Low-Dose Danazol for the Treatment of Telomere Related Diseases

May 28, 2026 updated by: National Heart, Lung, and Blood Institute (NHLBI)

Low Dose Danazol for the Treatment of Telomere Related Diseases

Background:

DNA is a structure in the body. It contains data about how the body develops and works. Telomeres are found on the end of chromosomes in DNA. Some people with short telomeres or other gene changes can develop diseases of the bone marrow, lung, and liver. Researchers want to see if low doses of the hormone drug danazol can help.

Objective:

To study the safety and effect of low dose danazol.

Eligibility:

People ages 3 and older with a telomere disease who have either very short telomeres and a specific gene change. They must also show signs of aplastic anemia, lung, or liver disease.

Design:

Participants will be screened in another protocol.

Participants will have:

  • Medical history
  • Physical exam
  • Blood tests

  • Lung exam. They will breathe into an instrument that records the amount and rate of air breathed in and out over a period of time.

    6-minute walking test.

  • Abdominal ultrasound and liver scan. These tests use sound waves to measure the fibrosis in the liver.

Some participants will have:

  • Pregnancy test
  • Small sample of the liver removed
  • Bone marrow biopsy. The bone will be numbed and a small needle will take a sample of the marrow.

All participants will have hormone levels checked.

All child participants will see a pediatric endocrinologist. Children may need to have a hand x-ray.

We will monitor patients for 6 months before starting danazol.

Participants will take danazol by mouth twice a day for 1 year.

Participants must return to the clinic at 6 months and 12 months while on danazol and 6 months after stopping it. They will have blood and urine tests, a lung exam, abdominal ultrasound, and liver scan.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Telomere disease is caused by accelerated telomere attrition and results in multi-organ dysfunction. Telomeres are nucleotide repeats of non-coding DNA at the end of the chromosomes which function as protective caps to prevent erosion of genomic DNA during cell division and to protect chromosomes from recognition as single stranded DNA. Telomeric DNA is elongated by the telomerase complex, which is comprised of a reverse transcriptase catalytic subunit (encoded by TERT), an RNA template (encoded by TERC) and associated proteins.

Telomerase activity is crucial in maintaining telomere length in cells with a high proliferative capacity, such as hematopoietic stem cells (HSCs) and lymphocytes. Presentation of telomeropathies can vary from severe aplastic anemia (SAA) and dyskeratosis congenital (DKC) early in childhood, to pulmonary or hepatic fibrosis later in life. There is no standard of care for the treatment of telomere disease.

Considerable evidence suggests that sex hormones regulate telomerase. Calado et al. demonstrated that human lymphocytes and CD34+ hematopoietic cells up regulate both TERT gene expression and telomerase enzymatic activity in response to androgens in vitro. A recent observational cohort study demonstrated hematologic response in 14 of 16 pediatric patients with DKC treated with androgens. In a prospective trial from our Branch, Townsley et al demonstrated that patients with telomere diseases who were treated with the synthetic sex hormone danazol showed telomere elongation, and hematologic response were seen in 79% of patients after only three months of treatment. This study used the highest dose of danazol, 800 mg daily, and known adverse effects, such as elevated liver enzyme levels and muscle cramps, occurred in 41% and 33% of patients, respectively. Overall the treatment was well tolerated, but some patients did require dose reduction. After 27 patients were enrolled, the study was halted early, because telomere attrition was reduced in all 12 patients who could be evaluated for the primary endpoint. Because of the limited power, we were unable to draw definitive conclusions regarding further clinical effect of danazol but stabilization or improvement was observed in a few cases in other organ function, measured by DLCO for pulmonary fibrosis and Fibroscan for cirrhosis.

We now propose a phase II study designed to determine the efficacy of low dose danazol in decreasing the rate of telomere attrition in subjects with a short age-adjusted telomere length. The secondary aim is to determine the clinical effect of this therapy in conditions that are related to short telomeres, to include cytopenia(s), pulmonary fibrosis, and/or hepatic fibrosis.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
18

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • Maryland
      • Bethesda, Maryland, United States, 20892
        • National Institutes of Health Clinical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

3 years and older (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

  • INCLUSION CRITERIA:

    1. Age-adjusted telomere length less than or equal to the first percentile by flow-FISH method. In patients with a known pathogenic or likely pathogenic mutation in a telomere maintenance gene, age adjusted telomere length less than or equal to the 10th percentile is sufficient.
    2. A mutation in telomere maintenance genes (TERT, TERC, DKC1, TINF2, NHP2, NOP10, WRAP53, TERF2, PARN, RTEL1, ACD, CTC1, USB1) as tested in a CLIA (or international equivalent) certified laboratory
    3. Age greater than or equal to 3 years

    4. Weight greater than or equal to 12 Kg

      AND

    5. At least one of the following criteria:

      1. Anemia with a hemoglobin less than or equal to 10 g/dL without red blood cell transfusion
      2. Thrombocytopenia with a platelet count less than or equal to 50,000/microliter without transfusion
      3. Neutropenia with an absolute neutrophil count less than or equal to 1,000/ microliter

      OR

      Pulmonary fibrosis diagnosed by either a lung biopsy or computed tomography scan of the chest according to guidelines from the American Thoracic Society and European Respiratory Society.

      OR

    6. Hepatic fibrosis diagnosed by Transient Elastography by Fibroscan value greater than 10 kpa or US evidence of cirrhotic liver or splenomegaly, or transjugular liver biopsy demonstrating fibrosis.

EXCLUSION CRITERIA:

  1. Patients on androgen hormones to include testosterone or high dose estrogen (estradiol 0.5 mg/day or greater) for the12 months prior to enrollment
  2. Patients with active thrombosis or thromboembolic disease and history of such events, undiagnosed abnormal genital bleeding, porphyria, androgendependent tumor, or prostatic hypertrophy
  3. Patients with pulmonary fibrosis who are receiving anti-fibrotic drug treatment, such as pirfenidone or nintedanib unless stable on anti-fibrotic drug for at least 6 months prior to starting on danazol as demonstrated by PFTs.
  4. Patients with active hepatitis B or C
  5. Patients who have received a bone marrow transplant
  6. Patient with other hereditary bone marrow failure syndromes such as Fanconi anemia or Diamond Blackfan anemia
  7. Patients with infections not adequately responding to appropriate therapy
  8. Current pregnancy, or unwillingness to take oral contraceptives or use the barrier methods of birth control or practice abstinence to refrain from pregnancy if of childbearing potential during the course of the study
  9. Lactating women, due to the potentially harmful effects on the nursing child
  10. Patients with cancer who are actively receiving systemic chemotherapeutic treatment or who take drugs with hematological effects
  11. Patients with decompensated liver disease to include persistent ascites, encephalopathy, variceal hemorrhage, or MELD score of 10 or greater
  12. Inability to understand the investigational nature of the study or to give informed consent or without a legally authorized representative or surrogate that can provide informed consent
  13. Inability to swallow a capsule

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: 200 mg Arm
100 mg twice a day
Drug: Danazol
Adult: 200 mg daily versus 400 mg daily Pediatric: 4 mg/kg/day divided in twice daily dose (max 400 mg daily) for 6 months or 2 mg/kg/day divided in twice daily dose (max 200 mg daily) for 6 months.
Active Comparator: 400 mg Arm
200 mg twice a day
Drug: Danazol
Adult: 200 mg daily versus 400 mg daily Pediatric: 4 mg/kg/day divided in twice daily dose (max 400 mg daily) for 6 months or 2 mg/kg/day divided in twice daily dose (max 200 mg daily) for 6 months.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Reduction of telomere attrition rate
Time Frame: Over 6 months
Reduction of telomere attrition rate (decreased rate of telomere attrition by 50%, as compared to the baseline rate)
Over 6 months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
Toxicities associated with low dose danazol use
Time Frame: During 12 months of treatment
During 12 months of treatment
Progression of pulmonary function testing
Time Frame: After 6 and 12 months of treatment
After 6 and 12 months of treatment
Progression of fibroscan and transient elastography by ARFI
Time Frame: After 6 and 12 months of treatment
After 6 and 12 months of treatment
Hematologic response
Time Frame: After 6 and 12 months of treatment
After 6 and 12 months of treatment

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
National Heart, Lung, and Blood Institute (NHLBI)

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Emma M Groarke, M.D., National Heart, Lung, and Blood Institute (NHLBI)

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
February 8, 2018

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 29, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
October 29, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 14, 2017

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 14, 2017

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 17, 2017

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 29, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 28, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 26, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 180004
  • 18-H-0004

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

It is not yet known

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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