What happened Shares of the clinical-stage biotech Aptinyx (NASDAQ: APTX) are up by an eye-catching 55% as of 9:55 a.m. Tuesday morning. The drugmaker's stock is ripping higher in response to a positive midstage trial for its post-traumatic stress disorder (PTSD) candidate known as NYX-783. Before the opening bell, Aptinyx announced that NYX-783 exhibited statistically significant and clinically meaningful efficacy results in a midstage trial consisting of 153 patients with PTSD. Equally as important, the company also reported that the drug showed a favorable adverse event and tolerability profile in the study. Image source: Getty Images. So what PTSD affects over 8.5 million Americans. Yet there are no drugs currently on the market that treat the underlying cause of this serious disorder. Aptinyx is hoping to change this situation for the better with NYX-783. Specifically, this novel NMDA receptor modulator is designed to target the root cause of PTSD, not simply alleviate symptoms associated with this disorder. So, in short, Aptinyx might have a major new drug on its hands -- perhaps one capable of generating blockbuster-level sales following approval (greater than $1 billion a year). That's a huge deal for a company with a market cap of only $263 million at the time of writing. Now what Aptinyx plans on discussing a registrational trial for the drug with regulators soon. So, if things go according to plan, NYX-783 may be in a late-stage study as soon as mid-2021. This small-cap biotech, in turn, will more than likely take advantage of this spike in its share price to raise funds for this upcoming trial. Phase 3 trials, after all, are an expensive endeavor. 10 stocks we like better than Aptinyx Inc.When investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Aptinyx Inc. wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of September 24, 2020 George Budwell has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source