Cytokinetics Pivots to Another ALS Drug After Phase 3 Failure

Cytokinetics’ bid to offer a new drug for amyotrophic lateral sclerosis (ALS) was dealt a setback after the company’s lead experimental treatment for the disease failed in a late-stage clinical trial.

The results mean the end for tirasemtiv, one of the drugs furthest along in clinical development for the muscle-weakening condition also known as Lou Gehrig’s disease. South San Francisco, CA-based Cytokinetics (NASDAQ: [[ticker:CYTK]]) says it will now shift its focus to a second experimental ALS drug in mid-stage clinical studies.

Investors frowned on the clinical trial failure, sending Cytokinetics’ stock price down more than 34 percent to $7.24 per share Tuesday morning.

ALS has no cure and few treatments. The disease progressively robs patients of the use of their muscles, including the skeletal muscles used in breathing. Patients usually die from respiratory failure. For years, the only approved ALS treatment was the now generic riluzole. Originally developed by French company Rhone-Poulenc Rorer, now a part of Sanofi (NYSE: [[ticker:SNY]]), the drug received FDA approval in 1995. In May, the U.S. regulator approved edaravone (Radicava), a drug developed by Japan’s Mitsubishi Tanabe Pharma. Both drugs are meant to slow the progression of ALS symptoms.

Cytokinetics aimed to help ALS patients breathe. The drug was developed to improve the contraction of skeletal muscles in the lungs. Cytokinetics tested the drug in a Phase 3 trial that enrolled 743 patients, according to clinicaltrials.gov. In the results released Tuesday, the company said patients treated with its drug did not show enough of a change in the amount of air that they could blow slowly, a measure called slow vital capacity. While patients receiving mid- and high doses of the drug showed the greatest changes in lung function compared to those given a placebo, the company says those differences were not statistically significant.

No new safety or tolerability problems were reported with tirasemtiv. But Cytokinetics did report that compared to the placebo group, more of the patients given the Cytokinetics drug dropped out of the study due to their inability to tolerate the drug. In Phase 2 studies, the most common side effect reported was dizziness. Cytokinetics plans to present results from the tirasemtiv clinical trial on Dec. 8 during the International ALS/MND Symposium in Boston.

Cytokinetics has another shot at treating ALS. In a prepared statement, CEO Robert Blum said the company believes that a second drug, CK-2127107, will be better tolerated by patients, and potentially more effective than tirasemtiv. Cytokinetics says results from a Phase 2 trial are expected next year.

Besides Cytokinetics, few companies have advanced their experimental ALS therapies as far as late-stage clinical trials. Hackensack, NJ-based Brainstorm Cell Therapeutics (NASDAQ: [[ticker:BCLI]]) and AB Science of France remain in Phase 3 studies for their respective drugs, according to the ALS Therapy Development Institute.

Public domain photo of Lou Gehrig by Wikimedia Commons.