By David Bautz, PhD
NASDAQ: ARWR
READ THE FULL ARWR RESEARCH REPORT
Business Update
Interim Data for ARO-MAPT Shows Promise for TRiM™ Platform in CNS Diseases
On October 14, 2026, Arrowhead Pharmaceuticals, Inc. (NASDAQ: ARWR) announced interim results for the Phase 1/2a study of ARO-MAPT, which is designed to silence expression of the microtubule associated protein tau (MAPT) gene that encodes for the tau protein, and held a webinar to discuss the program, which can be accessed here. The study is designed to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of ARO-MAPT in up to 64 normal healthy volunteers (NHV) and up to 48 subjects with early Alzheimer’s disease (AD). In Part 1a of the study, NHVs are receiving between one and three doses of ARO-MAPT or placebo by subcutaneous injection. In Parts 1b and 2a, NHVs and subjects with early AD will receive between two and three doses followed by one to two additional doses of ARO-MAPT or placebo.
The following image shows the reduction in tau in the cerebrospinal fluid (CSF) following three doses of ARO-MAPT on Days 1, 8, and 15. The maximum decrease in CSF tau was 85%, with a mean reduction of 73% at Day 105 for the 12.8 mg/kg dose, which was 90 days following the last dose. Thus, these data strongly support the potential for dosing once every three months.
The safety data for ARO-MAPT looks very encouraging, as the drug was generally well tolerated with no serious treatment-emergent adverse events (TEAEs), deaths, or TEAEs that led to discontinuation of study treatment or participation in the study. In addition, most TEAEs were Grade 1 or mild, with the most commonly reported being injection-site reactions, vessel puncture-site bruising, upper respiratory tract infection, back pain, and headache.
Arrowhead has completed enrollment and is working to complete dosing in the NHV cohorts. Simultaneously, the company is enrolling the early AD cohorts, and we anticipate a data update in 2027. Based on these results showing the drug successfully crossed the blood-brain barrier, the company will be initiating regulatory discussions regarding planned studies in MAPT-associated frontotemporal dementia and Progressive Supranuclear Palsy to expand the CNS pipeline.
Entry into FDA STAR Pilot Program for Plozasiran in sHTG
On October 7, 2026, Arrowhead announced the U.S. FDA has granted plozasiran entry into the Split Real Time Application Review (STAR) pilot program for the company’s upcoming supplemental new drug application (sNDA) for severe hypertriglyceridemia (sHTG). The purpose of the STAR program is to shorten the review time of an sNDA submission to six months compared to the standard 10-month review. In addition, the FDA is aiming for an “expedited review” for efficacy supplements in the STAR program, which means an action at least one month before the Priority Review goal date. Arrowhead does not need to use a Priority Review Voucher (PRV) since plozasiran was granted entry into the STAR program; thus, the company will retain the recently acquired PRV and use it for a future product, as PRVs do not have an expiration date. We continue to anticipate the sNDA filing for sHTG to be completed by the end of 2026, followed by additional regulatory activities ex-U.S. in the ensuing months.
Conclusion
The initial ARO-MAPT data are very encouraging as the company has now shown proof-of-concept for the subcutaneous administration of an siRNA product that can cross the blood-brain barrier and impact expression of genes in the CNS. This opens the door for Arrowhead to potentially target a wide range of diseases in the CNS, with the company initially focused on expanding to MAPT-associated frontotemporal dementia and Progressive Supranuclear Palsy. Based on these results, we have increased the probability for success of the MAPT program, along with the potential for several additional CNS indications, which has increased our valuation to $105 per share.
SUBSCRIBE TO ZACKS SMALL CAP RESEARCH to receive our articles and reports emailed directly to you. Please visit our website for additional information on Zacks SCR.
DISCLOSURE: Zacks SCR has received compensation from the issuer directly, from an investment manager, or from an investor relations consulting firm, engaged by the issuer, for providing research coverage for a period of no less than one year. Research articles, as seen here, are part of the service Zacks SCR provides and Zacks SCR receives payments totaling a maximum fee of up to $50,000 annually for these services provided to or regarding the issuer. Full Disclaimer HERE.