Study of gene-modified stem cells (FT024) in children with TCIRG1-related osteopetrosis using treosulfan, thiotepa, and plerixafor for treatment

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What is this study about?

This clinical trial is studying a treatment for children with autosomal recessive osteopetrosis, a rare genetic bone disease caused by mutations in the TCIRG1 gene. The condition causes bones to become unusually dense and prone to breaks. The study aims to evaluate a new treatment that uses modified stem cells from the patient’s own body. The treatment involves collecting blood-forming stem cells from the patient, modifying them in a laboratory to correct the genetic defect, and then returning them to the patient through an infusion.

The main treatment being tested is called FT024, which consists of specially processed stem cells that have been modified using a lentiviral vector (a tool that delivers genetic material into cells). Several other medications will be used as part of the treatment process, including Trecondi (treosulfan), Tepadina (thiotepa), and Mozobil (plerixafor). These medications help prepare the body for the stem cell treatment.

The study will monitor patients for two years after treatment to check if the modified stem cells successfully integrate into the body and improve the condition. Doctors will track various health measures, including blood cell counts, need for blood transfusions, bone health, and overall survival. The treatment’s safety will be closely monitored throughout the study period.

1 Initial preparation

Your eligibility for the study has been confirmed based on the following criteria: you have autosomal recessive osteopetrosis caused by mutations in the TCIRG1 gene, you are between 28 days and 2 years old, and your body weight is at least 4 kg.

The medical team will collect your stem cells (specifically CD34+ cells) for the treatment preparation.

2 Cell preparation

Your collected stem cells will be modified in a laboratory using a special technique to correct the genetic defect.

The modified cells will be expanded (multiplied) to reach the required amount for treatment.

3 Pre-treatment medication

You will receive Trecondi (treosulfan) through an intravenous infusion.

Tepadina (thiotepa) will be administered through an intravenous infusion.

Mozobil (plerixafor) will be given as an injection under the skin.

4 Cell infusion

The modified stem cells will be given back to you through an intravenous infusion.

Additional infusions (‘boost’) may be given if needed for your recovery.

5 Follow-up monitoring

Regular check-ups will occur at 1, 2, 3, 6, 9, 12, 18, and 24 months after the cell infusion.

During these visits, blood tests will be performed to monitor your recovery.

Your quality of life will be assessed at the start of treatment, and after 12 and 24 months.

Who Can Join the Study?

Patient must have a confirmed diagnosis of autosomal recessive osteopetrosis caused by mutations in the TCIRG1 gene, proven by either:
- Clinical features of the disease and documented genetic changes in the TCIRG1 gene that cause severe infantile osteopetrosis
- OR presence of severe symptoms such as:
  - Increased bone density throughout the body
  - Abnormally shaped long bones
  - Thickened skull base
  - Frequent bone fractures
  - Bone infections
  - Problems with vision or hearing due to nerve compression
  - Decreased bone marrow function
Patient must be between 28 days and 2 years old
Patient must weigh at least 4 kilograms (kg)
Both male and female patients can participate

Who Cannot Join the Study?

Active or uncontrolled infections that could interfere with the treatment
Major organ damage (such as severe heart, lung, liver or kidney problems)
Known HIV (Human Immunodeficiency Virus) infection
Active hepatitis B or hepatitis C infection
Previous unsuccessful bone marrow transplant or gene therapy
Participation in another clinical trial within the last 30 days
Any medical condition that could make the treatment unsafe
Inability to comply with study procedures and follow-up visits
Known allergies to medications used in the study
Pregnancy or breastfeeding
Mental conditions that prevent understanding of the study requirements
Blood disorders that could affect treatment success
Active cancer or history of cancer in the past 5 years
Severe neurological complications
Any condition that could interfere with the evaluation of study results

Where you can join this trial?

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Other Sites

Site Name	City	Country	Status
Ospedale San Raffaele S.r.l.	Milan	Italy

Trial status

Country	Status	Recruitment Start
Italy	Recruiting	01.07.2025

Trial locations

Investigated drugs:

TCIRG1 LVV-transduced hematopoietic stem cells are cells taken from the patient’s own blood or bone marrow that have been modified in a laboratory. These cells are genetically altered using a special virus (lentiviral vector) to carry a corrected version of the TCIRG1 gene. This therapy is designed to treat a rare bone condition called autosomal recessive osteopetrosis by helping the body produce properly functioning bone cells.

This is a cell and gene therapy where the patient’s own stem cells are collected, modified, and then returned to their body. The modified cells are intended to help correct the genetic defect that causes the bone disease.

Autosomal Recessive Osteopetrosis (ARO-1) – A rare genetic bone disorder caused by mutations in the TCIRG1 gene that affects how the body breaks down and rebuilds bone tissue. In this condition, bones become abnormally dense and hard, but they are actually more fragile than normal bones. The disease typically appears in early infancy and causes bones to grow abnormally throughout the body. This leads to various bone-related problems and can affect the formation of bone marrow cavities. The condition also impacts the blood-forming system, as the abnormally thick bones interfere with normal bone marrow function.

Trial ID:

2024-518972-30-00

Trial Phase:

Phase I and Phase II (Integrated) – First administration to humans

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Study of gene-modified stem cells (FT024) in children with TCIRG1-related osteopetrosis using treosulfan, thiotepa, and plerixafor for treatment

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?