Novel RNAi Therapy Uses Subcutaneous Delivery to Cross the Blood-Brain Barrier
Company:Arrowhead Pharmaceuticals has announced the initiation of a Phase 1/2a clinical trial for ARO-MAPT, an investigational RNA interference (RNAi) therapy being developed for the treatment of Alzheimer’s disease and other tauopathies. The company confirmed that the first subjects have been dosed in the study, marking a significant milestone in the advancement of RNAi therapeutics targeting neurodegenerative diseases.
ARO-MAPT is the company’s first RNAi-based therapy designed to cross the blood-brain barrier through subcutaneous administration using Arrowhead’s proprietary Targeted RNAi Molecule (TRiM™) platform. The therapy aims to silence the microtubule associated protein tau (MAPT) gene, which produces the tau protein linked to the progression of several neurodegenerative disorders.
Alzheimer’s disease remains the leading cause of dementia globally, affecting an estimated 32 million people worldwide. The disease is characterized by progressive cognitive decline and abnormal accumulation of tau tangles in neurons. Researchers increasingly believe tau pathology plays a central role in neurodegeneration, making tau-targeting therapies a promising therapeutic approach.
James Hamilton, M.D., Chief Medical Officer and Head of R&D at Arrowhead Pharmaceuticals, stated that currently approved disease-modifying therapies have largely focused on amyloid-beta plaque clearance but have delivered limited clinical benefits. He emphasized that targeting tau could potentially slow or halt disease progression by preventing tau protein accumulation.
According to the company, ARO-MAPT demonstrated strong preclinical performance in non-human primate studies presented at the RNA Leaders USA Congress 2025. The investigational therapy showed potent and durable suppression of MAPT mRNA and tau protein across the central nervous system, including deep brain regions, after subcutaneous injection. The data suggest the therapy could support monthly or quarterly dosing schedules.
Details of the AROMAPT-SC-1001 Trial
The ongoing AROMAPT-SC-1001 study (NCT07221344) is a placebo-controlled, dose-escalating Phase 1/2a trial designed to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of ARO-MAPT.
The trial is expected to enroll:
- Up to 64 healthy volunteers
- Up to 48 patients with early Alzheimer’s disease
The Alzheimer’s disease cohort includes individuals with mild cognitive impairment due to Alzheimer’s disease and mild Alzheimer’s disease dementia.
Study Structure
- Part 1a (Healthy Volunteers): Participants will receive either one or three weekly subcutaneous doses of ARO-MAPT or placebo.
- Part 1b (Healthy Volunteers) and Part 2a (Alzheimer’s Patients): Subjects will receive three weekly doses followed by three monthly doses, totaling six subcutaneous administrations.
Arrowhead expects initial clinical data from the first portions of the study in the second half of 2026.
Expanding RNAi Innovation in CNS Disorders
The initiation of the ARO-MAPT clinical program further strengthens Arrowhead Pharmaceuticals’ position in RNAi drug development and delivery technologies. The company’s ability to achieve systemic delivery to the central nervous system through a minimally invasive subcutaneous injection represents a potentially transformative advancement for neurodegenerative disease treatment.
If successful, ARO-MAPT could offer a new therapeutic option for patients with Alzheimer’s disease and other tauopathies by targeting one of the underlying drivers of neurodegeneration rather than focusing solely on amyloid-beta plaques.
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