Is the clinical malignant phenotype of prostate cancer a result of a highly proliferative immune-evasive B7-H3-expressing cell population?

Objectives: To assess the expression of the cell surface protein B7-H3 in prostate cancer, and its association to clinically relevant parameters after radical prostatectomy and to the proliferation marker Ki-67. Methods: Radical prostatectomy specimens from a cohort of 130 patients with a median clinical follow up of 8 years were used for the analysis. The expression of B7-H3 and the proliferation marker Ki-67, as well as other standard clinicopathological parameters, were evaluated. Results: A high expression of B7-H3 was associated with pathological stage T3a and T3b, high Gleason score, extraprostatic extension, seminal vesicle invasion and high proliferative activity. Univariable analysis showed that a high expression level of B7-H3 was also correlated with biochemical failure and clinical relapse, and with the expression of Ki-67. A high expression level of Ki-67 was associated with clinical progression and a tendency towards higher rates of prostate-specific antigen relapse in multivariate analyses. Conclusions: Our findings show that a high expression level of B7-H3 in prostate cancer correlates with the expression of the proliferation marker Ki-67, biochemical failure and clinical relapse. Thus, expression of the cell surface molecule B7-H3 adds to the malignant phenotype of prostate cancer cells expressing high levels of Ki-67. The impact of B7-H3 function on prostate cancer and its potential role in immunotherapy should be explored further.