A Study to Evaluate the Safety and Efficacy of VX-121 Combination Therapy in Subjects With Cystic Fibrosis
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ClinicalTrials.gov Identifier: NCT03912233 |
Recruitment Status :
Completed
First Posted : April 11, 2019
Results First Posted : April 20, 2023
Last Update Posted : April 20, 2023
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Condition or disease | Intervention/treatment | Phase |
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Cystic Fibrosis | Drug: VX-121 Drug: TEZ Drug: VX-561 Drug: TEZ/IVA Drug: IVA Drug: Placebo | Phase 2 |
Study Type : | Interventional (Clinical Trial) |
Actual Enrollment : | 87 participants |
Allocation: | Randomized |
Intervention Model: | Sequential Assignment |
Masking: | Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor) |
Primary Purpose: | Treatment |
Official Title: | A Phase 2, Randomized, Double-blind, Controlled Study to Evaluate the Safety and Efficacy of VX-121 Combination Therapy in Subjects Aged 18 Years and Older With Cystic Fibrosis |
Actual Study Start Date : | April 30, 2019 |
Actual Primary Completion Date : | December 10, 2019 |
Actual Study Completion Date : | December 10, 2019 |

Arm | Intervention/treatment |
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Placebo Comparator: Part 1: Placebo
Participants received placebo matched to VX-121/TEZ/VX-561 triple combination (TC) for 4 weeks in the treatment period and placebo matched to TEZ/VX-561 for 18 days in the washout period.
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Drug: Placebo
Placebos matched to VX-121, TEZ, and VX-561 for oral administration. |
Experimental: Part 1: VX-121/TEZ/VX-561 TC - Low Dose
Participants received VX-121 5 milligram (mg) once daily (qd)/TEZ 100 mg qd/VX-561 150 mg qd TC for 4 weeks in the treatment period and TEZ 100 mg qd/VX-561 150 mg qd for 18 days in the washout period
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Drug: VX-121
Tablets for oral administration. Drug: TEZ TEZ tablet for oral administration.
Other Names:
Drug: VX-561 Tablets for oral administration.
Other Names:
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Experimental: Part 1: VX-121/TEZ/VX-561 TC - Medium Dose
Participants received VX-121 10 mg qd/TEZ 100 mg qd/VX-561 150 mg qd TC for 4 weeks in the treatment period and TEZ 100 mg qd/VX-561 150 mg qd for 18 days in the washout period.
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Drug: VX-121
Tablets for oral administration. Drug: TEZ TEZ tablet for oral administration.
Other Names:
Drug: VX-561 Tablets for oral administration.
Other Names:
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Experimental: Part 1: VX-121/TEZ/VX-561 TC - High Dose
Participants received VX-121 20 mg qd/TEZ 100 mg qd/VX-561 150 mg qd TC for 4 weeks in the treatment period and TEZ 100 mg qd/VX-561 150 mg qd for 18 days in the washout period.
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Drug: VX-121
Tablets for oral administration. Drug: TEZ TEZ tablet for oral administration.
Other Names:
Drug: VX-561 Tablets for oral administration.
Other Names:
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Active Comparator: Part 2: TEZ/IVA
Following run-in period with TEZ 100 mg qd/IVA 150 mg every 12 hours (q12h) for 4 weeks, participants received TEZ 100 mg qd/IVA 150 mg q12h for 4 weeks in the treatment period and TEZ 100 mg/IVA 150 mg q12h for 4 weeks in the washout period.
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Drug: TEZ/IVA
Fixed-dose combination tablets for oral administration.
Other Names:
Drug: IVA Tablets for oral administration.
Other Names:
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Experimental: Part 2: VX-121/TEZ/VX-561 TC - High Dose
Following run-in period with TEZ 100 mg qd/IVA 150 mg q12h for 4 weeks, participants received VX-121 20 mg qd/TEZ 100 mg qd/VX-561 150 mg qd TC for 4 weeks in the treatment period and TEZ 100 mg qd/IVA 150 mg q12h for 4 weeks in the washout period.
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Drug: VX-121
Tablets for oral administration. Drug: TEZ TEZ tablet for oral administration.
Other Names:
Drug: VX-561 Tablets for oral administration.
Other Names:
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- Safety and Tolerability as Assessed by Number of Participants With Treatment-Emergent Adverse Events (AEs) and Serious Adverse Events (SAEs) [ Time Frame: From Day 1 Through Safety Follow-up (up to Day 75 for Part 1 and up to Day 85 for Part 2) ]
- Absolute Change in Percent Predicted Forced Expiratory Volume in 1 Second (ppFEV1) [ Time Frame: From Baseline Through Day 29 ]FEV1 is the volume of air that can forcibly be blown out in one second, after full inspiration.
- Absolute Change in Sweat Chloride (SwCl) Concentrations [ Time Frame: From Baseline Through Day 29 ]Sweat samples were collected using an approved collection device.
- Absolute Change in Cystic Fibrosis Questionnaire-Revised (CFQ-R) Respiratory Domain Score [ Time Frame: From Baseline at Day 29 ]The CFQ-R is a validated participant-reported outcome measuring health-related quality of life for participants with cystic fibrosis. Respiratory domain assessed respiratory symptoms, score range: 0-100; higher scores indicating fewer symptoms and better health-related quality of life.
- Observed Pre-dose Plasma Concentration (Ctrough) of VX-121, TEZ and Its Metabolite (M1-TEZ) and, VX-561 and Its Metabolites (M1-VX-561 and M6-VX-561) [ Time Frame: Pre-dose at Day 15 and Day 29 ]

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Ages Eligible for Study: | 18 Years and older (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Key Inclusion Criteria:
- Part 1: Heterozygous for F508del and an MF mutation (F/MF)
- Part 2: Homozygous for F508del (F/F)
- FEV1 value ≥40% and ≤90% of the predicted mean for age, sex, and height
Key Exclusion Criteria:
- History of clinically significant cirrhosis with or without portal hypertension
- Lung infection with organisms associated with a more rapid decline in pulmonary status
- History of solid organ or hematological transplantation
Other protocol-defined Inclusion/Exclusion criteria may apply

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03912233

Documents provided by Vertex Pharmaceuticals Incorporated:
Responsible Party: | Vertex Pharmaceuticals Incorporated |
ClinicalTrials.gov Identifier: | NCT03912233 |
Other Study ID Numbers: |
VX18-121-101 |
First Posted: | April 11, 2019 Key Record Dates |
Results First Posted: | April 20, 2023 |
Last Update Posted: | April 20, 2023 |
Last Verified: | March 2023 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Plan Description: | Details on Vertex data sharing criteria and process for requesting access can be found at: https://www.vrtx.com/independent-research/clinical-trial-data-sharing |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
Product Manufactured in and Exported from the U.S.: | Yes |
Cystic Fibrosis Fibrosis Pathologic Processes Pancreatic Diseases Digestive System Diseases Lung Diseases Respiratory Tract Diseases |
Genetic Diseases, Inborn Infant, Newborn, Diseases Ivacaftor Chloride Channel Agonists Membrane Transport Modulators Molecular Mechanisms of Pharmacological Action |