Analysts brand Huntington's trial 'underwhelming' as Sage no closer to proving dalzanemdor's efficacy

It remains to be seen whether Sage Therapeutics’ dalzanemdor can improve function in patients with Huntington's disease. While a phase 2 trial has clarified the science around cognitive decline in patients with the neurodegenerative disorder, analysts have labeled the data on the drug itself as “underwhelming.”

The company has lined up the NMDA receptor positive allosteric modulator for four midstage trials across Alzheimer’s, Huntington’s and Parkinson’s diseases, which are all set to read out this year. The first study didn’t deliver the goods in April, failing to show an improvement in cognitive performance among patients with Parkinson’s.

The latest top-line results, which come from the phase 2 SURVEYOR study in Huntington’s, was never statistically powered to detect whether dalzanemdor can improve cognitive performance. Instead, the study aimed to use six cognitive tests, known collectively as HD-Cognitive Assessment Battery (HD-CAB), to demonstrate a difference in the cognitive ability of 40 patients with the neurodegenerative disease compared to 29 healthy individuals also enrolled in the trial.

Once this main objective was successfully completed, the biotech then treated the Huntington’s disease patients with dalzanemdor or placebo for 28 days. Here, it noticed a “small numerical difference” observed between patients who received dalzanemdor or placebo when measured by HD-CAB.

“Other prespecified analyses suggested the potential for directionally positive signals in a number of individual component tests of the HD-CAB and in some functional assessments,” the company added. “Additional work is ongoing to further analyze and understand the data including the relationship of changes in cognition to changes in function.”

Sage described dalzanemdor as being generally well tolerated in the trial and said no new safety signals were observed. Eleven of the participants with Huntington’s disease experienced treatment-emergent adverse events, of which the “vast majority” were mild to moderate in severity and none of which led to discontinuations.

Safety aside, the nature of today’s trial results mean that dalzanemdor is yet to have any phase 2 data to really shout about, after the drug failed the midstage PRECEDENT trial in Parkinson’s two months ago. In a note this morning, analysts at William Blair described the latest results as “underwhelming.”

“While a small numerical change was observed on the HD-CAB between placebo and HD participants, we remain cautious on the asset and do not view the small numerical changes as definitive by any means,” they added in the April 24 note.

Judging by Sage’s stock price, which remained around the $10.90 mark in premarket trading this morning, investors are unmoved by this morning’s results.

“While symptoms of cognitive impairment can precede motor symptoms by up to 15 years, it is a historically underrecognized aspect of HD and there are no approved treatments for cognitive impairment in HD,” Sage Chief Medical Officer Laura Gault, M.D., Ph.D., said in this morning’s release. “The findings from the SURVEYOR study highlight the extent of cognitive impairment associated with HD and enhance our collective understanding of this devastating disease.”

To see whether dalzanemdor can succeed in Huntington’s, which Sage describes as its “potential lead indications,” investors and analysts will have to wait for the results of the phase 2 DIMENSION study. Both DIMENSION and the LIGHTWAVE trial in Alzheimer’s are due to read out this year.

The biotech has already dropped its Parkinson’s ambitions for the drug after seeing the PRECEDENT results.