NCT07428993

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

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

• Status: Not Yet Recruiting
• Phase: Phase 2
• Study type: Interventional
• Enrollment: 41 (estimated)
• Sponsor: St. Jude Children's Research Hospital · Academic / Other
• Sex: All
• Age: 21 Years
• Healthy volunteers: Not accepted

Summary

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.

Detailed description

This is a phase 2 study of SJCARB7H3\_41BBL for participants with newly diagnosed high-risk metastatic osteosarcoma who received standard chemotherapy. All participants will receive standard chemotherapy (for example methotrexate, anthracycline, platinum), local control surgery, and pulmonary metastasectomy if applicable, and this is not considered part of protocol therapy. Participants will undergo apheresis prior to standard local control surgery (about 12 weeks after diagnosis) for SJCARB7H3\_41BBL manufacture and then resume standard consolidation therapy. A safety run will initiate with Regimen A. For Regimen A, eligible participants with available SJCARB7H3\_41BBL product will receive lymphodepletion chemotherapy 14-28 days after the completion of standard chemotherapy (31 weeks after diagnosis), followed by SJCARB7H3\_41BBL infusion. If Regimen A is not cleared, then Regimen B will be evaluated, where lymphodepletion and SJCARB7H3\_41BBL infusion occur post pulmonary metastasectomy. Following successful clearance of either regimen A or, if necessary, regimen B, then the efficacy cohort will be initiated. Participants will be followed with serial disease evaluations for 2 years from SJCARB7H3\_41BBL infusion prior to transfer to our institutional long-term follow-up (LTFU) protocol. The total duration from completion of standard therapy, including experimental therapy and follow-up on 3CAR4OS, is approximately 2 years.

Conditions

• Pediatric Osteosarcoma

Interventions

Type	Name	Description
DRUG	Cyclophosphamide	IV
DRUG	Fludarabine	IV
DRUG	Mesna	IV prior to and again at 3, 6, and 9 hours following each dose of cyclophosphamide.
PROCEDURE	Apheresis	IV collection
PROCEDURE	SJCARB7H3_41BBL infusion	1X107 CAR+ T cells/kg

Timeline

• Start date: 2026-02-01
• Primary completion: 2034-12-01
• Completion: 2035-12-01
• First posted: 2026-02-24
• Last updated: 2026-02-24

Locations

1 site across 1 country: United States

Regulatory

• FDA-regulated drug study