A study to evaluate the use of leflutrozole to improve semen quality in men with non-obstructive azoospermia

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What is this study about?

This study focuses on Male Infertility, specifically a condition called Non-Obstructive Azoospermia, which is a type of infertility where there is an absence of sperm in the ejaculate due to issues with sperm production rather than a physical blockage. The purpose of this study is to investigate whether the aromatase inhibitor known as leflutrozole can improve sperm quality in certain men. An aromatase inhibitor is a type of medication that works by reducing the levels of certain hormones in the body.

Participants will take leflutrozole in the form of an oral capsule. During the study, various biological markers will be monitored, including hormones in the blood and semen, such as testosterone and follicle-stimulating hormone. Additionally, changes in certain substances in the blood, urine, and semen, as well as body mass index and blood sugar levels, may be tracked over the course of the treatment.

Who Can Join the Study?

You must provide a signed informed consent, which is a document where you agree to take part in the study after understanding all the details.
If you have a partner, they must also sign a consent form before you begin treatment to allow the collection of blood samples and information regarding fertility and pregnancy.
You must be between 18 and 55 years old.
You must have azoospermia, which means there are no sperm found in your semen, as confirmed by at least two separate tests.
Your semen must have an average volume of at least 1.0 ml, and there should be no signs of obstruction, which means nothing is physically blocking the path of the sperm.
Your levels of AMH (Anti-Müllerian Hormone) or Inhibin B, which are substances produced in the body related to sperm production, must be above the lowest measurable level.
Your testosterone level, a primary male hormone, must be less than 15 nmol/L.
Your estradiol level, a type of estrogen hormone, must be above the normal minimum level of 48 pmol/L.

Who Cannot Join the Study?

Having Klinefelter syndrome or other major genetic conditions, which are health issues caused by changes or missing pieces in a person’s DNA (the instructions that tell the body how to grow and function), specifically involving the sex chromosomes.
Having osteoporosis, a condition where bones become weak and brittle, that requires medical treatment.
Using any prescription or non-prescription medications that might interfere with how the study drug works in the body, such as herbal products, insulin (medicine for blood sugar), corticosteroids (steroid medicines used to reduce swelling), tricyclic antidepressants (a type of medicine used for depression), or atypical antipsychotics (medicines used to treat certain mental health conditions).
Having any surgery scheduled during the time of the study, unless it is a minor procedure that does not involve the stomach or intestines.
Having cancer, past or present, except for specific types of skin cancer, if the doctor believes it could affect the study results.
Having a prostate specific antigen (PSA) level higher than 3 ng/mL, which is a protein produced by the prostate gland that can indicate health issues.
Having a hematocrit level higher than 50%, which is the measurement of the percentage of red blood cells in your total blood volume.
Having mental incapacity, language barriers, or being unwilling to follow the study rules, which could make it difficult to understand or cooperate with the study.
Having an average testis size larger than 20 mL, unless a blockage (obstruction) has been ruled out.
Having undergone a TESE procedure (a surgery to collect sperm directly from the testicle) less than six months ago.
Having a Luteinizing Hormone (LH) concentration higher than 15 IU/L, which is a hormone that helps control the production of male sex hormones.
Currently using steroids in an abusive or excessive way.
Having a Body Mass Index (BMI) higher than 45 kg/m2, which is a measure of body fat based on height and weight.
Having severe chronic diseases (long-term illnesses) that require daily medication.
Having experienced a thromboembolic event (a blood clot that blocks a blood vessel) within the last 24 months.
Having a cardiovascular event (a heart or blood vessel problem) within the last 6 months that the doctor considers significant.

Where you can join this trial?

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Other Sites

Site Name	City	Country	Status
Hntcws Hapbesey	Herlev	Denmark

Trial status

Country	Status	Recruitment Start
Denmark	Not yet recruiting	15.03.2026

Trial locations

Leflutrozole is a medicine taken by mouth that works by blocking a specific enzyme in the body to change hormone levels, which may help improve sperm quality in certain men facing fertility challenges.

Investigated diseases:

Infertility male

Male Infertility – This condition occurs when a man is unable to achieve pregnancy with a female partner. It can involve issues with the production, structure, or movement of sperm. The process may involve a low number of sperm cells or sperm that do not move effectively. It can also be related to imbalances in certain hormones that regulate reproductive functions. Over time, these factors can affect the overall quality and presence of sperm in the semen.

Trial ID:

2025-524774-42-00

Trial Phase:

Therapeutic exploratory (Phase II)

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A study to evaluate the use of leflutrozole to improve semen quality in men with non-obstructive azoospermia

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?