Overexpression of HHLA2, a member of the B7 family, is associated with worse survival in human colorectal carcinoma

Background: Colorectal carcinoma (CRC) is one of the most common malignancies, and immunotherapy has opened a new field of cancer treatment in recent years. Generally, CRC does not benefit from immunotherapy. HHLA2, a member of the B7 family, is a novel immune checkpoint molecule, and the prognostic value of HHLA2 in CRC patients and the association between HHLA2 expression and clinicopathological characteristics remains unknown.

Materials and methods: This study included 63 patients diagnosed with CRC, and their resected specimens were obtained and constructed as a tissue microarray. Expression of HHLA2 and CD8 was detected by the double immunohistochemistry method. Based on follow-up data, correlations of HHLA2 expression and clinicopathological features, including overall survival, in CRC patients were evaluated.

Results: High HHLA2 expression was detected in CRC tumor tissues, compared to the adjacent noncancerous tissues. HHLA2 expression level was significantly related to the depth of invasion (P=0.044) and CD8⁺ T-cell infiltration status (P=0.016), and predicted high mortality rate (P=0.035). HHLA2 acted as an independent predictive factor in the overall survival of CRC patients (P=0.039, hazard ratio=2.162, 95% CI 1.041-3.084).

Conclusion: HHLA2 expression is upregulated in CRC patients, and HHLA2 is an independent prognostic factor of overall survival of CRC patients. High HHLA2 expression is closely correlated with CD8 T-cell infiltration status and can predict poor prognosis in CRC patients.