A Phase 1/2 interventional study of FT024 in Osteopetrosis, sponsored by Fondazione Telethon. Recruiting at 1 site in Italy. Open to participants aged 28 Days to 2 Years. Per ClinicalTrials.gov, last updated 2026-06-24.
Sponsored by Fondazione Telethon · Phase 1/2, Interventional, and Treatment
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).
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.
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).
22 studies on the registry are indexed under Osteopetrosis; 4 are open to participants now.
This study's planned enrollment of 8 is below the median of 15 across 17 interventional studies indexed under Osteopetrosis.
Browse Osteopetrosis studies →Fondazione Telethon is the lead sponsor of 12 studies on the registry; 3 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Diagnosis of autosomal recessive osteopetrosis caused by mutations in the TCIRG1 gene, defined by one of the following:
Adequate cardiac, pulmonary, renal and hepatic function as evidenced by:
Exclusion Criteria:
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 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.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
INR, PT and aPTT (clotting tests)
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Allogeneic and autologous transplant
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The 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.
Genetic: FT024
Autologous haematopoietic stem and progenitor cell population containing CD34+ cells transduced with a lentiviral vector encoding the TCIRG1 cDNA and expanded ex vivo.
Overall Survival
Overall survival following the first FT024 infusion.
Time frame: 12 months and 24 months
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).
Time frame: 12 months
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.
Time frame: Baseline
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.
Time frame: From Baseline up to Month 24.
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.
Time frame: 6, 12, and 24 months
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.
Time frame: Baseline and 24 months
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.
Time frame: From Day 0 up to Month 24
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.
Time frame: From Baseline to Day 6
Incidence of Replication Competent Lentivirus
Absence of replication competent lentivirus (RCL) assessed at 1, 6, 12, and 24 months after first ATMP infusion.
Time frame: Baseline and 1, 6, 12 and 24 months
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.
Time frame: 12 months
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.
Time frame: 1, 2, 3, 6, 9, 12, 18 and 24 months
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.
Time frame: Baseline and 1, 2, 3, 6, 12, 18 and 24 months
Effect of Boost Infusion on Hematologic Recovery
Change in neutrophil and platelet counts and transfusion requirements before and after boost infusion.
Time frame: Pre-boost and +30-60 days and +80-120 days post-boost
Engraftment of genetically corrected cells
Longitudinal analysis of vector copy number in leukocyte populations from blood and/or bone marrow.
Time frame: 1, 2, 3, 6, 9, 12, 18 and 24 months
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.
Time frame: 12 months
Health-Related Quality of Life
Assessed using PedsQL 4.0 Generic Core, PedsQL Infant Scales, and Stem Cell Transplant Module parent-proxy reports.
Time frame: Baseline, 12 months and 24 months
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