Frozen testicle tissue may help men become dads after childhood cancer

NCT ID NCT05414045

Disease control Sponsor: Universitair Ziekenhuis Brussel Source: ClinicalTrials.gov ↗

First seen Jun 27, 2026 · Last updated Jun 27, 2026

Summary

This study tests whether testicular tissue frozen before puberty can be transplanted back into adult men to restore sperm production. Five men who had fertility-threatening treatments as children will receive their own preserved tissue. The goal is to see if sperm can be found in the graft one year later, potentially enabling fatherhood.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance: autologous testicular tissue transplantation
What this could lead to: If it works, this could offer a way for men who lost fertility due to childhood cancer treatment to have biological children.
What could go wrong: This is a very early trial with only 5 participants, so success is far from guaranteed. The procedure is experimental and may not produce usable sperm, and there are surgical risks.

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Study facts

What this study's own registry entry says, in plain language.

Phase

Not a phased trial

Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.

Participants

About 5 people

The number the study aims to enrol. It can still change while the study runs.

Started

Nov 2024

Expected to finish

Oct 2030

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 50 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

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

The eligible patients opted as a prepubertal boy to enroll in the fertility preservation program and on the moment of cancer diagnosis or hematological disorder, their parents have agreed to cryopreserve testicular tissue for later autologous transplantation. Inclusion Criteria: * At least 18 years old * In case of female partner, age \< 43 year * Absence of spermatozoa that can be used for ICSI on 2 semen analyses * Normal standardised preliminary and preoperative bloodsampling results * Complete remission of the oncological or hematological disease * Approval of the treating oncologist or other specialist in case of non-oncological disease as reason for the testicular tissue preservation as a child * Risk for presence of malignant cells in testicular tissue is negligible (according to multidisciplinary assessment) * Presence of spermatogonial stem cells (positive MAGE staining) in one or two of the thawed fragments (If absence of spermatogonial stem cells in two of the thawed fragments, the case will be discussed multidisciplinary) * Written informed consent for the transplantation of cryopreserved testicular tissue and follow-up after the procedure and of children born eventually after this procedure Exclusion criteria: * Risk for presence of malignant cells in the testicular tissue * Contra-indication for surgery * Contra-indication for pregnancy in the female partner * BMI \> 32 * Heavy smoking (≥10 cigarettes/day) * Instable psychological condition

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Conditions

The condition(s) this trial relates to.

cancer hematologic disorder neoplasm sickle cell-beta plus-thalassemia sickle cell-beta-thalassemia disease syndrome

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Cancer Hematologic diseases Sickle cell thalassemia

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.

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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.

Frozen testicle tissue may help men become dads after childhood cancer

What the study statuses mean