Evaluating Efficacy of B7-H3-CAR T Cells Administered at the End of Upfront Map Chemotherapy in Patients With Newly Diagnosed High-Risk Osteosarcoma

The film gives the main points. The full list below is copied from the registry; the study team makes the final decision.

• AgeNo minimum to 21 Years
• SexAll
• Healthy volunteersNo

You may be able to join if

• Participant and/or legally authorized representative has signed the Informed Consent Form for this study
• Prior cancer therapy:
• Regimen A only: Completed all planned cycles of consolidation therapy between 14-28 days prior.
• Regimen B only: has completed all planned cycles of consolidation chemotherapy at least 14 days prior and if clinically indicated, participant has undergone pulmonary metastasectomy. They must have recovered from any surgical complications with no ongoing sequelae of category 2 or higher by the Clavien-Dindo classification system and less than 6 weeks must have passed from time of pulmonary metastasectomy.
• No evidence of progressive disease since enrolled on study
• Lansky performance status score of ≥ 50 for participants <16 years of age or Karnofsky score ≥ 50 for participants ≥ 16 years. Participants who are unable to walk because of paralysis, but who are up in a wheelchair, will be considered ambulatory for purposes of assessing performance status
• Adequate organ function as indicated by:
• Renal: Serum creatinine ≤ 1.5 X the upper limit of normal (ULN) based on enrollment eligibility table.
• Hepatic: Total bilirubin ≤ 3 times ULN for age OR conjugated bilirubin ≤ 2 mg/dL AND ALT (SGPT) ≤ 5 times ULN
• Cardiac: Shortening fraction ≥ 28% OR ejection fraction ≥ 50% as measured by echocardiogram
• Respiratory: Oxygen saturation ≥ 90% on room air without supplemental oxygen or mechanical ventilation
• Laboratory values meet the following criteria:
• Absolute Neutrophil Count (ANC) ≥ 750 cells/uL
• Platelet Count of ≥ 75,000 (can be transfused)
• Hemoglobin ≥ 7 g/dL (can be transfused)
• Participant is ≥ 7 days from receiving supra-physiologic dosing of systemic (IV or PO) corticosteroids. Glucocorticosteroid physiologic replacement therapy for management of adrenal insufficiency is allowed.
• Participant and/or legally authorized representative has signed the Informed Consent Form for the treatment phase of this study.

You cannot join if

• Major surgical adverse event related to the primary tumor local control defined as Clavien-Dindo category 3 requiring ongoing wound care.
• Evidence of clinically significant encephalopathy/new focal neurologic deficits.
• Presence of active severe infection, defined as:
• positive blood culture within 48 hours of enrollment, OR
• fever above 38.2° C, AND clinical signs of infection within 48 hours of enrollment
• Participant has received prior disease-directed therapy other than 1st line therapy with methotrexate, an anthracycline, and a platinum and local control surgery
• Regimen B only - okay to have undergone initial pulmonary metastasectomy
• Pregnant or breastfeeding
• Presence of any condition that, in the opinion of the investigator, would prohibit the participant from undergoing treatment under this protocol

This is how the treatment is meant to work. Whether it helps, and how safe it is, is what this trial is testing.

Treatments listed in the registry

• Cyclophosphamide (Drug): IV
• Fludarabine (Drug): IV
• Mesna (Drug): IV prior to and again at 3, 6, and 9 hours following each dose of cyclophosphamide.
• Apheresis (Procedure): IV collection
• SJCARB7H3_41BBL infusion (Procedure): 1X107 CAR+ T cells/kg

Na · Single Group · masking: None

As the registry describes them. Requirements to join, such as a tissue sample, are in the eligibility list above even when on-study procedures are optional. Ask the study team which steps apply to you.

• surgery: Part of the study plan
• leukapheresis: Part of the study plan

Main goals

• Event-free survival (EFS), defined as time from SJCARB7H3-41BBL infusion to disease relapse, progressive disease, new systemic therapy, secondary malignancy or death (Time from SJCARB7H3-41BBL infusion to time of first event, followed up to 24-months post-infusion)

Other goals

• Overall survival (OS), defined as time from SJCARB7H3-41BBL cell infusion to all-cause mortality.
• Number of participants experiencing protocol-specified regimen-related toxicities.
• Number of participants with successful manufacture of SJCARB7H3-41BBL cells of sufficient dose and planned product administration

Planned enrollment: 41 (estimated).

• St. Jude Children's Research Hospital, Memphis, Tennessee

Site status as of Oct 30, 2026. Check the live record before contacting a site.

• ClinicalTrials.gov NCT07428993

Registry record reviewed as fetched Oct 30, 2026, last updated by the sponsor Aug 31, 2026. Public record; not medical advice.