A Phase 1 interventional study of VX-581 in Cystic Fibrosis, sponsored by Vertex Pharmaceuticals Incorporated. Active, not recruiting at 1 site in United States. Open to male participants aged 18 Years to 55 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-27.
Sponsored by Vertex Pharmaceuticals Incorporated · Phase 1, Interventional, and Treatment
Among 119 studies in Cystic Fibrosis by Vertex Pharmaceuticals Incorporated — 3 open to participants now, 8 under way, 5 of them phase 3. Cystic Fibrosis · Vertex Pharmaceuticals Incorporated.
Among the 119 studies in Cystic Fibrosis by Vertex Pharmaceuticals Incorporated, this one is the 102nd largest by enrollment of the 110 interventional ones, is one of 3 that started in 2026, is one of 24 in phase 1, and was the 119th registered.
1,619 studies on the registry are indexed under Cystic Fibrosis; 199 are open to participants now.
This study's enrollment of 16 is below the median of 36 across 1,051 interventional studies indexed under Cystic Fibrosis.
Browse Cystic Fibrosis studies →3 of the 119 studies in Cystic Fibrosis by Vertex Pharmaceuticals Incorporated are open now, in 10 countries. Each count lists the studies.
Of the 154 Cystic Fibrosis studies recruiting now, 95 (62%) set no upper age limit and 43 (28%) stop at 75 or younger; 84 take children under 18; 41 take healthy volunteers.
This study: 18 Years to 55 Years · male · healthy volunteers too.
The full table on the hub →119 studies; the count open now beside each. This study's row is marked.
First in 2007; this study’s year is marked. 3 started in 2026.
Median enrollment 79 across the 110 interventional studies, 79 across the 5 observational. Of the 107 that completed or were terminated, 79 (74%) have results posted.
Vertex Pharmaceuticals Incorporated is the lead sponsor of 249 studies on the registry; 17 are open to participants now.
Of its 106 completed or terminated interventional studies of FDA-regulated products, 53 (50%) have results posted.
4 of the studies in Cystic Fibrosis by Vertex Pharmaceuticals Incorporated that are under way reach primary completion within a year, 2 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT05331183Phase 3Vertex Pharmaceuticals IncorporatedStudy to Evaluate Elexacaftor/Tezacaftor/Ivacaftor (ELX/TEZ/IVA) Long-term Safety and Efficacy in Subjects Without F508del | 2027-04-06 |
| NCT06460506Phase 3Vertex Pharmaceuticals IncorporatedEvaluation of Long-term Safety and Efficacy of ELX/TEZ/IVA in Cystic Fibrosis Participants 12 Months of Age and Older | 2027-09-30 |
| NCT07437105Vertex Pharmaceuticals IncorporatedDose Escalation Study Evaluating the Safety and Pharmacokinetics of VX-272 in Healthy Participants | 2027-06-26 |
| NCT07283770Vertex Pharmaceuticals IncorporatedEvaluation of VX-581 in Healthy Participants and in Participants With Cystic Fibrosis | 2027-07-12 |
Among the 119 studies in Cystic Fibrosis by Vertex Pharmaceuticals Incorporated, from their registry updates:
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.
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.).
Key Inclusion Criteria:
Key Exclusion Criteria:
Other protocol defined Inclusion/Exclusion criteria may apply.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
Drug: VX-581
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.
Drug: VX-581
Tablet and Suspension for Oral Administration.
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
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)
Plan to share: 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/
No publications or documents are linked to this record.
Started Sep 2026 (actual). Primary completion is estimated for Oct 2026, 1 month after the start.
Of 39 industry-sponsored phase 1 interventional studies under Cystic Fibrosis, half reached primary completion within 8 months of starting (the median), counting those still running; a quarter within 2 and three quarters within 16. This study's planned 1 month is below that.
Counting every sponsor, half of 62 studies reached it within 10 months; a quarter within 5 and three quarters within 34.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is active, not recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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