Sanjeev A. Vasudevan

Diagnostic Yield of Clinical Tumor and Germline Whole-Exome Sequencing for Children With Solid Tumors.

Importance Whole-exome sequencing (WES) has the potential to reveal tumor and germline mutations of clinical relevance, but the diagnostic yield for pediatric patients with solid tumors is unknown. Objective To characterize the diagnostic yield of combined tumor and germline WES for children with solid tumors. Design Unselected children with newly diagnosed and previously untreated central nervous system (CNS) and non-CNS solid tumors were prospectively enrolled in the BASIC3 study at a large academic childrens hospital during a 23-month period from August 2012 through June 2014. Blood and tumor samples underwent WES in a certified clinical laboratory with genetic results categorized on the basis of perceived clinical relevance and entered in the electronic health record. Main Outcomes and Measures Clinical categorization of somatic mutations; frequencies of deleterious germline mutations related to patient phenotype and incidental medically-actionable mutations. Results Of the first 150 participants (80 boys and 70 girls, mean age, 7.4 years), tumor samples adequate for WES were available from 121 patients (81%). Somatic mutations of established clinical utility (category I) were reported in 4 (3%) of 121 patients, with mutations of potential utility (category II) detected in an additional 29 (24%) of 121 patients. CTNNB1 was the gene most frequently mutated, with recurrent mutations in KIT, TSC2, and MAPK pathway genes (BRAF, KRAS, and NRAS) also identified. Mutations in consensus cancer genes (category III) were found in an additional 24 (20%) of 121 tumors. Fewer than half of somatic mutations identified were in genes known to be recurrently mutated in the tumor type tested. Diagnostic germline findings related to patient phenotype were discovered in 15 (10%) of 150 cases: 13 pathogenic or likely pathogenic dominant mutations in adult and pediatric cancer susceptibility genes (including 2 each in TP53, VHL, and BRCA1), 1 recessive liver disorder with hepatocellular carcinoma (TJP2), and 1 renal diagnosis (CLCN5). Incidental findings were reported in 8 (5%) of 150 patients. Most patients harbored germline uncertain variants in cancer genes (98%), pharmacogenetic variants (89%), and recessive carrier mutations (85%). Conclusions and Relevance Tumor and germline WES revealed mutations in a broad spectrum of genes previously implicated in both adult and pediatric cancers. Combined reporting of tumor and germline WES identified diagnostic and/or potentially actionable findings in nearly 40% of newly diagnosed pediatric patients with solid tumors.

Aurora A is a negative prognostic factor and a new therapeutic target in human neuroblastoma

We studied expression of the Aurora A gene and its clinical significance in a cohort of neuroblastoma patients. In addition, we investigated the antitumor activity of MLN8054, a novel small-molecule inhibitor of Aurora A kinase, on cultured NB cell lines in vitro. Aurora A mRNA expression was assessed by quantitative real-time PCR in tumor tissue specimens from 67 patients at diagnosis and in 9 human neuroblastoma cell lines. Western blot assays for Aurora A protein were done on tumor tissue of 53 patients. The results were correlated with various prognostic factors of neuroblastoma. Aurora A mRNA and protein expression were identified in 9 of 9 neuroblastoma cell lines. Overexpression of Aurora A mRNA in neuroblastoma tumor tissue is associated with high risk (P = 0.019), high-stage (International Neuroblastoma Staging System III and IV) tumors (P = 0.007), unfavorable histology (P = 0.007), MYCN amplification (P = 0.017), disease relapse (P = 0.019), and decreased progression-free survival (P < 0.0001) but not correlated with the age at diagnosis (P = 0.877). Similarly, Aurora A protein expression also significantly correlated with high risk (P = 0.011), high stage (P = 0.0028), unfavorable histology (P = 0.0006), MYCN amplification (P = 0.0029), and disease relapse (P = 0.044). Small interfering RNA–mediated knockdown of the endogenous Aurora A gene causes a proliferation defect and enhances chemosensitivity in human neuroblastoma cell lines. In support of these observations, the Aurora A kinase inhibitor, MLN8054, markedly inhibited growth of cultured neuroblastoma cell lines through an apoptosis-dependent pathway. Overexpression of Aurora A is associated with disease progression in neuroblastoma. Inhibition of this kinase is a promising modality for neuroblastoma treatment. [Mol Cancer Ther 2009;8(8):2461–9]

USP7 inhibitor P22077 inhibits neuroblastoma growth via inducing p53-mediated apoptosis

Neuroblastoma (NB) is a common pediatric cancer and contributes to more than 15% of all pediatric cancer-related deaths. Unlike adult tumors, recurrent somatic mutations in NB, such as tumor protein 53 (p53) mutations, occur with relative paucity. In addition, p53 downstream function is intact in NB cells with wild-type p53, suggesting that reactivation of p53 may be a viable therapeutic strategy for NB treatment. Herein, we report that the ubiquitin-specific protease 7 (USP7) inhibitor, P22077, potently induces apoptosis in NB cells with an intact USP7-HDM2-p53 axis but not in NB cells with mutant p53 or without human homolog of MDM2 (HDM2) expression. In this study, we found that P22077 stabilized p53 by inducing HDM2 protein degradation in NB cells. P22077 also significantly augmented the cytotoxic effects of doxorubicin (Dox) and etoposide (VP-16) in NB cells with an intact USP7-HDM2-p53 axis. Moreover, P22077 was found to be able to sensitize chemoresistant LA-N-6 NB cells to chemotherapy. In an in vivo orthotopic NB mouse model, P22077 significantly inhibited the xenograft growth of three NB cell lines. Database analysis of NB patients shows that high expression of USP7 significantly predicts poor outcomes. Together, our data strongly suggest that targeting USP7 is a novel concept in the treatment of NB. USP7-specific inhibitors like P22077 may serve not only as a stand-alone therapy but also as an effective adjunct to current chemotherapeutic regimens for treating NB with an intact USP7-HDM2-p53 axis.

Dual-specificity phosphatase 26 is a novel p53 phosphatase and inhibits p53 tumor suppressor functions in human neuroblastoma

Chemoresistance is a major cause of treatment failure and poor outcome in neuroblastoma. In this study, we investigated the expression and function of dual-specificity phosphatase 26 (DUSP26), also known as mitogen-activated protein kinase phophatase-8, in human neuroblastoma. We found that DUSP26 was expressed in a majority of neuroblastoma cell lines and tissue specimens. Importantly, we found that DUSP26 promotes the resistance of human neuroblastoma to doxorubicin-induced apoptosis by acting as a p53 phosphatase to downregulate p53 tumor suppressor function in neuroblastoma cells. Inhibiting DUSP26 expression in the IMR-32 neuroblastoma cell line enhanced doxorubicin-induced p53 phosphorylation at Ser20 and Ser37, p21, Puma, Bax expression as well as apoptosis. In contrast, DUSP26 overexpression in the SK-N-SH cell line inhibited doxorubicin-induced p53 phosphorylation at Ser20 and Ser37, p21, Puma, Bax expression and apoptosis. Using in vitro and in vivo assays, we found that DUSP26 binds to p53 and dephosphorylates p53 at Ser20 and Ser37. In this report, we show that DUSP26 functions as a p53 phosphatase, which suppresses downstream p53 activity in response to genotoxic stress. This suggests that inhibition of this phosphatase may increase neuroblastoma chemosensitivity and DUSP26 is a novel therapeutic target for this aggressive pediatric malignancy.

Gene Profiling of High Risk Neuroblastoma

Neuroblastoma, a cancer of young children, is well known for its diverse pattern of presentation. Approximately one-half of children have localized tumors that can be cured with surgery alone. The remaining children have widespread metastatic disease or quite large, aggressive, localized tumors. These children have a poor long-term survival rate of approximately 30%. We review the prognostically significant histologic and molecular features of high risk neuroblastoma and propose an algorithm to dissect further the differentially expressed genes that define the phenotype of this disease. Over the past 25 years, much effort has gone into establishing reliable prognostic indicators of high risk disease. For neuroblastoma, age, stage, and histopathology have time and again correlated well with outcomes. Chromosomal number, or ploidy, and amplification of the MYCN oncogene have proved to be equally as important and are commonly used to stratify patient risk. Other potentially lucrative markers include chromosome 1p deletion, chromosome 17q gain, receptor tyrosine kinases A and B (trk-A, trk-B), CD44, CXCR4, and multidrug resistance associated protein (MRP). With the onset of new technology, expression microarrays are now being used to profile advanced-stage neuroblastoma on a larger scale. Genes particular to cell cycle control, DNA/RNA replication, ribosomal synthesis, neuronal differentiation, and intracellular/extracellular signal transduction have been identified through differential expression analysis. We present our research on the MYCN transcription factor and target gene, MCM7, to show the utility of this approach.

Primary malignant pancreatic neoplasms in children and adolescents: A 20 year experience ☆

BACKGROUND Malignant pancreatic neoplasms in children and adolescents are rare. The clinical presentation, pathologic characteristics, management, and outcomes at two institutions are discussed. METHODS We retrospectively reviewed all pediatric patients (age <= 18 years) treated for malignant pancreatic neoplasms at two institutions between 1991 and 2011. RESULTS Thirty-one patients were identified with median age of 14.7 years (4-18 years). The most common histology was solid pseudopapillary tumor (SPT) (n=22, 71%) followed by neuroendocrine tumors (n=4, 13%), pancreatoblastoma (n=4, 13%), and one unclassified spindle cell neoplasm (3%). Most patients presented with abdominal pain (n=22, 71%). Complications included pancreatic leak, pseudocyst formation, pancreatitis, pancreatic insufficiency, and small bowel obstruction. The overall 1- and 5-year survival was 96% (95% CI 74%-99%) and 78% (95% CI 43%-93%). Median follow-up among patients alive at the end of follow-up was 20 months (<1 month-16.2 years). Patients with SPT had better overall survival compared to patients with neuroendocrine tumors or pancreatoblastomas (Log-rank; p=0.0143). CONCLUSION The majority of pediatric and adolescent patients present with SPTs which are usually resectable and associated with an excellent prognosis. Other histologic subtypes more often present with distant metastases and portend a worse prognosis.

A small-molecule inhibitor of UBE2N induces neuroblastoma cell death via activation of p53 and JNK pathways.

Neuroblastoma (NB) is the most common extracranial neoplasm in children. In NB, loss of p53 function is largely due to cytoplasmic sequestration rather than mutation. Ubiquitin-conjugating enzyme E2 N (UBE2N), also known as Ubc13, is an E2 ubiquitin-conjugating enzyme that promotes formation of monomeric p53 that results in its cytoplasmic translocation and subsequent loss of function. Therefore, inhibition of UBE2N may reactivate p53 by promoting its nuclear accumulation. Here, we show that NSC697923, a novel UBE2N inhibitor, exhibits potent cytotoxicity in a panel of NB cell lines evidenced by its ability to induce apoptosis. In p53 wild-type NB cells, NSC697923 induced nuclear accumulation of p53, which led to its increased transcriptional activity and tumor suppressor function. Interestingly, in p53 mutant NB cells, NSC697923 induced cell death by activating JNK pathway. This effect was reversible by blocking JNK activity with its selective inhibitor, SP600125. More importantly, NSC697923 impeded cell growth of chemoresistant LA-N-6 NB cell line in a manner greater than conventional chemotherapy drugs doxorubicin and etoposide. NSC697923 also revealed in vivo antitumor efficacy in NB orthotopic xenografts. Taken together, our results suggest that UBE2N is a potential therapeutic target in NB and provide a basis for the rational use of UBE2N inhibitors like NSC697923 as a novel treatment option for NB patients.

TAK1 inhibitor 5Z-7-oxozeaenol sensitizes neuroblastoma to chemotherapy.

Treatment failure in high risk neuroblastoma is largely due to development of chemoresistance. NF-κB activation is one of the resistance mechanisms for cancer cells to escape from chemotherapy-induced cell-death. TAK1 is an essential component in genotoxic stresses-induced NF-κB activation; however, the role of TAK1 in the development of chemoresistance in neuroblastoma remains unknown. Using a panel of neuroblastoma cell lines, we found that TAK1 inhibitor 5Z-7-oxozeaenol significantly augmented the cytotoxic effects of doxorubicin (Dox) and etoposide (VP-16) on neuroblastoma cell lines. TAK1 inhibition also enhanced the inhibitory effect of Dox and VP-16 on anchorage-independent growth. Treatment of neuroblastoma cells with 5Z-7-oxozeaenol blocked Dox- and VP16-induced NF-κB activation and enhanced Dox- and VP16-induced apoptosis. Moreover, 5Z-7-oxozeaenol was able to overcome the established chemoresistance in LA-N-6 neuroblastoma cells. Using an orthotopic neuroblastoma mouse model, we found that 5Z-7-oxozeaenol significantly enhanced chemotherapeutic efficacy in vivo. Together, our results provide a proof-of-concept that TAK1 inhibition significantly increases the sensitivity of neuroblastoma cells to chemotherapy-induced cell-death and can serve as an effective adjunct to current chemotherapeutic regimens for high risk diseases.

MTOR ATP-competitive inhibitor INK128 inhibits neuroblastoma growth via blocking mTORC signaling

High-risk neuroblastoma often develops resistance to high-dose chemotherapy. The mTOR signaling cascade is frequently deregulated in human cancers and targeting mTOR signaling sensitizes many cancer types to chemotherapy. Here, using a panel of neuroblastoma cell lines, we found that the mTOR inhibitor INK128 showed inhibitory effects on both anchorage-dependent and independent growth of neuroblastoma cells and significantly enhanced the cytotoxic effects of doxorubicin (Dox) on these cell lines. Treatment of neuroblastoma cells with INK128 blocked the activation of downstream mTOR signaling and enhanced Dox-induced apoptosis. Moreover, INK128 was able to overcome the established chemoresistance in the LA-N-6 cell line. Using an orthotopic neuroblastoma mouse model, we found that INK128 significantly inhibited tumor growth in vivo. In conclusion, we have shown that INK128-mediated mTOR inhibition possessed substantial antitumor activity and could significantly increase the sensitivity of neuroblastoma cells to Dox therapy. Taken together, our results indicate that using INK128 can provide additional efficacy to current chemotherapeutic regimens and represent a new paradigm in restoring drug sensitivity in neuroblastoma.

Parathyroid carcinoma in more than 1,000 patients: A population-level analysis.

BACKGROUND Parathyroid carcinoma (PC) is a rare malignancy with a moderate prognosis. The staging system, prognostic indicators, and optimal surgical management are still under debate. This large cohort explores prognostic factors for PC. METHODS 1,022 cases of PC in the 1998-2011 National Cancer Data Base that underwent surgery were examined for predictors of lower overall survival (OS) and relative risk (RR) of death at 5 years. RESULTS The 5-year OS was 81.1% in 528 patients with ≥ 60 months of follow-up. The overall cohort was mainly non-Hispanic (96.5%), white (77.4%), and insured (94.3%), with a median age of 57 years. Mean OS was lower and RR of death greater in older (P < .001), black (P = .007) patients with a secondary malignancy (P = .015) and ≥ 2 comorbidities (P = .005), whose surgical specimen had positive surgical margins (P = .026) or positive lymph nodes (P < .001). Multivariate cox regression demonstrated that positive lymph nodes (hazard ratio [HR], 6.47; 95% CI, 1.81-23.11) and older age (HR, 2.35; 95% CI, 1.25-4.43) were associated with lower OS. CONCLUSION PC is a rare malignancy with a 5-year OS of 81.1%. Positive lymph nodes and older age predict lower OS and an increased risk of death.