Cytokinetics Enrolls 700 ALS Patients in Phase 3 Study of Tirasemtiv

Cytokinetics recently announced that patient enrollment for its VITALITY-ALS clinical trial is now complete. The study, designed to assess the effects of tirasemtiv, a novel skeletal muscle activator, on respiratory function in ALS patients has enrolled over 700 people at 81 centers in 11 countries.

VITALITY-ALS (NCT02496767) is an international, randomized, double-blind and placebo-controlled trial in patients with possible, probable, or definite ALS. The study’s primary endpoint will measure, after 24 weeks, changes from baseline of slow vital capacity (SVC). Secondary endpoints include, among other measures of skeletal muscle strength, time to decline from baseline in percent predicted SVC by ≥ 20 percentage points, or the onset of respiratory insufficiency; time to decline from baseline in percent predicted SVC to ≤ 50 percent predicted, or the onset of respiratory insufficiency; and time to first occurrence of any use of assisted ventilation.

Patients enrolled in the trial will receive two-weeks of open-label treatment with tirasemtiv administered at 250 mg/day,  and will be then randomized to either placebo or to one of three target tirasemtiv dose levels (250 mg/day, 375 mg/day, 500 mg/day) for 48 weeks. Ttirasemtiv-treated patients will then continue for another four-week withdrawal period, randomized to either continuing receiving their current dosage or a placebo, and placebo-treated patients will continue on placebo.

At the study’s conclusion, all patients will be eligible to continue or start receiving tirasemtiv in an open-label study extension phase.

Tirasemtiv selectively activates the fast skeletal muscle troponin complex by increasing its sensitivity to calcium. In preclinical and early clinical studies, it demonstrated increases in skeletal muscle force in response to neuronal input, and delays in the onset of muscle fatigue and reductions in the degree.

“Completion of enrollment in VITALITY-ALS marks a significant milestone for Cytokinetics as well as the ALS community … advancing what could be the first potential new medicine for people with ALS in more than 20 years,” Fady I. Malik, Cytokinetics’ executive vice president, Research & Development, said in a press release. “We would like to express our thanks to the dedicated investigators and clinical site coordinators who are conducting the trial and also patients with ALS and their caregivers who are participating.”

Results from this Phase 3 study are expected in late 2017.