What happened Shares of Aeglea BioTherapeutics (NASDAQ: AGLE), a clinical-stage biopharmaceutical company, are falling today in response to mixed clinical-trial data. Investors nervous about the future of the company's lead candidate pushed the stock 36.6% lower as of 11:53 a.m. ET on Monday. So what Aegla BioTherapeutics' lead candidate, pegzilarginase, is an enzyme replacement therapy for patients with an ultra-rare amino-acid metabolism disorder called arginase 1 deficiency. The trial reached its primary endpoint by dramatically reducing circulating arginine by 80% compared to baseline measurements. Image source: Getty Images. The stock is getting beaten down today because investors are disappointed with two outcome measurements that were secondary endpoints in the pivotal study. Patients treated with pegzilarginase improved their average two-minute walking distance scores by 7.4 meters after 24 weeks. Unfortunately for Aeglea, that wasn't significantly better than the placebo group, which improved by 1.9 meters. Patient scores on the gross motor function test improved by 4.2 points compared to a 0.4 point worsening for the placebo group. While this indicates a benefit, there weren't enough patients tested to consider this improvement statistically significant, either. Now what Aeglea BioTherapeutics still plans to submit an application for pegzilarginase to the Food and Drug Administration (FDA) in the first half of 2022. The company already rolled all 32 patients from the phase 3 trial into a longer single-arm extension study. In a previous single-arm study, 11 out of 14 patients showed mobility measurement improvements after 56 weeks on pegzilarginase. Considering the dearth of available treatment options for patients with this progressively debilitating disorder, similarly positive long-term outcomes in the new extension study could be enough to convince the FDA to give pegzilarginase a green light. 10 stocks we like better than Aeglea BioTherapeuticsWhen our award-winning analyst team has 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.* They just revealed what they believe are the ten best stocks for investors to buy right now... and Aeglea BioTherapeutics 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 November 10, 2021 Cory Renauer 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