** Shares of Arrowhead Pharmaceuticals rise 2% to $67.95

** California-based drugmaker says it has begun testing its experimental drug ARO-DIMER-PA for mixed hyperlipidemia, a disorder marked by high levels of cholesterol and blood fat

** The drug is designed to silence two genes at once to lower LDL, or "bad" cholesterol, and triglycerides – both linked to heart disease, per co

** Co says the early-stage study will enroll up to 78 adults to assess safety and efficacy

** In earlier animal studies, the drug sharply reduced cholesterol and triglycerides, co say

** Shares up ~253% in 2025

(Reporting by Sahil Pandey in Bengaluru)

((Sahil.Pandey@thomsonreuters.com))