Shares in Arrowhead Pharmaceuticals Inc. rose 40 percent a day after the Pasadena-based biotechnology firm released positive results for a drug treating hepatitis B virus infection.

The stock price of ARWR shot up 40.3 percent to $19.74 by the close of trading Sept. 7 following the Thursday morning release of initial clinical data for its drug known as ARO-HBV.

The new data was presented at a World Gastroenterologists Summit in New Zealand, in which the company pointed toward a functional cure for hepatitis B. More data from an ongoing phase 1/2 clinical trial is expected to be released in November.

Arrowhead Pharmaceuticals employs a broad portfolio of RNA-interference (RNAi) drugs designed to inhibit harmful proteins by silencing the genes that cause them. Its Targeted RNAi Molecule (TRIM) targets specific genes in order to affect production of specific proteins.

The company announced early last month it had received a $10 million milestone payment from Amgen Inc., now developing an Arrowhead drug to treat cardiovascular disease.

Arrowhead licensed two of its RNAi compounds for cardiovascular disease to Amgen in 2016 in a deal valued up to $674 million, including milestones. The AMG 890 drug licensed to Amgen marks the third Arrowhead drug to enter clinical development this year.

Its stock has risen 430 percent this year, pushing its market capitalization to $1.7 billion.

Health business reporter Dana Bartholomew can be reached at [email protected]. Follow him on Twitter @_DanaBart.