Cytokinetics' pipeline tumble continues after ALS med flops in phase 3 interim look

Cytokinetics' commercial ambitions met another late-stage stonewall, with the company’s amyotrophic lateral sclerosis (ALS) prospect coming up short when investigators took a look under the clinical hood. 

The heart-focused company says that its ALS candidate, reldesemtiv, was ineffective in a phase 3 trial compared to placebo after a second interim analysis, according to an announcement Friday. The data monitoring committee recommended that the trial be discontinued and Cytokinetics says it will stop treating people with the drug, including patients in the open-label extension. 

The company was “extremely disappointed” and will “assess next steps relating to our neuromuscular development programs” in the coming months, CEO Robert Blum said in the release.

Reldesemtiv’s somber finale marks the end of a difficult clinical road. The med was the byproduct of a joint collaboration between Cytokinetics and Astellas Pharma but failed a phase 2 trial in 2019, unable to beat placebo in a test of lung function. Astellas later axed a separate, but related, deal between the two companies worth more than $450 million in biobucks. 

The phase 3 trial randomized 460 patients, 200 of which had reached the 24-week point for analysis. The primary endpoint was the change from baseline to week 24 on a functional ALS score, while the secondary endpoints included a combined ranking of ALS score, time to onset of respiratory inefficiency and survival. The company said no improvement was seen in treated patients compared to placebo on either the primary endpoint or key secondary endpoints. 

The news comes about a month after the company’s lead cardiac med omecamtiv mecarbil received a thumbs down from the FDA as a heart failure treatment. In December, FDA advisors voted against the risk-benefit profile of the med, knocking down the company’s argument that the treatment had value for a specific subset of patients.

Regulators suggested that Cytokinetics try again with another late-stage trial but that doesn’t appear to be on the cards. The company will instead focus on aficamten, an oral small molecule cardiac myosin inhibitor that’s currently in a phase 3 trial as an add-on therapy for patients with symptomatic obstructive hypertrophic cardiomyopathy. The trial is expected to enroll 270 people and recruitment is ongoing.