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Aptinyx stung by pain drug’s mid-stage miss

  • Aptinyx, an Illinois-based biotech, saw its share value dive roughly 70% Wednesday morning after announcing its lead candidate failed a Phase 2 study of patients with painful diabetic peripheral neuropathy.
  • Topline results showed there wasn’t enough of a treatment difference between NYX-2925 and placebo to hit the trial’s primary endpoint, which focused on the change in patients’ average daily pain scores after four weeks of therapy.
  • The trial tested three doses of the drug — 10 mg, 50 mg and 200 mg — and found patients treated with the higher two experienced greater change in average daily pain than those taking placebo, as measured by a pain scale ranging from 0 to 10. The 50 mg dose arm experienced the largest change, with a 1.61-point reduction from baseline. Still, that wasn’t statistically significant compared to the 1.23-point reduction seen in the placebo arm.

Aptinyx built some momentum over the past year. Its chemistry platform, which centers on cell-signaling proteins called NMDA receptors, got some big pharma validation in May when Allergan acquired one of the biotech’s investigational drugs. It would go on to raise $102 million the following month through an initial public offering.
By December, the biotech was reporting positive interim data from a Phase 2 exploratory study of NYX-2925 in fibromyalgia patients. While only available for a small pool of patients, the data suggested the therapeutic candidate​ is biologically active in central pain processing.
The failure announced Wednesday, however, significantly threatens the outlook for Aptinyx moving forward.
“We don’t regard the stock as ‘dead money’ after today’s news, but do recognize that a significant part of its prior valuation is now impaired,” Leerink analyst Geoffrey Porges wrote in a Jan. 16 investor note.
If Aptinyx decides to scrap NYX-2925 in the painful diabetic peripheral neuropathy indication, then its pipeline will be mostly comprised of early-stage assets targeting harder-to-treat conditions like post-traumatic stress disorder and Parkinson’s disease. That position could cause investor sentiment to dip further.
On the other hand, Aptinyx could attempt to carry on with NYX-2925. Porges argues the best route to do that would be conducting another Phase 2 study testing just the 50 mg and 200 mg doses.
Still, the analyst noted, such a trial would be expensive and likely wouldn’t read out until 2020, aspects that might not sit well with Aptinyx’s investors. Notably, the failed Phase 2 study was Aptinyx’s largest clinical endeavor to date, enrolling 300 patients.
The company plans on presenting more detailed results from the mid-stage study at an upcoming medical meeting.
“While the study did not meet its primary endpoint, we observed improvements on multiple measures, differential activity across dose levels, and a very favorable safety profile,” the biotech’s CEO Norbert Riedel said in a Jan. 16 statement.
“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,” he added.
Aptinyx also expects to disclose data from a full analysis of the exploratory fibromyalgia study in the first half of 2019.