A gene-based drug developed by Arrowhead Pharmaceuticals, for a condition that can increase the risk of sudden, potentially fatal pancreatic swelling.Two late-stage clinical trialssucceeded. The drug, namedplozasiran, is a synthetic small RNA fragment designed to lower fat levels in the blood. Its mechanism of action is to degrade the instructions that cells use to produce a protein that slows down triglyceride metabolism.

Plozasiran has been approved and is sold under theRedemplobrand for treating a rare disease that causes extremely high triglyceride levels. Arrowhead is trying to expand the drug's approved uses.

Positive results announced on Wednesday could help advance this goal. In the two trials, adults with "severe hypertriglyceridemia" were enrolled and received subcutaneous injections of Arrowhead's drug every three months. After one year, median triglyceride levels decreased by79%and81%, respectively. In contrast, patients in the placebo group saw reductions of about27%。

The study also examined cases of acute pancreatitis, which is often triggered by excessively high triglyceride levels. A pooled analysis showed that participants receiving plozasiran had a significant reduction in acute pancreatitis events. Overall, compared with the control group, the number of acute pancreatitis events decreased by78%。

Arrowhead stated that its drug continued to show a "favorable" safety and tolerability profile. No "clinically meaningful" adverse changes in liver enzymes were observed, nor were there abnormally low platelet counts or "hypersensitivity reactions"—an abnormal overreaction of the immune system.

In predefined patient subgroups, the study found no significant differences in average liver fat between the drug and placebo groups. Treatment-emergent adverse events were "consistent" with previous studies. The Redemplo label notes that the most common adverse reactions include headache, nausea, injection site reactions, and elevated blood sugar.

Arrowhead's CEOChristopher Anzalonesaid in a statement that the team is "more confident than ever" in plozasiran's potential. They believe the latest data are "compelling" and represent "best-in-class safety, activity, efficacy, and convenience." The company plans to formally apply to U.S. regulators by the end of the year to include severe hypertriglyceridemia in the drug's approved indications.

Late Wednesday morning, Arrowhead's stock surged23%to above$91 per share. Shares of this RNA-focused company have more than quintupled over the past year.

RBC Capital Markets analystLuca Issidescribed the trial results as a "best-case scenario" for Arrowhead. According to the analyst, the acute pancreatitis findings are particularly noteworthy because the trials were originally designed with triglyceride levels as the primary endpoint.

Although the numerical reduction in acute pancreatitis cases technically remains below the results shown by competitor Ionis Pharmaceuticals' drugTryngolza, doctors "may view the two drugs as equally effective," Issi wrote in a note to clients. He added that the bottom line is that, although Tryngolza was first to gain approval in severe hypertriglyceridemia, Arrowhead "is ready to compete, with its drug showing comparable benefits... and offering an advantage in dosing frequency." Tryngolza is administered once a month.

TD Cowen analystJoseph Thomewrote in another report that, while more detailed data are needed to truly compare Arrowhead's and Ionis's drugs, Wednesday's update suggests the former "could capture the majority of the market share." Both Thome and Issi noted that Tryngolza can increase average liver fat, which could be a differentiating advantage for plozasiran, as the latter does not appear to have this effect.

Arrowhead said it will provide more complete results from its Phase III trials at "future academic conferences."