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ARO-AAT

Phase 3

Alpha 1-Antitrypsin Deficiency | RNA therapy | Rare Disease |Arrowhead Pharmaceuticals, Inc.|Trials Updated: Dec 24, 2025

ARO-AAT development status

Highest phase Phase 3 run by Takeda (NCT05899673)
Phase scored for ARWRPhase 2
Registered trials 4 across 2 sponsors since May 2019

ARO-AAT target and mechanism

ModalityRNA therapy

Also known as ARO-AAT Injection, Fazirsiran Injection, TAK-999

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLED
Total Trials2
Total Enrollment61

FDA Designations

No designations recorded

ARO-AAT clinical trials

ARO-AAT · 2 trials · 1 indication

Phase 2 1Phase 1 1
NCT03946449Study of Fazirsiran (TAK-999, ARO-AAT) in Patients With Alpha-1 Antitrypsin Deficiency Associated Liver Disease (AATD)Alpha 1-Antitrypsin Deficiency
COMPLETED16 Analytics
PHASE2COMPLETED
Study of Fazirsiran (TAK-999, ARO-AAT) in Patients With Alpha-1 Antitrypsin Deficiency Associated Liver Disease (AATD)
Alpha 1-Antitrypsin DeficiencyUnlock trial analytics

Study Endpoints

Primary Endpoints

Percent Change From Baseline in Total Liver Z-AAT, Insoluble Liver-ZAAT, and Soluble Liver Z-AAT at Week 24: Cohorts 1/1b
Baseline, Week 24
Percent Change From Baseline in Total Liver Z-AAT, Insoluble Liver-ZAAT, and Soluble Liver Z-AAT at Week 48: Cohort 2
Baseline, Week 48
Number of Participants With Adverse Events (AEs) Possibly or Probably Related to Treatment
Part A (single-ascending dose [SAD] phase): up to 29 (+/- 2) days post-dose; Part B (multiple-ascending dose [MAD] phase): up to 113 (+/- 2) days post-dose

Secondary Endpoints

Percent Change From Baseline in Serum Z-AAT Over Time: Cohorts 1/1b
Baseline, Weeks 2, 4, 6, 16, 24
Percent Change From Baseline in Serum Z-AAT Over Time: Cohort 2
Baseline, Weeks 2, 4, 6, 16, 22, 28, 34, 40, 48
Alanine Aminotransferase (ALT) Values Over Time: Cohorts 1/1b
Baseline (Day 1), Day 2, Week 2, Week 4, Week 4 (24-48h post dose), Week 6, Week 16, Week 16 (24/48h post dose), Week 24
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Study Design & Arms

AllocationNON_RANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
ARO-AAT 100 mg Cohort 1bEXPERIMENTALPrimary Study Period (6-12 months): 100 mg dose of subcutaneous ARO-AAT for a minimum of 3 doses, with 2 optional treatment extension periods. Treatment Extension I (12 months): 100 mg dose of subcutaneous AROAAT every 12 weeks (Q12W). Treatment Extension II (up to 24 Months): 100 mg dose of subcutaneous ARO-AAT Q12W.
ARO-AAT 200 mg Cohort 1EXPERIMENTALPrimary Study Period (6-12 months): 200 mg dose of subcutaneous ARO-AAT for a minimum of 3 doses, with 2 optional treatment extension periods. Treatment Extension I (12 months): 200 mg dose of subcutaneous AROAAT Q12W. Treatment Extension II (up to 24 Months): 200 mg dose of subcutaneous ARO-AAT Q12W.
ARO-AAT 200 mg Cohort 2EXPERIMENTALPrimary Study Period (6-12 months): 200 mg dose of subcutaneous ARO-AAT for a minimum of 5 doses, with optional treatment extension periods. Treatment Extension I (12 months): 200 mg dose of subcutaneous AROAAT Q12W. Treatment Extension II (up to 24 Months): 200 mg dose of subcutaneous ARO-AAT Q12W.
ARO-AATACTIVE_COMPARATOR -
PlaceboPLACEBO_COMPARATOR -

Interventions

NameTypeDescription
ARO-AATDRUGsolution for subcutaneous injection
ARO-AAT InjectionDRUGSingle or multiple doses of ARO-AAT by subcutaneous (sc) injections
Sterile Normal Saline (0.9% NaCl)OTHERCalculated volume to match active comparator
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Eligibility Criteria

Age Range18 Years to 75 Years
SexALL
Healthy VolunteersNo
Study Sites4

Inclusion Criteria: * Diagnosis of AATD * Liver biopsy indicating Metavir F1-F3 liver fibrosis based on local pathology read. * Women of childbearing potential must have a negative pregnancy test, cannot be breast feeding, and must be willing to use contraception * Willing to provide written inform...

Countries:AustriaGermanyUnited KingdomNew Zealand
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Frequently asked questions about ARO-AAT

What is ARO-AAT used for?

ARO-AAT is an investigational RNA therapy being developed for alpha 1-antitrypsin deficiency, a rare genetic disorder. It is specifically studied in patients with alpha 1-antitrypsin deficiency associated liver disease. The drug is designed to reduce production of the abnormal alpha 1-antitrypsin protein that accumulates in the liver.

What does ARO-AAT target?

ARO-AAT targets alpha 1-antitrypsin, the protein that is deficient or abnormal in alpha 1-antitrypsin deficiency. By targeting this protein, the RNA therapy aims to reduce its production and accumulation in the liver, addressing the underlying cause of liver disease in affected patients.

Who is developing ARO-AAT?

ARO-AAT is being developed by Arrowhead Pharmaceuticals, Inc., which trades on the Nasdaq under the ticker ARWR. The company is responsible for the clinical development of this RNA therapy for alpha 1-antitrypsin deficiency associated liver disease.

What phase is ARO-AAT in?

ARO-AAT is in Phase 2 clinical development. It has completed two trials: a Phase 1 study in normal adult volunteers and a Phase 2 study in patients with alpha 1-antitrypsin deficiency associated liver disease. The drug is investigational and has not been approved by the FDA.

What clinical trials is ARO-AAT in?

ARO-AAT has been studied in two completed clinical trials. The Phase 2 trial, NCT03946449, enrolled 16 patients with alpha 1-antitrypsin deficiency associated liver disease in Austria, Germany, and the United Kingdom. The Phase 1 trial, NCT03362242, enrolled 45 healthy adult volunteers in New Zealand.

Is ARO-AAT the same as ARO-AAT Injection?

Yes, ARO-AAT Injection is another name for ARO-AAT. Both refer to the same investigational RNA therapy developed by Arrowhead Pharmaceuticals for alpha 1-antitrypsin deficiency associated liver disease.