Cytokinetics Reports ALS Candidate Fails in Phase 3 Trial

Rare Daily Staff

Cytokinetics said that will discontinue the phase 3 trial of reldesemtiv for the treatment of amyotrophic lateral sclerosis after the Data Monitoring Committee found to effect on primary or key secondary endpoints.

In a second planned interim analysis, the Data Monitoring Committee reviewed unblinded data from COURAGE-ALS and recommended the discontinuation of the clinical trial due to futility, as it found no evidence of effect in patients treated with reldesemtiv relative to placebo on the primary endpoint of change from baseline to 24 weeks in ALSFRS-R or in key secondary endpoints. Besides ending the COURAGE-ALS study, Cytokinetics plans to discontinue treatment with reldesemtiv in all patients including those in the open-label extension study.

“We are extremely disappointed with this outcome and would like to thank the people with ALS, caregivers, investigators and clinical trial staff for their participation in COURAGE-ALS,” said Robert Blum, Cytokinetics’ CEO and president. “In the coming months, we will assess next steps relating to our neuromuscular development programs.”

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that afflicts approximately 27,000 people in the United States and a comparable number of patients in Europe. Approximately 6,300 new cases of ALS are diagnosed each year in the United States. The average life expectancy of a person with ALS is approximately two to four years and only approximately 10 percent of people with ALS survive for more than 10 years. Death is usually due to respiratory failure because of diminished strength in the skeletal muscles responsible for breathing. Few treatment options exist for these patients, resulting in a high unmet need for new therapies to address functional deficits and disease progression.

Skeletal muscle contractility is driven by the sarcomere, the fundamental unit of skeletal muscle contraction and a highly ordered cytoskeletal structure composed of several key proteins. Skeletal muscle myosin is the motor protein that converts chemical energy into mechanical force through its interaction with actin. A set of regulatory proteins, which includes tropomyosin and the troponin complex, make the actin-myosin interaction dependent on changes in intracellular calcium levels. Reldesemtiv is an investigational, selective, small molecule fast skeletal muscle troponin activator that is designed to slow the rate of calcium release from the regulatory troponin complex of fast skeletal muscle fibers, which sensitizes the sarcomere to calcium, leading to an increase in skeletal muscle contractility.

The second interim analysis was triggered 24 weeks after at least one third of the planned sample size was randomized in COURAGE-ALS. At the interim analysis, approximately 460 patients had been randomized and over 200 had reached the 24-week assessment of the trial endpoints. This interim analysis assessed the primary and key secondary endpoints for potential futility as well as provided for a potential fixed increase in total enrollment, if it had been deemed necessary to augment the statistical power of the trial, or to continue the trial to its conclusion as planned. Cytokinetics intends to notify all regulatory agencies and clinical trial investigators involved in COURAGE-ALS of these interim findings. The full data set from this trial is being analyzed and more details will be presented at an upcoming medical meeting.

COURAGE-ALS was a phase 3, multi-center, double-blind, randomized, placebo-controlled trial of reldesemtiv designed to enroll approximately 555 patients with ALS. Patients were randomized 2:1 to receive 300 mg of reldesemtiv or matching placebo dosed orally twice daily for 24 weeks, followed by a 24-week period in which all patients received 300 mg of reldesemtiv twice daily. Eligible patients were within the first two years of their first symptom of muscle weakness, had a vital capacity of ≥65 percent predicted, and a screening ALS Functional Rating Scale – Revised (ALSFRS-R) ≤44. Patients taking stable doses of edaravone and/or riluzole were permitted to enroll, and randomization was stratified accordingly. The primary efficacy endpoint was change from baseline to 24 weeks in ALSFRS-R. Secondary endpoints included combined assessment of ALSFRS-R total score, time to onset of respiratory insufficiency and survival time up to week 24 using a joint rank test; change from baseline to 24 weeks for vital capacity; ALSAQ-40; and bilateral handgrip strength. The trial included two planned unblinded interim analyses conducted by the Data Monitoring Committee. The first interim analysis assessed for futility, 12 weeks after approximately one-third or more of the planned sample size were randomized. The second interim analysis assessed for futility with the option for a fixed increase in total enrollment, if it had been deemed necessary, to augment the statistical power of the trial.