Clene polishes tarnished ALS asset with long-term survival data

Clene has shared another cut of long-term data from its phase 2 amyotrophic lateral sclerosis (ALS) trial. The open-label extension linked a gold nanocrystal suspension to improved survival, but, with setbacks including a primary endpoint miss hanging over it, Clene’s share price remains in the basement. 

Salt Lake City-based Clene reported results from the phase 2 RESCUE-ALS trial late in 2021. The study missed its primary endpoint but, believing the study to be underpowered and seeing a trend in favor of its drug candidate, Clene continued collecting data in an open-label extension. Last summer, the biotech reported that patients initially randomized to the drug candidate, CNM-Au8, were living longer.  

The latest update shows what happened after Clene shared the first data from the open-label portion of the study. As of the latest cutoff, July 2023, median survival in the CNM-Au8 cohort was 34.2 months, compared to 14.9 months in the placebo group. The difference added up to a 75% lower risk of all-cause mortality.

Clene estimated the effect of CNM-Au8 on survival by taking data from all participants and subtracting the benefit from ex-placebo subjects who switched to the study drug for the open-label extension. The method is designed to provide a comparison of CNM-Au8 versus placebo across the entire study period. 

“The data that continues to be received from the RESCUE-ALS open label extension study is truly impressive, and now shows consistently significant decreased risk of death greater than 70% using two different long-term analysis models,” The University of Sydney’s Matthew Kiernan, Ph.D., one of the trial’s clinical advisers, said in a statement. “The survival benefit across treatment arms is linked to less worsening of disease, as experienced by ALS patients.” 

Clene’s open-label updates have failed to convince investors to overlook its earlier setbacks. In addition to the failure of the original RESCUE-ALS analysis, the biotech reported a missed primary endpoint in a second midphase trial of CNM-Au8 late last year. Clene’s share price rose 4% in premarket trading on the latest open-label data but remained stuck below $1.