Huntington's Disease (HD)Phase 2/3NCT07537075
An Extension of SKY-0515 in Participants With Huntington's Disease
A Phase 2/3 study testing SKY-0515 in people with Huntington's Disease (HD), run by Skyhawk Therapeutics, Inc. at 10 sites in 2 countries.
Trial summary
The goal of this clinical trial is to test if the drug SKY-0515, an oral medication, can lower harmful proteins linked to Huntington's Disease (HD) and improve the symptoms of participants with HD. Read more about this study
- Who is it for?
- Ages 25 years and older
- Conditions the study is for
- Huntington's Disease (HD)
- What is being tested?
- SKY-0515
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 500 participants
- Where
- 10 sitesin 2 countries
- Study dates
- 10 Apr 2026to Dec 2029
- Phase
- Phase 2/3
- Are there results?
- Not yet: the study is under way
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 25 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Must have completed treatment in a prior SKY-0515 treatment study and, in the opinion of the Investigator, have been compliant with the prior SKY-0515 treatment protocol study procedures.
- Must be able and willing to meet all study requirements in the opinion of the Investigator including:
- Participants must be able to tolerate blood draws
- Willing and able to comply with all scheduled visits, treatment plans,laboratory tests and other study procedures
- Women who can have children must have a negative pregnancy test before starting and use two types of birth control during the study and for 30 days after the last dose of the study drug.
- Men must agree to use birth control during the study and for 90 days after the last dose.
Who cannot join
- -Have any other conditions that, in the opinion of the Investigator or Sponsor, would make the participant unsuitable for inclusion, or could interfere with the participant participating in or completing the study.
Trial locations and contacts
10 sites in 2 countries. Contact the study team or a site near you to ask about taking part.
10 sites in 2 countries
Australia7 sites
Flinders Medical Centre
Adelaide, South Australia, 5042
Calvary Health Care Bethlehem
Caulfield South, Victoria, 3162
The University of Queensland
Herston, Queensland, 4006
The Perron Institute for Neurology and Translational Science (Perron Institute)
Nedlands, Western Australia, 6009
John Hunter Hospital
New Lambton Heights, New South Wales, 2305
The Royal Melbourne Hospital
Parkville, Victoria, 3050
Westmead Hospital
Westmead, New South Wales, 2145
New Zealand3 sites
Huntington's Disease Association
Auckland, 0604
New Zealand Brain and Research Institute
Christchurch, 8011
Wellington Hospital
Wellington, 6021
About this study
Official title: An Open Label Extension of SKY-0515 in Participants With Huntington's Disease Who Completed a Prior SKY-0515 Treatment Study
The goal of this clinical trial is to test if the drug SKY-0515, an oral medication, can lower harmful proteins linked to Huntington's Disease (HD) and improve the symptoms of participants with HD. This study includes men and women aged 25 and older who have HD confirmed by genetic testing and meet certain requirements for physical ability and independence.
Read the detailed description
This is an OLE study to investigate the long-term safety, tolerability, and efficacy of SKY-0515 administered orally in participants with HD. To be eligible for this OLE study, participants must have completed dosing in a prior SKY-0515 treatment study and meet eligibility criteria for this study at an approved clinical study site. The study is comprised of an enrollment visit, a treatment period, and a follow-up visit. Throughout the study, participants will be evaluated as specified in the Schedule of Activities. At the enrollment visit (which may be the same as the last treatment visit of the prior study), participants will be consented to enter the OLE study and initiate open label treatment with 9 mg tablets of SKY-0515. Open label SKY-0515 will be self-administered daily (QD).
- Conditions
- Huntington's Disease (HD)
- Being tested
- SKY-0515
- Keywords
- SKY-0515
- Medical subject headings
- Huntington Disease
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
SKY-0515Drug
Study Drug Name (INN): SKY-0515 Type: Drug (small molecule) Dosage Level(s): 9mg Route of Administration: Oral Dosage Frequency: Once daily Treatment Duration: until drug becomes commercially available or until the development of SKY-0515 is terminated by the Sponsor. Use: Experimental Sourcing: SKY-0515 will be provided centrally by the Sponsor or subsidiary, or designee Packaging and Labeling: Study drug will be provided in bottles labeled as required per country requirement. All packaging and labeling operations for the study drug will be performed according to current Good Manufacturing Practice for Medicinal Products and the relevant regulatory requirements.
| Study group | Role | What they receive |
|---|---|---|
| 9mg dose | Experimental | Drug: SKY-0515 Type: Small molecule Route of Administration: Oral Dosage Frequency: Once daily Duration: until study drug is approved or study is discontinued Use: Experimental Receives: Drug: SKY-0515 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Long-term safety and tolerability of SKY-0515
To investigate the long-term safety and tolerability of SKY-0515 through the Incidence, severity, and relationship of treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) (including withdrawals due to TEAEs)
Measured: Continuously from enrollment to study completion or approximately 36 months
Secondary outcomes (6)
Change From Baseline in the Z-score from the Composite Unified Huntington's Disease Rating Scale (cUHDRS)
cUHDRS includes the Total Functional Capacity (range, 0-13; higher score means better functioning), Total Motor Score (range, 0-124; higher score means worse motor severity), Symbol Digit Modality Test (range, 0-110, correctly paired numbers-symbols in 90 seconds; higher score means better cognitive performance), and Stroop Color and Word Test (range, 0-no max value, correctly read color words in 45 seconds; higher score means better cognitive performance) scores. A z-score for each test is calculated, which alone can be used to describe relationship between an individual's test score and the mean score of a target population. A z-score of 0 is the mean, and ±1 is 1 standard deviation from the mean. For cUHDRS, z-scores of each test are summed, whereby a higher cUHDRS score is better (score of -3.06-no max value) and a change of ≥1.2 is a meaningful worsening, shown to track functional decline.
Measured: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Change from Baseline in Total Motor Score (TMS)
The total motor score (TMS) assessed motor features of HD with standardized ratings of oculomotor function, dysarthria, chorea, dystonia, gait, and postural stability. Some items (such as chorea and dystonia) required grading each extremity (face, bucco-oral-lingual, and trunk) separately. Eye movements require both horizontal and vertical grades. The total motor impairment scores was the sum of all the individual 31 motor sub-items (each rated from 0 to 4), with higher scores indicating more severe motor impairment than lower scores. The range of TMS is 0-124.
Measured: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Change from Baseline in Total Functional Capacity (TFC)
TFC consists of five ordinally scaled items assessing a person's capacity with: (1) occupation; (2) financial affairs; (3) domestic responsibilities; (4) activities of daily living; and (5) independent living. Total score ranges from zero (worst) to 13 (best).
Measured: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Change from Baseline in Independence Scale Score (IS)
The independence scale assesses independence on a 0 to 100 scale with higher scores indicating better functioning.
Measured: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Change from Baseline in Symbol Digit Modalities Test (SDMT)
The SDMT assesses attention, visuoperceptual processing, working memory, and cognitive/psychomotor speed. The score is the number of correctly paired abstract symbols and specific numbers in 90 seconds with higher scores indicating better cognitive functioning.
Measured: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Change from Baseline in the Stroop Color and Word Test (SCWT)
In the Stroop Color and Word Test (SCWT) the number of words and colors read correctly is counted, with a higher score indicating better cognitive performance scores. There is no upper limit for SWR as it is a time-based task. The lower limit (worst possible) however is 0; higher score is better meaning less severity.
Measured: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Apr 2026
- Study start10 Apr 2026
- Primary completionDec 2029 (estimated)
- Study completionDec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Huntington's Disease (HD)Studies 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 2/3
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 500 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Skyhawk Therapeutics, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07537075
- Sponsor's protocol ID
- SKY-0515-008
- Status last verified
- Jul 2026
- First submitted
- 3 Apr 2026
- Last updated
- 24 Jul 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 24 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- An Open Label Extension of SKY-0515 in Participants With Huntington's Disease Who Completed a Prior SKY-0515 Treatment Study
- ClinicalTrials.gov ID
- NCT07537075
- Acronym / sponsor ID
- SKY-0515-008
- Conditions
- Huntington's Disease (HD)
- Keywords
- SKY-0515
- Phase
- Phase 2/3
- Study type
- Interventional
- Recruitment status
- Enrolling by invitation
- Enrolment
- 500 participants (estimated)
- Lead sponsor
- Skyhawk Therapeutics, Inc.Industry (pharma, biotech, devices)
- Study start
- 10 Apr 2026 (actual)
- Primary completion
- Dec 2029 (estimated)
- Study completion
- Dec 2029 (estimated)
- First posted
- 17 Apr 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this clinical trial is to test if the drug SKY-0515, an oral medication, can lower harmful proteins linked to Huntington's Disease (HD) and improve the symptoms of participants with HD. This study includes men and women aged 25 and older who have HD confirmed by genetic testing and meet certain requirements for physical ability and independence.
Detailed description
This is an OLE study to investigate the long-term safety, tolerability, and efficacy of SKY-0515 administered orally in participants with HD. To be eligible for this OLE study, participants must have completed dosing in a prior SKY-0515 treatment study and meet eligibility criteria for this study at an approved clinical study site. The study is comprised of an enrollment visit, a treatment period, and a follow-up visit. Throughout the study, participants will be evaluated as specified in the Schedule of Activities. At the enrollment visit (which may be the same as the last treatment visit of the prior study), participants will be consented to enter the OLE study and initiate open label treatment with 9 mg tablets of SKY-0515. Open label SKY-0515 will be self-administered daily (QD).
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| 9mg dose | Experimental | Drug: SKY-0515Drug: SKY-0515 Type: Small molecule Route of Administration: Oral Dosage Frequency: Once daily Duration: until study drug is approved or study is discontinued Use: Experimental |
Who may qualify
- Ages
- 25 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- Must have completed treatment in a prior SKY-0515 treatment study and, in the opinion of the Investigator, have been compliant with the prior SKY-0515 treatment protocol study procedures.
- Must be able and willing to meet all study requirements in the opinion of the Investigator including:
- Participants must be able to tolerate blood draws
- Willing and able to comply with all scheduled visits, treatment plans,laboratory tests and other study procedures
- Women who can have children must have a negative pregnancy test before starting and use two types of birth control during the study and for 30 days after the last dose of the study drug.
Key exclusion criteria (1 listed)
- -Have any other conditions that, in the opinion of the Investigator or Sponsor, would make the participant unsuitable for inclusion, or could interfere with the participant participating in or completing the study.
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 |
|---|---|---|
| SKY-0515Study Drug Name (INN): SKY-0515 Type: Drug (small molecule) Dosage Level(s): 9mg Route of Administration: Oral Dosage Frequency: Once daily Treatment Duration: until drug becomes commercially available or until the development of SKY-0515 is terminated by the Sponsor. Use: Experimental Sourcing: SKY-0515 will be provided centrally by the Sponsor or subsidiary, or designee Packaging and Labeling: Study drug will be provided in bottles labeled as required per country requirement. All packaging and labeling operations for the study drug will be performed according to current Good Manufacturing Practice for Medicinal Products and the relevant regulatory requirements. | Drug | 9mg dose |
Primary outcome
Long-term safety and tolerability of SKY-0515
Time frame: Continuously from enrollment to study completion or approximately 36 months
To investigate the long-term safety and tolerability of SKY-0515 through the Incidence, severity, and relationship of treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) (including withdrawals due to TEAEs)
6 secondary outcomes
Change From Baseline in the Z-score from the Composite Unified Huntington's Disease Rating Scale (cUHDRS)
Time frame: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Change from Baseline in Total Motor Score (TMS)
Time frame: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Change from Baseline in Total Functional Capacity (TFC)
Time frame: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Change from Baseline in Independence Scale Score (IS)
Time frame: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Change from Baseline in Symbol Digit Modalities Test (SDMT)
Time frame: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Change from Baseline in the Stroop Color and Word Test (SCWT)
Time frame: Every 3 months for the first year, beginning with enrollment, then every six months for approximately 36 months.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Jul 2026.
- Skyhawk Therapeutics WebsiteLink provided by the sponsor.
- 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.
The record lists no contact. Use the official record to reach the sponsor.
10 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2/3 study testing SKY-0515 in people with Huntington's Disease (HD), run by Skyhawk Therapeutics, Inc. at 10 sites in 2 countries.
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 6 inclusion and 1 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: enrolling by invitation, as of the sponsor's last update on 24 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 10 sites in Australia, New Zealand. 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 combined 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.
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
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?
Long-term safety and tolerability of SKY-0515 (time frame: Continuously from enrollment to study completion or approximately 36 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 24 Jul 2026.