The goal of this clinical trial is to test use of losartan in those with cystic fibrosis (CF) on modulator therapy. The main question it aims to answer is if treatment with losartan improves response of the CF transmembrane conductance regulator (CFTR) channel to modulator therapy. Participants will be asked take losartan or placebo for twelve weeks and will have changes in sweat chloride levels measured as a marker of CFTR function.



Eligible Ages
Over 12 Years
Eligible Genders
Accepts Healthy Volunteers

Inclusion Criteria

  • Established diagnosis of cystic fibrosis - Age 12 years and older - Stable use of elexacaftor/tezacaftor/ivacaftor for 90 days prior to enrollment - Sweat chloride concentration 50 mmol/L or greater while on elexacaftor/tezacaftor/ivacaftor

Exclusion Criteria

  • Prior lung transplant - BMI <18 - CF pulmonary exacerbation requiring hospitalization or intravenous antibiotics in the preceding 30 days - Systemic corticosteroid or regular non-steroidal anti-inflammatory use in the preceding 30 days - Chronic use of angiotensin receptor blockers or angiotensin converting enzyme inhibitors - Concomitant use of medications known to interact with losartan, including aliskiren - Chronic renal insufficiency (creatinine clearance <45 ml/min) - Pregnancy or lactation - Inability or unwillingness to comply with approved contraceptive method during the study period (females of childbearing age) - In the opinion of the investigator any severe or acute or chronic condition or laboratory abnormality that may increase the risk associated with trial participation or make the participant inappropriate for enrollment - Participation in another interventional trial that, in the opinion of the investigator, has the potential to affect the primary outcome

Study Design

Phase 2
Study Type
Intervention Model
Parallel Assignment
Primary Purpose
Double (Participant, Investigator)

Arm Groups

ArmDescriptionAssigned Intervention
Losartan 25mg twice daily for one week followed by 50mg twice daily through week 12.
  • Drug: Losartan
    Treatment with losartan through week 12
Placebo Comparator
Placebo twice daily through week 12
  • Drug: Placebo
    Treatment with placebo through week 12

Recruiting Locations

University of Kansas Medical Center
Kansas City, Kansas 66160
Charles Bengtson, MD, MSc

More Details

University of Kansas Medical Center

Study Contact

Heidi Hellwig

Detailed Description

This is a randomized, placebo-controlled, parallel group clinical trial in those those with CF on elexacaftor/tezacaftor/ivacaftor to determine if treatment with losartan improves response to modulator therapy using sweat chloride as an marker of CFTR function.


Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.