Company Announcements

 - In preclinical studies presented today at the RNA Leaders USA Congress 2025, investigational ARO-MAPT demonstrated potent and long-lasting MAPT mRNA and Tau protein suppression with uniform distribution throughout the CNS after subcutaneous administration in non-human primates

PASADENA, Calif.--(BUSINESS WIRE)--Sep. 10, 2025--

Arrowhead Pharmaceuticals, Inc. (NASDAQ: ARWR) today announced that it has filed a request for regulatory clearance to initiate a Phase 1/2a clinical trial of ARO-MAPT, the company’s investigational RNA interference (RNAi) therapeutic being developed as a potential treatment for tauopathies including Alzheimer’s disease, a progressive neurodegenerative disease characterized by cognitive and functional decline. Alzheimer’s disease is the most common cause of dementia and is estimated to affect 32 million people worldwide and is part of a group of neurodegenerative diseases called tauopathies that are marked by the abnormal accumulation and formation of tau tangles in neurons.

ARO-MAPT is Arrowhead’s first investigational RNAi-based therapy to utilize a new proprietary delivery system which, in preclinical studies, has achieved blood-brain-barrier penetration and deep knockdown of target genes across the central nervous system (CNS), including deep brain regions, after subcutaneous injections. This underscores Arrowhead’s leadership in the delivery of siRNA to multiple tissues and cell types throughout the body utilizing its proprietary and differentiated Targeted RNAi Molecule (TRiM^™) platform.

“ARO-MAPT is a potential treatment for Alzheimer’s disease designed to achieve delivery to deep brain regions after subcutaneous administration. Given the significant impact of Alzheimer’s disease, additional disease-modifying therapies are severely needed. The tau protein, which is the target of ARO-MAPT, has strong correlation with symptom severity and is a promising therapeutic target for Alzheimer’s disease and other tauopathies,” said James Hamilton, M.D., Chief Medical Officer and Head of R&D at Arrowhead. “New preclinical data on the TRiM^™ platform and ARO-MAPT, being presented today at the RNA Leaders USA Congress 2025, show improved delivery and knockdown of mRNA and protein throughout the CNS versus intrathecal administration, with long lasting protein reduction potentially enabling monthly or quarterly subcutaneous dosing. Filing of the CTA for ARO-MAPT represents further expansion of our broad TRiM^™ platform, which currently includes active clinical programs delivering siRNA to liver, lung, skeletal muscle, CNS, and adipose tissue.”

ARO-MAPT is designed to silence CNS expression of the microtubule associated protein tau (MAPT) gene, which encodes the tau protein. Aggregation of the toxic tau protein is believed to be a key driver in multiple tauopathies, including Alzheimer’s disease. By preventing or potentially reversing tau protein accumulation in subjects with mild cognitive impairment due to Alzheimer’s disease and mild Alzheimer’s disease dementia, ARO-MAPT has potential to prevent or slow disease progression.

An application for approval to initiate the clinical trial was submitted to the New Zealand Medicines and Medical Devices Safety Authority for review by the Standing Committee on Therapeutic Trials. Pending clearance, Arrowhead intends to proceed with a Phase 1/2a placebo-controlled dose-escalating study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of ARO-MAPT in up to 64 healthy subjects and up to 48 subjects with early Alzheimer’s disease, defined as mild cognitive impairment due to Alzheimer’s disease and mild Alzheimer’s disease dementia. In Part 1a of the study, subjects will receive one or three weekly doses of ARO-MAPT or placebo by subcutaneous injection, and in Parts 1b and Part 2a subjects will receive three weekly doses followed by three monthly doses for a total of six subcutaneous administrations of ARO-MAPT or placebo.

Presentation slides from the RNA Leaders USA Congress 2025 may be accessed on the Events and Presentations page under the Investors section of the Arrowhead website.

About Arrowhead Pharmaceuticals

Arrowhead Pharmaceuticals develops medicines that treat intractable diseases by silencing the genes that cause them. Using a broad portfolio of RNA chemistries and efficient modes of delivery, Arrowhead therapies trigger the RNA interference mechanism to induce rapid, deep, and durable knockdown of target genes. RNA interference, or RNAi, is a mechanism present in living cells that inhibits the expression of a specific gene, thereby affecting the production of a specific protein. Arrowhead’s RNAi-based therapeutics leverage this natural pathway of gene silencing.

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Source: Arrowhead Pharmaceuticals, Inc.

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Arrowhead Pharmaceuticals, Inc.
Vince Anzalone, CFA
626-304-3400
ir@arrowheadpharma.com

Investors:
LifeSci Advisors, LLC
Brian Ritchie
212-915-2578
britchie@lifesciadvisors.com

Media:
LifeSci Communications, LLC
Kendy Guarinoni, Ph.D.
724-910-9389
kguarinoni@lifescicomms.com

Source: Arrowhead Pharmaceuticals, Inc.