Arrowhead Shows Dual-Gene RNAi Therapy Data

Arrowhead Pharmaceuticals reported interim Phase 1/2a clinical data for ARO-DIMER-PA, marking the first clinical validation of an RNA interference therapeutic designed to silence two genes simultaneously using a single molecule.

Single doses of ARO-DIMER-PA achieved mean maximal reductions in serum PCSK9 of 72% and APOC3 of 88% in participants with mixed hyperlipidemia, according to an Arrowhead Pharmaceuticals press release. The trial results demonstrate the clinical viability of dual-gene silencing to address multiple lipid abnormalities concurrently.

"With these interim topline results, Arrowhead’s Targeted RNAi Molecule (TRiM™) platform has achieved clinical validation of its ability to target and silence two genes simultaneously in one molecule. This represents an important step forward and a first for the field of RNAi therapeutics. We look forward to presenting additional details on this advance at an upcoming medical congress," said Chris Anzalone, Ph.D., President and CEO at Arrowhead Pharmaceuticals.

Clinical Efficacy and Lipid Reductions

The simultaneous silencing of the PCSK9 and APOC3 genes triggered downstream improvements across multiple standard lipid parameters in trial participants. Data from the company's clinical update showed mean maximal reductions of 54% in low-density lipoprotein cholesterol (LDL-C), 73% in triglycerides, 61% in non-HDL cholesterol, and 50% in Apolipoprotein B (ApoB).

"The relationship between low-density lipoprotein-cholesterol (LDL-C) and Apolipoprotein B (ApoB) reduction and cardiovascular risk is one of the most consistently replicated findings in modern medicine," said James Hamilton, M.D., MBA, Chief Medical Officer and head of R&D at Arrowhead.

Single-dose escalation in the Phase 1/2a study has been completed through 400 mg. The trial reported an acceptable safety profile, with injection site events and headaches standing out as the most commonly observed treatment-emergent adverse events, and no drug-related serious adverse events recorded.

Targeting Residual Cardiovascular Risk

Mixed hyperlipidemia frequently persists despite standard interventions, leaving patients vulnerable to ongoing cardiovascular complications. Traditional treatments often require separate medications to manage distinct lipid abnormalities.

"Mixed hyperlipidemia is not adequately addressed by treating LDL-C alone. Even with intensive statin therapy and PCSK9 inhibitors, substantial ASCVD risk remains, and triglyceride-rich remnant lipoproteins may be an important part of that residual risk. This medication represents an approach to targeting multiple lipid abnormalities with a single therapy," said Steven Nissen, M.D., Chief Academic Officer for the Heart and Vascular Institute at the Cleveland Clinic.

Market Response and Valuation

Arrowhead Pharmaceuticals Inc (ARWR) stock traded at $67.74, up 2.96% from its previous close of $65.79, according to Finnhub market data as of September 17, 2026, at 20:00 UTC. The clinical readout highlights investor interest in expanding the therapeutic reach of RNA interference platforms toward complex metabolic conditions.