the allergy and respiratory therapeutic area in terms of R&D.  

The firms originally teamed up in 2005 and in 2007, Pfizer began the first trials of R343. The initial results have not yet been published but show the drug to be well tolerated, Rigel said, "and with beneficial improvement in both the early and late-phase asthmatic responses following an allergen challenge".

Rigel expects to design a Phase II trial with R343 later this year. Chief executive James Gower said that "it is rare in our business that one has the opportunity to develop an asset which is both promising and on which the R&D has been as well done as the package that Pfizer is transferring to us".