Cytokinetics, Inc. Announces Results from Benefit-ALS
April 29, 2014
At the recently completed American Academy of Neurology meetings in Philadelphia, PA Dr. Jeremy Shefner (SUNY Upstate Medical Center) presented the results of a large phase 2b study evaluating the effects of tirasemtiv, skeletal muscle activator, in patients with ALS. Benefit ALS was sponsored by Cytokinetics, Inc, the company that owns tirasemtiv and has been overseeing its development. In this trial 711 patients were enrolled, and were randomized to either tirasemtiv or placebo if they successfully completed one week of open label tirasemtiv at a dose of 250 mg/day. Over the course of the next several weeks, patients in the tirasemtiv arm had their dose increased to a maximum of 500 mg/day, and were studied every 4 weeks for a total of 12 weeks.
The primary efficacy measure was change in ALSFRS-R from baseline to the average of the values recorded at weeks 1 and 12. This measure did not show a significant benefit of tirasemtiv; in fact, treated patients did slightly worse on this measure than placebo treated patients. However, there were statistically significant and potentially meaningful benefits to tirasemtiv treatment as measured by slow vital capacity (a commonly used breathing measure) and in extremity strength. Tirasemtiv treated patients that had more adverse events and dropped out of the study more frequently than placebo patients. Among the adverse events were several GI related events; those patients with GI related events lost significantly more weight than those without, and this may have affected the ALSFRS-R scores.
While the results of this study are disappointing in that the primary efficacy endpoint did not favor tirasemtiv, this is the first large trial to show significant and positive effects of any therapy on breathing and extremity muscle strength in patients with ALS. Further studies of tirasemtiv are now being considered.
For more information, you can visit the Cytokinetics website here.