- 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 -

Arrowhead Pharmaceuticals, Inc. (NASDAQ:ARWR) today announced that it will present important new data at the European Society of Cardiology Congress (ESC) in Munich, Germany.

ESC 2026 Presentation Details

Date & Time: Sunday, August 30, 2026, 17:30 CEST

Session Title: HOT LINE 9 Late-breaking Science Session

Location: Munich Auditorium-Hall B3

Title: Plozasiran in patients with severe hypertriglyceridemia: the SHASTA-3 and SHASTA-4 pivotal trial 12-month results

Presenter: Gerald Watts, University of Western Australia, Perth, Australia

Discussant review: Borge G. Nordestgaard, Copenhagen University Hospital, Copenhagen, Denmark

Panel discussion

Date & Time: Monday, August 31, 2026, 9:00 am CEST

Session Title: Late-breaking science: Beyond statins: the next wave of lipid-lowering therapies

Location: Tripoli Auditorium-Hall B1

Title: A phase 3 clinical trial to evaluate the efficacy and safety of vsa003 (zodasiran) injection in Chinese adolescents and adults with homozygous familial hypercholesterolemia (HOFH)

Presenter: Zhuang Tian, Peking Union Medical College Hospital, Beijing, China

Arrowhead Investor Webcast

Date & Time: Monday, August 31, 2026, 14:00 CEST/ 8:00 am EDT/ 5:00 am PDT

Topic: Review SHASTA-3 and SHASTA-4 pivotal trial 12-month results, Q&A

Participants: Gerald Watts, Borde Nordestgaard, and Arrowhead management

Link to Register for Webcast: Events & Presentations, Arrowhead Pharmaceuticals Website

The recorded webcast will be made available on the Events and Presentations page under the Investors section of the Arrowhead website approximately two hours after the event.

About Severe Hypertriglyceridemia

Severe hypertriglyceridemia (sHTG) is characterized by triglyceride (TG) levels greater than 500 mg/dL, with the most severe form being familial chylomicronemia syndrome (FCS) where TGs typically exceed 880 mg/dL. SHTG significantly increases the risk of acute pancreatitis (AP), which can often include recurrent attacks requiring repeat hospital admissions and worsening outcomes. AP risk is proportional to the number, characteristics, and concentration of triglyceride rich lipoproteins (TRLs), particularly chylomicrons, and increases as TGs rise. Elevated TGs can also increase the risk of atherosclerotic cardiovascular disease (ASCVD). Limited treatment options exist to sustainably reduce TGs below guideline-directed risk thresholds.

About SHASTA-3 and SHASTA-4 Phase 3 Studies

SHASTA-3 (NCT06347003) and SHASTA-4 (NCT06347016) are global double-blind, placebo-controlled, Phase 3 studies to evaluate the efficacy and safety of plozasiran in adults with severe hypertriglyceridemia. Between the two studies, approximately 750 participants were randomized to receive 4 doses (once every 3 months) of 25 mg plozasiran or placebo. The primary endpoint is percent change in fasting serum triglyceride levels from baseline to Month 12 compared to placebo. After Month 12, eligible participants are offered an opportunity to continue in an optional open-label extension.

About REDEMPLO^® (plozasiran)

REDEMPLO (plozasiran) is currently approved by the U.S. Food and Drug Administration, Health Canada, China’s National Medical Products Administration, the Australian Therapeutic Goods Administration, and by the European Commission as an adjunct to diet to reduce triglycerides for adults with FCS. REDEMPLO is the first and only siRNA treatment approved in these countries to be studied in both clinically diagnosed and genetically confirmed patients living with FCS.

REDEMPLO is designed to suppress the production of apolipoprotein C-III (APOC3), a protein produced in the liver that raises triglyceride levels by slowing their breakdown and clearance. By targeting APOC3 with sustained silencing, REDEMPLO delivers significant reductions in triglyceride levels. REDEMPLO is self-administered via subcutaneous injection once every three months.

REDEMPLO has been granted Orphan Medicinal Product Designation by the EMA for the treatment of patients with FCS, and Breakthrough Therapy Designation, Fast Track Designation, and Orphan Drug Designation by the U.S. FDA for the treatment of patients with FCS and was also granted Breakthrough Therapy designation by the U.S. FDA in severe hypertriglyceridemia.

Sanofi acquired the rights to develop and commercialize REDEMPLO in Greater China, with Arrowhead retaining rights to REDEMPLO in all geographies, outside of Greater China.

For more information about REDEMPLO, visit Our Medicines.

About Homozygous Familial Hypercholesterolemia

Homozygous Familial Hypercholesterolemia is an ultra-rare treatment‐resistant genetic condition characterized by elevated LDL-C and early-onset cardiovascular disease. Most cases of HoFH are due to mutations in the gene that encodes the LDL receptor (LDLR). Thus, HoFH represents a unique disease where LDL-C lowering therapies not requiring functional LDL receptors may have benefit. If left untreated, individuals with HoFH can have median LDL-C levels above 400 mg/dL (over 10 mmol/L), leading to early clinical manifestations of coronary artery disease¹. Patients with HoFH may also have cholesterol deposits under the skin (xanthomas), around the eyes (xanthelasmas), or around the cornea (corneal arcus), but physical signs are not always present, particularly in children. HoFH remains challenging to treat and currently only patients with the more severe HoFH phenotypes get diagnosed and treated early. The estimated prevalence of HoFH globally is between 1:360,000 and 1:250,000¹.

About Zodasiran

Zodasiran, previously called ARO-ANG3, is a first-in-class investigational RNA interference (RNAi) therapeutic designed to reduce production of angiopoietin-like protein (ANGPTL3), which is a hepatocyte expressed regulator of lipid and lipoprotein metabolism with multiple potential modes of action, including inhibition of lipoprotein lipase (LPL) and endothelial lipase (EL)^2,3. ANGPTL3 is an emerging therapeutic target with relevance to hypercholesterolemia, hypertriglyceridemia, and mixed hyperlipidemia. Genetic studies suggest that individuals with ANGPTL3 loss-of-function variants have enhanced lipoprotein lipase and endothelial lipase activity, resulting in lower levels of atherogenic lipoproteins and a reduced risk of ASCVD^4-6. Zodasiran has received Orphan Drug Designation for the treatment of HoFH from the U.S. Food and Drug Administration.

In prior clinical studies, investigational zodasiran was associated with dose-dependent reductions in triglycerides, triglyceride rich lipoprotein remnants, and total atherogenic lipoproteins, including LDL-C, in patients with homozygous (HoFH) and heterozygous (HeFH) familial hypercholesterolemia and mixed hyperlipidemia. Zodasiran also showed a favorable safety profile. In the Phase 2 GATEWAY study in patients with HoFH, there were no drug discontinuations, drug-related serious adverse events, or deaths. The most frequent adverse events were COVID-19, nasopharyngitis, upper respiratory tract infection, and dizziness.

About Arrowhead Pharmaceuticals

Arrowhead Pharmaceuticals (NASDAQ:ARWR) is a commercial-stage pharmaceutical company developing medicines that treat intractable diseases by silencing the genes that cause them, harnessing the natural RNA interference (RNAi) mechanism. The company has built a broad portfolio of clinical and commercial RNAi therapeutics through its industry-leading targeted RNAi molecule (TRiM™) platform, which can precisely silence genes in a wide range of cell types, including liver, lung, muscle, adipose, and central nervous system tissue. At Arrowhead, we rapidly advance potential best- and first-in-class RNAi treatments for diseases with significant unmet medical need, because every day matters to the patients we serve.

For more information, please visit www.arrowheadpharma.com, or follow us on X (formerly Twitter) at @ArrowheadPharma, LinkedIn, Facebook, and Instagram. To be added to the Company's email list and receive news directly, please visit http://ir.arrowheadpharma.com/email-alerts.

Safe Harbor Statement under the Private Securities Litigation Reform Act:

This news release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. Any statements contained in this release except for historical information may be deemed to be forward-looking statements. Without limiting the generality of the foregoing, words such as "may," "will," "expect," "believe," "anticipate," "hope," "intend," "plan," "project," "could," "estimate," "continue," "target," "forecast" or "continue" or the negative of these words or other variations thereof or comparable terminology are intended to identify such forward-looking statements. In addition, any statements that refer to projections of our future financial performance, trends in our business, expectations for our product pipeline, products or product candidate or other characterizations of future events or circumstances are forward-looking statements. These forward-looking statements include, but are not limited to, statements about our beliefs and expectations regarding the long-term impacts of REDEMPLO^® (plozasiran) on patient health and the health care system; our beliefs and expectations regarding the pricing, value, or expected timing for availability of our drugs and drug candidates; and our beliefs and expectations around the potential uses and value of the TRiM™ platform. These statements are based upon our current expectations and speak only as of the date hereof. Actual results or outcomes may differ materially and adversely from those expressed in any forward-looking statements as a result of numerous factors and uncertainties the safety and efficacy of our products and product candidates, pricing and reimbursement decisions related to our products, demand for our products, decisions of regulatory authorities and the timing thereof, the duration and impact of regulatory delays in our clinical programs, our ability to finance our operations, the likelihood and timing of the receipt of future milestone and licensing fees, the future success of our scientific studies, the timing for starting and completing clinical trials, rapid technological change in our markets, the enforcement of our intellectual property rights, and the other risks and uncertainties described in our most recent Annual Report on Form 10-K, subsequent Quarterly Reports on Form 10-Q and other documents filed with the Securities and Exchange Commission from time to time. We assume no obligation to update or revise forward-looking statements to reflect new events or circumstances.

Source: Arrowhead Pharmaceuticals, Inc.

View source version on businesswire.com: https://www.businesswire.com/news/home/20260824400179/en/

Vince Anzalone, CFA

+1 626-304-3400

ir@arrowheadpharma.com

Paul Graves

+1-626-304-3400

media@arrowheadpharma.com

Investors:

LifeSci Advisors, LLC

Brian Ritchie

+1 212-915-2578

britchie@lifesciadvisors.com