Arrowhead Pharmaceuticals, Inc. (ARWR) on Wednesday shared interim data from an ongoing Phase 1/2a clinical trial for ARO-MAPT, an investigational RNA interference therapy targeting Alzheimer's disease and other tau-related disorders.

These early findings provide the first clinical validation of a novel platform that successfully delivers small interfering RNA across the blood-brain barrier, achieving significant target gene knockdown directly within the brain.

Substantial Tau Protein Reductions

The ARO-MAPT therapy aims to silence the expression of the microtubule-associated protein tau gene within the central nervous system. By doing so, the treatment effectively lowers the production of all six tau protein isoforms.

Abnormal accumulation of tau proteins acts as a primary driver for several severe neurodegenerative conditions, including Alzheimer's disease, Progressive Supranuclear Palsy, and MAPT-related frontotemporal dementia.

During the trial, healthy participants received subcutaneous injections of ARO-MAPT, which produced profound and lasting decreases in cerebrospinal fluid total tau levels.

Doses of 2.1 mg/kg and 6.4 mg/kg administered on days one, eight, and 15 resulted in average tau reductions of 40% and 69% by day 105. Furthermore, participants receiving a 12.8 mg/kg dose on days one and 15 experienced an average reduction of 73%, with a maximum drop of 85% observed at day 105.

Favorable Safety Profile and Next Steps

Since day 105 marks 90 days after the final administration, this sustained suppression suggests the therapy could support a convenient dosing schedule of once every three months or less.

Researchers are evaluating how ARO-MAPT affects cognitive function, tau tangles, and overall disease progression in actual patients in Part 2 of the current Phase 1/2a study.

Participants generally tolerated the experimental therapy well, experiencing primarily mild or Grade 1 adverse events. The trial reported no deaths, severe adverse events, or participant discontinuations.

The company has fully enrolled its healthy volunteer cohorts and plans to finish dosing these groups while actively enrolling patients with early-stage Alzheimer's disease.

ARWR Price Action: Arrowhead Pharma shares were down 0.72% at $57.71 at the time of publication on Wednesday, according to market data.