AstraZeneca builds pipeline with $232 mln Synairgen asthma deal

* Synairgen (LSE: SNG.L - news) gets $7.25 mln now, milestones up to $225 mln

* Deal bolsters Astra's key respiratory medicine business

* Continues bolt-on dealmaking after Pfizer (NYSE: PFE - news) 's failed bid

* Synairgen shares jump 46 percent (Adds jump in Synairgen shares, more on Pfizer bid approach)

By Ben Hirschler

LONDON, June 12 (Reuters) - AstraZeneca (NYSE: AZN - news) has struck a deal worth up to $232 million in milestone payments to acquire rights to a drug from Synairgen for treating respiratory tract viral infections in patients with severe asthma.

Britain's second-biggest drugmaker - subject of a $118 billion bid by Pfizer that failed last month - said on Thursday it would pay UK-based Synairgen a $7.25 million upfront fee and potential development, regulatory and commercial milestones of up to $225 million for rights to the drug, codenamed SNG001.

The deal, which sent in shares in Synairgen surging 46 percent by 0740 GMT, marks a continuation of AstraZeneca's strategy of striking bolt-on product licensing deals in key therapeutic areas, such as respiratory medicine.

Some analysts have speculated AstraZeneca might also consider a much larger acquisition to try to see off the threat of a renewed Pfizer approach. But others believe the British firm will come under pressure from shareholders to revive talks with its larger U.S. rival.

Under British takeover law, AstraZeneca can reach out to Pfizer in late August to discuss a sweetened bid, or Pfizer (TLO: PF-U.TI - news) could make renewed overtures in November, whether it is invited back or not.

Pfizer Chief Financial Officer Frank D'Amelio, speaking to the Goldman Sachs (NYSE: GS-PB - news) annual healthcare conference on Wednesday, said talks about a deal with AstraZeneca had fallen down over price, rather than any other issues.

Synairgen's SNG001 is an inhaled interferon beta medicine that was originally invented at the University of Southampton, southern England.

AstraZeneca plans to start a mid-stage Phase IIa study with the drug in early 2015 in patients with severe asthma, building on results from an initial Phase lla trial in a broad asthma population.

Severe asthma is a growing focus for major drugmakers, which are looking to a range of novel biotech medicines to help difficult-to-treat patients.

"SNG001 is an innovative and targeted therapy that has, if successful, the potential to offer a step-change in the treatment of severe asthma, and possibly COPD (chronic obstructive pulmonary disease)," said Maarten Kraan, AstraZeneca's head of respiratory, inflammation and autoimmune medicines.

In addition to making milestone payments and covering the future development costs for SNG001, AstraZeneca will also pay tiered royalties ranging from a single-digit up to mid-teens percentage rate on any eventual commercial sales.

Synairgen shares were up 24 pence or 45 percent at 76.03p by 0749 GMT, having risen as high as 85.95p, their highest since 2006. (Editing by Paul Sandle and David Holmes)