Clinical significance and correlation of PD-L1, B7-H3, B7-H4, and TILs in pancreatic cancer

B7-H3 is associated with the armored-cold phenotype and predicts poor immune checkpoint blockade response in melanoma

Melanoma is the most suitable tumor type for immunotherapy, but not all melanoma patients could respond to immunotherapy. B7 homolog 3 (B7-H3) belongs to the B7 family and is overexpressed in a number of malignant tumors, but the expression pattern of B7-H3 in melanoma has not been well summarized. The expression of B7-H3 was investigated in melanoma and its correlations with features of the tumor microenvironment (TME) by using various public databases, including the Cancer Genome Atlas (TCGA), the GEPIA, and the Human Protein Atlas databases. In addition, the in-house melanoma tissue microarray was applied to validate the results from public databases. Based on the public and in-house cohorts, we found that B7-H3 was overexpressed in melanoma tumor tissues and high B7-H3 expression was related to poor clinical outcome. Moreover, B7-H3 was negatively correlated with levels of tumor-infiltrating lymphocytes (TILs) and positively correlated with collagen infiltration. With clinical translational value, the predictive value of B7-H3 for conventional immunotherapy was detected using the Kaplan-Meier plotter tool, and the results showed that melanoma patients with high B7-H3 expression were insensitive to anti-PD-1 and anti-CTLA-4 immunotherapy. In conclusion, we first investigate the expression of B7-H3 in melanoma and its correlations with the TME features, and indicate B7-H3 as a promising therapeutic target in melanoma patients that are insensitive to conventional immunotherapy.

High B7-H3 expression with low PD-L1 expression identifies armored-cold tumors in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is generally regarded as the most aggressive subtype among breast cancers, but exhibits higher chemotherapeutic and immunotherapeutic responses due to its unique immunogenicity. Thus, appropriate discrimination of subtypes is critical for guiding therapeutic options in clinical practice. In this research, using multiple in-house and public cohorts, we investigated the expression features and immuno-correlations of B7-H3 in breast cancer and checked the anti-tumor effect of the B7-H3 monoclonal antibody in a mouse model. We also developed a novel classifier combining B7-H3 and PD-L1 expression in TNBC. B7-H3 was revealed to be related to immuno-cold features and accumulated collagen in TNBC. In addition, targeting B7-H3 using the monoclonal antibody significantly suppressed mouse TNBC growth, reversed the armored-cold phenotype, and also boosted anti-PD-1 immunotherapy. In addition, patients with B7-H3 high and PD-L1 low expression showed the lowest anti-tumor immune infiltration, the highest collagen level, and the lowest therapeutic responses to multiple therapies, which mostly belong to armored-cold tumors. Overall, this research provides a novel subtyping strategy based on the combination of B7-H3/PD-L1 expression, which leads to a novel approach for the management of TNBC.

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.

Bispecific antibody targeting both B7-H3 and PD-L1 exhibits superior antitumor activities

Clinical application of PD-1 and PD-L1 monoclonal antibodies (mAbs) is hindered by their relatively low response rates and the occurrence of drug resistance. Co-expression of B7-H3 with PD-L1 has been found in various solid tumors, and combination therapies that target both PD-1/PD-L1 and B7-H3 pathways may provide  additional therapeutic benefits. Up to today, however, no bispecific antibodies targeting both PD-1 and B7-H3 have reached the clinical development stage. In this study, we generated a stable B7-H3×PD-L1 bispecific antibody (BsAb) in IgG1-VHH format by coupling a humanized IgG1 mAb against PD-L1 with a humanized camelus variable domain of the heavy-chain of heavy-chain antibody (VHH) against human B7-H3. The BsAb exhibited favorable thermostability, efficient T cell activation, IFN-γ production, and antibody-dependent cell-mediated cytotoxicity (ADCC). In a PBMC humanized A375 xenogeneic tumor model, treatment with BsAb (10 mg/kg, i.p., twice a week for 6 weeks) showed enhanced antitumor activities compared to monotherapies and, to some degree, combination therapies. Our results suggest that targeting both PD-1 and B7-H3 with BsAbs increases their specificities to B7-H3 and PD-L1 double-positive tumors and induces a synergetic effect. We conclude that B7-H3×PD-L1 BsAb is favored over mAbs and possibly combination therapies in treating B7-H3 and PD-L1 double-positive tumors.

A novel PD-1/PD-L1 pathway molecular typing-related signature for predicting prognosis and the tumor microenvironment in breast cancer

BACKGROUND

Currently, the development of breast cancer immunotherapy based on the PD-1/PD-L1 pathway is relatively slow, and the specific mechanism affecting the immunotherapy efficacy in breast cancer is still unclear.

METHODS

Weighted correlation network analysis (WGCNA) and the negative matrix factorization (NMF) were used to distinguish subtypes related to the PD-1/PD-L1 pathway in breast cancer. Then univariate Cox, least absolute shrinkage and selection operator (LASSO), and multivariate Cox regression were used to construct the prognostic signature. A nomogram was established based on the signature. The relationship between the signature gene IFNG and breast cancer tumor microenvironment was analyzed.

RESULTS

Four PD-1/PD-L1 pathway-related subtypes were distinguished. A prognostic signature related to PD-1/PD-L1 pathway typing was constructed to evaluate breast cancer's clinical characteristics and tumor microenvironment. The nomogram based on the RiskScore could be used to accurately predict breast cancer patients' 1-year, 3-year, and 5-year survival probability. The expression of IFNG was positively correlated with CD8+ T cell infiltration in the breast cancer tumor microenvironment.

CONCLUSION

A prognostic signature is constructed based on the PD-1/PD-L1 pathway typing in breast cancer, which can guide the precise treatment of breast cancer. The signature gene IFNG is positively related to CD8+ T cell infiltration in breast cancer.

B7x in cancer immunity and immunotherapy

B7x (also called B7-H4) is a co-inhibitory molecule of B7 family that is highly expressed in non-inflamed or cold cancers, and its aberrant expression is contributed to cancer progression and poor outcomes. B7x preferentially expresses on antigen-presenting cells (APCs) and in tumor cells, and it acts as an alternative anti-inflammatory immune checkpoint for hampering peripheral immune responses. Augmented infiltration of immunosuppressive cells, reduced proliferation and effector function of CD4⁺ and CD8⁺ T cells, and increased generation of regulatory T cells (Tregs) are outcomes of increased B7x activity in cancer. Evaluation of B7x in sera can be exploited as an effective biomarker of response in cancer patients. B7x overexpression generally occurs in programmed death-ligand 1 (PD-L1)^- cancers and is involved in tumor resistance to anti-programmed death-1 (PD-1), anti-PD-L1 or anti-cytotoxic T lymphocyte associated antigen-4 (CTLA-4) therapy. Co-expression of B7x receptor with PD-1 on CD8⁺ T cells has made the anti-B7x a fruitful approach for reinvigoration of the functionality of exhausted T cells and is served as a complementary regimen in patients who are irresponsive to the common immune checkpoint inhibitor (ICI) therapy. An advance in the field is the development of bispecific antibodies against B7x with other regulatory molecules within tumor microenvironment (TME).

New frontiers in immune checkpoint B7-H3 (CD276) research and drug development

B7-H3 (CD276), a member of the B7 family of proteins, is a key player in cancer progression. This immune checkpoint molecule is selectively expressed in both tumor cells and immune cells within the tumor microenvironment. In addition to its immune checkpoint function, B7-H3 has been linked to tumor cell proliferation, metastasis, and therapeutic resistance. Furthermore, its drastic difference in protein expression levels between normal and tumor tissues suggests that targeting B7-H3 with drugs would lead to cancer-specific toxicity, minimizing harm to healthy cells. These properties make B7-H3 a promising target for cancer therapy.Recently, important advances in B7-H3 research and drug development have been reported, and these new findings, including its involvement in cellular metabolic reprograming, cancer stem cell enrichment, senescence and obesity, have expanded our knowledge and understanding of this molecule, which is important in guiding future strategies for targeting B7-H3. In this review, we briefly discuss the biology and function of B7-H3 in cancer development. We emphasize more on the latest findings and their underlying mechanisms to reflect the new advances in B7-H3 research. In addition, we discuss the new improvements of B-H3 inhibitors in cancer drug development.

Role of B7 family members in glioma: Promising new targets for tumor immunotherapy

Glioma, is a representative type of intracranial tumor among adults, usually has a weak prognosis and limited treatment options. Traditional therapies, including surgery, chemotherapy, and radiotherapy, have had little impact on patient survival time. Immunotherapies designed to target the programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1) signaling pathway have successfully treated various human cancers, informing the development of similar therapies for glioma. However, anti-PD-L1 response rates remain limited in glioma patients. Thus, exploring novel checkpoints targeting additional immunomodulatory pathways for activating durable antitumor immune responses and improving glioma outcomes is needed. Researchers have identified other B7 family checkpoint molecules, including PD-L2, B7-H2, B7-H3, B7-H4, and B7-H6. The current review article evaluates the expression of all 10 reported members of the B7 family in human glioma using The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) data, as well as summarizes studies evaluating the clinical meanings and functions of B7 family molecules in gliomas. B7 family checkpoints may contribute to different immunotherapeutic management options for glioma patients.

B7 family protein glycosylation: Promising novel targets in tumor treatment

Cancer immunotherapy, including the inhibition of immune checkpoints, improves the tumor immune microenvironment and is an effective tool for cancer therapy. More effective and alternative inhibitory targets are critical for successful immune checkpoint blockade therapy. The interaction of the immunomodulatory ligand B7 family with corresponding receptors induces or inhibits T cell responses by sending co-stimulatory and co-inhibitory signals respectively. Blocking the glycosylation of the B7 family members PD-L1, PD-L2, B7-H3, and B7-H4 inhibited the self-stability and receptor binding of these immune checkpoint proteins, leading to immunosuppression and rapid tumor progression. Therefore, regulation of glycosylation may be the "golden key" to relieve tumor immunosuppression. The exploration of a more precise glycosylation regulation mechanism and glycan structure of B7 family proteins is conducive to the discovery and clinical application of antibodies and small molecule inhibitors.