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OsteopetrosisPhase 1/2ARONCT07665021

Gene-Modified Stem Cell Therapy for Children With Autosomal Recessive Osteopetrosis (ARO)

A Phase 1/2 study testing FT024 in people with Osteopetrosis, run by Fondazione Telethon at 1 site in Italy.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

This is a non-randomized, one-arm, open label, single-center, phase I/II, prospective study, to assess safety, feasibility and efficacy of FT024 in 8 children (Age: ≥ 28 days and ≤ 2 years old, Body weight: ≥ 4 kg) affected by ARO-1. Read more about this study

Who is it for?
Ages 28 days to 2 years
Conditions the study is for
Osteopetrosis
What is being tested?
FT024
Type of treatment
Injection or infusion
Could I receive a placebo?
No, everyone receives an active treatment
How many people
8 participants
Where
1 siteItaly
Study dates
20 Jun 2026to 30 Jun 2031
Phase
Phase 1/2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 28 days to 2 years
  • All sexes
  • No healthy volunteers
  • Child

Who may be able to join

  • Diagnosis of autosomal recessive osteopetrosis caused by mutations in the TCIRG1 gene, defined by one of the following:
  • Clinical features of osteopetrosis and documented pathogenic/likely pathogenic biallelic variants (homozygosity or compound heterozygosity, whereby at least 1 allele must contain a known pathogenic mutation) in the TCIRG1 gene causing malignant infantile osteopetrosis.
  • If a patient presents with clinical features suggestive of severe osteopetrosis (i.e. generalized osteosclerosis, club-shaped long bones, skull base sclerosis, recurrent fractures and osteomyelitis, cranial nerve entrapment leading to visual and/or hearing loss, bone marrow insufficiency) and at least one pathogenic/likely pathogenic mutation of the TCIRG1 gene, the patient is eligible following discussion with an expert in this pathology.
  • Patient's parents/legal guardians' capacity to understand the study goals, the study requirements (i.e., attending study visits, completing questionnaires, taking study medications), potential risks associated with joining a study, and willingness to provide verbal and written informed consent.
  • Age: ≥ 28 days and ≤ 2 years old.
  • Body weight: ≥ 4 kg.
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  • Adequate cardiac, pulmonary, renal and hepatic function as evidenced by:
  • Left ventricular ejection fraction (LVEF) ≥45% by echo and normal electrocardiogram (ECG) or presence of abnormalities not significant for cardiac disease. Absence of clinically significant heart valve disease.
  • Pulse oximetry ≥90% in room air and no evidence for parenchymal lung disease on chest X-ray or CT scan.
  • serum creatinine <1.5x upper limit normal in the absence of any form of renal replacement therapy.
  • Alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) ≤2.5 x and total bilirubin ≤1.5x upper limit of normal (ULN). Normal coagulation tests (INR <1.5).

Who cannot join

  • Availability of a medically appropriate, logistically feasible, fully HLA-matched (10/10) sibling or unrelated donor. The chances of finding a suitable, fully matched unrelated donor should be estimated through a preliminary donor bank search by an experienced transplant team. If the patient is judged unlikely to be treated with a fully matched allogeneic HSCT within 6 weeks from activating search procedures, he/she can be considered eligible for this gene therapy study.
  • This criterion will not be applied to patients whose country of origin does not offer an allogeneic HSCT as a treatment option.
  • History of uncontrolled seizures or severe psychiatric symptoms.
  • Clinically relevant active viral, bacterial or fungal infection.
  • Positivity for HIV (serology or RNA), and/or HbsAg and/or HBV DNA and/or HCV RNA and/or active infection for Treponema Pallidum or Mycoplasma.
  • Known hypersensitivity to the drugs required for conditioning chemotherapy, or any excipients used in these products.
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  • Use of other investigational agents within 4 weeks prior to study enrolment (within 6 weeks if long-acting agents).
  • Previous allogeneic HSCT or gene therapy with a different product.
  • Patients affected by neoplasia, a familial predisposition to hematologic malignancies or any hematologic/cytogenetic alterations that may suggest a high risk of developing hematologic malignancies.
  • Patients with end-organ damage or any other severe condition which, in the judgment of the investigator, would make the patient inappropriate for either HSPC collection or autologous transplant.

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Francesca Tucci, Principal Incestigator contact

+390226439057

tucci.francesca@hsr.it

Italy1 site, 1 recruiting
  • Ospedale San Raffaele

    Milan, Italy, 20132

    Francesca Tucci, Principal Investigator, +39 02 26439057, tucci.francesca@hsr.it

    Recruiting

Other trials in Italy

About this study

Official title: A Phase I/II Open Label Study to Assess Safety, Feasibility and Efficacy of ex Vivo Expanded, Autologous Haematopoietic Stem and Progenitor Cell Populations That Contain CD34+ Cells Transduced With a Lentiviral Vector Encoding the TCIRG1 cDNA in Children With Autosomal Recessive Osteopetrosis Caused by Mutations in the TCIRG1 Gene.

This is a non-randomized, one-arm, open label, single-center, phase I/II, prospective study, to assess safety, feasibility and efficacy of FT024 in 8 children (Age: ≥ 28 days and ≤ 2 years old, Body weight: ≥ 4 kg) affected by ARO-1.

Once written informed consent has been obtained, and subsequently screening procedures have been completed, harvesting of HSPCs will occur. FT024 manufacturing will occur within a designated GMP manufacturing facility. Following FT024 release, patients will be admitted to the clinical center for the receipt of a reduced toxicity conditioning regimen based on Treosulfan and Thiotepa and then, the infusion of the FT024. Thereafter, regular follow-up of patients will occur for up to 2 years (+720 days).

Read more

In case of partial hematological recovery, additional FT024 boost will be administered without conditioning within + 180 days post first FT024 infusion. At the +720-day visit, patients will be invited to participate in a long-term follow-up study, which will last for an additional 13 years.

Patient recruitment is expected to take 3 years. The study will last approximately 5 years and 6 months, from the first visit of the first patient to the final visit of the last patient. Each patient will take part in the study for about 30 months, from screening to last follow up visit.

Read the detailed description

This phase I/IIa clinical trial is a non-randomized, open label, single-centre, therapeutic-exploratory, prospective study, to assess safety and efficacy of FT024 in up to 8 children affected by ARO aged ≤2 years of age and will be carried out at the Pediatric Clinical Research Unit/Pediatric Immuno-haematology and Bone Marrow Transplantation Unit, IRCCS Ospedale San Raffaele, Milan, Italy.

Once written informed consent has been obtained and subsequently screening procedures have been completed, harvesting of HSPCs will occur.

In cases of strong suspicion of osteopetrosis without a confirmed genetic diagnosis, and when the patient is unable to visit the clinical center for this inclusion criteria analysis due to their clinical condition, a preliminary remote evaluation for gene mutation analysis may be considered. In this case, remote signing of genetic analysis consent will be required before any evaluation and a blood sample will be sent to the laboratory in Milan, where the analysis will be performed. Blood sample will be collected at a local health care provider (HCP) or local healthcare facility or by home nursing.

If the diagnosis of TCIRG1-associated ARO is confirmed, patients who initially underwent genetic analysis remotely may proceed to Ospedale San Raffaele to complete the screening assessments. In such case, before undergoing any further screening procedures, the patient or parent/legal guardian will be asked to sign the main informed consent for participation in the clinical study. After completing the screening assessments and confirming eligibility, harvesting of HSPCs by leukapheresis or serial blood withdrawal will occur after mobilization and then sent to GMP facility to ATMP manufacturing.

Following ATMP release, patients will be admitted to hospital for receipt of a reduced toxicity conditioning regimen based on Treosulfan and Thiotepa, and infusion of the ATMP. In-patient monitoring will occur until haematological recovery occurred. Thereafter, regular follow-up of patients will take place until 2 years (+720 days). In case of logistical issues or patient's needs, remote visits can be performed. Within the first 180 days, the patient may be re-admitted to hospital for infusion of 1 or 2 ATMP boost doses if the criteria for incomplete hematologic recovery are fulfilled.

At the end of the study (+720 days), patients will be invited to continue long-term follow-up (up to 15 years after gene therapy administration), as required by the authorities (Guideline on safety and efficacy follow-up and risk management of Advanced Therapy Medicinal Products. January 2018, EMEA/149995/2008 rev.1, Committee for Medicinal Products for Human Use [CHMP]). Additional written informed consent will be obtained to participate in this long-term follow-up study.

Recruitment of the planned 8 patients is expected to take around 3 years. The study will last approximately 5 years and 6 months, from the first visit of the first patient to the final visit of the last patient. Each patient will take part in the study for about 30 months, from screening to last follow up visit. A total of 10 visits (minimum) will be required including assessments, day hospital visits and in-patient hospitalization(s).

Conditions
Osteopetrosis
Being tested
FT024
Keywords
autosomal recessive osteopetrosis caused by the mutations in TCRG1 gene
Medical subject headings
Osteopetrosis

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • FT024Genetic

    Autologous haematopoietic stem and progenitor cell population containing CD34+ cells transduced with a lentiviral vector encoding the TCIRG1 cDNA and expanded ex vivo.

Study groups in NCT07665021
Study groupRoleWhat they receive
Open Label study with ex vivo expanded FT024 drug productExperimentalThe dose range for ex vivo-expanded FT024 is as follows: * target dose: 100-200x106 CD34+ cells/kg body weight; * minimum dose: 50x106 CD34+ cells/kg body weight; * maximum dose: 300x106 CD34+ cells/kg body weight; The route of administration will be intravenous infusion.
Receives: Genetic: FT024

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Overall Survival

    Overall survival following the first FT024 infusion.

    Measured: 12 months and 24 months

  2. Percentage of Participants Achieving Long-Term Engraftment Without Severe Cytopenias, Regular Red Blood Cell Transfusions, or Rescue Treatment.

    Long-term engraftment of TCIRG1 LVV-Transduced Cells is defined as vector copy number (VCN) >0.2 in total blood or myeloid cells at 12 months after the first FT024 infusion. The endpoint is the percentage of participants who have no neutropenia or thrombocytopenia greater than Grade 3 and no regular red blood cell transfusion requirement compared with baseline, in the absence of rescue treatment (allogeneic transplantation with or without autologous back-up infusion).

    Measured: 12 months

Secondary outcomes (14)
  1. Percentage of Participants for Whom the Minimum Number of Autologous HSPCs Can Be Collected for Manufacturing

    Percentage of patients for whom at least the minimum number of autologous HSPC (>10x106 CD34+ cells/kg) can be obtained. The cumulative amount of CD34+ cells that has been collected during one or several apheresis and/or blood withdrawal sessions, will be calculated and referred to the patient weight at the time of the last HSPC harvest.

    Measured: Baseline

  2. Frequency and Severity of Adverse Events and Serious Adverse Events

    Frequency and severity of adverse events (AEs) and serious adverse events (SAEs) attributed to procedures related to hematopoietic stem cell harvesting, conditioning regimen, or ATMP administration.

    Measured: From Baseline up to Month 24.

  3. Incidence of Malignancy or Abnormal Clonal Proliferation

    Absence of malignancy or abnormal clonal proliferation assessed at 6, 12, and 24 months after first ATMP infusion. Evaluation includes clinical assessment, hematology and biochemistry tests, flow cytometry for lymphocyte subpopulations, vector copy number analysis, and bone marrow examination when clinically indicated. Additional investigations, including cytogenetic and molecular analyses, may be performed in case of suspected clonal expansion.

    Measured: 6, 12, and 24 months

  4. Disability-Free Survival

    Disability-free survival defined as absence of Grade ≥3 neutropenia or thrombocytopenia, no requirement for chronic blood product transfusion, no osteomyelitis, no requirement for major neurosurgery, and no pathologic bone fractures during the preceding 12 months.

    Measured: Baseline and 24 months

  5. Time to achieve hematologic recovery from the first ATMP infusion

    Hematologic recovery is defined as the first of 3 consecutive days with neutrophil count (ANC) >0.5x109/L and platelets >20x109/L, maintained for at least 7 days in the absence of transfusions and/or growth factor support.

    Measured: From Day 0 up to Month 24

  6. Percentage of Participants for Whom a Manufactured FT024 Product Meets Release Specifications

    Percentage of patients for whom a FT024 product conforming to specifications was manufactured and released to allow administration of minimum dose.

    Measured: From Baseline to Day 6

  7. Incidence of Replication Competent Lentivirus

    Absence of replication competent lentivirus (RCL) assessed at 1, 6, 12, and 24 months after first ATMP infusion.

    Measured: Baseline and 1, 6, 12 and 24 months

  8. Percentage of patients who do not require a rescue treatment

    Percentage of participants requiring rescue treatment including autologous back-up infusion and/or allogeneic hematopoietic stem cell transplantation.

    Measured: 12 months

  9. Assessment of haematological parameters indicative of haematological reconstitution

    Neutrophils and platelets levels will be measured as surrogate of haematological reconstitution at different time points. Modification of these levels correlates with effective haematological recovery.

    Measured: 1, 2, 3, 6, 9, 12, 18 and 24 months

  10. Red Blood Cell and Platelet Transfusion Requirement

    Change in monthly red blood cell and platelet transfusion requirements compared with the 30 days prior to first ATMP infusion.

    Measured: Baseline and 1, 2, 3, 6, 12, 18 and 24 months

  11. Effect of Boost Infusion on Hematologic Recovery

    Change in neutrophil and platelet counts and transfusion requirements before and after boost infusion.

    Measured: Pre-boost and +30-60 days and +80-120 days post-boost

  12. Engraftment of genetically corrected cells

    Longitudinal analysis of vector copy number in leukocyte populations from blood and/or bone marrow.

    Measured: 1, 2, 3, 6, 9, 12, 18 and 24 months

  13. Long-Term Engraftment of TCIRG1 LVV-Transduced Cells

    Percentage of participants with vector copy number >0.2 in total blood or myeloid cells at 12 months, without Grade ≥3 cytopenias, without regular red blood cell transfusion requirement, and without rescue treatment, stratified by number of boost infusions.

    Measured: 12 months

  14. Health-Related Quality of Life

    Assessed using PedsQL 4.0 Generic Core, PedsQL Infant Scales, and Stem Cell Transplant Module parent-proxy reports.

    Measured: Baseline, 12 months and 24 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted24 Jun 2026
  2. Study start20 Jun 2026 (estimated)
  3. Primary completion20 Jun 2030 (estimated)
  4. Study completion30 Jun 2031 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1/2
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
8 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07665021
Sponsor's protocol ID
ARO-FT024-01
Other IDs
2024-518972-30-00
Acronym
ARO
Status last verified
Jun 2026
First submitted
4 Jun 2026
Last updated
24 Jun 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No

Questions about this trial

What is this clinical trial studying?

A Phase 1/2 study testing FT024 in people with Osteopetrosis, run by Fondazione Telethon at 1 site in Italy.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 11 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 24 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Italy. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this combined phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Francesca Tucci, Principal Incestigator (+390226439057, tucci.francesca@hsr.it), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Overall Survival (time frame: 12 months and 24 months). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Jun 2026.

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