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VX-581

Phase 1

Cystic Fibrosis | Small molecule | Respiratory |Vertex Pharmaceuticals Incorporated|Last Updated: Jul 16, 2026

Target and mechanism

Molecular targetCFTR
Target classProtein
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLED
Total Trials1
Total Enrollment136

FDA Designations

No designations recorded

Clinical trial landscape

VX-581 · 1 trial · 1 indication

Phase 1 1
NCT07283770Dose Escalation Study Evaluating the Safety and Pharmacokinetics of VX-581 in Healthy ParticipantsCystic Fibrosis
RECRUITING136 Analytics
PHASE1RECRUITING
Dose Escalation Study Evaluating the Safety and Pharmacokinetics of VX-581 in Healthy Participants
Cystic FibrosisUnlock trial analytics

Study Endpoints

Primary Endpoints

Part A: Safety and Tolerability as Assessed by Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs)
From Day -1 up to Day 8
Part B: Safety and Tolerability as Assessed by Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs)
From Day -1 up to Day 17
Part C: Safety and Tolerability as Assessed by Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs)
From Day -1 up to Day 17

Secondary Endpoints

Part A: Maximum Observed Plasma Concentration (Cmax) of VX-581
On Day 1
Part A: Area Under the Concentration Versus Time Curve From the Time of Dosing Up to 24 Hours (AUC0-24h) Post-Dose of VX-581
On Day 1
Part B: Maximum Observed Plasma Concentration (Cmax) of VX-581
On Days 1, 7, and 10
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Part A: Single Ascending DoseEXPERIMENTALParticipants will be randomized to receive a single dose of VX-581.
Placebo: Part APLACEBO_COMPARATORParticipants will be randomized to receive a single dose of placebo matched to VX-581.
Part B: Multiple Ascending DoseEXPERIMENTALParticipants will be randomized to receive multiple doses of VX-581.
Placebo: Part BPLACEBO_COMPARATORParticipants will be randomized to receive multiple doses of placebo matched to VX-581.
Part C: VX-581 with TEZ/D-IVA or D-IVAEXPERIMENTALParticipants will be randomized to receive multiple doses VX-581 in combination with TEZ/D-IVA or D-IVA.
Placebo: Part CPLACEBO_COMPARATORParticipants will be randomized to receive placebo matched to VX-581 in combination with TEZ/D-IVA or D-IVA.

Interventions

NameTypeDescription
VX-581DRUGSuspension for Oral Administration.
PlaceboDRUGSuspension for Oral Administration.
D-IVADRUGTablet for Oral Administration.
TEZDRUGTablet for Oral Administration.
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Eligibility Criteria

Age Range18 Years to 55 Years
SexALL
Healthy VolunteersYes
Study Sites1

Key Inclusion Criteria: * Body mass index (BMI) of 18.0 to 32.0 kilogram per meter square (kg/m\^2) * A total body weight of more than (\>) 50 kg * Male and Female participants of non-childbearing potential Key Exclusion Criteria: * History of febrile illness or other acute illness that has not f...

Countries:United States
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Recent Changes (Last 90 Days)

MEDIUMJul 17, 2026NCT07283770Enrollment: 128 → 136
MEDIUMJul 17, 2026NCT07283770Enrollment: 128 → 136
MEDIUMJul 17, 2026NCT07283770Enrollment: 128 → 136

Frequently asked questions about VX-581

What is VX-581 used for?

VX-581 is an investigational small molecule being developed for the treatment of cystic fibrosis. It is currently in Phase 1 clinical development and is not yet approved by regulatory authorities. The drug is being studied in a clinical trial that includes healthy participants as well as those with cystic fibrosis.

What does VX-581 target?

VX-581 targets the CFTR protein, which is the molecular target for the drug. CFTR is a protein involved in cystic fibrosis, and the drug is designed to interact with this protein as part of its therapeutic approach. The drug is a small molecule modality.

Who is developing VX-581?

VX-581 is being developed by Vertex Pharmaceuticals Incorporated, a biopharmaceutical company. Vertex Pharmaceuticals is listed on the stock exchange under the ticker symbol VRTX. The company is conducting clinical trials to evaluate the safety and pharmacokinetics of VX-581.

What phase is VX-581 in?

VX-581 is in Phase 1 clinical development. It is an investigational drug, meaning it has not been approved by the FDA or other regulatory agencies. The drug is currently being studied in an early-stage clinical trial to evaluate its safety and pharmacokinetics in healthy participants.

What clinical trials is VX-581 in?

VX-581 is being studied in a Phase 1 clinical trial with the identifier NCT07283770. This trial is a dose escalation study evaluating the safety and pharmacokinetics of VX-581 in healthy participants. The study is currently recruiting and has an enrollment target of 136 participants. It is a randomized, double-blind, placebo-controlled trial conducted in the United States.

Is VX-581 the same as any other drug?

VX-581 is a distinct investigational drug candidate developed by Vertex Pharmaceuticals. It is not known to be the same as any other approved or marketed medication. The drug is being studied specifically for its potential role in treating cystic fibrosis, and it is currently in early-stage clinical development.