(Adds details on trial, share movement)
Nov 21 (Reuters) - Cytokinetics Inc said on Tuesday it would discontinue developing its drug to treat ALS, a fatal neuro-degenerative disorder, after the treatment failed in a late-stage trial.
The company's shares tumbled about 37 percent to $7.05 in premarket trading.
Cytokinetics said the drug's, tirasemtiv, ability to slow vital capacity, or the volume of air expelled from the lungs without force, in patients with amyotrophic lateral sclerosis, was not statistically significant when compared with a placebo.
While there were no new safety and tolerability issues, more patients who were given tirasemtiv discontinued the study than those given a placebo, Cytokinetics said.
The drugmaker said it would now shift its focus on its other ALS treatment, CK-2127107, which it is developing in collaboration with Astellas Pharma Inc.
Cytokinetics Chief Executive Robert Blum said he believes that the limitations of tirasemtiv will be addressed in CK-2127107.
"We believe CK-2127107 will be better tolerated and potentially more effective than tirasemtiv in patients with ALS," he said.
According to the ALS Association, more than 6,000 people in the United States are diagnosed with the disease each year. (Reporting by Divya Grover in Bengaluru; Editing by Savio D'Souza)