Press Releases

– Detailed Results from the Phase 1/2a Study of ARO-DIMER-PA, the First Dual-Functional Investigational RNAi Therapeutic for the Treatment of Mixed Hyperlipidemia, Will Be Presented at Late-breaking Featured Science Session.05 on Saturday, November 7 – – Pooled SHASTA -3/4 Analysis of Triglyceride

The UK Medicines and Healthcare products Regulatory Agency (MHRA) has granted Marketing Authorisation for REDEMPLO ® (plozasiran) as an adjunct to diet to reduce triglyceride levels in adult patients with Familial Chylomicronaemia Syndrome (FCS) diagnosed via genetic testing or clinical criteria 1

Arrowhead’s TRiM ™ platform achieves clinical validation for delivery of siRNA that crosses the blood-brain barrier after subcutaneous injection ARO-MAPT demonstrates mean cerebrospinal fluid total tau reduction of 73% on Day 105, with a maximum individual reduction of 85%, supporting the potential

- FDA STAR pilot program aims to shorten the time from complete supplement submission to the action date to allow earlier patient access to therapies that address an unmet medical need PASADENA, Calif. --(BUSINESS WIRE)--Oct. 7, 2026-- Arrowhead Pharmaceuticals, Inc.

– ARO-MAPT utilizes the Targeted RNAi Molecule (TRiM™) platform designed for subcutaneous administration and systemic delivery to the CNS by crossing the blood-brain barrier – PASADENA, Calif. --(BUSINESS WIRE)--Sep. 29, 2026-- Arrowhead Pharmaceuticals, Inc.

- ARO-DIMER-PA achieved deep and durable silencing of two genes with a single RNAi molecule - Mean maximal single dose reductions in serum PCSK9 of 72% and APOC3 of 88% - Clinical validation further demonstrates Arrowhead’s position as the leading innovator in siRNA therapies - PASADENA, Calif.

PASADENA, Calif. --(BUSINESS WIRE)--Sep. 3, 2026-- Arrowhead Pharmaceuticals, Inc. (NASDAQ: ARWR) today announced that it is scheduled to participate in the following upcoming investor events: 2026 Cantor Global Healthcare Conference – September 9-11, 2026 Type: Fireside Chat Presentation

- Plozasiran reduced triglycerides (TG) by 79% and 81% versus placebo in SHASTA -3 and SHASTA -4 across the broad sHTG population - - More than 90% of plozasiran-treated patients achieved triglycerides below thresholds for AP risk, 500 mg/dL at Month 12, and more than half achieved triglycerides

- Detailed results from the Phase 3 SHASTA-3 and SHASTA-4 Studies of Plozasiran in Patients with Severe Hypertriglyceridemia will be presented as a HOT LINE Late-Breaking Science Session on August 30, 2026 - - Arrowhead will host a webcast to review ESC data and Q&A on August 31, 2026 - PASADENA,

REDEMPLO® (plozasiran) is listed in the Lauer-Taxe® database as an adjunct to diet to reduce triglyceride levels in adult patients with familial chylomicronaemia syndrome (FCS), diagnosed either based on clinical symptoms alone or confirmed with a genetic test People living with this rare disease