Could a weekly pill help men with no sperm become fathers?
NCT ID NCT07571928
First seen Jun 26, 2026 · Last updated Jun 27, 2026 · Updated 1 time
Summary
This early study tests a drug called leflutrozole in 15 men who have no sperm in their semen due to a blockage-free cause. The drug is taken as a weekly capsule and aims to boost sperm production. Researchers will check if sperm appear in the semen after 12-20 weeks of treatment.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- leflutrozole (a drug that blocks estrogen production)
- What this could lead to
- If it works, this could point toward a new treatment for some men with infertility due to low sperm production.
- What could go wrong
- This is a very early, small trial with only 15 men. It may not work, and the drug could have side effects. Success is far from guaranteed.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
-
Phase 1/2
Runs two stages together: safety and dose first, then whether the treatment works.
- Participants
-
About 15 people
The number the study aims to enrol. It can still change while the study runs.
- Expected to start
-
May 2026
An estimate. Start dates often move.
- Expected to finish
-
Aug 2027
An estimate. End dates often move.
- Lead sponsor
-
Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
-
18 to 55 years
- Sex
-
Male participants only
- Healthy volunteers
-
Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * Signed informed consent by participant * Signed informed consent by participant's partner (must just be obtained before the par-ticipant starts treatment at Visit 1), if applicable, regarding blood samples, data collec-tion about fertility treatment as well as pregnancy and pregnancy outcome * 18-55 years * Azoospermia verified by at least 2 semen samples, average semen volume \>= 1,0 ml with no identifiable sign of obstruction (samples taken at Visit -1 and at Visit 0 prior to confirmation of eligibility and dosing). * Serum AMH or Inhibin B level above the lower limit of quantification (LLOQ) at screening or within 6 months prior to screening * Testosterone \< 15 nmol/L at screening or within 6 months prior to screening * Serum estradiol above the lower limit of normal range (48 pmol/L) at screening or within 6 months prior to screening Exclusion Criteria: * Klinefelter or other major genetic conditions including large deletions on sex chromosomes * Average testis size \> 20 mL unless obstruction has been excluded * TESE procedure \< ½ year ago * LH concentration \> 15 IU/L at screening * Current abuse of steroids * BMI \> 45 kg/m2 * Severe chronic diseases requiring daily medication * Prior thromboembolic event within the last 24 months * Cardiovascular event within the last 6 months judged as significant by the investigator * Osteoporosis requiring medical treatment * Use of any prescription or non-prescription medication (apart from routine vitamins, occasional use of paracetamol, acetylsalicylic acid, or ibuprofen) which could interfere with pharmacokinetic or pharmacodynamic results, as judged by the investigator, such as: * Herbal products and non-routine vitamins * Insulin * Medication such as systemic corticosteroids, tricyclic antidepressants, and atypical antipsychotics * Surgery scheduled for the trial duration period, except for minor, non-gastrointestinal surgical procedures at the discretion of the investigator * Cancer (past or present, except basal cell skin cancer or squamous cell skin cancer), which in the investigator's opinion could interfere with the results of the trial * Serum prostate specific antigen (PSA) \> 3 ng/mL at screening or within 6 months prior to screening * Hematocrit \>50% at screening or within 6 months prior to screening * Mental incapacity, language barriers or unwillingness to comply with the requirements of the protocol, which may preclude adequate understanding or co-operation during the trial, as judged by the investigator
Get updates
Get notified about this study
Sign up to get updates when this study changes or when new studies for Infertility due to azoospermia are added.
Genom att skicka in godkänner du våra Användarvillkor
Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
-
The places running it
1 site. The list below names each one and where it is.
-
The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
-
A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
-
Division of Translational Endocrinology, Department of Endocrinology and Internal Medicine, Copenhagen University Hospital Herlev., Herlev,
Herlev, 2100, Denmark
More trials for these conditions
Other studies related to the condition(s) this trial covers.
- Do infertility treatments leave a metabolic mark on children?
- New gel could boost fertility for couples struggling to conceive
- Could a natural tablet help men with low sperm count?
- Diamonds and sperm: a new way to detect fertility problems?
- Mindfulness may ease the emotional toll of infertility
- Seaweed supplement could boost sperm quality in infertile men