A Phase 1 interventional study of Fludarabine and Cyclophosphamide in Sarcoma, Childhood Osteosarcoma and Childhood Rhabdomyosarcoma, sponsored by St. Jude Children's Research Hospital. Recruiting at 1 site in United States. Open to participants aged Up to 21 Years. Per ClinicalTrials.gov, last updated 2026-02-09.
Sponsored by St. Jude Children's Research Hospital · Phase 1, Interventional, and Treatment
RAD3CAR is a phase I study designed to evaluatethe safety of B7-H3-CAR T cells and lymphodepletion in combination with hypofractionated radiation therapy.
Primary objective:
- To evaluate the safety of B7-H3-CAR T cell therapy after priming with hypofractionated radiation therapy (HFRT) and lymphodepleting chemotherapy in patients ≤ 21 years of age with relapsed/refractory B7-H3+ sarcomas.
Secondary objectives:
This study is a phase I study designed to describe the safety of B7-H3-CAR T cells and lymphodepletion in combination with hypofractionated radiation therapy for the treatment of pediatric patients with B7-H3+ sarcoma.
The study will contain two-part eligibility criterion: one to proceed with autologous apheresis and manufacturing of CAR T cells, and a second to proceed with CAR T cell treatment.
The primary intervention is the administration of autologous B7-H3-CAR T cells, after priming with HFRT and administration of lymphodepleting chemotherapy. Peripheral blood mononuclear cells (PBMC) will be collected by autologous apheresis. Treatment will include HFRT to at least one site of disease, administered in parallel with a single course of lymphodepleting chemotherapy (fludarabine/cyclophosphamide) and followed by CAR T cell infusion. Participants are evaluated for a post-treatment tumor biopsy and may choose to be evaluated for a pre-treatment tumor biopsy. Participants who meet specified criteria will be eligible for optional additional treatment courses.
250 studies on the registry are indexed under Sarcoma, Ewing; 69 are open to participants now.
This study's planned enrollment of 42 is above the median of 36 across 204 interventional studies indexed under Sarcoma, Ewing.
Browse Sarcoma, Ewing studies →St. Jude Children's Research Hospital is the lead sponsor of 440 studies on the registry; 102 are open to participants now.
Of its 61 completed or terminated interventional studies of FDA-regulated products, 37 (61%) have results posted.
Compared within Sarcoma, Ewing, this study's primary condition as ClinicalTrials.gg classifies it; the registry's first condition term is Sarcoma. The counts are of registry records indexed under each term, refreshed daily. How we classify →
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.
*a previously collected, autologous leukapheresis product can be used for T cell production
Collection and manufacturing eligibility
B7-H3+ sarcoma; B7-H3 expression will be evaluated by standard immunohistochemistry (IHC) using any previously obtained ; a tumor is considered B7-H3 positive with a H score greater than or equal to 100
Evaluable disease with presence of at least one lesion amenable to hypofractionated radiation therapy
or Lansky (age-dependent) performance score ≥ 60
For females of child-bearing age:
Treatment eligibility
Evaluable disease with the presence of at least one lesion amenable to hypofractionated radiation therapy
Karnofsky or Lansky (age-dependent) performance score ≥ 60
Adequate renal function as defined by not exceeding the maximum serum creatinine listed below by age:
For females of child-bearing age:
EXCLUSION CRITERIA
Collection and manufacturing eligibility
Treatment eligibility
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.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
A 0–100 scale of how well someone can carry out everyday activities. 100 is no complaints and no signs of illness; 70 is able to look after yourself but not to work or keep up normal activity; 50 is needing considerable help and frequent medical care.
Studies often ask for 60 or 70 and above. Your doctor gives the score.
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 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.
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.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
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.
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.
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.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Line of therapy
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Karnofsky performance status (KPS)
A 0–100 scale of how well someone can carry out everyday activities. 100 is no complaints and no signs of illness; 70 is able to look after yourself but not to work or keep up normal activity; 50 is needing considerable help and frequent medical care.
Studies often ask for 60 or 70 and above. Your doctor gives the score.
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.
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.
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.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Absolute neutrophil count (ANC)
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
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.
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.
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.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Peripheral blood mononuclear cells (PBMC) will be collected by autologous apheresis. Treatment will include HFRT to at least one site of disease, administered in parallel with a single course of lymphodepleting chemotherapy (fludarabine/cyclophosphamide) and followed by CAR T cell infusion.
Drug: Fludarabine · Drug: Cyclophosphamide · Drug: B7-H3-CAR T Cells · Radiation: Radiation Therapy
Intravenously on day -5, -4, -3 and -2
Intravenously on day -3, -2
Intravenously on day 0
5 or 8 treatment sessions (fractions), scheduled to complete on Day -2
Dose limiting toxicity (DLT) rate
Proportion of evaluable participants experiencing DLTs
Time frame: up to 4 weeks after CAR T cell infusion
Incidence of adverse events (AEs)
AEs will be assessed and graded using CTCAE v5.0, except for cytokine release syndrome (CRS) and immune effector cell associated neurotoxicity syndrome (ICANS), which will be graded according to ASTCT consensus guidelines. AEs will be summarized and reported descriptively
Time frame: up to 4 weeks after CAR T cell infusion
Clinical antitumor activity
Best overall response after treatment as determined by the Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, and if applicable bone marrow evaluation
Time frame: 4-12 weeks after CAR T cell infusion
B7-H3-CAR T cell trafficking to tumor sites
Evaluate for the presence of B7-H3-CAR T cells in post-treatment tumor biopsies
Time frame: 2 weeks after CAR T cell infusion
Started Jan 2026 (actual). Primary completion is estimated for Nov 2030, 57 months after the start.
Of 41 phase 1 interventional studies under Sarcoma, Ewing, half reached primary completion within 89 months of starting (the median), counting those still running; a quarter within 65 and three quarters within 134. This study's planned 57 months is below that.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
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