What happened? Shares of Arrowhead Pharmaceuticals (NASDAQ: ARWR) are up by 49.9% as of 11:35 a.m. EDT on Wednesday, after rising by as much as 51.1% earlier today. Investors are bidding up shares of the biopharmaceutical company today following the release of interim data from a phase 2 clinical trial for one of its pipeline candidates, ARO-AAT. So what Arrowhead Pharma is developing ARO-AAT as a treatment for liver disease associated with alpha-1 antitrypsin deficiency (AATD). Alpha-1 antitrypsin is a protein in the liver that protects body tissue from damage. Patients with AATD produce insufficient levels of alpha-1 antitrypsin, which can lead to severe liver problems. This morning, Arrowhead Pharma reported that in a phase 2 study, ARO-AAT had shown "clear evidence of a meaningful pharmacodynamic effect" on AATD patients after 24 weeks of treatment. In particular, ARO-AAT led to a decrease in liver stiffness and injury during the trial. Image source: Getty Images. "These are very exciting results and provide us with increased confidence in the potential of this program," Arrowhead Chief Medical Officer Javier San Martin said in a statement. "Based on these important data, we are actively assessing our clinical and regulatory path forward, including engaging with the U.S. Food and Drug Administration and other regulatory agencies, to identify areas where the program could potentially be streamlined and accelerated." Now what Arrowhead Pharma argues that there is currently a significant need in the AATD market, considering there are few therapy options and liver transplant is the only cure. With that said, the clinical trials the healthcare company reported on today only featured four participants. While the data is encouraging, it's important for investors to temper their expectations. 10 stocks we like better than Arrowhead PharmaceuticalsWhen 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 Arrowhead Pharmaceuticals 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 August 1, 2020 Prosper Junior Bakiny 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