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.

Hand drawing upward pointing graph on a board.

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.