(Reuters) - Synairgen Plc said its partner AstraZeneca Plc stopped a mid-stage study for testing Synairgen's drug candidate as a potential treatment for severe asthma, putting the brakes on the lead product in Synairgen's pipeline.
The drug developer's shares slumped more than a third on Wednesday to trade at 22.01 pence at 0722 GMT on the London Stock Exchange, becoming the biggest drag on the FTSE AIM Healthcare Index.
Synairgen had licensed the drug to AstraZeneca in 2014 in a deal worth $232 million. (reut.rs/2e0slma)
The company's pipeline has two more drugs, one being developed with AstraZeneca to treat chronic obstructive pulmonary disease, and the other being developed to treat a rare lung condition called idiopathic pulmonary fibrosis.
Synairgen said on Wednesday that fewer-than-expected patients had their asthma worsen in the study, making it difficult for AstraZeneca to gauge the drug's efficiency.
AstraZeneca plans to evaluate the data collected from the study with a focus on secondary goals, which could better predict when patients' asthma would worsen.
Synairgen said that full results from the study are expected in the first quarter of 2017.
AstraZeneca shares were down 1 percent at 4996 pence at 0735 GMT on the London Stock Exchange.
Reporting by Vidya L Nathan in Bengaluru; Editing by Amrutha Gayathri