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

Conditions

• Pediatric Osteosarcoma

Eligibility Criteria

Sex

ALL

Age

N/A - 21 Years

Healthy Volunteers

Not accepted

Interventions

• 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

Study Details

The purpose of this study is to assess the safety, feasibility, and effectiveness of a consolidative B7-H3 CAR T cell therapy in patients with newly diagnosed high-risk osteosarcoma who have undergone upfront standard chemotherapy. Primary Objectives: \- To evaluate 1-year RFS from the time of SJCARB7H3\_41BBL infusion for patients with newly diagnosed metastatic osteosarcoma who received standard chemotherapy. Secondary Objectives: * To evaluate the OS from time of SJCARB7H3\_41BBL infusion for patients with newly diagnosed metastatic osteosarcoma who received standard chemotherapy. * To evaluate the feasibility of delivering SJCARB7H3\_41BBL at the end of standard therapy in patients with newly diagnosed metastatic osteosarcoma. * To describe the safety of autologous SJCARB7H3\_41BBL therapy when delivered at the end of standard therapy in patients with newly diagnosed metastatic osteosarcoma.

Key Dates

Start date

Jun 30, 2026

Status verified

May 2026

Primary completion

Dec 31, 2034

Completion

Dec 31, 2035

Study Design

Enrollment

41 participants (estimated)

Allocation

NA

Intervention model

SINGLE_GROUP

Primary purpose

TREATMENT

Arms

• Experimental: 3CAR4OS Treatment
  All patients will receive standard of care chemotherapy, which is not considered part of protocol therapy. Eligible patients will undergo apheresis prior to standard local control surgery for CAR T cell manufacture and then resume standard therapy. In the absence of progressive disease, eligible patients with available SJCARB7H3\_41BBL product will receive lymphodepletion chemotherapy (fludarabine/cyclophosphamide) after the completion of standard chemotherapy, followed by SJCARB7H3\_41BBL infusion. Pulmonary metastasectomy will be performed as indicated according to the standard of care and will be timed after (Regimen A) or before (Regimen B) lymphodepletion and SJCARB7H3\_41BBL infusion. Following successful clearance of either regimen A or, if necessary, regimen B, the efficacy cohort will be initiated.

Primary Outcome Measure

Event-free survival (EFS), defined as time from SJCARB7H3_41BBL infusion to disease relapse, progressive disease, new systemic therapy, secondary malignancy or death [ Time Frame: Time from SJCARB7H3_41BBL infusion to time of first event, followed up to 24-months post-infusion ]

Central Contacts

• Julie Park, MD
  888-226-4343
  [email protected]
• Judith Durrell
  888-226-4343
  [email protected]

Locations (1)

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