Huntington DiseasePhase 2NCT04514367

An Open Label Study of ANX005 in Participants With, or at Risk for, Manifest Huntington's Disease

A Phase 2 study testing ANX005 in people with Huntington Disease, run by Annexon, Inc. at 6 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Trial summary

This study is a multi-center, open-label study of intravenous (IV) ANX005 in participants with, or at risk for, manifest Huntington's Disease (HD). Read more about this study

Who is it for?: Ages 18 years and older
Conditions the study is for: Huntington Disease
What is being tested?: ANX005
Type of treatment: Injection or infusion
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 28 participants
Where: 6 sitesUnited States
Study dates: 29 Sep 2020to 29 Aug 2022
Phase: Phase 2
Are there results?: Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 18 years and older
All sexes
No healthy volunteers
Adult, Older adult

Who may be able to join

Diagnosis of or at risk for HD: Genetically confirmed disease by direct deoxyribonucleic acid (DNA) testing, total cytosine-adenine-guanine (CAG)-Age Product (CAP) score > 400 and UHDRS independence score ≥ 80.
Able to walk independently and self-sufficient in basic activities of daily living (for example, eating, dressing, bathing).
All HD concomitant medications stable.
If female, must be postmenopausal (no menses for at least 2 years without an alternative medical cause), surgically sterilized (bilateral tubal ligation, bilateral oophorectomy, or hysterectomy), or agree to use highly effective methods of contraception.
Males with a woman of childbearing potential partner must agree to use highly effective methods of contraception.
Previously vaccinated against encapsulated bacterial pathogens (Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae) or willing to undergo vaccination.
Able to tolerate electroencephalogram (EEG) and lumbar puncture (LP) procedures.

Who cannot join

Be at risk of suicide or self-harm within the preceding 12 months.
Chorea and/or cognitive deficits severe enough to interfere with study assessments.
Participants with body weight > 150 kilograms (kg).
Clinically significant findings on the screening laboratory testing or physical examination that are not specific to HD and may interfere with the conduct of the study or the interpretation of the data or increase participant risk.
Signs and symptoms of, or a diagnosis consistent with a chronic autoimmune disorder and/or an antinuclear antibody (ANA) titer ≥ 1:160.
History of previous infusion reactions, sensitivities, allergic, or anaphylactic reactions to previous medications, environmental stimuli or other substances.

Show all 17Show fewer

Use of an experimental agent within 60 days or five half-lives prior to Screening or anytime over the duration of this study.
Prior treatment with any monoclonal antibody.
Presence of an implanted deep brain stimulation device.
Any history of gene therapy, ribonucleic acid (RNA) or DNA targeted HD specific investigational agents such as antisense oligonucleotides, cell transplantation or any experimental brain surgery.
Brain and spinal pathology that may interfere with cerebrospinal fluid homeostasis and circulation, increases intracranial pressure (implanted shunt or catheter), malformations or tumor.
Contraindication to undergoing an LP.
Hypersensitivity to any of the excipients in the ANX005 drug product.
Clinically significant intercurrent illness, medical condition, or medical history (including neurological or mental illness, human immunodeficiency virus [HIV], any active infection, including Hepatitis B or C) that would jeopardize the safety of the participant, limit participation, or compromise the interpretation of the data derived from the participant.
Any known genetic deficiencies of the complement-cascade system.
History of chronic oral or intravenous steroid use or immunosuppressant medication use.
Hemoglobin, bilirubin, or lactate dehydrogenase (LDH) values that are outside normal limits and clinically significant or suggestive of hemolytic anemia.

Trial locations and contacts

6 sites in 1 country.

City, postcode or hospital

6 sites in 1 country

United States6 sites

Annexon Investigational Site 02
Birmingham, Alabama, 35294
Annexon Investigational Site 06
Cincinnati, Ohio, 45221
Annexon Investigational Site 07
Durham, North Carolina, 27710
Annexon Investigational Site 03
Englewood, Colorado, 80113
Annexon Investigational Site 08
Kirkland, Washington, 98034
Annexon Investigational Site 04
Washington D.C., District of Columbia, 20057

Other trials in United States

About this study

Official title: A Phase 2a Open Label Study to Assess the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of Intravenous ANX005 in Subjects With, or at Risk for, Manifest Huntington's Disease

This study is a multi-center, open-label study of intravenous (IV) ANX005 in participants with, or at risk for, manifest Huntington's Disease (HD).

Read the detailed description

The objective of this study is to evaluate the effects of IV ANX005 administered for up to 22 weeks in participants with, or at risk for, manifest HD.

Participants will receive induction dosing of ANX005 administered by IV infusion on Days 1 and 5 or 6, followed by maintenance dosing every 2 weeks through Week 22, with follow up visits on Weeks 24, 28, and 36.

All participants will be contacted (in clinic visit or phone call) 6 months after study completion.

Conditions: Huntington Disease
Being tested: ANX005
Medical subject headings: Huntington Disease

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

ANX005Drug
Intravenous Infusion

Study groups in NCT04514367
Study group	Role	What they receive
ANX005	Experimental	Participants will receive induction dosing of ANX005 administered by IV infusion on Days 1 and 5 or 6, followed by maintenance dosing every 2 weeks (Weeks 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, and 22) with follow up visits on Weeks 24, 28, and 36. Receives: Drug: ANX005

What is being measured

The primary outcome is the main question the study is designed to answer.

Number of Participants With Treatment-Emergent Adverse Events (TEAEs)
An adverse event (AE) was defined as any untoward medical occurrence that developed or worsened in severity during the conduct of a clinical study and does not necessarily have a causal relationship to study drug. Serious AEs (SAEs) included death, a life-threatening AE, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant disability or, a congenital anomaly or birth defect, or an important medical event that jeopardized the participant and required medical intervention to prevent 1 of the outcomes listed in this definition. A TEAE was any AE with an onset on or after the day of infusion through Week 36 (end of study). AEs were graded per National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE): Grade: 1=Mild, 2=Moderate, 3=Severe or medically significant but not immediately life-threatening. A summary of serious and non-serious AEs regardless of causality is located in 'Reported Adverse Events module'.
Measured: From first dose of study drug up to end of study (Week 36)
Actual Dose of ANX005 Administered on Day 1
Measured: Day 1
Actual Dose of ANX005 Administered on Week 22
Measured: Week 22
Area Under the Concentration Versus Time Curve From Time 0 to t (AUC0-t) of ANX005 at Day 1
Measured: Pre-dose up to 4 hours post-dose on Day 1
CSF Free Complement Component 1q (C1q) at Day 1
Measured: Predose at Baseline (Day 1)
Blood Free C1q at Day 1
Measured: Predose at Baseline (Day 1)
Change From Baseline in Complement C4a in CSF at Week 24
Measured: Baseline, Week 24
Change From Baseline in Complement C4a in CSF at Week 36
Measured: Baseline, Week 36
Change From Baseline in CSF NfL Level at Week 24
Measured: Baseline, Week 24
Change From Baseline in CSF NfL Level at Week 36
Measured: Baseline, Week 36
Change From Baseline in Blood NfL Level at Week 24
Measured: Baseline, Week 24
Change From Baseline in Blood NfL Level at Week 36
Measured: Baseline, Week 36

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

29 Sep 202029 Aug 2022

First posted14 Aug 2020
Study start29 Sep 2020
Primary completion29 Aug 2022
Study completion29 Aug 2022

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Other trials for Huntington DiseaseStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 2
Primary purpose: Treatment
Allocation: Not applicable
Intervention model: Single group
Model description: ANX005 administered for up to 22 weeks
Masking: None (open label)
Enrolment: 28 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT04514367
Sponsor's protocol ID: ANX005-HD-01
Status last verified: Jul 2026
First submitted: 27 Jul 2020
Last updated: 25 Aug 2026
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: No

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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All Huntington Disease trials

Study at a glance

From the registry record, last updated by the sponsor on 25 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A Phase 2a Open Label Study to Assess the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of Intravenous ANX005 in Subjects With, or at Risk for, Manifest Huntington's Disease
ClinicalTrials.gov ID: NCT04514367
Acronym / sponsor ID: ANX005-HD-01
Conditions: Huntington Disease
Phase: Phase 2
Study type: Interventional
Recruitment status: Completed
Enrolment: 28 participants (actual)
Lead sponsor: Annexon, Inc.Industry (pharma, biotech, devices)
Study start: 29 Sep 2020 (actual)
Primary completion: 29 Aug 2022 (actual)
Study completion: 29 Aug 2022 (actual)
First posted: 14 Aug 2020 (actual)
Results: Posted 25 Aug 2026

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

This study is a multi-center, open-label study of intravenous (IV) ANX005 in participants with, or at risk for, manifest Huntington's Disease (HD).

Detailed description

The objective of this study is to evaluate the effects of IV ANX005 administered for up to 22 weeks in participants with, or at risk for, manifest HD.

All participants will be contacted (in clinic visit or phone call) 6 months after study completion.

Study design

Primary purpose: Treatment
Allocation: Not applicable
Intervention model: Single group
Masking: None (open label)
Number of arms: 1
Model description: ANX005 administered for up to 22 weeks

Arm	Type	Receives
ANX005	Experimental	Drug: ANX005Participants will receive induction dosing of ANX005 administered by IV infusion on Days 1 and 5 or 6, followed by maintenance dosing every 2 weeks (Weeks 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, and 22) with follow up visits on Weeks 24, 28, and 36.

Who may qualify

Ages: 18 years and older
Sex: All
Healthy volunteers: Not accepted
Age groups: Adult, Older adult

Key inclusion criteria (7 listed)

Diagnosis of or at risk for HD: Genetically confirmed disease by direct deoxyribonucleic acid (DNA) testing, total cytosine-adenine-guanine (CAG)-Age Product (CAP) score > 400 and UHDRS independence score ≥ 80.
Able to walk independently and self-sufficient in basic activities of daily living (for example, eating, dressing, bathing).
All HD concomitant medications stable.
If female, must be postmenopausal (no menses for at least 2 years without an alternative medical cause), surgically sterilized (bilateral tubal ligation, bilateral oophorectomy, or hysterectomy), or agree to use highly effective methods of contraception.
Males with a woman of childbearing potential partner must agree to use highly effective methods of contraception.

Key exclusion criteria (17 listed)

Be at risk of suicide or self-harm within the preceding 12 months.
Chorea and/or cognitive deficits severe enough to interfere with study assessments.
Participants with body weight > 150 kilograms (kg).
Clinically significant findings on the screening laboratory testing or physical examination that are not specific to HD and may interfere with the conduct of the study or the interpretation of the data or increase participant risk.
Signs and symptoms of, or a diagnosis consistent with a chronic autoimmune disorder and/or an antinuclear antibody (ANA) titer ≥ 1:160.

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
ANX005Intravenous Infusion	Drug	ANX005

Primary outcome

Number of Participants With Treatment-Emergent Adverse Events (TEAEs)
Time frame: From first dose of study drug up to end of study (Week 36)
An adverse event (AE) was defined as any untoward medical occurrence that developed or worsened in severity during the conduct of a clinical study and does not necessarily have a causal relationship to study drug. Serious AEs (SAEs) included death, a life-threatening AE, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant disability or, a congenital anomaly or birth defect, or an important medical event that jeopardized the participant and required medical intervention to prevent 1 of the outcomes listed in this definition. A TEAE was any AE with an onset on or after the day of infusion through Week 36 (end of study). AEs were graded per National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE): Grade: 1=Mild, 2=Moderate, 3=Severe or medically significant but not immediately life-threatening. A summary of serious and non-serious AEs regardless of causality is located in 'Reported Adverse Events module'.
Actual Dose of ANX005 Administered on Day 1
Time frame: Day 1
Actual Dose of ANX005 Administered on Week 22
Time frame: Week 22
Area Under the Concentration Versus Time Curve From Time 0 to t (AUC0-t) of ANX005 at Day 1
Time frame: Pre-dose up to 4 hours post-dose on Day 1
CSF Free Complement Component 1q (C1q) at Day 1
Time frame: Predose at Baseline (Day 1)
Blood Free C1q at Day 1
Time frame: Predose at Baseline (Day 1)
Change From Baseline in Complement C4a in CSF at Week 24
Time frame: Baseline, Week 24
Change From Baseline in Complement C4a in CSF at Week 36
Time frame: Baseline, Week 36
Change From Baseline in CSF NfL Level at Week 24
Time frame: Baseline, Week 24
Change From Baseline in CSF NfL Level at Week 36
Time frame: Baseline, Week 36
Change From Baseline in Blood NfL Level at Week 24
Time frame: Baseline, Week 24
Change From Baseline in Blood NfL Level at Week 36
Time frame: Baseline, Week 36

Results and safety

Results posted to the registry on 25 Aug 2026, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
ANX005	28	25

Primary outcome: Number of Participants With Treatment-Emergent Adverse Events (TEAEs)

Time frame: From first dose of study drug up to end of study (Week 36). Count of participants. Unit: Participants

Measure	ANX005 n = 28
Any TEAEs	28
SAEs	2
AEs related to ANX005	28
SAEs related to ANX005	2
Grade ≥3 AEs	12
Grade ≥3 AEs related to ANX005	11
AEs leading to study discontinuation	2
AEs leading to discontinuation of study medications	4

Population analysed: Safety population included all enrolled participants who received at least 1 dose of study drug.

Primary outcome: Actual Dose of ANX005 Administered on Day 1

Time frame: Day 1. Mean (Standard Deviation). Unit: milligrams (mg)/kilogram (kg)

Measure	ANX005 n = 28
Value	75.0624 (2.6694)

Population analysed: Safety population included all enrolled participants who received at least 1 dose of study drug.

Primary outcome: Actual Dose of ANX005 Administered on Week 22

Time frame: Week 22. Mean (Standard Deviation). Unit: mg/kg

Measure	ANX005 n = 23
Value	102.6609 (2.7408)

Population analysed: Safety population included all enrolled participants who received at least 1 dose of study drug. Here, 'Overall number of participants analyzed' = participants evaluable for this outcome measure.

Primary outcome: Area Under the Concentration Versus Time Curve From Time 0 to t (AUC0-t) of ANX005 at Day 1

Time frame: Pre-dose up to 4 hours post-dose on Day 1. Mean (Standard Deviation). Unit: days*µg/milliliter (mL)

Measure	ANX005 n = 28
Value	4290 (818)

Population analysed: PK analysis set included all participants who received any amount of ANX005 and had evaluable ANX005 concentration data.

Adverse events

Time frame: From first dose of study drug up to end of study (Week 36). Other adverse events reported at 5% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
ANX005	2 of 28 (7.1%)	28 of 28 (100%)	0 of 28

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 25 Aug 2026.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Individual participant dataSharing planned: No

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Benjamin Hoehn, MD study director

Annexon, Inc.

6 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing ANX005 in people with Huntington Disease, run by Annexon, Inc. at 6 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 7 inclusion and 17 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 25 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 6 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 25 Aug 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Number of Participants With Treatment-Emergent Adverse Events (TEAEs) (time frame: From first dose of study drug up to end of study (Week 36)). The study lists 12 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04514367.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 25 Aug 2026.