Abstract 3967: BET protein inhibitor OTX015 has selective anti-tumoral activity in preclinical models of MYCN- amplified neuroblastoma

Neuroblastomas harboring MYCN amplifications are highly lethal tumors. They are often resistant to standard chemotherapy, yet the development of targeted therapies has been hampered by a lack of compounds targeting MYCN. We and others have recently discovered that targeting BET bromodomain proteins, especially BRD4, disrupts epigenetic regulation of MYCN and its targets in neuroblastoma. OTX015, a new BET protein inhibitor, is the first lead into clinical phase I/II trials and has shown promising pharmacological properties in adults. Here, we investigate the preclinical efficacy of OTX015 in MYCN-amplified neuroblastoma.

We tested in vitro OTX015 efficacy in 6 established neuroblastoma (NB) cell lines. We performed cell cycle profiling and analyzed markers for apoptosis and proliferation after 72h-treatment at 500 nM OTX015. The effect of OTX015 on MYCN expression and global MYCN-associated transcriptional activity was assessed by quantitative real time PCR and gene expression microarray profiling, respectively. In vivo efficacy of orally OTX015 was assessed in IMR5 xenografts, a N-MYC driven NB model, using diffent treatment schedules (50mg/kg/day, 100mg/kg/day and 50mg/kg/bidaily).

Treatment of MYCN-amplified neuroblastoma cells with OTX015 resulted in decreased cell viability, induction of apoptosis and reduced proliferation. Concentrations of 50% inhibition (IC50) ranged between 50nM and 500nM. OTX015 treatment also resulted in an increase in the percentage of cells in G1 phase. This corresponded with the downregulation of MYCN mRNA and protein levels and MYCN-associated transcriptional activity. Interestigly, MYCN amplified cell lines were most sensitive to OTX015 treatment. In contrast, no effect was observed with OTX15 on normal cells. In vivo treatment with OTX015, significantly decreased tumor burden after 4 weeks and prolonged survival as compared to vehicle-treated mice. These preclinical findings highlight the promise of BET bromodomain inhibitors as novel agents for MYCN-driven neuroblastomas and serve as rationale to move forward with early phase clinical trials for children with these highly lethal tumors.

Citation Format: Johannes H. Schulte, Kristina Althoff, Emma Bell, Andrea Odersky, Anneleen Beckers, Frank Speleman, Simon Schäfers, Alexander Schramm, Angelika Eggert, Frank Westermann, Eugenia Riveiro, Esteban Cvitkovic, Anton Henssen. BET protein inhibitor OTX015 has selective anti-tumoral activity in preclinical models of MYCN- amplified neuroblastoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3967. doi:10.1158/1538-7445.AM2014-3967

A Cre-conditional MYCN-driven neuroblastoma mouse model as an improved tool for preclinical studies

Neuroblastoma, a childhood cancer that originates from neural crest-derived cells, is the most common deadly solid tumor of infancy. Amplification of the MYCN oncogene, which occurs in approximately 20–25% of human neuroblastomas, is the most prominent genetic marker of high-stage disease. The availability of valid preclinical in vivo models is a prerequisite to develop novel targeted therapies. We here report on the generation of transgenic mice with Cre-conditional induction of MYCN in dopamine β-hydroxylase-expressing cells, termed LSL-MYCN;Dbh-iCre. These mice develop neuroblastic tumors with an incidence of >75%, regardless of strain background. Molecular profiling of tumors revealed upregulation of the MYCN-dependent miR-17–92 cluster as well as expression of neuroblastoma marker genes, including tyrosine hydroxylase and the neural cell adhesion molecule 1. Gene set enrichment analyses demonstrated significant correlation with MYC-associated expression patterns. Array comparative genome hybridization showed that chromosomal aberrations in LSL-MYCN;Dbh-iCre tumors were syntenic to those observed in human neuroblastomas. Treatment of a cell line established from a tumor derived from a LSL-MYCN;Dbh-iCre mouse with JQ1 or MLN8237 reduced cell viability and demonstrated oncogene addiction to MYCN. Here we report establishment of the first Cre-conditional human MYCN-driven mouse model for neuroblastoma that closely recapitulates the human disease with respect to tumor localization, histology, marker expression and genomic make up. This mouse model is a valuable tool for further functional studies and to assess the effect of targeted therapies.

miRBase Tracker: keeping track of microRNA annotation changes

Since 2002, information on individual microRNAs (miRNAs), such as reference names and sequences, has been stored in miRBase, the reference database for miRNA annotation. As a result of progressive insights into the miRNome and its complexity, miRBase underwent addition and deletion of miRNA records, changes in annotated miRNA sequences and adoption of more complex naming schemes over time. Unfortunately, miRBase does not allow straightforward assessment of these ongoing miRNA annotation changes, which has resulted in substantial ambiguity regarding miRNA identity and sequence in public literature, in target prediction databases and in content on various commercially available analytical platforms. As a result, correct interpretation, comparison and integration of miRNA study results are compromised, which we demonstrate here by assessing the impact of ignoring sequence annotation changes. To address this problem, we developed miRBase Tracker (www.mirbasetracker.org), an easy-to-use online database that keeps track of all historical and current miRNA annotation present in the miRBase database. Three basic functionalities allow researchers to keep their miRNA annotation up-to-date, reannotate analytical miRNA platforms and link published results with outdated annotation to the latest miRBase release. We expect miRBase Tracker to increase the transparency and annotation accuracy in the field of miRNA research.

Database URL:www.mirbasetracker.org

[The history of the pituitary gland: evolution of mental representation and concepts over time]

The hypothalamo pituitary axis, as the true conductor of the endocrine orchestra, is frequently involved in a large variety of pathological conditions such as acromegaly, behavioral disorders, obesity or dwarfism. It is paradoxical to note that, in spite of its importance, this system has been almost ignored by the physiologists of the late centuries. From the physiological conceptions of the physicians and philosophers of antiquity to the theories of the medieval and of the Renaissance physiologists, we will try to understand why the role of pituitary remained so long unrecognized.

The need for transparency and good practices in the qPCR literature

Two surveys of over 1,700 publications whose authors use quantitative real-time PCR (qPCR) reveal a lack of transparent and comprehensive reporting of essential technical information. Reporting standards are significantly improved in publications that cite the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines, although such publications are still vastly outnumbered by those that do not.

[The thyrogastric syndrome: its effects on micronutriments and gastric tumorigenesis]

The thyrogastric autoimmune syndrome (TAS) was described in patients in whom the serum cross-reacted both with gastric parietal cells antigens and thyroid antigens. We report two cases illustrating the spectrum of pathogical features of TAS. The first case associates Hashimoto's thyroiditis and anemia perniciosa,and develops a gastric neuroendocrine tumor during follow up. The second case presents with a Graves' disease and an autoimmune reversible gastritis, secondary to Helicobacter pylori. Whereas type III autoimmune polyendocrinopathy is rare, TAS is frequent in our experience. Some 13% (32/240) of patients that we have prospectively followed affected with thyroiditis have also autoimmune gastritis. Helicobacter pylori is clearly implicated in 16% of autoimmune gastritis cases. Infection, malabsorption and gastritis are potentially reversible after bacterial eradication treatment. In the other 84% of gastritis patients, no histological or serological proof of Helicobacter pylori is found. Gastric autoimmunity is then irreversible, leading to gastric severe atrophy, hypochlorhydria and hypergastrinemia. Hypergastrinemia stimulates enterochromaffin cell hyperplasia, possibly progressing to neuroendocrine tumors. We propose a diagnostic approach to improve the characterization of TAS. We review the literature on the subject and discuss some interesting animal models of infectious gastric autoimmunity.

[Management of prolactinoma]

The prevalence of pituitary adenoma is of 1/1000 and has been fora long time underestimated. Prolactinomas represent the most frequent subtype (60%). From the mid eighties, their treatment is usually simple and efficient, allowing clinical, biological and tumoral control in most cases. However, management of carcinoma or resistant prolactinoma can be challenging. In these particular cases, a multimodal therapy approach is needed. Recently, progress in genetics of pituitary adenoma has allowed a better understanding and management of these particular cases. In consequence, genetic evaluation is recommended in FIPA (Familial Isolated Pituitary Adenoma) cases and in young patients with macroprolactinomas.

2013 European thyroid association guidelines for the diagnosis and treatment of thyrotropin-secreting pituitary tumors

Hyperthyroidism is mainly due to autoimmune thyroid disorders or toxic goiter, and very rarely to the presence of thyrotropin (TSH)-secreting pituitary adenomas (TSHomas). These tumors are characterized by high levels of circulating free thyroid hormones (FT4 and FT3) in the presence of nonsuppressed serum TSH concentrations. Failure to correctly diagnose TSHomas may result in inappropriate thyroid ablation, which results in a significant increase of pituitary tumor mass. The diagnosis is mainly achieved by measuring TSH after T3 suppression and TRH stimulation tests. These dynamic tests, together with pituitary imaging and genetic testing are useful in distinguishing TSHomas from the syndromes of resistance to thyroid hormone action. The treatment of choice is surgery. In cases of surgical failure, somatostatin analogs have been found to be effective in normalizing TSH secretion in more than 90% of patients.

MiR-137 functions as a tumor suppressor in neuroblastoma by downregulating KDM1A

Neuroblastoma is the most common extracranial solid tumor of childhood, and accounts for ∼15% of all childhood cancer deaths. The histone demethylase, lysine-specific demethylase 1 (KDM1A, previously known as LSD1), is strongly expressed in neuroblastomas, and overexpression correlates with poor patient prognosis. Inducing differentiation in neuroblastoma cells has previously been shown to down regulate KDM1A, and siRNA-mediated KDM1A knockdown inhibited neuroblastoma cell viability. The microRNA, miR-137, has been reported to be downregulated in several human cancers, and KDM1A mRNA was reported as a putative target of miR-137 in colon cancer. We hypothesized that miR-137 might have a tumor-suppressive role in neuroblastoma mediated via downregulation of KDM1A. Indeed, low levels of miR-137 expression in primary neuroblastomas correlated with poor patient prognosis. Re-expressing miR-137 in neuroblastoma cell lines increased apoptosis and decreased cell viability and proliferation. KDM1A mRNA was repressed by miR-137 in neuroblastoma cells, and was validated as a direct target of miR-137 using reporter assays in SHEP and HEK293 cells. Furthermore, siRNA-mediated KDM1A knockdown phenocopied the miR-137 re-expression phenotype in neuroblastoma cells. We conclude that miR-137 directly targets KDM1A mRNA in neuroblastoma cells, and activates cell properties consistent with tumor suppression. Therapeutic strategies to re-express miR-137 in neuroblastomas could be useful to reduce tumor aggressiveness.

[Malabsorption of thyroid hormones ... or simply poor patient compliance?]

We report the case of a patient presenting with L-thyroxine pseudomalabsorbtion, a figure in which patients are in a state of biological, and, frequently, clinical hypothyroidism secondary to a lack of adherence to substitutive thyroid treatment. We then review the different causes of true thyroid hormones malabsorption and the different approaches to these situations. We also suggest diagnostic and therapeutic attitudes for clinicians facing suspicious cases of hormone malabsorption.

[Thyroid dysfunction: interactions between genetic and environmental conditions]

Thyroid dysfunction (TD) is a very common entity in clinical practice nowadays. Prevalence may be underestimated because of the limitations of epidemiological studies. There are mainly genetic and environmental factors that interact on thyroid function. Genetic factors are extensively described in literature but molecular advance on the field may change older classifications based on B-cell or T-cell mediated disorders. The dominant pattern of inheritance makes family predisposition a relevant question in patient medical history but clinical research show that immune system is not enough to cause overt dysfunction. The role of environmental factors generates debate on medical literature. Some classic factors as iodine intake are well characterized but others as fetal microhimerism or new antineoplastic agents are less known. A review of medical literature on thyroid dysfunction has been performed and genetic and environmental factors are described in this article.

[Clinical case of the month. Cardiac complications of acromegaly: a rare cause of dilated cardiomyopathy]

Acromegaly is a disease characterized by chronic growth hormone hypersecretion. Cardiovascular complications represent the main cause of death. We present here a rare case of dilated cardiomyopathy whose diagnosis revealed an acromegaly. This will provide the opportunity to review an uncommon disease and its recently reassessed prevalence.

Adrenal involvement in MEN1. Analysis of 715 cases from the Groupe d'etude des Tumeurs Endocrines database

OBJECTIVE

Limited data regarding adrenal involvement in multiple endocrine neoplasia type 1 (MEN1) is available. We describe the characteristics of MEN1-associated adrenal lesions in a large cohort to provide a rationale for their management.

METHODS

Analysis of records from 715 MEN1 patients from a multicentre database between 1956 and 2008. Adrenal lesions were compared with those from a multicentre cohort of 144 patients with adrenal sporadic incidentalomas.

RESULTS

Adrenal enlargement was reported in 20.4% (146/715) of patients. Adrenal tumours (>10 mm in size) accounted for 58.1% of these cases (10.1% of the whole patient cohort). Tumours were bilateral and >40 mm in size in 12.5 and 19.4% of cases respectively. Hormonal hypersecretion was restricted to patients with tumours and occurred in 15.3% of them. Compared with incidentalomas, MEN1-related tumours exhibited more cases of primary hyperaldosteronism, fewer pheochromocytomas and more adrenocortical carcinomas (ACCs; 13.8 vs 1.3%). Ten ACCs occurred in eight patients. Interestingly, ACCs occurred after several years of follow-up of small adrenal tumours in two of the eight affected patients. Nine of the ten ACCs were classified as stage I or II according to the European Network for the Study of Adrenal Tumors. No evident genotype/phenotype correlation was found for the occurrence of adrenal lesions, endocrine hypersecretion or ACC.

CONCLUSIONS

Adrenal pathology in MEN1 differs from that observed in sporadic incidentalomas. In the absence of relevant symptoms, endocrine biology can be restricted to patients with adrenal tumours and should focus on steroid secretion including the aldosterone-renin system. MEN1 is a high-risk condition for the occurrence of ACCs. It should be considered regardless of the size of the tumour.

Inadvertent epidural injection of drugs for intravenous use. A review

INTRODUCTION

The frequency of inadvertent injection of drugs in the epidural space is probably underestimated and underreported, but it can cause serious morbidity and possibly mortality.

OBJECTIVE

The aim of this review is to collate reported incidents of this type, to describe the potential mechanisms of occurrence and to identify possible therapeutic solutions.

METHODS

We searched into medical databases and reviewed reference lists of papers retrieved.

RESULTS

A list is reported of more than 50 drugs that were inadvertently injected into the epidural space. This list includes drugs which produce no, little or short-lasting neurological deficits, but also includes drugs that may be more etching and can result in temporary or even permanent neurological deficit.

DISCUSSION

Most drugs do not lead to sequelae other than pain during injection or transient neurological complaints. Other drugs may have more deleterious consequences, such as paraplegia. Both the dose of the inadvertent injected drug and the time frame play an important role in the patient's outcome. "Syringe swap", "ampoule error", and epidural/intravenous line confusion due to inaccurate or absent colour coding of epidural catheters were the main sources of error. Preventive strategies, including non Luer-lock epidural injection ports, might increase safety.

Gender-related differences in MEN1 lesion occurrence and diagnosis: a cohort study of 734 cases from the Groupe d'etude des Tumeurs Endocrines

CONTEXT

Multiple endocrine neoplasia type 1 (MEN1) disease is an autosomal dominant syndrome that is believed to equally affect men and women. This assumption has never been confirmed.

OBJECTIVE

The aims of this study were to evaluate the impact of gender on the prevalence of MEN1 lesions, on their lifetime probability of occurrence, and on the diagnosis of MEN1.

DESIGN

Data regarding a study of 734 cases of MEN1 from the multicenter 'Groupe d'étude des Tumeurs Endocrines' were analyzed.

RESULTS

There were 57.8% females. The prevalence and probability of pancreatic tumors were higher in males than in females (P=0.06, P=0.0004). This difference was due to gastrinomas. The prevalence and probability of developing pituitary tumors were significantly greater in females (P<0.001, P<0.0001). Thymic tumors were exclusively found in men. There were no significant gender differences in the prevalence and the probability of developing hyperparathyroidism, or adrenal and bronchial tumors, or in the proportion of positive genetic tests. A family history of MEN1 was more frequently found in men than in women at the time of diagnosis (P=0.02). In the case of pituitary tumor, the proportion of patients diagnosed with MEN1 at the time of the first lesion was lower in women (44.2%) than in men (67.3%).

CONCLUSION

The phenotype expression of the MEN1 disease gene was different in males and females. In female patients, the possibility of MEN1 is not sufficiently taken into account. Any patient presenting a lesion that belongs to the MEN1 spectrum, such as a pituitary tumor, should be closely questioned about their family history and should be tested for hypercalcemia.

Resistant prolactinomas

Prolactinomas are the most common hormonally active pituitary tumors and are usually successfully treated with dopamine agonists. A small proportion, however, appears not to respond to such treatment and such cases are termed resistant prolactinomas. Resistance is generally defined as failure to achieve normoprolactinemia and inability to induce tumor shrinkage. Reduced dopamine receptor density on lactotroph cells is currently considered the major underlying mechanism of resistance. Treatment options in resistant cases usually include substitution with another dopamine agonist, increasing the dose of the drug, as well as surgery, radiotherapy, and experimental medical therapies.

The role of germline AIP, MEN1, PRKAR1A, CDKN1B and CDKN2C mutations in causing pituitary adenomas in a large cohort of children, adolescents, and patients with genetic syndromes

The prevalence of germline mutations in MEN1, AIP, PRKAR1A, CDKN1B and CDKN2CI is unknown among pediatric patients with pituitary adenomas (PA). In this study, we screened children with PA for mutations in these genes; somatic GNAS mutations were also studied in a limited number of growth hormone (GH) or prolactin (PRL)-secreting PA. We studied 74 and 6 patients with either isolated Cushing disease (CD) or GH- or PRL-secreting PA, respectively. We also screened four pediatric patients with CD, and four with GH/PRL-secreting tumors who had some syndromic features. There was one AIP mutation (p.Lys103Arg) among 74 CD patients. Two MEN1 mutations that occurred in patients with recurrent or difficult-to-treat disease were found among patients with CD. There was one MEN1 and three AIP mutations (p.Gln307ProfsX104, p.Pro114fsX, p.Lys241X) among pediatric patients with isolated GH- or PRL-secreting PA and one additional MEN1 mutation in a patient with positive family history. There were no mutations in the PRKAR1A, CDKN1B, CDKN2C or GNAS genes. Thus, germline AIP or MEN1 gene mutations are frequent among pediatric patients with GH- or PRL-secreting PA but are significantly rarer in pediatric CD; PRKAR1A mutations are not present in PA outside of Carney complex.

The R304X mutation of the aryl hydrocarbon receptor interacting protein gene in familial isolated pituitary adenomas: Mutational hot-spot or founder effect?

BACKGROUND

Mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene have been described in about 15% of kindreds with familial isolated pituitary adenomas and in a minority of early onset sporadic pituitary adenomas (PA). Among the AIP mutations reported so far, the R304X (AIPR304X) represents, together with the "Finnish mutation" Q14X, the most common one.

METHODS

Three AIPR304X Italian families, including a newly reported kindred, have been genotyped for 12 genetic markers surrounding the AIP gene in order to look for a potential founder effect in Italy. Disease penetrance and genotype-phenotype correlations were also addressed.

RESULTS

Analysis of chromosome 11' genetic markers revealed a common haplotype in 2 AIPR304X kindreds originating from central Italy. Overall, 17 mutations carriers were identified, including 7 patients and 10 unaffected subjects, respectively, arguing in this case for a disease penetrance of 41%. Mean age at diagnosis was 19.1±6.7 yr old, with females tending to be older than males. Though most PA were somatotropinomas (6/7), a great variability in disease severity was observed, even between subjects sharing the same at-risk haplotype.

CONCLUSION

These data provide strong evidence for a new founder effect of the AIPR304X mutation in central Italy and the observed variations in disease severity point out the role of additional genetic or environmental factors in such kindreds.

[How to explore ... congenital isolated hypogonadotrophic hypogonadism]

Congenital Isolated hypogonadotropic hypogonadism (CIHH) is caused by an inherited mechanism of impairment of the pituitary-gonadal axis, interfering with gonads' control. Currently, different forms of HHCI with (Kallmann syndrome or KS) or without anosmia-hyposmia are known. There are six forms of KS already described but in several cases no genetic mutation is found. The genetic anomalies already described are: KAL1 (locus Xp23) coding for anosmine-1, KAL-2 or FGFRI (8p11. locus 2 - p11.1) coding for Fibroblast Growth Factor Receptor 1 (FGFR1), KAL4 or PROk2 (locus 3p21.1) and KAL3 or ProKR2 (locus 20p13) coding respectively for the Prokinecitin-2 and its receptor, KAL5 or CHD7 (locus_8q12.1) coding for a chromodomain helicase DNA-binding protein-7 gene (CHD7) and lastly KAL6 or FGF8 (10Q 24 loci) coding for Fibroblast Growth Factor 8. The other genetic anomalies without anosmia are less frequent. These are associated either with Gnrhl gene (8p2-11. 2), GnRHR (4q21.2), GPR54 (19p13),TAC3R or neurokinine receptor 3 (4 q 25), LH (19q13.32) or FSH (11p13). The isolated congenital hypogonadotrophic hypogonadism phenotype is variable depending on gender, the importance of the deficit, and ultimately, according to a specific regulatory mechanism of the axis, affected by an inherited genetic anomaly. In this review, we describe the essential aspects of the different phenotypes and genotypes of HHCI, in order to assess clinicians an early disease's diagnosis and management.

Familial pituitary adenomas

Pituitary adenomas are benign intracranial neoplasms that present a major clinical concern because of hormonal overproduction or compression symptoms of adjacent structures. Most arise in a sporadic setting with a small percentage developing as a part of familial syndromes such as multiple endocrine neoplasia type 1 (MEN1), Carney complex (CNC), and the recently described familial isolated pituitary adenomas (FIPA) and MEN-4. While the genetic alterations responsible for the formation of sporadic adenomas remain largely unknown, considerable advances have been made in defining culprit genes in these familial syndromes. Mutations in MEN1 and PRKAR1A genes are found in the majority of MEN1 and CNC patients, respectively. About 15% of FIPA kindreds present with mutations of the aryl hydrocarbon receptor-interacting protein (AIP) gene. Mutations in the CDKN1B gene, encoding p27(Kip)¹ were identified in MEN4 cases. Familial tumours appear to differ from their sporadic counterparts not only in genetic basis but also in clinical characteristics. Evidence suggests that, especially in MEN1 and FIPA, they are more aggressive and affect patients at younger age, therefore justifying the importance of early diagnosis. In this review, we summarize the genetic and clinical characteristics of these familial pituitary adenomas.

[Current opinion on primary aldosteronism]

In recent years, a greater interest has been focused on primary aldosteronism (PA), which shows a higher prevalence rate than previously thought. The consequences of PA are life threatening such as a refractory hypertension with serious cardiovascular damages.The evaluation of a suspected PA should follow a step-by-step approach (screening test, then confirmatory test and, in some cases, adrenal venous sampling). This protocol may seem tedious, but it allows an accurate etiologic diagnosis that leads to an appropriate therapy with better blood pressure control,improvement of quality of life, and, in some cases even,cure of hypertension.