Aptinyx seeks $80M IPO to push NMDA drug platform

With the ink barely dry on a partnership deal with Allergan, Aptinyx has announced plans for an $80 million IPO to accelerate work on its drugs for neurological disorders.

The Evanston, Illinois-based biotech—founded three years ago—is focused on the development of drugs that interact with the NMDA receptor, and the company says it will use the funds to advance drugs for chronic pain, post-traumatic stress disorder (PTSD) and cognitive impairment in Parkinson’s disease.

The IPO play comes right after Allergan exercised an option to acquire rights to Aptinyx’s NMDA-based depression candidate AGN-241751, which came out of a research collaboration set up between the companies shortly after Allergan bought Naurex, from which Aptinyx was spun out in 2015. Allergan paid a $1 million option fee and Aptinyx says it will receive "no further economic consideration from this product candidate."

According to the biotech’s IPO prospectus, lead drug NYX-2925—which has FDA fast-track status—will have a phase 2 readout in pain associated with diabetic neuropathy and fibromyalgia in the first half of 2019.  

It estimates that painful diabetic neuropathy affects around 5.5 million people in the U.S., with another 5 million having fibromyalgia, and sees significant potential for a drug that can improve on current treatments—mainly opioid analgesics—that often lack efficacy and put people at risk of dependency.

Running pivotal trials in chronic pain will be costly, and Aptinyx acknowledges that even if it hits its IPO fundraising target, it will need more capital to take the NYX-2925 project through phase 3. It also made $70 million via a series B last December, and had raised a total of $135 million by the end of March.

Meanwhile, PTSD candidate NYX-783 will generate midstage results in the latter half of 2019, and the biotech also says it filed for FDA approval this month to start trials of third candidate NYX-458 in PD-related cognition. It’s aiming to have phase 1 results from that program early next year.

NMDA is a glutamate and ion channel receptor found on neurons that seems to play an important role in maintaining connections between nerve cells—a process known as synaptic plasticity—and is affected by a host of psychoactive drugs including the anesthetic ketamine and memantine, a drug used to treat cognitive deficits in Alzheimer’s disease.

Aptinyx’s take on NMDA is that its drug candidates bind to a different area of the receptor than current drugs that crudely switch it completely on or off. In contrast, says the biotech, its drugs act on a "pocket" in the receptor that "enables normalization" of the NMDA receptor’s function and enhances synaptic plasticity.

NYX-2925 and NYX-783 both emerged from the chemistry and discovery platform that gave rise to fellow NMDA modulator rapastinel, the depression prospect that underpinned Allergan’s takeover of Naurex.

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