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Toxicant ExposurePhase 1/2ENGINENCT07226440

Examining a Novel Gastrointestinal Intervention to Negate Environmental Toxicants (ENGINE)

A Phase 1/2 study testing Colesevelam in people with Toxicant Exposure and Firefighter, run by University of California, San Francisco at 1 site in United States.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

This randomized, placebo-controlled crossover trial will test the feasibility and acceptability of using colesevelam in male firefighters with high per- and polyfluoroalkyl substances (PFAS) exposure. Read more about this study

Who is it for?
Ages 18 years and older, men only
What is being tested?
Colesevelam
Type of treatment
Pill or oral medicine
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
50 participants
Where
1 siteUnited States
Study dates
1 Mar 2026to Dec 2028
Phase
Phase 1/2
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 years and older
  • Men only
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Male firefighter, active or retired
  • California resident
  • Age 18 or older
  • English-speaking
  • Access to a reliable internet connection
  • Willing to attend 3 in-person study visits in the San Francisco Bay Area over about 6.5 months
Show all 10Show fewer
  • Willing to receive weekly text message reminders to complete online surveys
  • Willing to complete a mail-based, at-home finger-prick blood test
  • Willing to take 3 tablets (each tablet about the size of a multivitamin) orally twice daily for a total of 6 months
  • Evaluated by study team to have an elevated risk of PFAS exposure (e.g., duration of firefighting service, prior NASEM-7 result greater than or equal to 10 ng/mL)

Who cannot join

  • Gastroparesis or other severe gastrointestinal motility disorders
  • Bowel obstruction
  • History of major gastrointestinal tract surgery
  • Dysphagia or difficulty swallowing (due to tablet size)
  • History of hypertriglyceridemia (triglycerides exceeding 500 mg/dL)
  • History of hypertriglyceridemia-induced pancreatitis
Show all 12Show fewer
  • Type 1 or 2 diabetes
  • History of fat-soluble vitamin deficiencies, i.e., vitamins A, D, E, or K
  • Phenylketonuria
  • History of known bleeding/clotting disorders
  • Medications or treatments that may impact the excretion of PFAS, such as activated charcoal, other bile acid sequestrants, chelation therapies, etc.
  • Unalterable plans to donate blood or plasma during the study participation period

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Ashley Mason, PhD contact

415-514-6820

enginestudy@ucsf.edu

Leena Pandya, ND contact

415-502-1619

leena.pandya@ucsf.edu

United States1 site, 1 recruiting

  • UCSF Osher Center for Integrative Health

    San Francisco, California, 94115

    Leena Pandya, ND, enginestudy@ucsf.edu

    Ashley E Mason, PhD

    Recruiting

Other trials in United States

About this study

Official title: Assessing the Impact of a Bile Acid Sequestrant on Serum PFAS Levels in Highly Exposed Individuals

This randomized, placebo-controlled crossover trial will test the feasibility and acceptability of using colesevelam in male firefighters with high per- and polyfluoroalkyl substances (PFAS) exposure. This trial will also explore whether colesevelam lowers blood PFAS levels and urine environmental toxicant and mold mycotoxin levels.

Read the detailed description

Firefighters experience elevated exposure to per- and polyfluoroalkyl substances (PFAS) through firefighting foams, turnout gear, and dust in fire stations. PFAS persist in the body due to their long biological half-lives, leading to bioaccumulation and raising concern for adverse effects on hormone regulation, immune function, reproduction, and cancer risk. Despite growing awareness, there are no approved treatment options to reduce PFAS levels in humans. Bile acid sequestrants, such as colesevelam, bind bile acids in the gastrointestinal tract and may interrupt enterohepatic recirculation of PFAS, thereby enhancing elimination. Observational studies and one small randomized trial suggest that bile acid sequestrants can meaningfully reduce PFAS levels. This trial will evaluate the feasibility, adherence, and acceptability of colesevelam in male firefighters with elevated PFAS, while exploring its effects on serum PFAS concentrations and urine environmental toxicant and mold mycotoxin levels.

Being tested
Colesevelam, Placebo
Keywords
Per- and polyfluoroalkyl substances, PFAS, Firefighters, Occupational exposure, Bile acid sequestrants, Colesevelam
Medical subject headings
Progressive Encephalomyelitis with Rigidity

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • ColesevelamDrug

    Also called Welchol

    Colesevelam in 625-mg tablets. Participants will take 3 tablets orally, twice daily (total daily dose 3.75 g) for 12 weeks.

  • PlaceboDrug

    Also called Inert oral tablets

    Matching inert oral tablets designed to mimic colesevelam 625 mg tablets in size, shape, and color, but containing no active pharmaceutical ingredient. Participants will take 3 orally, twice per day for 12 weeks.

Study groups in NCT07226440
Study groupRoleWhat they receive
Colesevelam firstActive comparatorParticipants randomized to this arm will receive colesevelam, taking 3 tablets twice daily for 12 weeks, followed by a 2-week washout period, and then 12 weeks of matching placebo tablets taken on the same schedule. Both the study drug and the placebo will be provided in identical-appearing bottles to maintain blinding.
Receives: Drug: Colesevelam; Drug: Placebo
Placebo firstPlacebo comparatorParticipants randomized to this arm will receive placebo tablets, taking 3 tablets twice daily for 12 weeks, followed by a 2-week washout period, and then 12 weeks of colesevelam (3 tablets twice daily). Both the study drug and the placebo will be provided in identical-appearing bottles to maintain blinding.
Receives: Drug: Colesevelam; Drug: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Retention

    Proportion completing all study blood draws after consent

    Measured: Enrollment to Week 27

  2. Adherence to study drug

    Proportion taking ≥80% of colesevelam doses

    Measured: Enrollment to Week 27

  3. Adherence to placebo

    Proportion taking ≥80% of placebo doses

    Measured: Enrollment to Week 27

  4. Acceptability

    Proportion endorsing "likely" or "very likely" to refer a co-worker to the study

    Measured: Week 27

  5. Likability

    Proportion endorsing "likely" or "very likely" to participate again

    Measured: Week 27

Secondary outcomes (1)

  1. Serum PFAS Levels

    Between-period and within-person changes in serum concentrations of the National Academy of Sciences, Engineering, and Medicine (NASEM)-7 PFAS score (sum of seven PFAS analytes). Higher scores mean higher PFAS levels in the body. Scores range from 0 to an unknown maximum.

    Measured: Baseline (Week 0) to the end of each 12-week intervention period (Weeks 13 and 27)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted10 Nov 2025
  2. Study start1 Mar 2026
  3. Primary completionDec 2028 (estimated)
  4. Study completionDec 2028 (estimated)

Resources

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 1/2
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Crossover
Model description
This is a randomized, double-blind, placebo-controlled, crossover trial with a 2-week washout between treatment periods. Participants are assigned to one of two sequences: colesevelam followed by placebo, or placebo followed by colesevelam.
Masking
Triple blind
Who is masked
Participant, Investigator, Outcomes assessor
Enrolment
50 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07226440
Sponsor's protocol ID
ENGINE-01
Acronym
ENGINE
Status last verified
Apr 2026
First submitted
6 Nov 2025
Last updated
24 Apr 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: The investigative team will share de-identified data, an associated codebook, and an abbreviated study protocol.

Publications

  • Johnson JD, Gibson SJ, Ober RE. Cholestyramine-enhanced fecal elimination of carbon-14 in rats after administration of ammonium [14C]perfluorooctanoate or potassium [14C]perfluorooctanesulfonate. Fundam Appl Toxicol. 1984 Dec;4(6):972-6. doi: 10.1016/0272-0590(84)90235-5.

    PubMed 6519377

  • Mazumder NU, Hossain MT, Jahura FT, Girase A, Hall AS, Lu J, Ormond RB. Firefighters' exposure to per-and polyfluoroalkyl substances (PFAS) as an occupational hazard: A review. Front Mater. 2023;10:10.3389/fmats.2023.1143411. doi: 10.3389/fmats.2023.1143411. Epub 2023 Mar 23.

    PubMed 38074949

  • Young AS, Sparer-Fine EH, Pickard HM, Sunderland EM, Peaslee GF, Allen JG. Per- and polyfluoroalkyl substances (PFAS) and total fluorine in fire station dust. J Expo Sci Environ Epidemiol. 2021 Sep;31(5):930-942. doi: 10.1038/s41370-021-00288-7. Epub 2021 Feb 5.

    PubMed 33542478

  • Lucas K, Gaines LGT, Paris-Davila T, Nylander-French LA. Occupational exposure and serum levels of per- and polyfluoroalkyl substances (PFAS): A review. Am J Ind Med. 2023 May;66(5):379-392. doi: 10.1002/ajim.23454. Epub 2022 Dec 27.

    PubMed 36573587

  • Moller JJ, Lyngberg AC, Hammer PEC, Flachs EM, Mortensen OS, Jensen TK, Jurgens G, Andersson A, Soja AMB, Lindhardt M. Substantial decrease of PFAS with anion exchange resin treatment - A clinical cross-over trial. Environ Int. 2024 Mar;185:108497. doi: 10.1016/j.envint.2024.108497. Epub 2024 Feb 13.

    PubMed 38367552

  • Ducatman A, Luster M, Fletcher T. Perfluoroalkyl substance excretion: Effects of organic anion-inhibiting and resin-binding drugs in a community setting. Environ Toxicol Pharmacol. 2021 Jul;85:103650. doi: 10.1016/j.etap.2021.103650. Epub 2021 Apr 2.

    PubMed 33819618

  • Seyyedsalehi MS, Boffetta P. Per- and Poly-fluoroalkyl Substances (PFAS) Exposure and Risk of Kidney, Liver, and Testicular Cancers: A Systematic Review and Meta-Analysis. Med Lav. 2023 Oct 24;114(5):e2023040. doi: 10.23749/mdl.v114i5.15065.

    PubMed 37878255

Questions about this trial

What is this clinical trial studying?

A Phase 1/2 study testing Colesevelam in people with Toxicant Exposure and Firefighter, run by University of California, San Francisco 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 10 inclusion and 12 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: looking for participants now, as of the sponsor's last update on 24 Apr 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. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this combined 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.

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

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?

Contact Ashley Mason, PhD (415-514-6820, enginestudy@ucsf.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Retention (time frame: Enrollment to Week 27). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07226440, which also lists 7 linked publications.

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 24 Apr 2026.

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