Targeting immunotherapy for bladder cancer using anti-CD3× B7-H3 bispecific antibody

CD276-dependent efferocytosis by tumor-associated macrophages promotes immune evasion in bladder cancer

Interplay between innate and adaptive immune cells is important for the antitumor immune response. However, the tumor microenvironment may turn immune suppressive, and tumor associated macrophages are playing a role in this transition. Here, we show that CD276, expressed on tumor-associated macrophages (TAM), play a role in diminishing the immune response against tumors. Using a model of tumors induced by N-butyl-N-(4-hydroxybutyl) nitrosamine in BLCA male mice we show that genetic ablation of CD276 in TAMs blocks efferocytosis and enhances the expression of the major histocompatibility complex class II (MHCII) of TAMs. This in turn increases CD4 + and cytotoxic CD8 + T cell infiltration of the tumor. Combined single cell RNA sequencing and functional experiments reveal that CD276 activates the lysosomal signaling pathway and the transcription factor JUN to regulate the expression of AXL and MerTK, resulting in enhanced efferocytosis in TAMs. Proving the principle, we show that simultaneous blockade of CD276 and PD-1 restrain tumor growth better than any of the components as a single intervention. Taken together, our study supports a role for CD276 in efferocytosis by TAMs, which is potentially targetable for combination immune therapy.

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.

Preconditioning of radiotherapy enhances efficacy of B7-H3-CAR-T in treating solid tumor models

AIMS

Limited efficacy of chimeric antigen receptor T (CAR-T) cells in treating solid tumors is largely due to the antigen heterogeneity and immunosuppressive tumor microenvironment (TME). B7-H3 is over-expressed in most kind of solid tumors, making it a promising target for cancer treatment. This study aims to explore the effect of B7-H3-CAR-T therapy combined with radiotherapy in treating solid tumor models.

METHODS

Irradiated tumor cell lines were prepared and tested. A humanized B7-H3-CAR-T was constructed, and it was evaluated that B7-H3-CAR-T cytotoxicity against solid tumor models with preconditioning of radiotherapy in vitro and vivo.

RESULTS

Irradiation was found to increase expression level of B7-H3 in pancreatic cancer (PANC-1), colorectal cancer (HCT-15, SW620), acute myelocytic leukemia (AML-5), epidermoid carcinoma (KB) and glioma (U87-MG) human cell lines significantly. 6Gy irradiation was also found to up-regulate tumor-infiltration molecule like intracellular adhesion molecule-1 ICAM-1 or FAS in HCT-15 cells, supporting a possible synergistic enhancement effect of radiotherapy. In vitro and in vivo experiments demonstrated that irradiation indeed significantly enhanced the ability of B7-H3-CAR-T to infiltrate and kill tumors. Interestingly in dual-tumor mouse model study, not only tumor cells on irradiation side were eradicated completely, irradiation also enhanced CAR-T tumor-killing ability on non-irradiated side, confirming the abscopal effect of irradiation existed with CAR-T therapy.

CONCLUSIONS

Our results suggest that B7-H3-CAR-T therapy combined with radiotherapy may be a promising modality in treating solid tumors.

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.

GPC3-targeted CAR-T cells secreting B7H3-targeted BiTE exhibit potent cytotoxicity activity against hepatocellular carcinoma cell in the in vitro assay

Hepatocellular carcinoma (HCC), the most common primary liver cancer has a high mortality in China, and it is usually diagnosed at a late stage, thereby leaving patients with few effective treatment options. Chimeric antigen receptor-T (CAR-T) cell therapy, a novel immunotherapy that has shown promising results in leukemia, lymphoma and multiple myeloma, is also expected to work well in solid tumors, including HCC. However, the ideal therapeutic efficacy has not yet been achieved, in part due to tumor antigen escape caused by antigen heterogeneity. To overcome such challenge, we screened a panel of biomarkers in HCC cell lines and found that GPC3 and B7H3 were highly expressed on HCC with expression heterogeneity. Then we developed a novel bispecific T cell engagers CAR-T (CAR.T-BiTEs) that drives the expression of a CAR specific for GPC3 and BiTEs against CD3 and B7H3, herein referred to as “GPC3-BiTE CAR.” We found that BiTEs promoted the increased activation of untransduced T cells and IFN-γ release. Moreover, BiTEs secreted by GPC3-BiTE CAR-HEK293T cells promoted increased cytotoxicity activity of untransduced T cells against GPC3+/B7H3+ (GPC3 positive/B7H3 positive) and GPC3-/B7H3+(GPC3 negative/B7H3 positive) HCC cell lines. In vitro function assays showed that GPC3-BiTE CAR-T cells exhibited greater cytotoxicity activity against GPC3+/B7H3+ HCC cell lines than GPC3 CAR-T cells (GPC3-targeted CAR-T cells) and B7H3 CAR-T cells (B7H3-targeted CAR-T cells). Furthermore, GPC3-BiTE CAR-T cells exhibited superior cytotoxicity against GPC3 negative HCC cell lines compared with GPC3 CAR T cells. In conclusion, our study showed that GPC3-BiTE CAR T cells exhibited superior antitumor activity than single-target CAR-T cells and can overcome tumor escape induced by antigen heterogeneity, suggesting that this could be a promising therapeutic strategy for HCC.

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The expression of GPC3 and B7H3 was heterogeneous in HCC tissues.

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BiTEs enhanced the cytotoxicity of untransduced T cells against HCC cell lines.

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GPC3-BiTE CAR-T cells showed enhanced cytotoxicity against GPC3+/B7H3+ cells.

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GPC3-BiTE CAR-T cells can resist GPC3 antigen escape in the in vitro assay.

Insights on recent innovations in bladder cancer immunotherapy

Bladder carcinoma is the most common genitourinary cancer, with a high prevalence and global incidence. In addition to early detection by cytology, the management of bladder cancer has recently advanced, not only by improvements in conventional treatments such as surgery and chemotherapy, but also through the introduction of immunotherapeutic strategies. The number of approved immunotherapeutic agents has dramatically increased, with various preclinical and clinical applications in cancer drug discovery. Some bladder cancer immunotherapies include immune checkpoint inhibitors, adoptive cell therapy, cytokine-based therapy, bispecific antibodies, and antibody-drug conjugates. This review provides an overview of some of the innovative immunotherapeutic agents approved and in development that can potentially be used in the treatment of bladder cancer.

Elevated Expression of the Immune Checkpoint Ligand CD276 (B7-H3) in Urothelial Carcinoma Cell Lines Correlates Negatively with the Cell Proliferation

The cell surface molecule CD276 (B7-H3) is an immune checkpoint antigen. The elevated expression of CD276 on tumors contributes to the suppression of anti-tumor T-cell responses and correlates with poor prognosis.

METHODS

The expression of CD276 was explored in vitro on eight urothelial carcinoma cell lines (UM-UC) in comparison to eight normal urothelial cells (NUCs) by RT-qPCR, Western blotting, and flow cytometry. Cell proliferation was enumerated over consecutive passages. The expression of cancer stem cell markers CD24 and CD44, cytokeratins, and vimentin was investigated by immunofluorescence. The expression of CD276 in bladder tumor samples and metastases was explored by immunohistochemistry.

RESULTS

Expression of CD276 on cell surfaces was elevated on UM-UCs when compared to NUCs. In UM-UCs, CD276 transcripts correlated moderately positive with CD276 protein expression (ρ = 0.660) and strongly positive with CD276 surface-expression (ρ = 0.810). CD276 mRNA expression (ρ = -0.475) and CD276 protein expression (ρ = -0.417) had a significant negative correlation with proliferation, while a significant correlation between proliferation and cell surface expression was not observed in UM-UCs.

CONCLUSION

The expression of CD276 on UM-UC bladder tumor cell surfaces is elevated. Slow proliferating UM-UC cells express more CD276 mRNA and protein than fast proliferating cells. In patients, slow proliferating CD276high tumor (stem) cells may evade immune surveillance. However, cancer therapy targeting CD276 may be effective in the treatment of slow proliferating tumor cells.

A Novel Anti-B7-H3 × Anti-CD3 Bispecific Antibody with Potent Antitumor Activity

B7-H3 plays an important role in tumor apoptosis, proliferation, adhesion, angiogenesis, invasion, migration, and evasion of immune surveillance. It is overexpressed in various human solid tumor tissues. In patients, B7-H3 overexpression correlates with advanced stages, poor clinical outcomes, and resistance to therapy. The roles of B7-H3 in tumor progression make it a potential candidate for targeted therapy. Here, we generated a mouse anti-human B7-H3 antibody and demonstrated its binding activity via Tongji University Suzhou Instituteprotein-based and cell-based assays. We then developed a novel format anti-B7-H3 × anti-CD3 bispecific antibody based on the antibody-binding fragment of the anti-B7-H3 antibody and single-chain variable fragment structure of anti-CD3 antibody (OKT3) and demonstrated that this bispecific antibody mediated potent cytotoxic activities against various B7-H3-positive tumor cell lines in vitro by improving T cell activation and proliferation. This bispecific antibody also demonstrated potent antitumor activity in humanized mice xenograft models. These results revealed that the novel anti-B7-H3 × anti-CD3 bispecific antibody has the potential to be employed in treatment of B7-H3-positive solid tumors.

Targeting the immune checkpoint B7-H3 for next-generation cancer immunotherapy

Immune checkpoint inhibitors (ICIs) for programmed death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) have become preferred treatment strategies for several advanced cancers. However, response rates for these treatments are limited, which encourages the search for new ICI candidates. Recent reports have underscored significant roles of B7 homolog 3 protein (B7-H3) in tumor immunity and disease progression. While its multifaceted roles are being elucidated, B7-H3 has already entered clinical trials as a therapeutic target. In this review, we overview the recent results of clinical trials evaluating the antitumor activity and safety of B7-H3 targeting drugs. On this basis, we also discuss the challenges and opportunities arising from the application of these drugs. Finally, we point out current gaps to address in the understanding of B7-H3 function and regulation in order to fully unleash the future clinical utility of B7-H3-based therapies for the treatment of cancer.

Expression patterns of the immune checkpoint ligand CD276 in urothelial carcinoma

BACKGROUND

CD276 is an immune checkpoint molecule. Elevated CD276 expression by urothelial carcinoma is associated with poor prognosis, but little is known about its expression across different tumor stages. We therefore investigated CD276 expression in bladder cancer (BC) cells and in tissue samples of BC stages from pT2 to pT4.

METHODS

CD276 expression was explored in 4 urothelial cancer cell lines and 4 primary normal urothelial cell populations by quantitative RT-PCR, Western blot and flow cytometry. CD276 was investigated in bladder tumors from 98 patients by immunohistochemistry using a score (0-300) incorporating both, staining intensity and area of CD276 staining. Normal appearing urothelium in the bladder of the same patients served as controls.

RESULTS

The urothelial carcinoma cell lines expressed significantly higher levels of CD276 on transcript (p < 0.006), total protein levels (p < 0.005), and on the cell surface (p < 0.02) when compared to normal urothelial cells. In pT2-T4 tumor tissue samples, CD276 was overexpressed (median score 185) when compared to corresponding healthy tissues from the same patients (median score 50; p < 0.001). No significant differences in CD276 expression were recorded in late, locally advanced ≥ pT3a tumors (median score 185) versus organ-confined < pT3a tumors (median score 190), but it was significantly lower in the normal urothelial tissue associated with ≥ pT3a tumors (median score 40) versus < pT3a tumors (median score 80; p < 0.05).

CONCLUSION

CD276 expression is significantly elevated in urothelial carcinoma cells in all stages but varies between individuals considerably. Reduced CD276 expression in normal urothelial cells may imply that these cells would be protected from CD276-mediated immuno therapies.

CXCL12 and CD3E as Indicators for Tumor Microenvironment Modulation in Bladder Cancer and Their Correlations With Immune Infiltration and Molecular Subtypes

Bladder cancer (BLCA) represents the ninth most common malignant tumor in the world and is characterized by high recurrence risk. Tumor microenvironment (TME) plays an important role in regulating the progression of BLCA. Immunotherapy, including Bacillus Calmette-Guerin (BCG) and programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1), is closely associated with TME and is widely used for treating BLCA. But parts of BLCA patients have no response to these treatment ways, thus a better understanding of the complex TME of BLCA is still needed. We downloaded the gene expression profile and corresponding clinical information of 414 BLCA patients from the TCGA database. Via the ESTIMATE and CIBERSORT algorithm, we identified the two hub genes (CXCL12 and CD3E) and explored their correlations with immune infiltration. We found that BLCA patients with higher expression of CXCL12 and lower expression of CD3E had prolonged survival. Gene set enrichment analysis (GSEA) revealed that both CXCL12 and CD3E were enriched in immune-related pathways. We also discovered that stromal score and the level of CXCL12 were higher in luminal subtype, and immune score and the level of CD3E were higher in the basal subtype. Furtherly, we found that CXCL12 was associated with naive B cells, resting mast cell, M2 macrophages, follicular helper T cells, and dendritic cells. CD8⁺ T cells, CD4⁺ T cells, regulatory T cells (Tregs), and macrophages were correlated with CD3E. In conclusions, we found that CXCL12 and CD3E might serve as indicators of TME modulation in BLCA. Therapy targeting CXCL12 and CD3E had the potential as novel therapeutic strategy.

Overcoming Challenges for CD3-Bispecific Antibody Therapy in Solid Tumors

Immunotherapy of cancer with CD3-bispecific antibodies is an approved therapeutic option for some hematological malignancies and is under clinical investigation for solid cancers. However, the treatment of solid tumors faces more pronounced hurdles, such as increased on-target off-tumor toxicities, sparse T-cell infiltration and impaired T-cell quality due to the presence of an immunosuppressive tumor microenvironment, which affect the safety and limit efficacy of CD3-bispecific antibody therapy. In this review, we provide a brief status update of the CD3-bispecific antibody therapy field and identify intrinsic hurdles in solid cancers. Furthermore, we describe potential combinatorial approaches to overcome these challenges in order to generate selective and more effective responses.

B7-H3 Immune Checkpoint Protein in Human Cancer

B7-H3 belongs to the B7 family of immune checkpoint proteins, which are important regulators of the adaptive immune response and emerging key players in human cancer. B7-H3 is a transmembrane protein expressed on the surface of tumor cells, antigen presenting cells, natural killer cells, tumor endothelial cells, but can also be present in intra- and extracellular vesicles. Additionally, B7-H3 may be present as a circulating soluble isoform in serum and other body fluids. B7-H3 is overexpressed in a variety of tumor types, in correlation with poor prognosis. B7-H3 is a promising new immunotherapy target for anti-cancer immune response, as well as a potential biomarker. Besides its immunoregulatory role, B7-H3 has intrinsic pro-tumorigenic activities related to enhanced cell proliferation, migration, invasion, angiogenesis, metastatic capacity and anti-cancer drug resistance. B7-H3 has also been found to regulate key metabolic enzymes, promoting the high glycolytic capacity of cancer cells. B7-H3 receptors are still not identified, and little is known about the molecular mechanisms underlying B7-H3 functions. Here, we review the current knowledge on the involvement of B7-H3 in human cancer.

B7-H3 Induces Ovarian Cancer Drugs Resistance Through An PI3K/AKT/BCL-2 Signaling Pathway

Purpose

This study was aimed to investigate the underlying mechanism of B7-H3 induced ovarian cancer proliferation and drugs resistance.

Materials and methods

We compared the expression of B7-H3 in ovarian tumor tissues from high-malignant or low-malignant patients by immunohistochemistry. We established B7-H3 overexpression and knockout ovarian cells by CRISPR-Cas9 technology and examined the expression of the PI3K/AKT/BCL-2 signals in tumor cells by Western blot or immunofluorescence. We detected the B7-H3 overexpression ovarian cancer cells drugs resistance by CCK8 cell proliferation analysis and Annexin V/PI staining. Tumor-bearing mice were used to investigate the anticancer effects of PI3K/AKT inhibitors in combination with B7-H3 neutralizing antibodies.

Results

Enhanced expression of B7-H3 was observed in ovarian tumor tissues from high-malignant patients compared to those from low-malignant patients. Notably, B7-H3 overexpression caused enhanced cells proliferation and chemo-resistance in vitro and in vivo through the activation of PI3K/AKT signaling pathways and up-regulation of BCL-2 protein. Combination of chemotherapeutic agents and B7-H3 neutralizing antibodies efficiently reverses the drugs resistance induced by B7-H3, resulting in improved anticancer effects in ovarian cancer.

Conclusion

B7-H3 expression induces the activation the PI3K/AKT signaling pathway and up-regulates BCL-2 in protein level, resulting in the sustained growth and chemo-resistance in ovarian cancer. Blockade of B7-H3 signals efficiently reverses the chemo-resistance, which provides an innovative target in ovarian cancer treatment.

T cell cytotoxicity toward hematologic malignancy via B7-H3 targeting

T cells are important effectors in anti-tumor immunity, and aberrant expression of B7 family members may contribute to tumor evasion. In this study, we analyzed expression of costimulatory molecules on human hematologic tumor cells and explored whether B7-H3, a member of the B7 superfamily, is an effective target for T cell mediated cytotoxicity toward hematologic malignancy. We investigated the bispecific antibody anti-CD3 × anti-B7-H3 (B7-H3Bi-Ab) for its ability to redirect T cells to target B7-H3 positive hematologic tumors, including Thp-1, K562, Daudi cells and a primary culture. The capacity of T cells armed with B7-H3Bi-Ab to kill hematologic tumors was evaluated by lactate dehydrogenase assay, flow cytometry, ELISA, and luciferase quantitative assay at an effector/target ratio of 5:1. Compared with unarmed T cells, B7-H3Bi-Ab-armed T cells exhibited significant cytotoxicity toward hematological tumor cells. Moreover, B7-H3Bi-Ab-armed T cells secreted more IFN-γ, TNF-α, IL-2, and Granzyme B and expressed higher levels of activating marker CD69 compared to unarmed T cells. In conclusion, B7-H3Bi-Ab enhances the ability of T cells to kill hematologic tumor cells, and B7-H3 may serve as a novel target for immunotherapy against hematologic malignancy.

Targeting immunotherapy for bladder cancer using anti-CD3× B7-H3 bispecific antibody

OBJECTIVE

B7-H3 is attractive for cancer immunotherapy with B7-H3 overexpressed tumors. To explore whether B7-H3 is an effective target for patients with bladder cancer, anti-CD3× anti-B7-H3 bispecific antibodies (B7-H3Bi-Ab) was armed with activated T cells (ATC) to kill bladder cancer cells.

METHODS

High expressions of B7-H3 on human bladder cancer cells were detected, including Pumc-91 and T24 cells, and their chemotherapeutic drug-resistant counterparts. ATC generated from healthy donors were stimulated with anti-CD3 monoclonal antibody and interleukin-2 (IL-2) for 13 days. The ability of ATC armed with B7-H3Bi-Ab to kill bladder cancer cells was detected by flow cytometry, LDH, Elisa, and luciferase quantitative assay. Moreover, ATC generated from bladder cancer patients was armed with B7-H3Bi-Ab to verity the cell killing by the methods as previously described.

RESULTS

Compared with unarmed ATC, a significant increased cytotoxicity of B7-H3Bi-Ab-armed ATC against bladder cancer cells was discovered. The B7-H3Bi-Ab-armed ATC secreted more IFN-γ, TNF-α, and expressed high levels of activation marker CD69. Interestingly, despite the presence of immunosuppression in patients and resistance in chemotherapeutic drug-resistant cancer cell lines, B7-H3Bi-Ab-armed ATC from patients with bladder cancer still showed significant cytotoxic activity against bladder cancer cells and their chemotherapeutic drug-resistant counterparts.

CONCLUSION

B7-H3 is an effective target for bladder cancer. B7-H3Bi-Ab enhances the ability of ATC to kill bladder cancer cells. B7-H3Bi-Ab-armed ATC is promisingly to provide a novel strategy for current bladder cancer therapy.