Phase 2b Study Shows NMDAR Positive Allosteric-Modulator did not Achieve Statistically Significant Separation From Placebo

In a phase 2b clinical trial for N-methyl-d-aspartate receptor (NMDAR) positive allosteric-modulator (NYX-2925; Aptinyx Inc, Evanston, IL), treatment of fibromyalgia, resulted in not achieving statistically significant separation from placebo. During the trial there was assessment of change from baseline in average daily pain on the numeric rating scale (NRS) during week 12.

“We are very disappointed that, despite the evidence of activity observed in a prior biomarker study in fibromyalgia patients, in this follow-up phase 2b study NYX-2925 did not achieve statistical separation from placebo,” said Andy Kidd, MD, president and chief executive officer of Aptinyx. “We greatly appreciate the contributions made by patients, investigators, collaborators, and our dedicated Aptinyx team in the evaluation of NYX-2925’s utility in pain. The results of this study highlight the challenges of developing novel therapies for pain. As we continue to analyze the data from the study, we will focus our resources on supporting additional readouts from our pipeline in PTSD and cognitive impairment, including the readout of our phase 2 study of NYX-458 in cognitive impairment associated with Parkinson’s disease, expected in the first quarter of next year.”

Participants receiving NMDAR positive allosteric-modulator at both dose levels initially showed a trend toward clinically meaningful improvement in pain, as well as in some secondary endpoints compared with placebo by week 4. By week 12, the placebo group had improved such that, although NYX-2925 remained numerically better, the separation was not clinically meaningful. 

Following a screening period for eligibility, participants were randomized to receive oral doses of 50 mg, 100 mg, or placebo once daily over the treatment period. The trial enrolled approximately 300 participants with fibromyalgia.