Background: Renal cancer is one of the most common malignancies. However, the mechanisms underlying its development are still ambiguous. B7-H3 has been described as an important tumor antigen in various human tumors. An abnormal high expression of B7-H3 molecules is often observed in tumor cells and tumor stromal cells in the tumor microenvironment. On the basis of the above findings, we hypothesized that cancer-associated fibroblasts (CAFs) clustered in the renal cell microenvironment can survive for a long time with the anti-apoptotic effect of B7-H3, and then secrete cytokines to enhance the malignant behavior of renal cancer cells. Methods: The expression of B7-H3 protein in CAFs was detected in renal cancer tissues. Then, the CAFs cells were stably transfected with shRNA and their expression was silenced to determine the role of B7-H3 in CAFs. Western blot was used to detect the expression of apoptosis-related proteins, hepatocyte growth factor (HGF) protein and stromal cell-derived factor-1 (CXCL12) protein. CAF-NC cells and CAFs-shRNA cells were co-cultured with A498 cells to assess the biological function changes of A498. Results: A group of CAFs were found with B7-H3 expression in renal cancer. B7-H3 can stimulate CAFs to secrete HGF and Cxcl-12, and has strong anti-apoptotic effect on CAFs. We also found that CAFs-NC promotes the proliferation, invasion and migration of A498 cells in vitro and promotes the tumor formation of A498 in vivo. Conclusion: B7-H3⁺ CAFs promote the invasion and metastasis in renal cancer.

Background: B7-H3, an immune-checkpoint molecule and a transmembrane protein, is overexpressed in non-small cell lung cancer (NSCLC), making it an attractive therapeutic target. Here, we aimed to systematically evaluate the value of B7-H3 as a target in NSCLC via T cells expressing B7-H3-specific chimeric antigen receptors (CARs) and bispecific killer cell engager (BiKE)-redirected natural killer (NK) cells.

Methods: We generated B7-H3 CAR and B7-H3/CD16 BiKE derived from an anti-B7-H3 antibody omburtamab that has been shown to preferentially bind tumor tissues and has been safely used in humans in early-phase clinical trials. Antitumor efficacy and induced-immune response of CAR and BiKE were evaluated in vitro and in vivo. The effects of B7-H3 on aerobic glycolysis in NSCLC cells were further investigated.

Results: B7-H3 CAR-T cells effectively inhibited NSCLC tumorigenesis in vitro and in vivo. B7-H3 redirection promoted highly specific T-cell infiltration into tumors. Additionally, NK cell activity could be specially triggered by B7-H3/CD16 BiKE through direct CD16 signaling, resulting in significant increase in NK cell activation and target cell death. BiKE improved antitumor efficacy mediated by NK cells in vitro and in vivo, regardless of the cell surface target antigen density on tumor tissues. Furthermore, we found that anti-B7-H3 blockade might alter tumor glucose metabolism via the reactive oxygen species-mediated pathway.

Conclusions: Together, our results suggest that B7-H3 may serve as a target for NSCLC therapy and support the further development of two therapeutic agents in the preclinical and clinical studies.

Keywords: B7-H3; BiKE; Bispecific antibody; CAR T; Chimeric antigen receptor; Non-small cell lung cancer; PD-L1.

Gastric cancer remains the second leading cause of cancer-related deaths worldwide. Adjuvant therapy has been shown to improve survival and is delivered either postoperatively (chemoradiotherapy) or perioperatively (chemotherapy) in Western countries. Debate continues regarding which of these approaches is an optimal strategy. Radioresistance in gastric cancer cells remains a serious concern. B7 homologue 3 (B7-H3, CD276), a newly found member of B7 immunoregulatory family, was found to be expressed in aberrant gastric cancer cells, and played a direct role in gastric cancer progression systems in a previous study. With upregulation or downregulation of B7-H3, it was observed that B7-H3 could increase radiotherapy resistance of gastric cancer cells by modulating apoptosis, cell cycle progression, and DNA double-strand breaks. Furthermore, it was found that B7-H3 could regulate baseline levels of cell autophagy. B7-H3 expression was negatively correlated with LC3-B expression in gastric cancer tissues. It was found that increasing baseline levels of cell autophagy with rapamycin in B7-H3-overexpressing cells could improve their sensitivity to radiation. This protein also exerted its function by modulating apoptosis and DNA double-strand breaks. Overall, it is demonstrated that B7-H3 increases the radiotherapy resistance of gastric cancer cells through regulating baseline levels of cell autophagy.

Objectives: B7 family members were identified as co-stimulators or co-inhibitors of the immune response and played important roles in cancer immunotherapy; however, their dysregulation in gastric cancer is still unclear. Methods: Data were obtained from TCGA and GTEX database. B7 mutations, association with DNA methylation and affected proteins were analyzed in cBioportal. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis and Gene Ontology (GO) project was studied by DAVID to find the downstream signaling pathway and important metabolic process, respectively. Protein-protein interaction network was analyzed in STRING and Cytoscape. A total of 160 paired specimens in tissue microarray from patients with gastric cancer were used to detect the expression levels of seven B7 family members via immunohistochemical analysis. Results: Bioinformatics studies revealed dysregulation of B7 members in gastric cancer. Gene and protein alteration were found in B7 family members. Furthermore, DNA methylation and gene alteration may be both involved in B7 member dysregulation in gastric cancer. Importantly, the high expression of B7-H6 is associated with good overall patient survival. B7 family members primarily affect the EGFR tyrosine kinase inhibitor resistance signaling pathway in gastric cancer and TP53 may be an important target of the family. The low expression of B7-1 and high expression of B7-H3 and B7-H7 were validated by IHC staining. Conclusions: Our results provide insight into B7 family member expression in gastric cancer and stress their importance in stomach tumorigenesis, which may be beneficial for designing future cancer treatments.

Prostate cancer is the most frequent malignancy in the worldwide male population; it is also one of the most common among all the leading cancer-related death causes. In the last two decades, the therapeutic scenario of metastatic castration-resistant prostate cancer has been enriched by the use of chemotherapy and androgen receptor signaling inhibitors (ARSI) and, more recently, by immunotherapy and poly(ADP-ribose) polymerase (PARP) inhibitors. At the same time, several trials have shown the survival benefits related to the administration of novel ARSIs among patients with non-castration-resistant metastatic disease along with nonmetastatic castration-resistant cancer too. Consequently, the therapeutic course of this malignancy has been radically expanded, ensuring survival benefits never seen before. Among the more recently emerging agents, the so-called "antibody-drug conjugates" (ADCs) are noteworthy because of their clinical practice changing outcomes obtained in the management of other malignancies (including breast cancer). The ADCs are novel compounds consisting of cytotoxic agents (also known as the payload) linked to specific antibodies able to recognize antigens expressed over cancer cells' surfaces. As for prostate cancer, researchers are focusing on STEAP1, TROP2, PSMA, CD46 and B7-H3 as optimal antigens which may be targeted by ADCs. In this paper, we review the pivotal trials that have currently changed the therapeutic approach to prostate cancer, both in the nonmetastatic castration-resistant and metastatic settings. Therefore, we focus on recently published and ongoing trials designed to investigate the clinical activity of ADCs against prostate malignancy, characterizing these agents. Lastly, we briefly discuss some ADCs-related issues with corresponding strategies to overwhelm them, along with future perspectives for these promising novel compounds.

Keywords: B7-H3; CD46; PSMA; STEAP1; TROP2; antibody drug conjugates; prostate cancer; target therapy.

Medulloblastoma (MB) is the most common embryonal neuroepithelial tumor, with poor patient outcomes and secondary complications. In this study, we investigated the role of the B7 family of immune checkpoint homolog 3 (B7-H3) expression in MB angiogenesis. B7-H3, a co-inhibitory immune checkpoint, is highly expressed and is associated with lower overall survival in MYC⁺ MB's. Evidence for a direct transcriptional role of MYC on the B7-H3 gene promoter was confirmed by MYC inhibition and anti-MYC antibody ChIP analysis. Interestingly, MYC inhibition not only downregulated the B7-H3 protein expression, but also rescued miR-29 expression, thus indicating a triangular regulatory relationship between MYC, miR-29, and B7-H3 in Group 3 MB cells. From RNA seq and IPAD assay, we observed a negative feedback loop between miR-29 and MYC that may control B7-H3 expression levels in MB cells. Our studies show that B7-H3 expression levels play a crucial role in promoting MB angiogenesis which can be inhibited by miR-29 overexpression via miR-29-mediated B7-H3 downregulation. The tumor suppressor role of miR-29 is mediated by the activation of JAK/STAT1 signaling that further plays a role in MYC-B7-H3 downregulation in MB. This study highlights B7-H3 as a viable target in MB angiogenesis, and that the expression of miR-29 can inhibit B7-H3 and sensitize MB cells to treatment with MYC-inhibiting drugs.

B7-H3 is a transmembrane protein widely expressed in a variety of cancers and has been shown to play a role in anti-tumor immunity. This study aims to develop a molecular imaging probe to identify B7-H3 expression in tumors and to develop 89Zr-DS-5573a as a theranostic that could aid patient selection in clinical Phase I studies. Methods: The anti-B7-H3 humanised monoclonal antibody DS-5573a was labeled with zirconium-89 (89Zr-), and assessed for radiochemical purity, immunoreactivity (Lindmo analysis), antigen binding affinity (Scatchard analysis), and serum stability in vitro. In vivo biodistribution and imaging studies were performed with positron emission tomography and magnetic resonance imaging (PET/MRI) studies to identify and quantitate 89Zr-DS-5573a tumor uptake in a B7-H3-positive breast cancer model (MDA-MB-231) and a B7-H3-negative murine colon cancer model (CT26). Imaging and biodistribution studies were also performed in MDA-MB-231 tumor-bearing SCID mice in the absence and presence of therapeutic DS-5573a antibody dose (3 mg/kg DS-5573a). Results:89Zr-DS-5573a showed high and specific binding to B7-H3-expressing MDA-MB-231 cells (immunoreactivity on day 0, 75.0 ± 2.9%), and low binding to B7-H3-negative CT26 cells (immunoreactivity on day 0, 10.85 ± 0.11%) in vitro. 89Zr-DS-5573a demonstrated good serum stability in vitro with 57.2 ± 2.0% of immunoreactivity remaining on day 7. In vivo biodistribution studies showed high uptake of 89Zr-DS-5573a in B7-H3-expressing MDA-MB-231 tumor-bearing mice, achieving 32.32 ± 6.55 %ID/g on day 7 post injection in BALB/c nu/nu mice and 25.76 ± 1.79 %ID/g in SCID mice, with minimal evidence of non-specific uptake in normal tissues, and excellent tumor localization on PET/MRI. In a combined imaging/therapy study, receptor saturation was demonstrated in tumors responding to therapy. Conclusion:89Zr-DS-5573a demonstrates specific and prolonged targeting of B7-H3-expressing tumors in vivo. Saturation of binding sites was demonstrated in tumors responding to DS-5573a therapy. These results indicate that 89Zr-DS-5573a has potential to target B7-H3-expressing tumors in cancer patients. Furthermore 89Zr-DS-5573a has the potential to provide important insights into T cell biology through its specific binding to B7-H3.

Osteosarcomas are aggressive bone tumors for which therapeutic advances have not improved over several decades. Unlike most pediatric tumors, the osteosarcoma genome is remarkably unstable, characterized by numerous copy number alterations and chromosomal structural aberrations. In this study, we asked if the targetable immune checkpoints CD274 (PD-L1), PDCD1LG2 (PD-L2), CD276 (B7-H3) and IDO1 are impacted by copy number alterations in osteosarcoma. Of the 215 osteosarcoma samples investigated, PD-L1/PD-L2, B7-H3 and IDO1 were independently gained at frequencies of approximately 8-9%, with a cumulative frequency of approximately 24%. RNA sequencing data from two independent cohorts revealed that B7-H3 is the most highly expressed immune checkpoint gene among the four investigated. We also show that IDO1 is preferentially expressed in pediatric solid tumors and that increased protein expression of B7-H3 and IDO1 are significantly associated with inferior survival in patient samples. Using human osteosarcoma cell lines, we demonstrate that IDO1 is gained in MG63 and G292 cells and that the IDO1 inhibitor, epacadostat, inhibits the enzymatic activity of IDO1 in a dose-dependent manner in these cells. Together, these data reveal the genomic and transcriptomic profiles of PD-L1, PD-L2, B7-H3 and IDO1 in osteosarcoma and identifies a potential context for targeted immunotherapeutic intervention in a subset of patients.

Fibrolamellar carcinoma (FLC) is a rare type of liver cancer that affects adolescents and young adults. The most effective treatment for FLC is surgical resection, but no standardized systemic therapy exists for patients with recurrent or unresectable FLC. As a first step to understand the immune microenvironment of FLC, we investigated targetable immune-checkpoint pathways, PD-1, PD-L1, B7-H3, IDO-1, and LAG3, in relation to CD8⁺ cytotoxic T-lymphocyte density. Thirty-two FLC tumor specimens were analyzed using IHC staining for PD-L1, CD8, PD-1, IDO, LAG3, and B7-H3. Sixty-three percent of FLC cases demonstrated membranous PD-L1 expression on tumor cells, and almost 70% of cases demonstrated PD-L1⁺ tumor-infiltrating lymphocytes and tumor-associated macrophages (TIL/TAM). Myeloid-derived cells appeared to be a major component of PD-L1⁺ tumor-infiltrating immune cells. Forty percent of the cases showed B7-H3 expression in the tumor zone, with 91% cases showing B7-H3 expression in TILs and TAMs. IDO and PD-1 expression was highest in the tumor interface zone. B7-H3 or IDO expression on tumor cells significantly correlated with higher CD8⁺ T-cell density. In conclusion, a high proportion of FLC cases showed robust expression of PD-1, PD-L1, B7-H3, and IDO in an adaptive immune-resistance pattern. Our findings provide further basis for targeting these different immune-checkpoint axes in FLC.

Over the last decade, a new understanding of tumor-immune system interplay has been ushered in, lead in large part by the discovery of immune checkpoints mediated through B7-CD28 family interactions. Therapeutic blockade of the PD-L1 immune checkpoint pathway has already shown great success as a cancer immunotherapy for advanced urothelial carcinoma, leading to durable clinical remissions in an otherwise incurable disease. There are newly described members of the B7-CD28 family including B7-H3, B7x, and HHLA2. These ligands are thought to play an essential role in suppressing T-cell response, leading to immune tolerance of tumors. This feature makes them attractive targets for novel immunotherapy treatment paradigms. Here, we review the literature of current strategies and future directions of immune checkpoint blockade therapy for bladder cancer.

Human endogenous retrovirus-H long terminal repeat-associating protein 2 (HHLA2) and transmembrane and immunoglobulin domain containing 2 (TMIGD2) are new immune checkpoint molecules of the B7:CD28 family; however, little research has been performed on these immune checkpoint molecules. In this study, we used oral squamous cells carcinoma (OSCC) tissue microarrays and immunohistochemistry methods to investigate the expression patterns of HHLA2 and TMIGD2 in OSCC. After comparing the HHLA2 and TMIGD2 expression levels in OSCC, dysplasia, and mucosa, we found increased HHLA2 expression in OSCC and dysplasia, while the TMIGD2 expression was decreased in OSCC and dysplasia. Using the Kaplan-Meier method and log-rank test, we found that higher HHLA2 or TMIGD2 expression levels in OSCC indicate poor prognosis. Furthermore, two-tailed Pearson's statistical analysis revealed that the HHLA2 expression levels in OSCC, dysplasia, and mucosa were positively correlated with the T cell immunoglobulin and mucin-domain containing-3 (TIM3), lymphocyte-activation gene 3 (LAG3), B7 homolog 3 protein (B7-H3), B7 homolog 4 protein (B7H4), and V-domain Ig suppressor of T cell activation (VISTA) levels, while the TMIGD2 expression levels in OSCC, dysplasia, and mucosa were inversely correlated with the TIM3, LAG3, and B7H3 levels. Our current study demonstrates that HHLA2 may serve as an immune target for OSCC therapy and that the TMIGD2 expression level in OSCC could forecast patient prognosis.

Glioblastoma multiforme (GBM) is the most common and aggressive malignant primary brain tumor in adults. Current treatment options typically consist of surgery followed by chemotherapy or more frequently radiotherapy, however, median patient survival remains at just over 1 year. Therefore, the need for novel curative therapies for GBM is vital. Characterization of GBM cells has contributed to identify several molecules as targets for immunotherapy-based treatments such as EGFR/EGFRvIII, IL13Rα2, B7-H3, and CSPG4. Cytotoxic T lymphocytes collected from a patient can be genetically modified to express a chimeric antigen receptor (CAR) specific for an identified tumor antigen (TA). These CAR T cells can then be re-administered to the patient to identify and eliminate cancer cells. The impressive clinical responses to TA-specific CAR T cell-based therapies in patients with hematological malignancies have generated a lot of interest in the application of this strategy with solid tumors including GBM. Several clinical trials are evaluating TA-specific CAR T cells to treat GBM. Unfortunately, the efficacy of CAR T cells against solid tumors has been limited due to several factors. These include the immunosuppressive tumor microenvironment, inadequate trafficking and infiltration of CAR T cells and their lack of persistence and activity. In particular, GBM has specific limitations to overcome including acquired resistance to therapy, limited diffusion across the blood brain barrier and risks of central nervous system toxicity. Here we review current CAR T cell-based approaches for the treatment of GBM and summarize the mechanisms being explored in pre-clinical, as well as clinical studies to improve their anti-tumor activity.

Keywords: CAR T cell; clinical trial; glioblastoma; immunotherapy; preclinical; tumor antigen.

The aim of the present study was to investigate the role of immune regulatory molecules B7-H3 [also known as cluster of differentiation 276] and triggering receptor expressed on myeloid cell-like transcript-2 (TLT-2) in patients with oral squamous cell carcinoma (OSCC). Human OSCC samples were obtained from 76 patients (female, 32; male, 44; age range, 23-81 years; median age, 50.9 years) that underwent resection for OSCC at Peking University Shenzhen Hospital (Shenzhen, China) between 2007 and 2010. In addition, control oral mucosal samples were obtained from 76 healthy individuals (female, 36; male, 40; age range, 21-62 years; median age, 45.3 years) during wisdom tooth extraction. Protein and gene expression levels of B7-H3 and TLT-2 were determined by immunohistochemical analysis and reverse transcription-polymerase chain reaction (RT-PCR). In the healthy oral mucosa samples, B7-H3 expression was identified to be weak, while the expression of TLT-2 was only detected sporadically in the cell membrane and cytoplasm. By contrast, the two regulatory molecules were widely expressed in the aforementioned localizations in human OSCC specimens upon immunohistochemical examination. Furthermore, quantitative RT-PCR confirmed the presence of significantly higher B7-H3 and TLT-2 expression levels in OSCC specimens compared with the oral mucosa of healthy individuals. The significantly higher expression levels of B7-H3 and TLT-2 in human OSCC specimens may indicate an inhibitory role of these molecules in the antitumoral immune response. To investigate interactions between these two molecules and individual antitumoral immune response in OSCC patients, prospective clinical studies with an adequate sample size are required.

BACKGROUND

Recent studies have shown that B7-H3, a recently identified B7 family member, plays a critical role in the development of asthma.

OBJECTIVE

This study is to explore the expression of B7-H3 in children with asthma exacerbation.

METHODS

Twenty-one Chinese children with asthma exacerbation as well as 18 nonasthmatic control Chinese children were enrolled. B7-H3 level and cytokines (interferon [IFN]-γ, interleukin [IL]-4, and IL-10) determination were performed by enzyme-linked immunosorbent assay (ELISA) technique. Meanwhile, clinical parameters including laboratory findings, forced expiratory volume in one second (FEV(1)) and fractional exhaled nitric oxide were obtained.

RESULTS

Children with asthma exacerbation had significantly higher levels of B7-H3 than controls (4.46 ± 1.33 versus 3.42 ± 1.48 ng/mL; p = 0.027). Plasma IL-4 level was significantly higher in asthma exacerbation subjects than controls (157.98 ± 21.57 versus 121.92 ± 24.37 pg/mL; p < 0.0001), and IFN-γ level was significantly lower in asthma exacerbation subjects (292.73 ± 152.47 versus 421.78 ± 145.84 pg/mL; p = 0.0107). Level of B7-H3 in asthma exacerbation subjects with inhaled corticosteroid (ICS) treatment recently was significantly lower than subjects without ICS treatment (t = 2.706; p = 0.0136). Additionally, levels of B7-H3 decreased remarkably after prednisone treatment. Level of sB7-H3 in asthma exacerbation subjects was inversely correlated with level of IFN-γ (r(p) = -0.605; p = 0.005) after adjustment.

CONCLUSIONS

B7-H3 may play an important role in asthma exacerbation and was a useful clinical biomarker to evaluate asthma exacerbation.

Stem/Progenitor cells in the postnatal pituitary gland are embedded in a marginal cell layer around Rathke's pouch. However, the nature and behavior of anterior pituitary progenitor cells remain unclear. We established bovine anterior pituitary progenitor cell line (BAPC)-1 from the anterior pituitary gland, which expressed stem/progenitor cell-related genes and several inflammatory cytokines. To characterize and localize these pituitary progenitor cells, we produced a mAb (12B mAb) against BAPC-1. The 12B mAb recognized the 4Ig-B7-H3 molecule, which is a costimulatory molecule and negative regulator in T cell activation. WC1(+) gammadelta T cells in young bovine PBMC express the 4Ig-B7-H3 molecule, but few or no 4Ig-B7-H3-immunoreactive cells are expressed in PBMC in adult cattle. The 12B-immunoreactive cells in the bovine anterior pituitary gland were localized around Rathke's pouch and expressed IL-18 and MHC class II. However, the number of 12B-immunoreactive cells was lower in adult than in young cattle. BAPC-1 expressed IL-18 and MHC class II, and demonstrated phagocytotic activity. BAPC-1 also had the ability to promote CD25 expression in PBMC after 5 days of coculture, and blocking 4Ig-B7-H3 x 12B mAb enhanced their expression of CD25. In addition, the 12B-immunoreactive cells were observed around the pars tuberalis closely bordering the median eminence and in the blood vessels of the primary portal plexus in the anterior pituitary gland. These results suggest that an established BAPC-1 may originate from these progenitor cells, and that the progenitor cells with 4Ig-B7-H3 may play a critical role in the immunoendocrine network.

UNASSIGNED

The aims of this study were to investigate the relationship between Golgi phosphoprotein 2 (GOLPH2) and oral squamous cell carcinoma (OSCC) and explore the clinical significance of GOLPH2 in OSCC.

UNASSIGNED

Tissue microarrays from human OSCC samples were stained for GOLPH2 expression and clinicopathologic features. Kaplan-Meier analysis was used to compare the survival of patients with high GOLPH2 expression and patients with low GOLPH2 expression.

UNASSIGNED

We found GOLPH2 is highly expressed in OSCC tissue, and the GOLPH2 expression in metastatic lymph nodes is higher than in tumor tissue. Our data indicate that patients with higher GOLPH2 expression have poor overall survival compared with those with lower GOLPH2 expression. This study demonstrated that GOLPH2 was associated with CD44, SOX2, Slug, B7-H3, B7-H4, TIM3, and VISTA.

UNASSIGNED

These findings suggest GOLPH2 is a potential marker for estimating the patient's prognosis and may be a target for molecular-targeted therapy against OSCC.

Both membrane-bound and soluble forms of costimulatory molecules play important roles in immune-regulatory networks. B7-H3, a member of the B7 family, has been found with aberrant expression in tumors and infectious disease. However, the significance of sB7-H3 expression in systemic lupus erythematosus (SLE) has not been investigated. Using the peripheral blood of 78 SLE patients, we established a comprehensive database containing clinical data and relevant laboratory tests. We found that sB7-H3 expression in SLE patients was significantly lower compared with the healthy individuals. In addition, sB7-H3 levels in the patients were positively correlated with the disease activity as indicated by SLE disease activity index score, rashes, fever, and inflammatory cytokines. Moreover, sB7-H3 was associated with the counts of red blood cells and hemoglobin. Our findings suggest that sB7-H3 might counteract the aberrant immune response and potentially serve as a monitoring indicator of disease progression and therapeutic target in SLE treatment.

BACKGROUND

We recently validated monoclonal antibody (mAb) 376.96 as an effective carrier for targeted α-particle radioimmunotherapy (RIT) with 212Pb in ovarian cancer mouse models. In this study, we tested the binding of radiolabeled mAb 376.96 to human pancreatic ductal adenocarcinoma (PDAC) cells and localization in xenografts in immune-deficient mice and evaluated 212Pb-labeled 376.96 (212Pb-376.96) for PDAC therapy.

METHODS

In vitro Scatchard assays assessed the specific binding of 212Pb-376.96 to human PDAC3 adherent differentiated cells and non-adherent cancer initiating cells (CICs) dissociated from tumorspheres. In vitro clonogenic assays were used to measure the proliferation of adherent PDAC3 cells and CIC-enriched tumorspheres treated with 212Pb-376.96 or the irrelevant isotype-matched 212Pb-F3-C25. Mice bearing patient derived pancreatic cancer Panc039 xenografts were i.v. injected with 0.17-0.70 MBq 212Pb-376.96 or isotype control 212Pb-F3-C25, and used for biodistribution and tumor growth inhibition studies. Mice bearing orthotopic PDAC3 xenografts were i.v. co-injected with 99mTc-376.96 and 125I-F3-C25 and used for biodistribution studies.

RESULTS

212Pb-376.96 specifically bound to PDAC3 adherent and dissociated tumorsphere CICs; Kd values averaged 9.0 and 21.7 nM, respectively, with 104-105 binding sites/cell. 212Pb-376.96 inhibited the clonogenic survival of PDAC3 cells or CICs dissociated from tumorspheres 3-6 times more effectively than isotype-matched control 212Pb-F3-C25. Panc039 s.c. tumors showed significantly higher uptake of 212Pb-376.96 (14.0 ± 2.1% ID/g) compared to 212Pb-F3-C25 (6.5 ± 0.9% ID/g, p < .001) at 24 h after dosing. Orthotopic PDAC3 tumors showed significantly higher uptake of 99mTc-376.96 (6.4 ± 1.8% ID/g) compared to 125I-F3-C25 (3.9 ± 0.9% ID/g, p < .05) at 24 h after dosing. Panc039 tumor growth was significantly inhibited by 212Pb-376.96 compared to 212Pb-F3-C25 or non-treated control tumors (p < .05).

CONCLUSIONS

Our results provide evidence for the efficacy of B7-H3 targeted RIT against preclinical models of pancreatic ductal adenocarcinoma (PDAC) and support future studies with 212Pb-376.96 in combination with chemotherapy to potentiate efficacy against PDAC.

Reliable predictors of benefit from immune checkpoint inhibitors in non-small-cell lung cancer (NSCLC) are still limited. We aimed to evaluate the association between the expression of selected molecules involved in immune response and clinical outcomes in NSCLC patients receiving nivolumab. In our study, the outcomes of 46 NSCLC patients treated with nivolumab in second or subsequent lines (Nivolumab Cohort) were compared with the expression of PD-L1, PD-L2, PD-1, B7-H3, and B7-H4 assessed by immunohistochemistry (IHC). Samples from 17 patients (37.0%) in the Nivolumab Cohort were positive for B7-H4 expression. At univariate analyses, only B7-H4 expression was associated with significantly decreased progression-free survival (PFS; 1.7 vs. 2.0 months; p = 0.026) and with a disadvantage in terms of overall survival (OS) close to statistical significance (4.4 vs. 9.8 months; p = 0.064). At multivariate analyses, B7-H4 expression was significantly associated with decreased PFS (hazard ratio (HR) = 2.28; p = 0.021) and OS (HR = 2.38; p = 0.022). Subsequently, B7-H4 expression was compared with clinical outcomes of 27 NSCLC patients receiving platinum-based chemotherapy (Chemotherapy Cohort), but no significant association was observed. Our results suggest a negative predictive role of B7-H4 in a population of NSCLC treated with immune checkpoint inhibitors, which deserves further research.

Dysregulation of B7-H3 has been observed in a variety of types of human cancers. In the present study, the mRNA expression level of B7-H3 was analyzed in bladder cancer by performing semi-quantitative reverse transcription-polymerase chain reaction on clinical specimens from transitional cell carcinomas (TCCs) and their normal adjacent tissues (NATs). Immunohistochemical analysis was performed to compare the protein expression level of B7-H3 in TCCs and the paired NATs. The present study indicated that the B7-H3 mRNA expression level was significantly higher in the TCC samples compared with the paired NAT samples. Furthermore, immunohistochemical analyses indicated that the B7-H3 protein expression level was significantly upregulated in the TCC samples compared with in the paired NAT samples, indicating that B7-H3 dysregulation may be important in the progression of bladder cancer.

We explored the use of intraventricular ¹³¹I-Omburtamab targeting B7-H3 in patients with ETMR.

Patients were enrolled in an IRB approved, phase 1, 3 + 3 dose escalation trial. Patients with CNS disease expressing the antibody target antigen B7-H3 were eligible. We report on a cohort of three patients with ETMR who were enrolled on the study. Three symptomatic children (ages 14 months, 3 and 3.5 years) had large parietal masses confirmed to be B7-H3-reactive ETMR. Patients received 2 mCi ¹³¹I-Omburtamab as a tracer followed by one or two therapeutic ¹³¹I-Omburtamab injections. Dosimetry was based on serial CSF, blood samplings and region of interest (ROI) on nuclear scans. Brain and spine MRIs and CSF cytology were done at baseline, 5 weeks after ¹³¹I-Omburtamab, and approximately every 3 months thereafter. Acute toxicities and survival were noted.

Patients received surgery, focal radiation, and high dose chemotherapy. Patients 1 and 2 received ¹³¹I-Omburtamab (80 and 53 mCi, respectively). Patient 3 had a local recurrence prior to ¹³¹I-Omburtamab treated with surgery, external beam radiation, chemotherapy, then ¹³¹I-Omburtamab (36 mCi). ¹³¹I-Omburtamab was well-tolerated. Mean dose delivered by ¹³¹I-Omburtamab was 68.4 cGy/mCi to CSF and 1.95 cGy/mCi to blood. Mean ROI doses were 230.4 (ventricular) and 58.2 (spinal) cGy/mCi. Patients 1 and 2 remain in remission 6.8 years and 2.3 years after diagnosis, respectively; patient 3 died of progressive disease 7 months after therapy (2 years after diagnosis).

¹³¹I-Omburtamab appears safe with favorable dosimetry therapeutic index. When used as consolidation following surgery and chemoradiation therapy, ¹³¹I-Omburtamab may have therapeutic benefit for patients with ETMR.

B7 Homolog 3 (B7-H3), a newly identified member of the B7 family, is over-expressed in various human cancers and plays a vital role in tumor progression. To identify the expression pattern of B7-H3 in human salivary adenoid cystic carcinoma (AdCC) and its underlying mechanisms, we characterized B7-H3 expression in AdCC tissue microarrays using immunohistochemical staining, and analyzed potentially associated molecules. The results showed that B7-H3 was highly expressed in salivary AdCC, compared with normal salivary glands. Statistical analyses of immunohistochemical staining showed that B7-H3 was closely correlated with Slug and p-STAT3. Functional studies showed that knockdown of B7-H3 in AdCC cell lines using RNA interference did not influence cell growth and apoptosis, but decreased migration and invasion in vitro. Further mechanism studies suggested that B7-H3 influenced the migration and invasion of AdCC cells by regulating the epithelial-mesenchymal transition via JAK2/STAT3 pathway components. Collectively, these findings suggested that B7-H3 may be a potential therapeutic target for AdCC.