Clinical significance of B7-H3 and HER2 co-expression and therapeutic value of combination treatment in gastric cancer

Survival and clinicopathological significance of B7-H3 in bladder cancer: a systematic review and meta-analysis

BACKGROUND

B7-H3 has been implicated in clinical pathological features and prognosis across various cancer types, suggesting its potential as a cancer biomarker. Nevertheless, consensus remains elusive regarding its clinical-pathological and prognostic significance in bladder cancer. To address this gap, we conducted a systematic review and meta-analysis.

METHODS

We systematically searched PubMed, Embase, Web of Science, Cochrane, and CNKI databases from their inception up to October 6, 2022. We evaluated the literature's quality using the Newcastle-Ottawa Scale. We performed meta-analysis using Review Manager 5.3 and STATA 12.0, synthesizing data and calculating odds ratios (ORs) or hazard ratios (HRs) with corresponding 95% confidence intervals (CIs).

RESULTS

After applying eligibility criteria and conducting assessments, we included data from 8 studies, encompassing 1622 bladder cancer patients. Bladder tumor tissues exhibited significantly elevated B7-H3 protein expression compared to normal bladder tissues. Elevated B7-H3 expression was notably associated with patient age, tumor infiltration, and recurrence in bladder cancer. However, no significant correlations were observed with other clinical characteristics. Our pooled HR analysis indicated no significant association between B7-H3 expression and overall survival in bladder cancer patients.

CONCLUSION

Our meta-analysis unveils the complex role of B7-H3 in bladder cancer progression. It appears to be directly involved in tumor infiltration and recurrence but cannot definitively serve as a prognostic biomarker for bladder cancer. To validate these findings, further well-designed studies, encompassing larger sample sizes and diverse racial backgrounds, are warranted.

PROSPERO REGISTRATION

No. CRD42022364688.

New Emerging Targets in Cancer Immunotherapy: The Role of B7-H3

Immune checkpoints (ICs) are molecules implicated in the fine-tuning of immune response via co-inhibitory or co-stimulatory signals, and serve to secure minimized host damage. Targeting ICs with various therapeutic modalities, including checkpoint inhibitors/monoclonal antibodies (mAbs), antibody-drug conjugates (ADCs), and CAR-T cells has produced remarkable results, especially in immunogenic tumors, setting a paradigm shift in cancer therapeutics through the incorporation of these IC-targeted treatments. However, the large proportion of subjects who experience primary or secondary resistance to available IC-targeted options necessitates further advancements that render immunotherapy beneficial for a larger patient pool with longer duration of response. B7-H3 (B7 Homolog 3 Protein, CD276) is a member of the B7 family of IC proteins that exerts pleiotropic immunomodulatory effects both in physiologic and pathologic contexts. Mounting evidence has demonstrated an aberrant expression of B7-H3 in various solid malignancies, including tumors less sensitive to current immunotherapeutic options, and has associated its expression with advanced disease, worse patient survival and impaired response to IC-based regimens. Anti-B7-H3 agents, including novel mAbs, bispecific antibodies, ADCs, CAR-T cells, and radioimmunotherapy agents, have exhibited encouraging antitumor activity in preclinical models and have recently entered clinical testing for several cancer types. In the present review, we concisely present the functional implications of B7-H3 and discuss the latest evidence regarding its prognostic significance and therapeutic potential in solid malignancies, with emphasis on anti-B7-H3 modalities that are currently evaluated in clinical trial settings. Better understanding of B7-H3 intricate interactions in the tumor microenvironment will expand the oncological utility of anti-B7-H3 agents and further shape their role in cancer therapeutics.

B7-H3 and CD47 co-expression in gastric cancer is a predictor of poor prognosis and potential targets for future dual-targeting immunotherapy

BACKGROUND

Gastric cancer (GC) is one of the most prevalent types of cancer worldwide. B7-H3, an immune checkpoint molecule with promising potential, has been found to be overexpressed in various cancers. CD47 is an anti-phagocytic molecule that interacts with the signal regulatory protein alpha (SIRPα) to affect phagocytes. The relationship between the expression of B7-H3 and CD47, two potential therapeutic targets found in tumor cells, remains unknown. In this study, our objective is to investigate the clinical significance of co-expression of B7-H3 and CD47, as well as the potential therapeutic value of combination therapy in GC.

METHODS

We utilized immunohistochemistry (IHC) to assess the expression of B7-H3, CD47, CD68, CD86 and CD163 in tissue microarrays obtained from 268 GC patients who underwent surgeries. Western blotting was employed to assess the protein level of B7-H3 and CD47 in GC tissues. The co-localization of B7-H3/CD47 and CD68 in GC tissues was determined using multiplex immunohistochemistry (m-IHC). We further verified the relationship between B7-H3/CD47 and macrophage infiltration via flow cytometry. To estimate the clinical outcomes of patients from different subgroups, we employed the Kaplan-Meier curve and the Cox model.

RESULTS

Among the 268 GC cases, a total of 180 cases exhibited positive expression of B7-H3, while 122 cases showed positive expression of CD47. In fresh GC clinical tissues, B7-H3 and CD47 protein level was also higher in tumor tissue than in adjacent normal tissue. Remarkably, 91 cases demonstrated co-expression of B7-H3 and CD47. We observed a significant correlation between B7-H3 expression and tumor stage (P = 0.001), differentiation (P = 0.045), and depth (P = 0.003). Additionally, there was a significant association between B7-H3 and CD47 expression (P = 0.018). The percentage of B7-H3 and CD47 double positive cells in fresh GC tumor tissues were elevated compared with control adjacent tissues regardless of CD45- or CD45+ cells (P = 0.0029, P = 0.0012). Patients with high B7-H3 or CD47 expression had significantly lower overall survival (OS) rates compared to those with low expression levels (P = 0.0176 or P = 0.0042). Surprisingly, patients with combined high expression of B7-H3 and CD47 exhibited a considerably worse prognosis than others (P = 0.0007). Univariate analysis revealed that cases with high expression of B7-H3, CD47, or both had significantly higher hazard ratios (HR) than cases with low expression of these markers. Furthermore, the results of multivariate analysis indicated that B7-H3/CD47 co-expression and CD47 expression alone are independent prognostic factors for overall survival. Moreover, significant correlations were observed between B7-H3 and CD68 expression, CD47 and CD68 expression, as well as B7-H3/CD47 co-expression and CD68 expression in GC patients (P < 0.001, P = 0.003, and P < 0.001). Flow cytometry test showed that the percentage of CD68-positive cells but not CD86-positive cells among B7-H3-positive or CD47-positive immune cells in GC tumor tissue was elevated significantly compared with adjacent tissue.

CONCLUSION

Our findings demonstrated a correlation between B7-H3 expression and CD47 expression in GC patient tissues. Co-expression of B7-H3 and CD47 can serve as an indicator of poor prognosis in GC patients. In GC tumor tissue, but not adjacent tissue, B7-H3 and CD47 expression was accompanied with macrophage infiltration.

B7-H3 immunoregulatory roles in cancer

B7 homolog 3 (B7-H3, also called CD276) is a checkpoint of B7 family that is aberrantly and consistently expressed in several human cancers, and its overexpression correlates with weak prognosis. B7-H3 is expressed on a number of cells, and it acts as a driver of immune evasion. This is mediated through hampering T cell infiltration and promoting exhaustion of CD8⁺ T cells. Increased B7-H3 activity also promotes macrophage polarity toward pro-tumor type 2 (M2) phenotype. In addition, high B7-H3 activity induces aberrant angiogenesis to promote hypoxia, a result of which is resistance to common immune checkpoint inhibitor (ICI) therapy. This is mediated through the impact of hypoxia on dampening CD8⁺ T cell recruitment into tumor area. The immunosuppressive property of B7-H3 offers insights into targeting this checkpoint as a desired approach in cancer immunotherapy. B7-H3 can be a target in blocking monoclonal antibodies (mAbs), combination therapies, chimeric antigen receptor-modified T (CAR-T) cells and bispecific antibodies.