Aptinyx’ Losing Streak Continues as Parkinson’s Candidate Falls Short

Aptinyx’s NYX-458 fell short of the primary endpoint in a Phase II trial of patients with cognitive impairment associated with Parkinson’s disease and dementia with Lewy bodies.

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Aptinyx’s NYX-458 fell short of the primary endpoint in a Phase II trial of patients with cognitive impairment associated with Parkinson’s disease and dementia with Lewy bodies, the Illinois biotech announced Tuesday.

The company will no longer develop NYX-458.

Aptinyx will also initiate cost-cutting measures to preserve its capital while it looks for other strategic business alternatives, according to Tuesday’s press release. These measures include the termination of a Phase IIb trial of NYX-783 in post-traumatic stress disorder.

The company will conduct “early analysis of the data” generated to date for NYX-783 to identify the appropriate next steps for the candidate and explore alternative options “to support the advancement of our NMDA receptor modulation platform,” Andy Kidd, M.D., president and CEO, said in a prepared statement.

In what has become a common industry refrain, an Aptinyx spokesperson told BioSpace this program is being terminated due to capital constraints.

“In light of challenges to raising capital, the timeline for completion and readout of the full PTSD study extends beyond the point where our debt and other obligations are expected to exceed our available cash,” the spokesperson said.

Discovered through Aptinyx’s proprietary platform, NYX-458 is an oral small-molecule drug that modulates – rather than blocks or hyper-activates – the N-methyl-D-aspartate receptor, abnormal activation of which could underpin several different conditions of the central nervous system.

In the failed Phase II trial, 99 patients were randomly assigned to receive a 30-mg dose of NYX-458 or placebo. After 12 weeks, the treatment arms were compared in terms of everyday function and cognitive performance. Across all measures, NYX-458 failed to show clinically meaningful improvements relative to placebo.

NYX-783 is also an oral NMDA modulator. Aside from PTSD, the candidate is being trialed in opioid use disorder.

Aptinyx’s Losing Streak

NYX-458 isn’t Aptinyx’s first failure in the CNS space.

In April 2022, the company announced that NYX-2925, also an oral modulator of the NMDA receptor, failed to demonstrate significant benefit in a Phase IIb trial in patients with painful diabetic peripheral neuropathy (DPN).

While patients treated with Aptinyx’s candidate saw improvements in their average daily pain scores, the overall effect was not strong enough to statistically distinguish NYX-2925 from placebo. No safety issues were observed.

After its DPN flop, Aptinyx remained hopeful that NYX-2925 could deliver promising results in an upcoming Phase IIb study of fibromyalgia, a chronic pain disorder.

In August 2022, however, the candidate fell short of its primary endpoint in this indication as well. While there was an early trend toward clinically meaningful pain improvement in patients treated with NYX-2925, this effect was not sustained throughout the study and the overall benefit of the candidate was not significantly better than placebo.

In its Q3 2022 results, Aptinyx revealed it was discontinuing NYX-2925 in chronic pain.

Tristan is an independent science writer based in Metro Manila, with more than eight years of experience writing about medicine, biotech and science. He can be reached at tristan.manalac@biospace.com, tristan@tristanmanalac.com or on LinkedIn.