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ALS: Experimental Drug Tirasemtiv Fails To Show Efficacy in Phase 2b Trial


Tirasemtiv is an experimental drug being developed by biotechnology company Cytokinetics for the treatment of amyotrophic lateral sclerosis (ALS) and potentially other neuromuscular disorders. The drug is a skeletal muscle activator that increases the sensitivity of muscle fibers to calcium, thereby potentially allowing these fibers to contract even if the signal from the nervous system is weaker than normal.

South San Francisco-based Cytokinetics announced in a press release on April 25, 2014, that tirasemtiv failed to show efficacy in phase 2b trial that included 711 ALS patients. Detailed results will be presented during the 66th annual meeting of the American Academy of Neurology meeting in Philadelphia on Tuesday, April 29.

The phase 2b trial, known as BENEFIT-ALS (Blinded Evaluation of Neuromuscular Effects and Functional Improvement with Tirasemtiv in ALS), did not achieve its “primary efficacy endpoint,” which would have been a significant difference on the ALS Functional Rating Scale-Revised Version compared to a placebo, the company said in its April 25 announcement. Cytokinetics said analyses of the effects of tirasemtiv on respiratory function and other measures of skeletal muscle function produced mixed results.

“Patients with ALS desperately need new therapeutic alternatives to slow the course of their disease and loss of function,” said Robert Blum, president and CEO of Cytokinetics. “The results from BENEFIT-ALS are just now becoming available to our team at Cytokinetics and will be shared in more detail with the broader scientific and medical community focused to research in ALS in the next few days. Understanding these results will require significant review. Once we have fully evaluated the data from BENEFIT-ALS, we expect to determine whether there is a potential development path forward for tirasemtiv for the potential treatment of ALS and what may be the appropriate next steps.”

MDA did not fund this study.

MDA statement:

“Today’s news is disappointing,” said neurologist Valerie A. Cwik, M.D. executive vice president and chief medical and scientific officer at MDA. “We’re eager to see all the data to better understand why the drug failed in this large-scale trial after showing promise in earlier, smaller trials. Our organization remains committed to a deep and comprehensive portfolio of projects that will give us a better understanding of this complex disease. Currently, MDA is supporting nearly 50 ALS research projects worldwide, and we remain hopeful that research underway will lead to effective drugs for this devastating disease.”