Aptinyx fails phase 2 pain test, sparking stock crash

Data from an exploratory phase 2 trial of NYX-2925 in fibromyalgia are due in the first half of the year. (Getty Images)

A phase 2 trial of Aptinyx’s NYX-2925 has missed its primary endpoint in patients with painful diabetic peripheral neuropathy (DPN). The failure wiped two-thirds off the value of Aptinyx, which went public last year with a $118 million IPO.

Aptinyx, a spinout from Naurex, pulled in the IPO haul on the back of optimism about the potential of its NMDA receptor modulators to treat neurological disorders. As the most advanced candidate in Aptinyx’s pipeline, NYX-2925 is an important waypost to whether the Illinois-based startup can justify that optimism. 

Investigators enrolled 300 patients with painful DPN in the phase 2 and randomized them to receive one of three doses of NYX-2925 or placebo. Aptinyx hoped to link treatment with four weeks of daily oral doses of NYX-2925 to improved scores on a pain scale.

None of the doses of NYX-2925 performed statistically better than placebo. To compound matters, no dose response was seen against the primary endpoint. The middle 50 mg dose performed the best numerically, delivering a bigger reduction in pain scores than the 200 mg dose. Patients in the 50 mg arm improved by 1.61 points on the 10-point scale, compared to a 1.23 benefit in the placebo cohort.

Faced with the wipeout, Aptinyx latched onto small positives, highlighting data from a pre-specified subpopulation while noting that the 50 mg dose “showed the most meaningful improvements across multiple measures” and was still improving pain scores at the end of the four-week study.

Aptinyx’s problem is that NYX-2925 performed statistically no better than placebo during the study. Despite that, Aptinyx continues to think that NYX-2925 has a future in the treatment of chronic pain.

“Coupled with the positive evidence of biological activity relevant to central pain processing from our recently announced interim analysis of a fibromyalgia study, we believe the total body of clinical data indicates the potential of NYX-2925 to treat chronic pain. We will continue to interrogate the full dataset to determine the most appropriate path forward for NYX-2925 in development for chronic pain,” Aptinyx CEO Norbert Riedel said in a statement.

Investors took a bleaker view of the situation, wiping two-thirds off the value of the company’s stock. Aptinyx’s schedule of readouts gives it a chance to bounce back quickly from the setback. Data from an exploratory phase 2 trial of NYX-2925 in fibromyalgia are due in the first half of the year.