Cystic FibrosisPhase 1NCT07813039
A Phase 1 Relative Bioavailability Study of a VX-581 Tablet Formulation
A Phase 1 study testing VX-581 in people with Cystic Fibrosis, run by Vertex Pharmaceuticals Incorporated at 1 site in United States.
Trial summary
The purpose of this study is to evaluate the relative bioavailability of VX-581 tablet formulation compared to a suspension formulation along with its safety and tolerability. Read more about this study
- Who is it for?
- Ages 18 to 55 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Cystic Fibrosis
- What is being tested?
- VX-581
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 16 participants
- Where
- 1 siteUnited States
- Study dates
- 23 Sep 2026to 27 Oct 2026
- Phase
- Phase 1
- 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 18 to 55 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Body mass index (BMI) of 18.0 to 32.0 kilogram per meter square (kg/m^2), inclusive
- Total body weight of greater than (>) 50 kg
- Nonsmoker or ex-smoker for at least 3 months before screening with current nonsmoking status confirmed by urine or blood cotinine at screening
Who cannot join
- History of febrile illness or other acute illness that has not fully resolved within 14 days before the first dose of study drug
- Any condition possibly affecting drug absorption
- Other protocol defined Inclusion/Exclusion criteria may apply.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: A Phase 1, Open-label, Randomized, Crossover Study to Evaluate the Relative Bioavailability of a Tablet Formulation of VX-581 in Healthy Adult Subjects
The purpose of this study is to evaluate the relative bioavailability of VX-581 tablet formulation compared to a suspension formulation along with its safety and tolerability.
Read the detailed description
The purpose of this study is to evaluate the relative bioavailability of VX-581 tablet formulation compared to a suspension formulation along with its safety and tolerability in healthy human participants. Note: This clinical trial information was submitted voluntarily under the applicable law and, therefore, certain submission deadlines may not apply. (That is, clinical trial information for this applicable clinical trial was submitted under section 402(j)(4)(A) of the Public Health Service Act and 42 CFR 11.60 and is not subject to the deadlines established by sections 402(j)(2) and (3) of the Public Health Service Act or 42 CFR 11.24 and 11.44.).
- Conditions
- Cystic Fibrosis
- Being tested
- VX-581
- Medical subject headings
- Cystic Fibrosis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
VX-581Drug
Tablet and Suspension for Oral Administration.
| Study group | Role | What they receive |
|---|---|---|
| Sequence 1 | Experimental | Participants will be randomized to receive VX-581 suspension in dosing period 1 followed by VX-581 tablet in dosing period 2. A washout period of 10 days will be maintained between the 2 dosing periods. Receives: Drug: VX-581 |
| Sequence 2 | Experimental | Participants will be randomized to receive VX-581 tablet in dosing period 1 followed by VX-581 suspension in dosing period 2. A washout period of 10 days will be maintained between the 2 dosing periods. Receives: Drug: VX-581 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Maximum Observed Plasma Concentration (Cmax) of VX-581
Measured: Period 1 and Period 2: From Day 1 up to Day 21
Area Under the Concentration Versus Time Curve (AUC) of VX-581
Measured: Period 1 and Period 2: From Day 1 up to Day 21
Secondary outcomes (1)
Safety and Tolerability as Assessed by Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs)
Measured: From Signing of Informed Consent Form (ICF) up to Safety Follow Up (Up to Day 21)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Sep 2026
- Study start23 Sep 2026
- Primary completion27 Oct 2026 (estimated)
- Study completion27 Oct 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Cystic FibrosisStudies of the same condition, open and under way.
- More trials run by Vertex Pharmaceuticals IncorporatedThe sponsor's other registered studies.
- 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 1
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 16 participants (actual)
Sponsor and investigators
- Lead sponsor
- Vertex Pharmaceuticals Incorporated
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07813039
- Sponsor's protocol ID
- VX25-581-002
- Status last verified
- Oct 2026
- First submitted
- 4 Sep 2026
- Last updated
- 27 Oct 2026
- Results posted
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No: Details on Vertex data sharing criteria and process for requesting access can be found at: https://www.vrtx.com/our-science/clinical-trials-data-sharing/
Study at a glance
From the registry record, last updated by the sponsor on 27 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 1, Open-label, Randomized, Crossover Study to Evaluate the Relative Bioavailability of a Tablet Formulation of VX-581 in Healthy Adult Subjects
- ClinicalTrials.gov ID
- NCT07813039
- Acronym / sponsor ID
- VX25-581-002
- Conditions
- Cystic Fibrosis
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 16 participants (actual)
- Lead sponsor
- Vertex Pharmaceuticals IncorporatedIndustry (pharma, biotech, devices)
- Study start
- 23 Sep 2026 (actual)
- Primary completion
- 27 Oct 2026 (estimated)
- Study completion
- 27 Oct 2026 (estimated)
- First posted
- 10 Sep 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 purpose of this study is to evaluate the relative bioavailability of VX-581 tablet formulation compared to a suspension formulation along with its safety and tolerability.
Detailed description
The purpose of this study is to evaluate the relative bioavailability of VX-581 tablet formulation compared to a suspension formulation along with its safety and tolerability in healthy human participants. Note: This clinical trial information was submitted voluntarily under the applicable law and, therefore, certain submission deadlines may not apply. (That is, clinical trial information for this applicable clinical trial was submitted under section 402(j)(4)(A) of the Public Health Service Act and 42 CFR 11.60 and is not subject to the deadlines established by sections 402(j)(2) and (3) of the Public Health Service Act or 42 CFR 11.24 and 11.44.).
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Sequence 1 | Experimental | Drug: VX-581Participants will be randomized to receive VX-581 suspension in dosing period 1 followed by VX-581 tablet in dosing period 2. A washout period of 10 days will be maintained between the 2 dosing periods. |
| Sequence 2 | Experimental | Drug: VX-581Participants will be randomized to receive VX-581 tablet in dosing period 1 followed by VX-581 suspension in dosing period 2. A washout period of 10 days will be maintained between the 2 dosing periods. |
Who may qualify
- Ages
- 18 to 55 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- Body mass index (BMI) of 18.0 to 32.0 kilogram per meter square (kg/m^2), inclusive
- Total body weight of greater than (>) 50 kg
- Nonsmoker or ex-smoker for at least 3 months before screening with current nonsmoking status confirmed by urine or blood cotinine at screening
Key exclusion criteria (3 listed)
- History of febrile illness or other acute illness that has not fully resolved within 14 days before the first dose of study drug
- Any condition possibly affecting drug absorption
- Other protocol defined Inclusion/Exclusion criteria may apply.
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 |
|---|---|---|
| VX-581Tablet and Suspension for Oral Administration. | Drug | Sequence 1, Sequence 2 |
Primary outcome
Maximum Observed Plasma Concentration (Cmax) of VX-581
Time frame: Period 1 and Period 2: From Day 1 up to Day 21
Area Under the Concentration Versus Time Curve (AUC) of VX-581
Time frame: Period 1 and Period 2: From Day 1 up to Day 21
1 secondary outcome
Safety and Tolerability as Assessed by Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs)
Time frame: From Signing of Informed Consent Form (ICF) up to Safety Follow Up (Up to Day 21)
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 27 Oct 2026.
- Individual participant dataSharing planned: No. Details on Vertex data sharing criteria and process for requesting access can be found at: https://www.vrtx.com/our-science/clinical-trials-data-sharing/
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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.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing VX-581 in people with Cystic Fibrosis, run by Vertex Pharmaceuticals Incorporated at 1 site 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 3 inclusion and 3 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: under way, not looking for participants, as of the sponsor's last update on 27 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site 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 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
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?
Maximum Observed Plasma Concentration (Cmax) of VX-581 (time frame: Period 1 and Period 2: From Day 1 up to Day 21). The study lists 2 primary outcomes in all. 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 27 Oct 2026.