B7-H3
Summary
B7-H3 (CD276) is a tumor-associated immune-related protein that is markedly upregulated across EGFR-positive malignancies while showing minimal expression in healthy tissues, making it a tumor-selective binding target. It can mediate cis-inhibition in the context of an EGFR/B7-H3 bispecific antibody, supporting a mechanism for enhanced anti-tumor efficacy with reduced toxicity (PMID:41735305). In colorectal cancer, B7-H3 expression was significantly elevated in an immune-resistant organoid fraction, linking it to therapy resistance and immune escape (PMID:41920069). B7-H3 is also enriched in exosomes, where it influences exosome biogenesis, signaling, and tumor progression, and these exosomes may serve as diagnostic, prognostic, and predictive biomarkers in colorectal cancer, non-small cell lung cancer, and prostate cancer (PMID:41964005). Therapeutically, B7-H3 is being targeted by next-generation antibody-drug conjugates and bispecific T cell engagers, including approaches in pediatric solid tumors (PMID:41984108). Mechanistically, it is reported to activate PI3K and STAT3 pathways, further supporting roles in tumor growth and immune modulation.
Key Findings
EGFR-positive malignancies and bispecific antibody targeting
- A 2026 Nature Communications study showed that ibi334 uses B7-H3 for tumor-selective binding and cis-inhibition of EGFR, enhancing anti-tumor efficacy while minimizing toxicities (PMID:41735305).
- B7-H3 was described as markedly upregulated across EGFR-positive malignancies with minimal expression in healthy tissues, supporting its suitability as a selective therapeutic target (PMID:41735305).
- The reported mechanism links B7-H3 to cis-inhibition within a bispecific antibody format, rather than direct EGFR blockade alone (PMID:41735305).
Colorectal cancer and immune resistance
- B7-H3 expression was significantly elevated in the immune-resistant colorectal cancer organoid fraction, associating it with resistance phenotypes (PMID:41920069).
- The protein was highlighted as an immune-related factor in tumor adaptation under immune pressure (PMID:41920069).
- These findings support B7-H3 as a candidate marker of immune-resistant disease states in colorectal cancer (PMID:41920069).
Exosomes, tumor microenvironment, and biomarkers
- A 2026 Cell Communication and Signaling review emphasized B7-H3-enriched exosomes as regulators of exosome biogenesis, signaling, and tumor progression (PMID:41964005).
- B7-H3-enriched exosomes were proposed to modulate the tumor microenvironment to promote immune evasion, metastasis, and therapy resistance (PMID:41964005).
- The same work suggested diagnostic, prognostic, and predictive biomarker potential in colorectal cancer, non small cell lung cancer, and prostate cancer (PMID:41964005).
Pediatric solid tumors and antibody-based therapeutics
- B7-H3 was identified as a tumor-associated antigen targeted by next-generation antibody-drug conjugates in pediatric solid tumors (PMID:41984108).
- The 2026 review also noted bispecific T cell engager strategies directed at B7-H3 as part of multimodal immunotherapy development (PMID:41984108).
- These approaches reflect growing interest in B7-H3 as a broadly applicable oncology target beyond adult epithelial cancers (PMID:41984108).