Experimental Wilms Research Articles

Palisaded Neutrophilic and Granulomatous Dermatitis-Like Reaction Associated with Wilms Tumor 1 Protein-Derived Peptide Vaccine: A Case and Review of the Literature

Palisaded neutrophilic and granulomatous dermatitis (PNGD) is an inflammatory cutaneous reaction that is associated with underlying autoimmune diseases. In rare cases, PNGD has been attributed to systemic medications. Here we report one case of a cutaneous injection-site reaction that occurred after intradermal administration of an experimental Wilms Tumor 1 (WT1) protein-derived peptide vaccine in a woman being treated for recurrent ovarian cancer. This is the first reported case of a PNGD-like reaction associated with immunotherapy injections. In this article, we discuss this case and summarize the literature related to the diagnosis and management of PNGD, as well as other injection site reactions related to immunotherapies and experimental vaccines.

The Epithelial Mesenchymal Transition Process in Wilms Tumor

Until now, only a few mouse-transplanted human tumors or experimental Wilms tumor (WT) cell lines have been described. The aim of this study was to show the biological behavior, including histology, immunohistochemistry (IHC), and molecular biology, of a WT including the original tumor and metastasis transferred into nude mice and followed for successive generations in xenografts. A WT metastasis was xenotransplanted into nude mice and the mice was monitored for 7 passages over a period of 29 months; the original neoplasm was comparatively studied. The morphology was evaluated by optical and electron microscopy. The protein expression was analyzed by immunohistochemistry in whole sections and in tissue microarray. The molecular studies were carried out by multiplex ligation-dependent probe amplification and polymerase chain reaction analysis. The histology changed markedly between the fourth and fifth transfer. The tumor exhibited an increased epithelial component (>40%) together with a slowing in the growth rate (8 mo). An epithelial-mesenchymal transition seemed to take place in the fourth passage and increased thereafter. The genetic studies also showed a WT5 deletion and a MYCN gain in all the tumor samples in passage 4 and beyond, but did not show E-cadherin, β-catenin, and APC mutations. An epithelial pattern was associated with slow tumor growth, whereas the predominance of mesenchymal spindle cells with striated muscle cell differentiation was related with a high growth rate. The in vivo reorganization of the tumor components (blastemal, epithelial, and mesenchymal) does not seem to be related with the Wnt and EMT pathways.

Effects of potent VEGF blockade on experimental Wilms tumor and its persisting vasculature

We characterized the effect of potent vascular endothelial growth factor (VEGF) blockade on early-stage Wilms tumor xenograft growth, vasculature and metastasis. VEGF is a key mediator of both physiologic and tumor angiogenesis. We recently described that potent VEGF blockade induces regression of established Wilms tumor xenografts and vessels, also reducing the size but not the incidence of pre-existing metastases. In these studies, we examined the effects of potent VEGF blockade on earlier stages of experimental Wilms tumors, focusing on tumor growth, vasculature and metastasis. Athymic mice received intrarenal human Wilms tumor cell implants. Biweekly treatment with vehicle or the VEGF-Trap, a high-affinity soluble decoy receptor incorporating regions of VEGFR1 and VEGFR2, was begun 1 week later (100 or 500 micrograms/dose, n=20 in each group). Mice were euthanized at week 6 to examine tumor weight, incidence of lung metastases, vascularity and expression of angiogenic factors. A cohort of mice was examined 2 weeks after cessation of treatment. Compared to controls, VEGF-Trap treated tumors were significantly smaller (100 micrograms/dose: 92.7% smaller, p=0.0017; 500 micro g/dose: 99.0% smaller, p=0.0009). The incidence of lung metastasis also decreased significantly (p<0.0055). VEGF-Trap nearly eradicated tumor vasculature. Rare persisting vessels were characterized by large caliber, quiescence (lacking proliferation/apoptosis) and arterialization (both phenotypic and molecular). Potent VEGF blockade caused near-arrest of experimental Wilms tumor growth, resulted in nearly avascular tumors, and also decreased the incidence and size of metastases. Persistent vessels in tumors treated with VEGF-Trap displayed specific morphologic and molecular features, suggestive of arterialization. Future strategies that target these persisting vessels may enhance the efficacy of VEGF blockade therapy.

Human epidermal growth factor receptor signaling contributes to tumor growth via angiogenesis in her2/ neu-expressing experimental Wilms’ tumor

Background: The human epidermal growth factor family (HER) members play a significant role in the mesenchymal-to-epithelial transition during renal tubulogenesis. HER misexpression has been linked also to loss of growth control, invasiveness, and promotion of angiogenesis in breast cancers and other human malignant tumors Methods: The authors screened Wilms’ tumor samples and derived cell lines for expression of her2/ neu, which was detected in both unfavorable and favorable histology tissues. Xenografts were implanted in mice using her2/ neu(+) and her2/ neu(−) cell lines and the effect of specific blockade tested using monoclonal anti-her2/ neu antibody. Results: Blocking antibody suppressed tumor growth in her2/ neu(+) but not her2/ neu(−) experimental Wilms’ tumor. In addition, antibody exposure resulted in suppression of tumor angiogenesis but no decrease in tumor cell proliferation in her2/ neu(+) xenografts. Conclusions: Her2/ neu contributes to the growth of some Wilms’ tumors, and an important mechanism of its action is promotion of angiogenesis.

Blockade of her2/neu decreases VEGF expression but does not alter HIF-1 distribution in experimental Wilms tumor

Her2/neu regulates angiogenesis in human breast cancer, in part by stabilizing hypoxia-inducible factor 1alpha (HIF-1alpha), causing accumulation of the HIF-1 heterodimer and thus increasing expression of the proangiogenic cytokine VEGF. Her2/neu has recently been shown to be overexpressed in a subset of Wilms tumors. Using her2/neu (+) and her2/neu (-) Wilms tumor cell lines, we tested the effect of blocking anti-her2/neu antibody in vitro and in vivo. Blocking antibody did not alter VEGF expression in vitro, but decreased expression of VEGF in her2/neu (+) Wilms tumor xenografts. Tumor suppression was less marked than in parallel experiments using agents directly blocking VEGF. HIF-1alpha immunostaining was not altered in her2/neu (+) xenografts exposed to blocking antibody. These results suggest that her2/neu contributes to Wilms tumor angiogenesis in vivo by regulating VEGF, but other processes may act to rescue HIF-1alpha and thus to support tumor growth in this system.

Novel use of an established agent: Topotecan is anti-angiogenic in experimental Wilms tumor

Background/Purpose: Antiangiogenic agents offer a new approach to the treatment of aggressive neoplasms, yet very few agents are available for current use. The authors have shown previously the efficacy of antiangiogenic therapy in experimental Wilms tumor, using an investigative antibody. They hypothesized that topotecan, administered in a regimen targeting endothelial cells, would suppress tumor growth and angiogenesis in experimental Wilms tumor. Methods: Experimental tumors were induced in the left kidneys of athymic mice by injection of cultured Wilms tumor cells. Topotecan (0.36, 0.6, 1.0, 2.0, and 3.0 mg/kg) or vehicle was injected intraperitoneally in 2 cycles over a 6-week period. Fluorescein angiograms and platelet endothelial cell adhesion molecule-1 staining of primary tumors were performed to ascertain vascular architecture. Endothelial apoptosis was assessed by TdT-mediated dUTP nick end labeling assay. Results: Tumor weights were reduced significantly in treated versus control animals, even in the lowest-dose group. Endothelial cell staining and angiography results showed relatively sparse vascularity in treated xenografts. Endothelial apoptosis was observed in treated but not control tumors. Conclusions: Topotecan, delivered in an “antiangiogenic” regimen, even at very low doses, significantly inhibited growth of experimental Wilms tumors. No adverse effects were noted at low doses. Thus, the established chemotherapy agent topotecan may be useful in a novel role: as antiangiogenic therapy. J Pediatr Surg 36:1781-1784. Copyright © 2001 by W.B. Saunders Company.

Combination antiangiogenic therapy: Increased efficacy in a murine model of Wilms tumor

Background/Purpose: Antibody to vascular endothelial growth factor (anti-VEGF) suppresses tumor growth and metastasis in experimental Wilms tumor. However, tumor growth accelerates if antibody is withdrawn. As recently shown, low-dose, frequently administered topotecan, a topoisomerase-1 inhibitor, has anti-angiogenic activity. The authors hypothesized that combined topotecan/anti-VEGF therapy would suppress tumor growth and metastasis more durably than either agent alone. Methods: Xenografts were induced by intrarenal injection of human Wilms tumor cells in athymic mice (n = 59). Mice were divided into control (n = 10), anti-VEGF (n = 16), topotecan (n = 17), and topotecan plus anti-VEGF (n = 16) groups. All control and half the treated mice were killed at week 6. Remaining (“rebound”) mice were maintained without treatment until week 8. Tumor vasculature was mapped by fluorescein angiography/PECAM immunostaining. Endothelial apoptosis was assessed by TUNEL assay. Results: 6 weeks: Tumor weights were reduced significantly in treated mice (P <.003 v control). Seven of ten control and 1 of 25 treated mice displayed lung metastases (P <.003). Rebound tumors were largest in topotecan-only, intermediate in antibody-treated, and smallest in combination-treated mice. Immunostaining and angiography results showed sparse vascularity in treated xenografts. Endothelial apoptosis was observed only in treated tumors. Conclusion: Combination low-dose topotecan and anti-VEGF antibody therapy is antiangiogenic and suppresses tumor growth and metastasis in experimental Wilms tumor more durably than either agent alone. J Pediatr Surg 36:1177-1181. Copyright © 2001 by W.B. Saunders Company.

Highly specific antiangiogenic therapy is effective in suppressing growth of experimental Wilms tumors

Background/Purpose: Pathologic angiogenesis in tumors is a potential target for novel therapies. Vascular endothelial growth factor (VEGF) is an angiogenic promoter present in a wide variety of human tumors. VEGF is expressed as 4 isoforms; one of these, VEGF165, predominates in human tumors. The authors hypothesized that antagonism of VEGF165 by a specific aptamer would block tumor growth in an experimental model of Wilms tumor. Methods: VEGF isoform expression in clinical (n = 2) and experimental tumors were evaluated by reverse transcription polymerase chain reaction (RT-PCR). Tumors were induced in NCR nude mice (n = 32) by intrarenal injection of 106 cultured Wilms tumor cells. At 1 week, aptamer (n = 16) or vehicle (n = 16) treatment was started and continued daily for 5 weeks. Results: At 6 weeks tumors weighed 84% less in treated versus control animals (0.69 v 4.41 g; P <.028), without observed adverse effects and similar to suppression previously reported using nonisoform-specific anti-VEGF antibody (94% to 96%). Conclusions: Anti-VEGF165 aptamer effectively suppressed primary tumor growth in experimental animals with no observed adverse effects. Development of highly specific antiangiogenic therapies may be of particular benefit to pediatric patients. J Pediatr Surg 36:357-361. Copyright © 2001 by W.B. Saunders Company.

Metastasis correlates with production of vascular endothelial growth factor in a murine model of human Wilms' tumor

Background/Purpose: The growth and spread of solid tumors are critically dependent on the induction of angiogenesis. We hypothesized that vascular endothelial growth factor (VEGF) would be detected in Wilms' tumors, and that both growth and metastasis would parallel VEGF levels in a murine model.Methods: Primary tumors were established in the right kidneys of nude mice (n = 21). Mice were killed at 3, 4.5, or 6 weeks. Tumor-bearing and control kidneys were subjected to enzyme-linked immunosorbent assay (ELISA) for VEGF. Representative sections were assessed by histology and immunohistochemistry. Lungs were examined for metastases. Clinical specimens of Wilms' tumor (n = 12) also were assayed for VEGF.Results: The authors detected VEGF by ELISA with increasing frequency, and in increasing quantity, as experimental Wilms' tumors were grown over time. Immunohistochemistry demonstrated accumulation of VEGF in areas of viable tumor. Lung metastases occurred in 8 of 10 animals with VEGF-positive tumors, but in only 3 of 11 animals with VEGF-negative tumors, an association that was statistically significant. VEGF was found in 10 of 12 clinical Wilms' tumor specimens tested.Conclusions: VEGF is present in both clinical and experimental Wilms' tumors. In a murine model, absolute VEGF levels increase as primary tumors grow, and VEGF production is significantly associated with tumor metastasis.

Regional chemotherapy in an experimental model of Wilms' tumor in rats

A s.c. experimental model of Wilms' tumor in rats was used to compare the effects of intratumoral treatment with vincristine plus actinomycin D to i.v. treatment with these chemotherapeutic drugs. The Wilms' tumor model is a fast-growing solid tumor that has been shown to be resistant to traditional clinical treatment procedures used for Wilms' tumor in man. Injection of the chemotherapeutic drugs directly into the tumor mass was found to be more effective than i.v. therapy in causing long-term remission of the tumor. Intratumoral therapy was also less toxic to the animals than i.v. therapy when measured by post-treatment survival rates and weight loss during the 1st week following treatment. However, intratumoral treatment caused an initial fibrosis of the tumor tissue, which resulted in a slower rate of absorption of the resultant fibrotic tumor mass than was seen in tumors treated i.v. Also, intratumoral injection resulted in necrosis of the overlying skin, which healed as the fibrotic tumor tissue was absorbed. Intratumoral treatment of a cervical tumor was found to cause the remission of a second major tumor mass located at some distance from the initial injection (i.e., in the lumbar region). No significant benefits were noted when dimethylsulfoxide (DMSO) was used in place of aqueous mannitol as a vehicle to deliver the chemotherapeutic agents. There was a significant correlation between the drug dose-to-tumor-size ratio (D/T ratio) and the effectiveness of the chemotherapy. When this ratio was high enough, a single treatment with a combination of vincristine and actinomycin D usually resulted in total remission of the experimental Wilms' tumor in response to either intratumoral or i.v. therapy.