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Supplementary Figures S1-S6 from Sustained VEGF Blockade Results in Microenvironmental Sequestration of VEGF by Tumors and Persistent VEGF Receptor-2 Activation

Vascular endothelial growth factor (VEGF) blockade has been validated clinically as a treatment for human cancers, yet virtually all patients eventually develop progressive disease during therapy. In order to dissect this phenomenon, we examined the effect of sustained VEGF blockade in a model of advanced pediatric cancer. Treatment of late-stage hepatoblastoma xenografts resulted in the initial collapse of the vasculature and significant tumor regression. However, during sustained treatment, vessels recovered, concurrent with a striking increase in tumor expression of perlecan, a heparan sulfate proteoglycan. Whereas VEGF mRNA was expressed at the periphery of surviving clusters of tumor cells, both secreted VEGF and perlecan accumulated circumferential to central vessels. Vascular expression of heparanase, VEGF receptor-2 ligand binding, and receptor activation were concurrently maintained despite circulating unbound VEGF Trap. Endothelial survival signaling via Akt persisted. These findings provide a novel mechanism for vascular survival during sustained VEGF blockade and indicate a role for extracellular matrix molecules that sequester and release biologically active VEGF. (Mol Cancer Res 2008;6(1):1–9)

Purpose: Aflibercept is a novel decoy receptor that efficiently neutralizes circulating VEGF. A pediatric phase I trial was conducted to define the dose-limiting toxicities (DLT), maximum tolerated dose (MTD), and pharmacokinetics (PK) of aflibercept.Experimental Design: Cohorts of three to six children with refractory solid tumors received aflibercept intravenously over 60 minutes every 14 days, at 2.0, 2.5, or 3.0 mg/kg/dose. PK sampling and analysis of peripheral blood biomarkers were conducted with the initial dose.Results: Twenty-one eligible patients were enrolled; 18 were fully evaluable for toxicity. One of six patients receiving 2.0 mg/kg/dose developed dose-limiting intratumoral hemorrhage and two of six receiving 3.0 mg/kg/dose developed either dose-limiting tumor pain or tissue necrosis. None of the six patients receiving 2.5 mg/kg/dose developed DLTs, defining this as the MTD. The most common non-DLTs were hypertension and fatigue. Three patients with hepatocellular carcinoma, hepatoblastoma and clear cell sarcoma had stable disease for >13 weeks. At the MTD, the ratio of free-to-bound aflibercept serum concentration was 2.10 on day 8 but only 0.44 by day 15. A rapid decrease in VEGF (P < 0.05) and increase in placental growth factor (PlGF; P < 0.05) from baseline was observed in response to aflibercept by day 2.Conclusions: The aflibercept MTD in children of 2.5 mg/kg/dose every 14 days is lower than the adult recommended dose of 4.0 mg/kg. This dose achieves, but does not sustain, free aflibercept concentrations in excess of bound. Tumor pain and hemorrhage may be evidence of antitumor activity but were dose-limiting. Clin Cancer Res; 18(18); 5081–9. ©2012 AACR.

CCR Translation for This Article from A Phase I Trial and Pharmacokinetic Study of Aflibercept (VEGF Trap) in Children with Refractory Solid Tumors: A Children's Oncology Group Phase I Consortium Report

Supplementary Figure 3 from A Notch1 Ectodomain Construct Inhibits Endothelial Notch Signaling, Tumor Growth, and Angiogenesis

Supplementary Figure 4 from A Notch1 Ectodomain Construct Inhibits Endothelial Notch Signaling, Tumor Growth, and Angiogenesis

Supplementary Figures S1-S12 and Legends. Supplementary Figure S1. Combined Inhibition of Notch and VEGF disrupts interaction of pericytes with endothelial cells in primary tumors Supplementary Figure S2. Inhibition of Notch increases liver metastases. Supplementary Figure S3. Inhibition of Notch increases liver metastases as measured by bioluminescence in liver homogenates. Supplementary Figure S4. Notch blockade does not increase metastases to other organs. Supplementary Figure S5. N1D does not affect proliferation, invasion or migration of neuroblastoma cell lines. Supplementary Figure S6. N1KD decreases Hes1 and Hey1 but does not affect proliferation of NGP cells Supplementary Figure S7. Increased vasculature of liver metastases with Notch blockade Supplementary Figure S8. Activation of HSCs in liver metastases with Notch blockade Supplementary Figure S9. SEC expression of ICAM-1 is regulated by Notch Supplementary Figure S10. AdN1D increases expression of liver ICAM-1 but does not increase retention of tumor cells in the liver. Supplementary Figure S11. Notch1 decoy variants increase proliferation of mSEC but not NGP cells Supplementary Figure S12. Jag1 siRNA decreases expression of Jag1 in NGP cells.

The Notch pathway plays multiple key roles in tumorigenesis, and its signaling components have therefore aroused great interest as targets for emerging therapies. Here, we show that inhibition of Notch, using a soluble receptor Notch1 decoy, unexpectedly caused a remarkable increase in liver metastases from neuroblastoma and breast cancer cells. Increased liver metastases were also seen after treatment with the γ-secretase inhibitor PF-03084014. Transgenic mice with heterozygous loss of Notch1 demonstrated a marked increase in hepatic metastases, indicating that Notch1 signaling acts as metastatic suppressor in the liver microenvironment. Inhibition of DLL1/4 with ligand-specific Notch1 decoys increased sprouting of sinusoidal endothelial cells into micrometastases, thereby supporting early metastatic angiogenic growth. Inhibition of tumor-derived JAG1 signaling activated hepatic stellate cells, increasing their recruitment to vasculature of micrometastases, thereby supporting progression to macrometastases. These results demonstrate that inhibition of Notch causes pathologic activation of liver stromal cells, promoting angiogenesis and growth of hepatic metastases. Our findings have potentially serious implications for Notch inhibition therapy. Cancer Res; 75(8); 1592–602. ©2015 AACR.

Supplementary Table 1. Antibodies utilized in this study.

Supplementary Figure 1 from A Notch1 Ectodomain Construct Inhibits Endothelial Notch Signaling, Tumor Growth, and Angiogenesis

Supplementary Methods. Reverse transcription and quantitative PCR. BrdU Proliferation Assay. In vivo BrdU assay. Migration and Invasion Assays. Adenovirus production and Injection. siRNA transfection.

Supplementary Figure 2 from A Notch1 Ectodomain Construct Inhibits Endothelial Notch Signaling, Tumor Growth, and Angiogenesis

Purpose: The aim of this study is to characterize the effects of high-dose radiation therapy (HDRT) on Notch signaling components of the tumor vasculature. Methods and Materials: Human umbilical vein endothelial cells monolayers were exposed to different single fraction doses of irradiation; ribonucleic acid RNA was isolated and polymerase chain reaction was performed for Notch signaling components. The vascular response to radiation therapy was examined in a xenograft model of neuroblastoma. Tumors were treated with 0 Gy, 2 Gy, and 12 Gy single fraction doses and analyzed by double immunofluorescence staining for Notch1, Notch ligands Jagged1 and Dll4, and the endothelial cell (EC) marker endomucin. To assess the role of Notch in vivo, NGP xenograft tumors expressing Fc or Notch1-1–24-decoy (a novel Notch inhibitor) were treated with 0 Gy and 12 Gy. Immunofluorescence staining for endomucin and endomucin/αSMA was performed to analyze the effect of combination treatment on tumor EC and endothelial-to-mesenchymal-transition (EndMT), respectively. Results: In human umbilical vein endothelial cells monolayers doses ≥8 Gy increased expression of NOTCH1, JAG1, and Notch target genes HEY1 and HEY2 as early as 6 hours after irradiation. In vivo, 12 Gy significantly increased Notch1 and Jagged1 in tumor ECs compared with 0 Gy or 2 Gy after 72 hours. Combining HDRT with Notch inhibition using the Notch1-1–24-decoy resulted in a greater loss of EC coverage of tumor vessels than HDRT alone at 6 hours and 72 hours post treatment. Notch inhibition reduced EndMT induced by HDRT, as indicated by diminished αSMA staining in ECs. Conclusions: HDRT induced Notch1 expression and increased Notch1 signaling in the endothelial component of tumor vasculature, which was not observed with lower doses. This increase in Notch1 activation might protect tumor vessels from HDRT induced damage and regulate EndMT process., Summary High-dose radiation (HDRT) not only has a direct cytotoxic effect on tumor cells but can also effect the tumor vasculature. Our study examined HDRT and Notch signaling in a xenograft model of neuroblastoma. We observed an increased Notch signaling in endothelial cells after HDRT. Notch1 inhibition augments the effect of HDRT on endothelial cell loss and reduces radiation-induced endothelial-to-mesenchymal transition.

Pigmented epithelioid melanocytoma (PEM) is an intermediate-grade melanocytic tumor with considerable histologic overlap with other melanocytic neoplasms such as epithelioid blue nevus (EBN), which is associated with the neoplastic syndrome Carney complex (CC). Next-generation sequencing is a valuable tool for identifying the primary drivers of melanocytic neoplasms and differentiating them from one another. While germline variants in the protein kinase cAMP-dependent regulatory type 1 alpha (PRKAR1A) gene have been associated with EBN and CC, fusions in protein kinase C-alpha (PRKCA) have been shown as sporadic drivers of PEM. Herein, we report the diagnosis and workup of a case of pigmented epithelioid melanocytoma with a novel protein kinase C-beta (PRKCB) fusion.

Malignant rhabdoid tumors (MRTs) are rare, aggressive pediatric solid tumors, characterized by a 22q11 deletion that inactivates the SMARCB1 gene. Outcomes remain poor despite multimodality treatment. MRTs are among the most genomically stable cancers and lack therapeutically targetable genetic mutations. We utilized metaVIPER, an extension of the Virtual Inference of Protein-activity by Enriched Regulon (VIPER) algorithm, to computationally infer activated druggable proteins in the tumor of an eight month old patient and then expanded the analysis to TCGA and TARGET cohorts.In vitrostudies were performed on a panel of MRT and atypical teratoid/rhabdoid tumor cell lines. Two patient-derived xenograft (PDX) mouse models of MRT were used forin vivoefficacy studies. MetaVIPER analysis from the patient’s tumor identified significantly high inferred activity of nuclear export protein Exportin-1 (XPO1). Expanded metaVIPER analysis of TCGA and TARGET cohorts revealed consistent elevations in XPO1 inferred activity in MRTs compared to other cancer types. All MRT cell lines demonstrated baseline activation of XPO1. MRT cell lines demonstratedin vitrosensitivity to the XPO1 inhibitor, selinexor which led to cell cycle arrest and induction of apoptosis. Targeted inhibition of XPO1 in patient-derived xenograft models of MRT using selinexor resulted in abrogation of tumor growth. Selinexor demonstrates efficacy in preclinical models of MRT. These results support investigation of selinexor in a phase II study in children with MRT and illustrate the importance of an N-of-1 approach in driving discovery beyond the single patient.Statement of Translational RelevanceWe describe the patient-driven discovery of XPO1 activation as a non-genetically encoded vulnerability in MRTs. The application of metaVIPER analysis to tumors lacking actionable oncogenic alterations represents a novel approach for identifying potential therapeutic targets and biomarkers of response. Our preclinical validation of selinexor confirms XPO1 inhibition as a promising therapeutic strategy for the treatment of MRT.

Malignant rhabdoid tumors (MRT) represent a distinct group of aggressive tumors usually occurring in infancy involving a variety of anatomic locations including the kidney, brain, soft tissue and liver. The molecular hallmark of these tumors is the presence of deletions and/or mutations of SMARCB1 or rarely SMARCA4 that lead to the absence of INI1 or BRG1 proteins, core components of the SWI/SNF chromatin remodeling complex. MRT of the liver are rare tumors that comprise less than 5% of malignant pediatric liver tumors. They are currently diagnosed on the basis of documenting both INI1 negative immunoreactivity and rhabdoid morphology. In the absence of molecular testing, MRT lacking classic rhabdoid morphology are currently classified as small cell undifferentiated hepatoblastoma (HB). Here we report a case of MRT initially classified as a INI1 negative small cell HB. Whole Exome Sequencing with Transcriptome subsequently showed homozygous deletion of SMARCB1 on chromosome 22q11.23 with evidence of loss of expression of the gene, establishing the diagnosis of MRT. As molecular testing of these tumors is performed on a more routine basis, this case illustrates that the INI negative small cell undifferentiated variant of HB actually represents MRT, a tumor unrelated to HB.

Despite the identification of MYCN amplification as an adverse prognostic marker in neuroblastoma, MYCN inhibitors have yet to be developed. Here, by integrating evidence from a whole-genome shRNA library screen and the computational inference of master regulator proteins, we identify transcription factor activating protein 4 (TFAP4) as a critical effector of MYCN amplification in neuroblastoma, providing a novel synthetic lethal target. We demonstrate that TFAP4 is a direct target of MYCN in neuroblastoma cells, and that its expression and activity strongly negatively correlate with neuroblastoma patient survival. Silencing TFAP4 selectively inhibits MYCN-amplified neuroblastoma cell growth both in vitro and in vivo, in xenograft mouse models. Mechanistically, silencing TFAP4 induces neuroblastoma differentiation, as evidenced by increased neurite outgrowth and upregulation of neuronal markers. Taken together, our results demonstrate that TFAP4 is a key regulator of MYCN-amplified neuroblastoma and may represent a valuable novel therapeutic target.

We report a case of disseminated Trichosporon asahii in a patient on systemic antifungal therapy who presented with multiple cutaneous nodules suggestive of fungal infection. Histologic features resembled neutrophilic eccrine hidradenitis but staining with periodic acid-Schiff and Gomori methenamine silver confirmed the clinical diagnosis. This case highlights the importance of maintaining suspicion for trichosporonosis and contextualizing histologic findings within the underlying clinical picture.

Background Precision medicine approaches are ideally suited for rare tumors where comprehensive characterization may have diagnostic, prognostic, and therapeutic value. We describe the clinical case and molecular characterization of an adolescent with metastatic poorly differentiated carcinoma (PDC). Given the rarity and poor prognosis associated with PDC in children, we utilized genomic analysis and preclinical models to validate oncogenic drivers and identify molecular vulnerabilities. Methods We utilized whole exome sequencing (WES) and transcriptome analysis to identify germline and somatic alterations in the patient’s tumor. In silico and in vitro studies were used to determine the functional consequences of genomic alterations. Primary tumor was used to generate a patient-derived xenograft (PDX) model, which was used for in vivo assessment of predicted therapeutic options. Results WES revealed a novel germline frameshift variant (p.E1554fs) in APC, establishing a diagnosis of Gardner syndrome, along with a somatic nonsense (p.R790*) APC mutation in the tumor. Somatic mutations in TP53, MAX, BRAF, ROS1, and RPTOR were also identified and transcriptome and immunohistochemical analyses suggested hyperactivation of the Wnt/ß-catenin and AKT/mTOR pathways. In silico and biochemical assays demonstrated that the MAX p.R60Q and BRAF p.K483E mutations were activating mutations, whereas the ROS1 and RPTOR mutations were of lower utility for therapeutic targeting. Utilizing a patient-specific PDX model, we demonstrated in vivo activity of mTOR inhibition with temsirolimus and partial response to inhibition of MEK. Conclusions This clinical case illustrates the depth of investigation necessary to fully characterize the functional significance of the breadth of alterations identified through genomic analysis. Electronic supplementary material The online version of this article (doi:10.1186/s13073-016-0366-0) contains supplementary material, which is available to authorized users.

The MYCN proto-oncogene is amplified in a number of advanced-stage human tumors, such as neuroblastomas. Similar to other members of the MYC family of oncoproteins, MYCN (also known as N-Myc) is a transcription factor, and its stability and activity are tightly controlled by ubiquitination-dependent proteasome degradation. Although numerous studies have demonstrated that N-Myc is a driver of neuroblastoma tumorigenesis, therapies that directly suppress N-Myc activity in human tumors are limited. Here we have identified ubiquitin-specific protease 7 (USP7; also known as HAUSP) as a regulator of N-Myc function in neuroblastoma. HAUSP interacts with N-Myc, and HAUSP expression induces deubiquitination and subsequent stabilization of N-Myc. Conversely, RNA interference (RNAi)-mediated knockdown of USP7 in neuroblastoma cancer cell lines, or genetic ablation of Usp7 in the mouse brain, destabilizes N-Myc, which leads to inhibition of N-Myc function. Notably, HAUSP is more abundant in patients with neuroblastoma who have poorer prognosis, and HAUSP expression substantially correlates with N-Myc transcriptional activity. Furthermore, small-molecule inhibitors of HAUSP's deubiquitinase activity markedly suppress the growth of MYCN-amplified human neuroblastoma cell lines in xenograft mouse models. Taken together, our findings demonstrate a crucial role of HAUSP in regulating N-Myc function in vivo and suggest that HAUSP inhibition is a potential therapy for MYCN-amplified tumors.

OBJECTIVES/GOALS: Neuroblastoma (NB) is the most common extra-cranial solid tumor with outcomes varying from spontaneous regression to metastatic with high mortality rates. The tumor immune microenvironment (TIME) may play a significant role in this disease. In this study we analyze the TIME comparing high-risk (HR) and low-risk (LR) NBs using multiplex platforms. METHODS/STUDY POPULATION: Two tissue microarrays (TMAs) with 2mm cores were created from 41 patients treated at Columbia University Irving Medical Center. Five micron TMA slides were stained for Digital Spatial Profiling (DSP, nanoString) and multiplex immunofluorescence (mIF). For DSP, a 24-patient subset including 11 HR, 8 LR and 4 intermediate risk patients was analyzed for 34 proteins. Protein expression among risk groups was compared using Mann-Whitney t-test. For mIF, TMA FFPE slides were stained for DAPI, CD3, CD8, CD68, HLA-DR, PDL1 and Chromogranin A. Whole TMA cores were captured as 9 -20X multispectral images (MSIs) stitched into a 3x3 MSI using Vectra (Akoya). MSIs were processed with inForm and qualitative analysis performed comparing HR and LR tumors. RESULTS/ANTICIPATED RESULTS: With DSP, we find significantly more HLA-DR in HR compared to LR tumors (p = 0.016). When controlling for immune cells with CD45 we find HLA-DR/CD45 to be higher in HR than LR tumors (p = 0.026). We found increased PD1 and PDL1 expression in all groups without significant difference between LR and HR (p = 0.778 and p = 0.310, respectively). Preliminary analysis of mIF on 9 patients (4 HR and 5 LR) finds HR tumors appear to have more immune cells than LR tumors, specifically more CD3+CD8- T cells while total CD8+ cells may be similar. There may be less macrophages in the HR compared to LR tumors. Completion of image processing and quantitative analysis of mIF data is underway. DISCUSSION/SIGNIFICANCE OF IMPACT: Increased expression of immune markers in NB TIME correlates with higher risk, which is unlike many other tumors. We compared TIME in HR and LR NB using multiplex platforms, DSP and mIF. We find that HLA-DR is more expressed in HR NB while PD1 and PDL1 expression is consistently high and not different between risk groups. Further analysis is underway. CONFLICT OF INTEREST DESCRIPTION: Robyn D. Gartrell-Corrado received grant support from nanoString for Digital Spatial Profiling and received honoraria and travel support from Northwest Biotherapeutics and PerkinElmer, respectively.

Indications for everolimus and other drugs within the mammalian target of rapamycin inhibitor class have recently expanded to include tuberous sclerosis complex. Everolimus is generally well tolerated, but it is important for physicians to identify and manage associated cutaneous adverse effects. We report the first case of a child developing erythema nodosum while undergoing everolimus therapy.

The clinical management of pediatric liver tumors involves stratification into risk groups. One previously defined, high-risk group of hepatoblastomas is the small cell undifferentiated variant. In light of molecular studies showing SMARCB1 deletion in these tumors, it is now recognized that most small cell, undifferentiated liver tumors represent an aggressive unrelated tumor&mdash, the malignant rhabdoid tumor (MRT). SMARCB1 is a member of the chromatin remodeling SWI/SNF complex and encodes the INI1 protein. The histologic diagnosis of MRT is currently based on INI1 negative immunoreactivity and the presence of rhabdoid morphology. INI1-negative small cell liver tumors lacking classic rhabdoid morphology are often misclassified as small cell undifferentiated hepatoblastomas (SCUD-HB), according to the current classification. Pediatric liver tumors diagnosed between 2003&ndash, 2017 as SCUD-HB (four cases) or MRT (two cases) were identified from the Columbia University Pathology Department Archives. All tumors were associated with normal or low serum alpha fetoprotein levels, and showed an absence of immunohistochemical staining of hepatocellular markers (Hep-par1, Arginase) and loss of INI1 staining. Two cases were initially diagnosed as MRT, one with prominent rhabdoid morphology, the other with predominant small cell morphology. The remaining four cases with small cell morphology were classified as SCUD-HB. Ancillary molecular studies confirmed the loss of SMARCB1, supporting the diagnosis of MRT in all cases, proving morphology an unreliable criterion. It is critical to eliminate the term INI1-negative hepatoblastoma from the current classification scheme, and classify INI1-negative tumors as MRT, particularly since high-risk HB-chemotherapy regimens are not effective for treating MRT.

Background Molecular characterization has the potential to advance the management of pediatric cancer and high-risk hematologic disease. The clinical integration of genome sequencing into standard clinical practice has been limited and the potential utility of genome sequencing to identify clinically impactful information beyond targetable alterations has been underestimated. Methods The Precision in Pediatric Sequencing (PIPseq) Program at Columbia University Medical Center instituted prospective clinical next generation sequencing (NGS) for pediatric cancer and hematologic disorders at risk for treatment failure. We performed cancer whole exome sequencing (WES) of patient-matched tumor-normal samples and RNA sequencing (RNA-seq) of tumor to identify sequence variants, fusion transcripts, relative gene expression, and copy number variation (CNV). A directed cancer gene panel assay was used when sample adequacy was a concern. Constitutional WES of patients and parents was performed when a constitutionally encoded disease was suspected. Results were initially reviewed by a molecular pathologist and subsequently by a multi-disciplinary molecular tumor board. Clinical reports were issued to the ordering physician and posted to the patient’s electronic medical record. Results NGS was performed on tumor and/or normal tissue from 101 high-risk pediatric patients. Potentially actionable alterations were identified in 38% of patients, of which only 16% subsequently received matched therapy. In an additional 38% of patients, the genomic data provided clinically relevant information of diagnostic, prognostic, or pharmacogenomic significance. RNA-seq was clinically impactful in 37/65 patients (57%) providing diagnostic and/or prognostic information for 17 patients (26%) and identified therapeutic targets in 15 patients (23%). Known or likely pathogenic germline alterations were discovered in 18/90 patients (20%) with 14% having germline alternations in cancer predisposition genes. American College of Medical Genetics (ACMG) secondary findings were identified in six patients. Conclusions Our results demonstrate the feasibility of incorporating clinical NGS into pediatric hematology-oncology practice. Beyond the identification of actionable alterations, the ability to avoid ineffective/inappropriate therapies, make a definitive diagnosis, and identify pharmacogenomic modifiers is clinically impactful. Taking a more inclusive view of potential clinical utility, 66% of cases tested through our program had clinically impactful findings and samples interrogated with both WES and RNA-seq resulted in data that impacted clinical decisions in 75% of cases. Electronic supplementary material The online version of this article (doi:10.1186/s13073-016-0389-6) contains supplementary material, which is available to authorized users.

O1 IL-15 primes an mTOR-regulated gene-expression program to prolong anti-tumor capacity of human natural killer cells #### Andreas Lundqvist1, Vincent van Hoef1, Xiaonan Zhang1, Erik Wennerberg2, Julie Lorent1, Kristina Witt1, Laia Masvidal Sanz1, Shuo Liang1, Shannon Murray3, Ola Larsson1

Purpose: Aflibercept is a novel decoy receptor that efficiently neutralizes circulating VEGF. A pediatric phase I trial was conducted to define the dose-limiting toxicities (DLT), maximum tolerated dose (MTD), and pharmacokinetics (PK) of aflibercept. Experimental Design: Cohorts of three to six children with refractory solid tumors received aflibercept intravenously over 60 minutes every 14 days, at 2.0, 2.5, or 3.0 mg/kg/dose. PK sampling and analysis of peripheral blood biomarkers were conducted with the initial dose. Results: Twenty-one eligible patients were enrolled; 18 were fully evaluable for toxicity. One of six patients receiving 2.0 mg/kg/dose developed dose-limiting intratumoral hemorrhage and two of six receiving 3.0 mg/kg/dose developed either dose-limiting tumor pain or tissue necrosis. None of the six patients receiving 2.5 mg/kg/dose developed DLTs, defining this as the MTD. The most common non-DLTs were hypertension and fatigue. Three patients with hepatocellular carcinoma, hepatoblastoma and clear cell sarcoma had stable disease for >13 weeks. At the MTD, the ratio of free-to-bound aflibercept serum concentration was 2.10 on day 8 but only 0.44 by day 15. A rapid decrease in VEGF (P < 0.05) and increase in placental growth factor (PlGF; P < 0.05) from baseline was observed in response to aflibercept by day 2. Conclusions: The aflibercept MTD in children of 2.5 mg/kg/dose every 14 days is lower than the adult recommended dose of 4.0 mg/kg. This dose achieves, but does not sustain, free aflibercept concentrations in excess of bound. Tumor pain and hemorrhage may be evidence of antitumor activity but were dose-limiting. Clin Cancer Res; 18(18); 5081–9. ©2012 AACR.

Microbubble ultrasound contrast agents are being developed as image-guided gene carriers for targeted delivery in vivo. In this study, novel polyplex-microbubbles were synthesized, characterized and evaluated for systemic circulation and tumor transfection. Branched polyethylenimine (PEI; 25 kDa) was modified with polyethylene glycol (PEG; 5 kDa), thiolated and covalently attached to maleimide groups on lipid-coated microbubbles. The PEI-microbubbles demonstrated increasingly positive surface charge and DNA loading capacity with increasing maleimide content. The in vivo ultrasound contrast persistence of PEI-microbubbles was measured in the healthy mouse kidney, and a two-compartment pharmacokinetic model accounting for free and adherent microbubbles was developed to describe the anomalous time-intensity curves. The model suggested that PEI loading dramatically reduced free circulation and increased nonspecific adhesion to the vasculature. However, DNA loading to form polyplex-microbubbles increased circulation in the bloodstream and decreased nonspecific adhesion. PEI-microbubbles coupled to a luciferase bioluminescence reporter plasmid DNA were shown to transfect tumors implanted in the mouse kidney. Site-specific delivery was achieved using ultrasound applied over the tumor area following bolus injection of the DNA/PEI-microbubbles. In vivo imaging showed over 10-fold higher bioluminescence from the tumor region compared to untreated tissue. Ex vivo analysis of excised tumors showed greater than 40-fold higher expression in tumor tissue than non-sonicated control (heart) tissue. These results suggest that the polyplex-microbubble platform offers improved control of DNA loading and packaging suitable for ultrasound-guided tissue transfection.

Background: Abscopal effect (AbE) is a rare phenomenon in pediatric oncology, defined as regression of tumor at distal sites following radiation therapy. AbE is widely believed to result from the local activation and expansion of tumor-specific T cells in the area radiated, followed by the migration of these T cells to distant sites. We present a case of AbE in a 1-year-old with congenital fibrosarcoma (forearm) bearing a novel EML4-NTRK3 fusion who developed bilateral lung metastasis 6 months post resection of the initial forearm tumor. The patient’s lung lesions were unresponsive to chemotherapy prompting palliative, hypofractionated radiation therapy (RT) to the right lung lesion only. One month following RT, patient showed significant decrease in size of bilateral lung lesions, with no evidence of disease at 3 months post RT. Using whole-exome sequencing (WES), high-throughput sequencing of T cell receptors (TCRseq), and quantitative multiplex immunofluorescence (qmIF), we investigated the relationship between tumor progression and metastasis, the pre- and post-RT microenvironment, and the co-evolution of the tumor-infiltrating lymphocyte (TIL) populations in this patient. We believe this unusual case offers key insights into mechanisms underlying AbE. Methods: Formalin-fixed, paraffin-embedded (FFPE) tissue specimens from the initial diagnostic lesion (forearm), pretreatment lung tumor, and bilateral post-RT lung lesions (right (RT treated) and left (outside RT field) were obtained. An FFPE slide was stained for each specimen using traditional immunohistochemistry (IHC) for CD3 and CD8 and qmIF for 7 biomarkers including DAPI, CD3, CD4, CD8, CD68, HLA-DR, and Ki67. QmIF images were taken using MANTRA and cell density analysis was performed using inForm software and R. DNA was isolated, from the tissue specimens and peripheral blood, for profiling using WES and TCRseq, generating a multiplex snapshot of each site. The TIL populations were described by the complementarity determining region 3 (CDR3) of each TCR (as identified by Adaptive), followed by analysis of the bias, diversity, and divergence of these TIL populations using entropy-based statistics. Results: IHC and qmIF of the primary fibrosarcoma and pre-RT lung tumor showed very low immune cell infiltration. In contrast, immune infiltration was markedly increased (both CD4+ and CD8+) post-RT, particularly in the nonirradiated lung lesion (left). TIL populations were analyzed using TCRseq, revealing little similarity between those of the primary fibrosarcoma and the recurrent lung lesions. However, the TCR repertoires comparing the post-RT lung lesions, irradiated (right) and non-irradiated (left), showed substantial similarity, sharing a larger percentage of CDR3 sequences with each other (6.7% of combined total) than with the primary tumor (≤0.6% combined total) or the pre-RT lung tumor (≤1.6% combined total). Additionally, the extent of the TIL repertoire and its binding-associated divergence from the peripheral blood was greatest in the irradiated (right) lung tumor post RT, suggesting a direct link between the evolution of trans-acting immunity and antigen-driven immunogenicity at that site. Of note, comparative WES of the initial fibrosarcoma and subsequent lung tumors identified the same EML4-NTRK3 fusion, validating their metastatic relationship, although the number of coding mutations had expanded upon recurrence. Conclusion: Using qmIF and TCRseq, we have extensively characterized immune infiltration in the tumor microenvironment prior to and following metastasis and RT, in the first reported case of AbE in a pediatric tumor. Our data show evidence of immune stimulation elicited by RT, and antitumor T-cell specificities are shared inside and outside of the radiation field. These data offer insight into AbE and how combination of radiation and immunotherapy may be useful to induce response in pediatric tumors. Citation Format: Robyn D. Gartrell, Jennifer S. Sims, Sunjay M. Barton, Angela Kadenhe-Chiweshe, Filemon Dela Cruz, Andrew T. Turk, Andrew L. Kung, Jeffrey N. Bruce, Yvonne M. Saenger, Darrell J. Yamashiro, Eileen P. Connolly. Multiparameter profiling of abscopal effect (AbE) in a pediatric fibrosarcoma with EML4-NTRK3 fusion [abstract]. In: Proceedings of the AACR Special Conference: Pediatric Cancer Research: From Basic Science to the Clinic; 2017 Dec 3-6; Atlanta, Georgia. Philadelphia (PA): AACR; Cancer Res 2018;78(19 Suppl):Abstract nr B31.

Clear cell sarcoma of the kidney (CCSK) is uncommon pediatric renal tumor and can present a significant therapeutic challenge in those patients whose tumors spread beyond the kidney. Thus, identifying potential novel targets for treatment may be clinically important. Clear cell sarcoma of the kidney is characterized by a unique vascular pattern, in which nests of tumor cells are separated by regularly-spaced, fine fibrovascular septa. This distinctive histopathology raises the possibility that understanding the factors which drive angiogenesis in CCSK tumors may suggest new therapeutic targets. Here, we describe a case of CCSK and present immunohistochemical studies of its vasculature.

An association between neuroblastoma and opsoclonus-myoclonus syndrome (OMS) was described as early as 1927 within the first report on the transformation of malignant neuroblastoma to a benign ganglioneuroma. It was not recognized at that time nor was it appreciated in the subsequent follow-up report on the same patient in 1959. Myoclonic encephalopathy of infancy, an alternative name for OMS, was described by a pediatric neurologist in 1962; however, its connection to neuroblastoma was not known. It was only in 1968 that the association between these two conditions was first reported. The neuroblastoma tumors associated with OMS are almost all small, stage I-II with no associated MYCN amplification or metastases. OMS occurs in 2-3% of patients with neuroblastoma, but neuroblastoma is found in as many as 50% of children who present with OMS. Nearly 100% of the children with neuroblastoma associated with OMS survive, and this has led to speculation that the OMS is a result of an autoimmune process, not metastases. Affected children are treated with steroids, ACTH, or intravenous immunoglobulin, but many have persistent neurologic and developmental deficits. Using the original case reported in 1927, we summarize a century of literature in this review on OMS and its association with neuroblastoma.

Notch signaling is required for vascular development and tumor angiogenesis. Although inhibition of the Notch ligand Delta-like 4 can restrict tumor growth and disrupt neovasculature, the effect of inhibiting Notch receptor function on angiogenesis has yet to be defined. In this study, we generated a soluble form of the Notch1 receptor (Notch1 decoy) and assessed its effect on angiogenesis in vitro and in vivo. Notch1 decoy expression reduced signaling stimulated by the binding of three distinct Notch ligands to Notch1 and inhibited morphogenesis of endothelial cells overexpressing Notch4. Thus, Notch1 decoy functioned as an antagonist of ligand-dependent Notch signaling. In mice, Notch1 decoy also inhibited vascular endothelial growth factor–induced angiogenesis in skin, establishing a role for Notch receptor function in this process. We tested the effects of Notch1 decoy on tumor angiogenesis using two models: mouse mammary Mm5MT cells overexpressing fibroblast growth factor 4 (Mm5MT-FGF4) and NGP human neuroblastoma cells. Exogenously expressed FGF4 induced Notch ligand expression in Mm5MT cells and xenografts. Notch1 decoy expression did not affect tumorigenicity of Mm5MT-FGF4 cells in vitro but restricted Mm5MT-FGF4 xenograft growth in mice while markedly impairing neoangiogenesis. Similarly, Notch1 decoy expression did not affect NGP cells in vitro but disrupted vessels and decreased tumor viability in vivo. These results strongly suggest that Notch receptor signaling is required for tumor neoangiogenesis and provides a new target for tumor therapy. [Cancer Res 2008;68(12):4727–35]

Purpose We conducted a pediatric phase I trial of the vascular endothelial growth factor (VEGF)–neutralizing antibody bevacizumab (BV). Primary aims included estimating the maximum-tolerated dose (MTD) and determining the dose-limiting toxicities (DLTs), pharmacokinetics, and biologic effects of BV in children with cancer. Patients and Methods BV (5, 10, 15 mg/kg) was administered intravenously every 2 weeks in 28-day courses to children with refractory solid tumors. Results Twenty-one patients enrolled, 20 (median age, 13 years) were eligible, and 18 completed one course and were fully assessable for toxicity. A total of 67 courses were administered (median, three courses per patient; range, one to 16 courses). Treatment was well tolerated with no DLTs observed. Non-DLTs included infusional reaction, rash, mucositis, proteinuria, and lymphopenia. Increases in systolic and diastolic blood pressure not meeting Common Terminology Criteria for Adverse Events (CTCAEv3) pediatric-specific criteria for hypertension were observed. There was no hemorrhage or thrombosis. Growth perturbation was not detected in a limited sample over the first course. The serum exposure to BV as measured by area under the concentration-time curve (AUC) seemed to increase in proportion to dose. The median clearance of BV was 4.1 mL/d/kg (range, 3.1 to 15.5 mL/d/kg), and the median half-life was 11.8 days (range, 4.4 to 14.6 days). No objective responses were observed. Exploratory analyses on circulating endothelial mobilization and viability are consistent with the available adult data. Conclusion BV is well tolerated in children. Phase II pediatric studies of BV in combination with chemotherapy in dosing schedules similar to adults are planned.

Classically known for its role in development and differentiation, an oncogenic role for Notch was first discovered for T-cell acute lymphoblastic leukemia [1], and later extended to a variety of tumors [2]. Notch signaling has been mechanistically linked to regulate tumor growth, angiogenesis and metastatic progression. Consequently, in the last decade we have witnessed multiple therapeutic approaches to target Notch, including γ-secretase inhibitors (GSIs), which block cleavage and activation of Notch receptors, soluble Notch decoy receptors, and antibodies to either Notch receptors or ligands [3]. However due to widespread function and highly pleotropic nature, Notch inhibition raises the possibility of unanticipated adverse effects in host tissues including gastrointestinal toxicity after GSI treatment or formation of vascular tumors after DLL4 ligand blockade [4, 5]. Our current work published in the journal Cancer Research, has raised one such concern about Notch inhibition therapy [6]. Inhibition of Notch with the soluble receptor Notch1 decoy (N1D), markedly increased liver metastatic burden, of neuroblastoma and breast cancer cells lines after intrarenally or intracardiac injection (spontaneous vs. experimental metastasis models). Additionally, pharmacologic inhibition of Notch with the GSI PF-03084014, while having no effect on primary tumor growth, significantly increased liver metastases. Interestingly, we did not observe in any of the experimental models, an increase in metastasis to other organs including spleen, kidney and bone marrow, suggesting that Notch blockade specifically promotes metastases to the liver. Our studies determined that the increased liver metastases are a result of a direct effect of Notch inhibition on host liver, with the loss of tumor cell-intrinsic Notch1 signaling inconsequential. Tumor cells expressing N1D showed no change in prometastatic characteristics such as migration and invasion. Loss of Notch signaling in tumor cells by knocking down Notch1 also failed to promote liver metastases. However, intracardiac injection of tumor cells into immunodeficient (Rag2−/−, Il2rg−/−) Notch1 +/− mice, where host Notch signaling was deficient due to heterozygous deletion of Notch, demonstrated a marked increase in hepatic metastases, indicating that Notch1 signaling acts as metastatic suppressor in the liver microenvironment. The liver microenvironment is composed of a variety of cell types, including sinusoidal endothelial cells (SECs), hepatic stellate cells (HSCs), and macrophage Kupffer cells, which express Notch receptors and ligands [7]. One striking characteristic of the liver metastases promoted by Notch blockade was their markedly increased vascularity. We observed a significant increase in the sprouting of hepatic SECs into early stage, micrometastases. Utilizing Notch decoy variants that are specific for the Notch ligands DLL and JAGGED, we determined that the increased sprouting was due to blockade of DLL on SECs. In the later stage, macrometastases, there was a marked increase in larger diameter vasculature that was α-smooth muscle actin (+), indicating activation and recruitment of HSCs into the vasculature. This was likely due to the loss of tumor derived JAG1, as indicated by blockade with a JAGGED specific decoy. Our data support a concept of Notch signaling maintaining the quiescence of SECs via DLL and HSCs via JAG1, with disruption of this quiescence promoting a prometastatic environment. Figure 1 Notch inhibition activates sinusoidal endothelial cells and hepatic stellate cells to promote hepatic metastases. Our study was primarily focused on Notch1, however, it would be interesting to investigate if other Notch receptors have similar roles since they are reported to regulate SEC and HSC function to maintain liver home-ostasis [7]. Given that metastasis progression is a multistep process it would also be interesting to investigate if Notch signaling regulates other steps including survival against host innate immunity. Nonetheless, our study shows that Notch inhibition results in pathological activation of liver stromal cells creating a host microenvironment favorable for metastases. Given that Notch components have emerged as potential therapeutic targets and Notch inhibitors are entering clinical trials these findings point out the potentially serious implication of Notch inhibition therapy.

Purpose To characterize the effects of high-dose radiation therapy (HDRT) on neuroblastoma tumor vasculature, including the endothelial cell (EC)–pericyte interaction as a potential target for combined treatment with antiangiogenic agents. Methods and Materials The vascular effects of radiation therapy were examined in a xenograft model of high-risk neuroblastoma. In vivo 3-dimensional contrast-enhanced ultrasonography (3D-CEUS) imaging and immunohistochemistry (IHC) were performed. Results HDRT significantly reduced tumor blood volume 6 hours after irradiation compared with the lower doses used in conventionally fractionated radiation. There was a 63% decrease in tumor blood volume after 12-Gy radiation compared with a 24% decrease after 2 Gy. Analysis of tumor vasculature by lectin angiography showed a significant loss of small vessel ends at 6 hours. IHC revealed a significant loss of ECs at 6 and 72 hours after HDRT, with an accompanying loss of immature and mature pericytes at 72 hours. Conclusions HDRT affects tumor vasculature in a manner not observed at lower doses. The main observation was an early reduction in tumor perfusion resulting from a reduction of small vessel ends with a corresponding loss of endothelial cells and pericytes.

To understand genetic and epigenetic pathways in Wilms' tumors, we carried out a genome scan for loss of heterozygosity (LOH) using Affymetrix 10K single nucleotide polymorphism (SNP) chips and supplemented the data with karyotype information. To score loss of imprinting (LOI) of the IGF2 gene, we assessed DNA methylation of the H19 5′ differentially methylated region (DMR). Few chromosomal regions other than band 11p13 (WT1) were lost in Wilms' tumors from Denys-Drash and Wilms' tumor-aniridia syndromes, whereas sporadic Wilms' tumors showed LOH of several regions, most frequently 11p15 but also 1p, 4q, 7p, 11q, 14q, 16q, and 17p. LOI was common in the sporadic Wilms' tumors but absent in the syndromic cases. The SNP chips identified novel centers of LOH in the sporadic tumors, including a 2.4-Mb minimal region on chromosome 4q24-q25. Losses of chromosomes 1p, 14q, 16q, and 17p were more common in tumors presenting at an advanced stage; 11p15 LOH was seen at all stages, whereas LOI was associated with early-stage presentation. Wilms' tumors with LOI often completely lacked LOH in the genome-wide analysis, and in some tumors with concomitant 16q LOH and LOI, the loss of chromosome 16q was mosaic, whereas the H19 DMR methylation was complete. These findings confirm molecular differences between sporadic and syndromic Wilms' tumors, define regions of recurrent LOH, and indicate that gain of methylation at the H19 DMR is an early event in Wilms' tumorigenesis that is independent of chromosomal losses. The data further suggest a biological difference between sporadic Wilms' tumors with and without LOI.

When first conceived, antiangiogenic therapy for cancer offered the possibility of universal efficacy, low toxicity, and little possibility of resistance. Blockade of the vascular endothelial growth factor (VEGF) pathway has yielded the most promising results both in animal models and in patients. However, resistance to VEGF blockade has been found even when given in combination with chemotherapy or other antiangiogenic agents. This resistance is associated with remodeled vasculature and with increased expression of angiogenic factors, such as PDGF-B and angiopoietin-1, which may contribute to vessel stabilization. Future efforts must be directed towards the identification of factors associated with vascular remodeling in order to improve the efficacy of antiangiogenic therapy.

TNP-470 (AGM-1470), an analogue of fumagillin, was one of the first molecules proposed to have antiangiogenic properties. This concept was based on its ability to inhibit both endothelial proliferation in vitro and tumor growth in vivo in a number of xenograft models. Yet, subsequent investigations indicated that the biochemical activities associated with TNP-470 are not selective for endothelial cells. Moreover, recent evidence suggests that this agent inhibits tumor growth in vivo, but without a corresponding decrease in angiogenesis. Therefore, we performed a detailed comparison of TNP-470 to a validated antiangiogenic agent, a VEGF inhibitor termed VEGF-Trap, using a xenograft model of Wilms tumor. Treatment with TNP-470 for 5 weeks significantly suppressed xenograft growth (83%). Surprisingly, this inhibition was not associated with a decrease in angiogenesis, but instead with an increase in tiny neovessels. To determine whether this was a direct effect of TNP-470 on tumor vessels, we examined its effect in a short-term assay using large tumors with established vasculature. In contrast to treatment with VEGF-Trap, which led to rapid vessel regression and tumor hypoxia, tumors exposed to TNP-470 for 1 day displayed increased capillary sprouting, with significantly increased microvessel density, vessel length, and branch points. TNP-470 did not induce tumor hypoxia as demonstrated by minimal pimonidazole staining and VEGF expression. TNP-470 did, however, cause a marked increase in apoptosis of tumor cells. Our results indicate that the antitumor effects of TNP-470 cannot be attributed to prevention of neoangiogenesis, but instead to its direct action on tumor cells.

The potential for avoiding acquired resistance to therapy has been proposed as one compelling theoretical advantage of antiangiogenic therapy based on the normal genetic status of the target vasculature. However, previous work has demonstrated that tumors may resume growth after initial inhibition if antiangiogenic blockade is continued for an extended period. The mechanisms of this recurrent growth are unclear. In these studies, we characterized molecular changes in vasculature during apparent resumption of xenograft growth after initial inhibition by vascular endothelial growth factor blockade, “metronome” topotecan chemotherapy, and combined agents in a xenograft murine model of human Wilms' tumor. Tumors that grew during antiangiogenic blockade developed as viable clusters surrounding strikingly remodeled vessels. These vessels displayed significant increases in diameter and active proliferation of vascular mural cells and expressed platelet-derived growth factor-B, a factor that functions to enhance vascular integrity via stromal cell recruitment. In addition, remodeled vessels were marked by expression of ephrinB2, required for proper assembly of stromal cells into vasculature. Thus, enhanced vascular stability appears to characterize tumor vessel response to chronic antiangiogenesis, features that potentially support increased perfusion and recurrent tumor growth.

It is widely accepted that tumour growth beyond a few cubic millimetres cannot occur without the induction of a new vascular supply. Inhibiting the development of new blood vessels (antiangiogenesis) is a potential approach to cancer therapy that has attracted interest in recent years. In theory, this approach should be relatively selective for tumour cells. The endothelial cells which form new vascular networks in tumours are responding to angiogenic stimuli produced by the tumour, but are themselves genetically normal. Endothelium in normal tissue, by contrast, is usually quiescent. Vascular endothelial growth factor (VEGF) is the best-characterised pro-angiogenic factor. It is virtually ubiquitous in human tumours, and higher levels have been correlated with more aggressive disease. Effective blockade of the VEGF pathway has been demonstrated with multiple agents: neutralising antibody, receptor tyrosine kinase inhibitors, and ribozyme or antisense molecules targeting expression. Promising preclinical data document the potential of these agents for tumour growth inhibition and even tumour regression, yet translation of novel therapeutics targeting the VEGF pathway to the clinic has proved a substantial challenge in itself. While showing clear evidence of antitumour activity over a broad spectrum of experimental tumours, the proper selection, dose, timing and sequence of anti-VEGF treatment in human cancer is not at all obvious. Classic Phase I dose escalation trial design may need to be modified, as higher doses may not be optimal in all patients or for all tumours. In addition, alternate or secondary biological end points (e.g., non-progression) may be needed for early phase studies to document true activity, so as not to abandon effective agents. Recent studies of the neutralising antibody bevacizumab, and small molecule tyrosine kinase inhibitor SU5416, demonstrate that, while unlikely to be effective as monotherapy, incorporation of VEGF blockade into cytotoxic regimens may increase overall response rates. However, incorporation may also produce new toxicities, including thromboembolic complications and bleeding. Newer oral agents, such as SU6668, SU11248, PTK787/ZK222584 and ZD6474, are particularly interesting for their potential for chronic therapy. Future clinical trials are likely to build on past experience with stricter entry criteria, supportive care guidelines and the use of surrogate markers.

Background: The authors have shown previously that experimental neuroblastoma is partially inhibited (48%) by antivascular endothelial growth factor (anti-VEGF) antibody. The topoisomerase-I inhibitor, topotecan, has been shown to have antiangiogenic activity when administered in a low-dose, high-frequency regimen. We hypothesized that combining topotecan with anti-VEGF would suppress neuroblastoma more effectively than either agent alone. Methods: A total of 10 6 neuroblastoma cells were implanted intrarenally in athymic mice. Animals received vehicle, topotecan, anti-VEGF, or topotecan plus anti-VEGF (n = 9, 20, 20, 20, respectively). All control and half the treated mice were killed at 6 weeks. Remaining (rebound) mice were maintained without treatment for 3 more weeks. Patterns of vasculature and apoptosis were determined immunohistochemically. Results: Tumor weights at 6 weeks were reduced significantly in topotecan-only (0.07g) and combination-treated animals (0.08 g), compared with controls or anti-VEGF[ndash ]treated mice (1.18 g, 0.53 g; P [lt ] .0007, all). At 9 weeks, rebound tumor weights were greatest in anti-VEGF (2.82 g), intermediate in topotecan (1.82 g), and least in combination-treated animals (1.47 g); however, the only significant difference was between anti-VEGF and combination therapy ( P = 0.04). All treated tumors were vascularized sparsely in comparison with controls at 6 weeks, but exhibited brisk neoangiogenesis at 9 weeks. Conclusions: Topotecan either with or without anti-VEGF antibody significantly suppresses neuroblastoma xenograft growth in comparison with controls or anti-VEGF antibody alone. Combining topotecan with anti-VEGF antibody significantly inhibited rebound tumor growth in comparison with anti-VEGF antibody alone. Combination therapy may improve durability of antiangiogenic inhibition of neuroblastoma.