ErbB2 is a tumor associated antigen and a suitable therapeutic target in Wilms tumor

Trastuzumab Deruxtecan, Antibody-Drug Conjugate Targeting HER2, Is Effective in Pediatric Malignancies: A Report by the Pediatric Preclinical Testing Consortium

HER2 is expressed in many pediatric solid tumors and is a target for innovative immune therapies including CAR-T cells and antibody-drug conjugates (ADC). We evaluated the preclinical efficacy of trastuzumab deruxtecan (T-DXd, DS-8201a), a humanized monoclonal HER2-targeting antibody conjugated to a topoisomerase 1 inhibitor, DXd, in patient- and cell line-derived xenograft (PDX/CDX) models. HER2 mRNA expression was determined using RNA-seq and protein expression via IHC across multiple pediatric tumor PDX models. Osteosarcoma (OS), malignant rhabdoid tumor (MRT), and Wilms tumor (WT) models with varying HER2 expression were tested using 10 mice per group. Additional histologies such as Ewing sarcoma (EWS), rhabdomyosarcoma (RMS), neuroblastoma (NB), and brain tumors were evaluated using single mouse testing (SMT) experiments. T-DXd or vehicle control was administered intravenously to mice harboring established flank tumors at a dose of 5 mg/kg on day 1. Event-free survival (EFS) and objective response were compared between treatment and control groups. HER2 mRNA expression was observed across histologies, with the highest expression in WT (median = 22 FPKM), followed by MRT, OS, and EWS. The relationship between HER2 protein and mRNA expression was inconsistent. T-DXd significantly prolonged EFS in 6/7 OS, 2/2 MRT, and 3/3 WT PDX models. Complete response (CR) or maintained CR (MCR) were observed for 4/5 WT and MRT models, whereas stable disease was the best response among OS models. SMT experiments also demonstrated activity across multiple solid tumors. Clinical trials assessing the efficacy of a HER2-directed ADC in pediatric patients with HER2-expressing tumors should be considered.

Therapeutic Potential of T Cell Chimeric Antigen Receptors (CARs) in Cancer Treatment: Counteracting Off-Tumor Toxicities for Safe CAR T Cell Therapy

A chimeric antigen receptor (CAR) is a recombinant fusion protein combining an antibody-derived targeting fragment with signaling domains capable of activating T cells. Recent early-phase clinical trials have demonstrated the remarkable ability of CAR-modified T cells to eliminate B cell malignancies. This review describes the choice of target antigens and CAR manipulations to maximize antitumor specificity. Benefits and current limitations of CAR-modified T cells are discussed, with a special focus on the distribution of tumor antigens on normal tissues and the risk of on-target, off-tumor toxicities in the clinical setting. We present current methodologies for pre-evaluating these risks and review the strategies for counteracting potential off-tumor effects. Successful implementation of these approaches will improve the safety and efficacy of CAR T cell therapy and extend the range of cancer patients who may be treated.

Expression of TGF-β1 in Wilms' tumor was associated with invasiveness and disease progression

OBJECTIVE

To detect the expression of TGF-β1 in Wilms' tumor and association with disease progression.

METHODS

Immunohistochemistry was used to examine TGF-β1 expression in 51 primary tumors and 17 invasions/metastases. Transient transfection was performed to establish Wilms' tumor cells with high TGF-β1 expression (TGF-β1-WT), and the expression level of TGF-β1 was detected by Western blot analysis. Invasive capacity of the transfected cells was evaluated by transwell analysis.

RESULTS

The positive expression rate of TGF-β1 was 50.98% (26/51) and 82.35% (14/17) in primary WT tissues and associated invasive/metastatic tissues, respectively. The higher level of TGF-β1 expression in primary WT tumors was relative to invasion/metastasis (p = 0.048). The expression of TGF-β1 between primary WT and matched invasive/metastatic tissues was concordant (p = 0.219). TGF-β1-WT cells showed more invasive capacity than GFP-WT and WT cells. TGF-β1 expression status was associated with disease-free survival (DFS) (50.2 months vs. 75.4 months, p = 0.022) but not overall survival (OS) (62.3 months vs. 75.8 months, p = 0.141).

CONCLUSIONS

Positive expression of TGF-β1 in WT was correlated with tumor invasion and disease progression, which might be useful in identifying patients at high risk of unfavorable outcomes.

Establishment of a patient-derived Wilms' tumor xenograft model: a promising tool for individualized cancer therapy

OBJECTIVE

Lack of appropriate approaches that reliably predict response of Wilms' tumor (WT) to anticancer agents remains a major deficiency in clinical practice of individualized cancer therapy. The aim of this study was to establish a patient-derived tumor tissue (PDTT) xenograft model of WT for individualized chemotherapeutic regimen selection in accordance with the patient's tumor nature.

MATERIAL AND METHODS

Tumor specimens of a primary WT were orthotopically implanted into three nude mice, and after 4 weeks xenografts were harvested for serial heterotopic transplantation in 20 nude mice that were divided into three experimental groups and one control group. In vitro and in vivo chemosensitivity to doxorubicin, actinomycin-D, and vincristine were evaluated. Hematoxylin and eosin (H&E) staining and immunohistochemical examination with desmin, vimentin, myogenin, and neuron-specific enolase (NSE) were also applied to determine histological stability of the xenograft during serial transplantation compared with the original tumor tissue.

RESULTS

The xenograft model was successfully established. Histopathologic characteristics of the xenograft tumors were similar to the patient's tumor. Early passage of the PDTT showed a similar chemosensitivity pattern to the original tumor tissue.

CONCLUSIONS

PDTT xenograft of WT provides an appropriate model for individualized cancer therapeutic regimen selection by means of its biological stability compared with original patient's tumor.

β-Catenin and K-RAS synergize to form primitive renal epithelial tumors with features of epithelial Wilms' tumors

Wilms' tumor (WT) is the most common childhood renal cancer. Although mutations in known tumor-associated genes (WT1, WTX, and CATNB) occur only in a third of tumors, many tumors show evidence of activated β-catenin-dependent Wnt signaling, but the molecular mechanism by which this occurs is unknown. A key obstacle to understanding the pathogenesis of WT is the paucity of mouse models that recapitulate its features in humans. Herein, we describe a transgenic mouse model of primitive renal epithelial neoplasms that have high penetrance and mimic the epithelial component of human WT. Introduction of a stabilizing β-catenin mutation restricted to the kidney is sufficient to induce primitive renal epithelial tumors; however, when compounded with activation of K-RAS, the mice develop large, bilateral, metastatic, multifocal primitive renal epithelial tumors that have the histologic and staining characteristics of the epithelial component of human WT. These highly malignant tumors have increased activation of the phosphatidylinositol 3-kinase-AKT and extracellular signal-regulated kinase pathways, increased expression of total and nuclear β-catenin, and increased downstream targets of this pathway, such as c-Myc and survivin. Thus, we developed a novel mouse model in which activated K-RAS synergizes with canonical Wnt/β-catenin signaling to form metastatic primitive renal epithelial tumors that mimic the epithelial component of human WT.

Distribution of exogenous endothelial progenitor cells in a rat model of hepatoma and their impact on liver cancer formation

AIM: To investigate the role of endothelial progenitor cells (EPCs) in the formation of liver cancer and to explore the possibility of using EPCs as a delivery vehicle for the treatment of liver cancer.

METHODS: Isolated and cultured EPCs were labeled with DAPI in vitro. Sprague-Dawley rats were divided into three groups: control group, model group, and EPC group. The model group and EPC group were intraperitoneally injected with diethylnitrosamine (DEN) to induce liver cancer, while the control group was injected with saline. Rats of the EPC group were further divided into three subgroups and intravenously injected with 1 mL of low (1 × 10⁵/150 μL), medium (2 × 10⁵/150 μL), and high (4 × 10⁵/150 μL) concentrations of EPCs-DAPI suspension, respectively, while the control group and model group were injected with equal volume of saline. At weeks 4, 6 and 8, rats were killed to take liver tissue samples to detect the expression of EPCs markers CD34, CD133, and KDR, and serum samples to measure the levels of ALT, AST, and AFP. EPCs-DAPI-positive area (PA) was quantified using the Imagepro plus image analysis software.

RESULTS: Positive expression of cell surface markers CD34, CD133, and KDR could be detected on cultured cells after 7 days of culture. Serum ALT, AST, and AFP differed significantly between the low-concentration EPC group and model group at week 4, between the medium-concentration EPC group and model group at week 6, and between the high-concentration EPC group and model group at week 8 (all P < 0.01). Positive DAPI was detected in all the EPC groups, and the positive rate of DAPI was dependent on the concentration of injected EPCs and injection duration. PA was significantly different among rats injected with different concentrations of EPCs at all time points (all P < 0.05), but showed no significant differences among rats injected with the same concentration of EPCs at different time points (all P > 0.05).

CONCLUSION: EPCs affect liver function in the rat model of liver cancer in a concentration- and time-dependent manner. EPCs in the liver can promote the formation of liver cancer. EPCs have a tropism to liver cancer in vivo.

What can surrogate tissues tell us about the oxidative stress status of the prostate? A hypothesis-generating in-vivo study

BACKGROUND

Prostatic oxidative stress (OS) is androgen-regulated and a key event in the development of prostate cancer (PC). Thus, reducing prostatic OS is an attractive target for PC prevention strategies. We sought to determine if the individual's prostatic OS status can be determined by examining the OS in surrogate androgen regulated tissues from the same host.

METHODOLOGY/PRINCIPAL FINDINGS

Adult male rats were divided equally into three groups: (A-) underwent bilateral orchiectomy, (A+) received continuous testosterone supplementation or (C) were eugonadal. Serum testosterone, 8-hydroxy-2-deoxyguanosine (8-OHdG) and anti-oxidative capacity (AOC) were determined after 72 hrs and the prostate, salivary glands and the hair follicles' Dermal Papillary Cells (DPC) from each animal were harvested, embedded into tissue microarray and examined for the expression of 8-OHdG by immuno-staining. Multi-variate regression was used to analyze inter-individual differences in OS staining within each androgen group and if there was a correlation between serum testosterone, 8-OHdG or AOC and Prostatic OS in tissues of same host. At the group level, 8-OHdG staining intensity directly correlated with serum testosterone levels in all three target tissues (p>0.01, Mann-Whitney Test). Although different levels of prostatic OS were noted between rats with similar serum testosterone levels and similar systemic OS measurements (p<0.01), there were no intra-individual differences between the OS status of the prostate and DPC (p<0.05).

CONCLUSIONS/SIGNIFICANCE

The level of prostatic OS is correlated with the OS of hair follicles and salivary glands, but not systemic OS. Moreover, systemic AOC negatively correlates with both prostatic and hair follicle OS. This suggests that hair follicle and salivary gland OS can serve as surrogate markers for the efficiency of OS reduction. This has tremendous potential for the rational evaluation of patient response to prevention strategies.

Candidate genes and potential targets for therapeutics in Wilms' tumour

Wilms' tumour (WT) is the most common malignant renal tumour of childhood. During the past two decades or so, molecular studies carried out on biopsy specimens and tumour-derived cell lines have identified a multitude of chromosomal and epigenetic alterations in WT. In addition, a significant amount of evidence has been gathered to identify the genes and signalling pathways that play a defining role in its genesis, growth, survival and treatment responsiveness. As such, these molecules and mechanisms constitute potential targets for novel therapeutic strategies for refractory WT. In this report we aim to review some of the many candidate genes and intersecting pathways that underlie the complexities of WT biology.

Amplification and expression of EGFR and ERBB2 in Wilms tumor

Wilms tumor is one of the most common solid tumors in children. We evaluated expression and amplification of a number of genes and their prognostic significance in 45 patients with Wilms tumor, using tissue microarray technology. The expression of EGFR, ERBB2, MDM2, CCND1, MLH1, MSH2, TP53, and ABCB1 (alias MDR1) was studied by immunohistochemistry. Amplification of the EGFR, ERBB2, MDM2, CCND1, CTTN (previously EMS1), RAF1, MYC, FGF3 (previously INT2), WNT1, GLI1, CDK4, and NCOA3 (alias AIB1) genes was assessed by fluorescence in situ hybridization. Expression of EGFR was seen in 17 of the 45 cases (38%) but was not associated with gene amplification. The ERBB2 gene was neither overexpressed nor amplified in any case. Tissue microarray and immunohistochemistry analyses for ERBB2 in whole-tumor sections were also negative in all cases. Strong p53 reactivity was noted in blastemal cells in two cases with an unfavorable outcome. ABCB1 reactivity was seen in five cases with favorable histology and outcome. Only one case showed nuclear cyclin D1 positivity. All tumors showed MLH1 and MSH2 expression. All examined genes showed normal copy numbers. Unfavorable histology correlated with poor prognosis (P=0.03). There was no significant association between gene expression and prognosis. Overexpression of the EGFR gene in many Wilms tumor cases warrants further study to determine the therapeutic benefit of EGFR inhibitors in combination with other therapies in Wilms tumor patients.

Expression of multidrug resistance-related protein (MRP-1), lung resistance-related protein (LRP) and topoisomerase-II (TOPO-II) in Wilms' tumor: immunohistochemical study using TMA methodology

AIMS

MRP-1, LRP and TOPO-II are all associated with protection of the cells from the adverse effects of various chemotherapeutics. The aim of this study was to measure the expression of these proteins in Wilms' tumor (WT).

MATERIALS AND METHODS

TMA block was constructed from 14 samples of WT's and from xenografts derived from them. Sections of the TMA were used for immunostaining against MRP-1, LRP and TOPO-IIa.

RESULTS

All normal kidneys expressed MRP-1 but were either weakly or negatively stained for LRP and TOPO-IIa. In WT samples, MRP-1 was universally expressed, exclusively in the tubular component, while there was no expression of LRP and TOPO-IIa showed heterogeneous distribution. The xenografts varied in their MRP-1 and TOPO-IIa expression and exhibited weak/negative staining of LRP.

CONCLUSIONS

This study shows that although all the proteins evaluated, had different expression patterns in the tumor samples, the most prominent changes in expression were found for MRP-1. The exact clinical implications of these changes in expression and their relevance to the resistance of these tumors to chemotherapy requires further investigation. The finding of different expression profiles for the multidrug resistance proteins in the original WT's and their xenografts suggests that the results of animal cancer models may be difficult to interpret.

Expression of cyclooxygenase-2 in Wilms tumor: immunohistochemical study using tissue microarray methodology

PURPOSE

Cyclooxygenase-2, a key enzyme in prostaglandin biosynthesis, has been shown to be involved in the modulation of cell growth, inflammation and apoptosis. Its involvement in the development of several human neoplasms has also been documented as well as the significant antitumor effects of its inhibitors. To our knowledge cyclooxygenase-2 expression in Wilms tumor has not been studied.

MATERIALS AND METHODS

A tissue microarray multitissue block was prepared from 14 samples of Wilms tumor, each from a different patient, from xenografts derived thereof, and from normal human lung, liver, renal cortex and medulla tissues as controls. Each sample was represented in the block by 3 or 4 cores 0.6 mm in diameter. After serial slicing to 4 mum the histological slides were stained with hematoxylin and eosin, and immunostained with anti-cyclooxygenase-2 antibodies. Immunostaining was graded semiquantitatively according to the percent of stained cells with the cytoplasmic pattern of staining and according to staining intensity.

RESULTS

All authentic human pathological samples except 1 anaplastic Wilms tumor as well as Wilms tumor xenografts expressed cyclooxygenase-2 in all Wilms tumor cellular components except the stroma. Expression was also observed in Wilms tumor lung metastasis and in tumors that overgrew chemotherapy. In comparison, cyclooxygenase-2 expression in normal kidneys was less prominent than in Wilms tumor samples and it was confined to the tubular epithelium in the cortex and medulla.

CONCLUSIONS

Cyclooxygenase-2 expression is characteristic of all nonanaplastic Wilms tumors at all stages. It is similar to the previously observed pan-expression of ErbB2 receptors in these tumors. The potential therapeutic role of cyclooxygenase-2 inhibitors should be evaluated for Wilms tumor.

Multiple imprinted and stemness genes provide a link between normal and tumor progenitor cells of the developing human kidney

Wilms' tumor (WT), the embryonic kidney malignancy, is suggested to evolve from a progenitor cell population of uninduced metanephric blastema, which typically gives rise to nephrons. However, apart from blastema, WT specimens frequently contain cells that have differentiated into renal tubular or stromal phenotypes, complicating their analysis. We aimed to define tumor-progenitor genes that function in normal kidney development using WT xenografts (WISH-WT), in which the blastema accumulates with serial passages at the expense of differentiated cells. Herein, we did transcriptional profiling using oligonucleotide microarrays of WISH-WT, WT source, human fetal and adult kidneys, and primary and metastatic renal cell carcinoma. Among the most significantly up-regulated genes in WISH-WT, we identified a surprising number of paternally expressed genes (PEG1/MEST, PEG3, PEG5/NNAT, PEG10, IGF2, and DLK1), as well as Meis homeobox genes [myeloid ecotropic viral integration site 1 homologue 1 (MEIS1) and MEIS2], which suppress cell differentiation and maintain self-renewal. A comparison between independent WISH-WT and WT samples by real-time PCR showed most of these genes to be highly overexpressed in the xenografts. Concomitantly, they were significantly induced in human fetal kidneys, strictly developmentally regulated throughout mouse nephrogenesis and overexpressed in the normal rat metanephric blastema. Furthermore, in vitro differentiation of the uninduced blastema leads to rapid down-regulation of PEG3, DLK1, and MEIS1. Interestingly, ischemic/reperfusion injury to adult mouse kidneys reinduced the expression of PEG3, PEG10, DLK1, and MEIS1, hence simulating embryogenesis. Thus, multiple imprinted and stemness genes that function to expand the renal progenitor cell population may lead to evolution and maintenance of WT.

ERBB2 in pediatric cancer: innocent until proven guilty

Adult oncologists and their research colleagues have "led the charge" in the war on cancer. Their efforts have generated effective new chemotherapies that target cancer causing molecular alterations. It is hoped that these successes will be repeated within the pediatric oncology community. Testing whether molecular targeted therapies of adult cancers are also effective against childhood cancers might allow the rapid introduction of these exciting new agents into the pediatric clinic. However, it is imperative that we do not introduce blindly these agents into the pediatric population. We must ensure that molecular targets in adult cancers also fulfill a number of important criteria within the pediatric disease. This review addresses the issues surrounding the identification of molecular targets in pediatric cancers by focusing on studies of the ERBB2 oncogene.

Nephroblastic Neoplasms

Nephroblastoma, or Wilms tumor, is a malignant embryonal neoplasm that is derived from nephrogenic blastemal cells, with variable recapitulation of renal embryogenesis. The pathogenesis of nephroblastoma is complex and has been linked to alterations of several genomic loci, including WT1, WT2, FWT1, and FWT2. Generally, nephroblastoma is composed of variable proportions of blastema, epithelium, and stroma, each of which may exhibit a wide spectrum of morphologic variations. Distinguishing nephroblastoma with favorable histology from tumors that exhibit anaplasia is an integral component of histologic assessment because of its prognostic and therapeutic implications. Nephrogenic rests and a special variant of nephroblastoma, cystic partially differentiated nephroblastoma, also are discussed.