Arthritis, lupus and asthma data a shot in arm for AstraZeneca

(Adds detail on asthma drugs)

LONDON, May 12 (Reuters) - AstraZeneca (NYSE: AZN - news) , fighting a $106 billion bid approach from Pfizer (NYSE: PFE - news) , received a fillip on Monday as four experimental drugs for rheumatoid arthritis, lupus and asthma showed promising results in mid-stage clinical trials.

Mavrilimumab produced a rapid improvement in signs and symptoms of rheumatoid arthritis, while sifalimumab reduced disease activity in patients with lupus in Phase IIb tests, the drugmaker said.

Benralizumab and tralokinumab both showed improvements in control of asthma in patients with specific, severe forms of the breathing disorder.

All the drugs are being developed by MedImmune, the U.S.-based biotech company acquired by AstraZeneca in 2007 that is responsible for many of the more promising compounds in the British company's pipeline.

The four drugs were among those highlighted by AstraZeneca (EUREX: AZNF.EX - news) management in a presentation last week, designed to prove the group had a bright future as an independent concern. (Reporting by Ben Hirschler; Editing by David Goodman)