Synairgen loses half its value as AstraZeneca dumps drug

British biotech firm Synairgen lost nearly half its value on Thursday as partner AstraZeneca pulled the plug on an experimental drug designed to help patients fight common cold viruses.

AstraZeneca announced the decision to discontinue development of the inhaled interferon therapy, licensed from Synairgen, alongside its quarterly results.

The drugmaker had hoped to develop the medicine for vulnerable patients with asthma and chronic lung disease, but it will now return rights to the product, known as AZD9412, to Synairgen.

Synairgen had licensed the drug to AstraZeneca in 2014 in a deal worth $232 million. Serious doubts about the product emerged in October 2016, however, when AstraZeneca stopped a mid-stage clinical study.

Synairgen shares were down 47 percent by 1000 GMT, valuing the group at around 12.5 million pounds ($16 million).

($1 = 0.7751 pounds)

(Reporting by Ben Hirschler; editing by Jason Neely)