68Ga-B7-H3 Nanobody ImmunoPET in Osteosarcoma

Clinical Evaluation of a 68Ga-Labeled B7-H3 Nanobody for ImmunoPET Imaging in Patients With Osteosarcoma

This study aims to evaluate the safety, feasibility, and imaging performance of a novel 68Ga-labeled B7-H3 nanobody for immunoPET imaging in patients with osteosarcoma. Participants with suspected or histologically confirmed osteosarcoma will undergo 68Ga-B7-H3 nanobody PET/CT imaging according to the study protocol. Imaging findings will be compared with conventional imaging and, when available, histopathological results. The study will assess tracer biodistribution, tumor uptake, lesion detectability, and safety to determine the potential clinical value of B7-H3-targeted immunoPET for the diagnosis and evaluation of osteosarcoma.

B7-H3 (CD276) is an immune checkpoint molecule that is highly expressed in a variety of malignant tumors, including osteosarcoma, while showing limited expression in most normal tissues. Because of its high tumor-associated expression, B7-H3 has emerged as a promising molecular imaging and therapeutic target.

This is a prospective, single-center clinical study designed to evaluate a novel 68Ga-labeled B7-H3 nanobody as an immunoPET imaging agent in patients with osteosarcoma. Eligible participants will receive an intravenous administration of the investigational radiotracer followed by PET/CT imaging at the prespecified imaging time point(s). Safety assessments will include monitoring of adverse events and other clinically relevant evaluations as specified in the protocol.

Imaging findings will be analyzed to characterize tracer biodistribution and tumor uptake and will be compared with standard imaging examinations and histopathological findings whenever available. The study is intended to investigate the feasibility and diagnostic performance of 68Ga-B7-H3 nanobody immunoPET for the detection and evaluation of osteosarcoma and to provide clinical evidence supporting the further development of B7-H3-targeted molecular imaging.

Inclusion Criteria:

• Age ≥10 years.
• Histologically confirmed osteosarcoma.
• Relapsed or refractory disease following failure of first- or second-line systemic therapy.
• Ability to understand the study procedures and provide written informed consent (or assent with parental/legal guardian consent, where applicable).

Exclusion Criteria:

• Pregnant or breastfeeding.
• Severe uncontrolled systemic disease or medical condition that, in the investigator's judgment, may interfere with study participation or image interpretation.
• Unable to undergo PET/CT examination.
• Any condition that, in the investigator's judgment, makes the participant unsuitable for enrollment.