Purpose Release of inhibitory coregulatory proteins into the circulation may represent one mechanism by which tumors thwart immune responses. Our objective was to determine whether sB7-H1 levels in patients with clear cell renal cell carcinoma (ccRCC) are associated with pathologic features and patient outcome. Experimental Design We developed an ELISA for quantification of sB7-H1 in biologic fluids. Biochemical confirmation of the measured analyte as sB7-H1 was done by protein micro-sequencing using supernates from tumor cell lines. Biological activity of sB7-H1 was assessed in vitro utilizing T cell apoptosis assays. We tested sB7-H1 levels in the sera from 172 ccRCC patients and correlated sB7-H1 levels with pathologic features and patient outcome. Results sB7-H1 was detected in the cell-supernatants of some B7-H1-positive tumor cell lines. Protein sequencing established that the measured sB7-H1 retained its receptor-binding domain and could deliver pro-apoptotic signals to T cells. Higher preoperative sB7-H1 levels were associated with larger tumors (p<0.001), tumors of advanced stage (p=0.017) and grade (p=0.044), and tumors with necrosis (p=0.003). A doubling of sB7-H1 levels was associated with a 41% increased risk of death (p=0.010). Conclusion Our observations suggest that sB7-H1 may be detected in the sera of ccRCC patients and that sB7-H1 may systemically impair host immunity, thereby fostering cancer progression and subsequent poor clinical outcome.

B7 coregulatory ligands can be aberrantly expressed in human disease. In the context of cancer, these ligands may act as antigen-specific inhibitors of T-cell-mediated antitumoral immunity. We recently reported that B7-H1 expression by carcinomas of the kidney and bladder portends aggressive disease and diminished survival. The expression of these proteins in prostate cancer, however, has not been investigated. We evaluated B7-H3 and B7-H1 protein expression in the pathologic specimens of 338 men treated for clinically localized prostate cancer between 1995 and 1998 with radical retropubic prostatectomy. Expression levels of B7-H3 in prostate cancer were correlated with pathologic indicators of aggressive cancer as well as clinical outcome. We report that B7-H3 is uniformly and aberrantly expressed by adenocarcinomas of the prostate, high-grade prostatic intraepithelial neoplasia, and four prostate cancer cell lines, whereas B7-H1 is rarely expressed. B7-H3 is expressed by benign prostatic epithelia, although at a more reduced level relative to neoplastic tissue. Increasing levels of B7-H3 intensity correlate with worsening clinicopathologic features of prostate cancer. Marked B7-H3 intensity, present in 67 (19.8%) specimens, confers a >4-fold increased risk of cancer progression after surgery (risk ratio, 4.42; P < 0.001). A survey of normal tissues revealed that B7-H3 is expressed within the liver, urothelium, and fetal kidney. In summary, B7-H3 is aberrantly expressed in all prostate cancers and represents an independent predictor of cancer progression following surgery. Moreover, B7-H3 encompasses a novel diagnostic and potential therapeutic target for the clinical management of prostate cancer and, perhaps, other malignancies as well. [Cancer Res 2007;67(16):7893-900]

Purpose: Although the prognostic value of B7-H1and B7-H4 expression by tumor cells in clear cell renal cell carcinoma (ccRCC) has been established, the role of B7-H3 is unknown. As such, we evaluated the association of B7-H3 expression with clinicopathologic outcomes in patients treated for ccRCC. Experimental Design: Nephrectomy specimens from 743 consecutive patients treated for ccRCC at our institution from 1990 to 1999 were evaluated for B7-H3 expression by immunohistochemical staining. Associations of B7-H3 expression with clinical and pathologic features were evaluated using m 2 and Fisher's exact tests. Associations of B7-H3 expression with death from RCC were evaluated using Cox proportional hazards regression models. Results: B7-H3 expression by tumor cells or tumor vasculature was noted in 17% and 95% of specimens, respectively. The presence of either tumor cell or diffuse tumor vasculature expression of B7-H3 was present in 46% of specimens and was associated with multiple adverse clinical and pathologic features. After multivariable adjustment, the presence of either tumor cell or diffuse tumor vasculature B7-H3 expression was significantly associated with an increased risk of death from RCC (risk ratio, 1.38; 95 % confidence interval, 1.03-1.84; P = 0.029). Conclusions: Both tumor cell and tumor vasculature B7-H3 expression convey important information to predict ccRCC outcomes. Collectively, our past and present studies pertaining to B7-H ligand expression indicate that ccRCC may use redundant mechanisms to compromise host antitumoral immunity. Future studies will focus on the effect of combined B7-H ligand expression in RCC.

Foxp3À T cells, which may represent a unique set of Tregs or activated helperTcells, was significantly associated with outcome.

BACKGROUND PD‐L1 (programmed death ligand 1, B7‐H1) is a cell surface glycoprotein that can impair T‐cell function. PD‐L1 is aberrantly expressed by multiple human malignancies and has been shown to carry a highly unfavorable prognosis in patients with kidney cancer. The role of PD‐L1 was evaluated as a mechanism for local stage progression in urothelial carcinoma (UC) of the bladder. METHODS Using immunohistochemistry, PD‐L1 expression was evaluated in a cohort of 280 high‐risk UCs of the bladder. PD‐L1 was modeled as a predictor of bladder cancer stage using ordinal logistic regression. Other covariates evaluated as potential confounders included age, gender, tumor grade, and lymphocytic infiltration. Further, PD‐L1 was evaluated as a potential mechanism of bacillus Calmette‐Guerin (BCG) failure in the subset of high‐risk nonmuscle‐invasive tumors that received this treatment. RESULTS PD‐L1 expression was observed in 7% of pTa, 16% of pT1, 23% of pT2, 30% of pT3/4, and 45% of carcinoma in situ (CIS) tumors. PD‐L1 expression was associated with high‐grade tumors (odds ratio [OR] = 2.4, P = .009) and tumor infiltration by mononuclear cells (OR = 5.5, P = .004). We observed that the key determinants of stage progression in this cohort were World Health Organization/International Society of Urologic Pathology (WHO/ISUP) high‐grade tumor pathology (OR = 4.77, 95% confidence interval [CI]: 2.73–8.34; P < .001) and PD‐L1 expression (OR = 2.20, P = .012). PD‐L1 expression was found to be extremely abundant in the BCG‐induced bladder granulomata in 11 of 12 patients failing BCG treatment. CONCLUSIONS Collectively, these data indicate that tumor PD‐L1 may facilitate localized stage‐advancement of UC and attenuate responses to BCG immunotherapy by neutralizing T cells that normally guard against cancer invasion from the epithelium into the bladder musculature. Cancer 2007. © 2007 American Cancer Society.

Tumor cells aberrantly express several T cell inhibitory molecules including members of the B7-H co-regulatory family. Presumably tumor-expressed B7-H1 and B7-H3 confer resistance to elimination by the immune system. In addition, elevated levels of soluble B7-H1 (sB7-H1) has been identified in the sera of cancer patients, including renal carcinoma patients and is associated with increased cancer related death. Here we report that sB7-H1 is produced and released by activated mature dendritic cells (mDC). Immature DC, macrophages, monocytes, or T cells are refractory to releasing sB7-H1. Exposure of CD4+ and CD8+ T cells to mDC-derived sB7-H1 molecules induced apoptosis. These data suggest that the immunobiology of B7-H1 is perhaps more complex than previously thought. sB7-H1 molecules may represent an unanticipated contributing factor to immune homeostasis. That both immune and tumor cells can be sources of sB7-H1 suggests that optimization of co-regulatory blockade immunotherapy for solid malignancies of necessity will require impact of targeting tumor and immune-derived B7-H1 molecules.

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Agonists of TLR have been explored as vaccine adjuvants for tumor immunotherapy. However, their immunological consequences are not fully understood. Although TLR signaling increases the functional potential of dendritic cells (DCs) for priming T cells, coinduction of potentially negative immunoregulatory capacities may impair effector T cell generation. We examined the expression and function of B7 family costimulatory molecules on DCs after activation with the TLR3 agonist, polyinosinic:polycytidylic acid. We demonstrated that polyinosinic:polycytidylic acid consistently up-regulated both B7-2 and B7-H1 molecules on resident, migratory DCs from spleen and lymph nodes. Depletion or blockade of B7-H1 on activated DCs increased the magnitude of effector CD8 T cell expansion. DC-based or protein-based tumor vaccines, in combination with B7-H1 blockade, induced strong effector CD8 T cell responses, resulting in protective immunity against newly established tumors. Our studies suggest that TLR3 signaling has the potential to up-regulate both positive and negative coregulatory molecules on APCs. Selective blockade of negative regulatory molecules in combination with TLR3 agonist may be an effective strategy for increasing the efficacy of tumor vaccines.