Cytokinetics Says Goodbye to Phase 3 ALS Drug


San Francisco-based Cytokinetics has ended the development of its lead drug candidate, tirasemtiv. The biotech came to this decision when the drug, in a study of over 700 patients with amyotrophic lateral sclerosis (ALS), was unsuccessful defeating the placebo against the primary endpoint and any of the secondary goals.

The twenty-four-week study examined whether tirasemtiv, which is a fast-skeletal muscle troponin activator, would indicate greater advancements on a measure of lung capacity than a placebo. Tirasemtiv indicated the latter.

Cytokinetics did report statistical differences between the decreased vital abilities of the placebo and treatment arms, specifically among patients who were able to tolerate higher doses. The biotech still decided to scrap the drug candidate. “We have decided to suspend the development of tirasemtiv,” said Cytokinetics CEO Robert Blum.

That was a forthright decision due to complete failure of the phase 3 trial. The primary endpoint miss was the drug’s failure to defeat the placebo against any of the trial’s 48-week secondary endpoints. These endpoints examined the tirasemtiv’s effect on an ALS functional rating scale as well as muscle strength. In 2014, the drug also failed a phase 2b in ALS.

Cytokinetics’ conclusion to trash tirasemtiv was also prompted by the company’s idea that another candidate in its pipeline will address the failures of its former star asset. The canidate, CK-2127107, is also a fast-skeletal muscle activator that reported phase 1 data which revealed it offers improved tolerability and efficacy as tirasemtiv’s capability to cross the blood-brain barrier hindered its therapeutic period.

Cytokinetics presently has over $300 million in assists and the ability to drive CK-2127107 down its pipeline without needing to ask for help from its investors to get it done. Following news of the phase 3 failure, shares in the biotech dropped 27%.


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