LONDON (Reuters) - AstraZeneca (AZN.L) said on Wednesday its experimental lung drug PT003 for chronic lung disease had proved successful in two final-stage Phase III trials, boosting hopes for the company's respiratory pipeline.

The drug, which AstraZeneca acquired after buying Pearl Therapeutics two years ago, combines a long-acting beta-2 agonist (LABA) and a long-acting muscarine antagonist (LAMA). AstraZeneca plans to file PT003 for approval commencing in 2015.

Rival firms also have LAMA/LABA drugs that are more advanced than PT003, but AstraZeneca's drug is administered with a pressurised meter-dose inhaler instead of a dry-powder inhaler, which may suit elderly patients in particular.

(Reporting by Ben Hirschler, editing by Louise Heavens)