Biallelic variants in ZNF142 lead to a syndromic neurodevelopmental disorder.

Biallelic variants of the gene encoding for the zinc-finger protein 142 (ZNF142) have recently been associated with intellectual disability (ID), speech impairment, seizures, and movement disorders in nine individuals from five families. In this study, we obtained phenotype and genotype information of 26 further individuals from 16 families. Among the 27 different ZNF142 variants identified in the total of 35 individuals only four were missense. Missense variants may give a milder phenotype by changing the local structure of ZF motifs as suggested by protein modeling; but this correlation should be validated in larger cohorts and pathogenicity of the missense variants should be investigated with functional studies. Clinical features of the 35 individuals suggest that biallelic ZNF142 variants lead to a syndromic neurodevelopmental disorder with mild to moderate ID, varying degrees of delay in language and gross motor development, early onset seizures, hypotonia, behavioral features, movement disorders, and facial dysmorphism. The differences in symptom frequencies observed in the unpublished individuals compared to those of published, and recognition of previously underemphasized facial features are likely to be due to the small sizes of the previous cohorts, which underlines the importance of larger cohorts for the phenotype descriptions of rare genetic disorders.

MYT1L-associated neurodevelopmental disorder: description of 40 new cases and literature review of clinical and molecular aspects.

Pathogenic variants of the myelin transcription factor-1 like (MYT1L) gene include heterozygous missense, truncating variants and 2p25.3 microdeletions and cause a syndromic neurodevelopmental disorder (OMIM#616,521). Despite enrichment in de novo mutations in several developmental disorders and autism studies, the data on clinical characteristics and genotype-phenotype correlations are scarce, with only 22 patients with single nucleotide pathogenic variants reported. We aimed to further characterize this disorder at both the clinical and molecular levels by gathering a large series of patients with MYT1L-associated neurodevelopmental disorder. We collected genetic information on 40 unreported patients with likely pathogenic/pathogenic MYT1L variants and performed a comprehensive review of published data (total = 62 patients). We confirm that the main phenotypic features of the MYT1L-related disorder are developmental delay with language delay (95%), intellectual disability (ID, 70%), overweight or obesity (58%), behavioral disorders (98%) and epilepsy (23%). We highlight novel clinical characteristics, such as learning disabilities without ID (30%) and feeding difficulties during infancy (18%). We further describe the varied dysmorphic features (67%) and present the changes in weight over time of 27 patients. We show that patients harboring highly clustered missense variants in the 2-3-ZNF domains are not clinically distinguishable from patients with truncating variants. We provide an updated overview of clinical and genetic data of the MYT1L-associated neurodevelopmental disorder, hence improving diagnosis and clinical management of these patients.

Pathogenic variants in CDH11 impair cell adhesion and cause Teebi hypertelorism syndrome.

Teebi hypertelorism syndrome (THS; OMIM 145420) is a rare craniofacial disorder characterized by hypertelorism, prominent forehead, short nose with broad or depressed nasal root. Some cases of THS have been attributed to SPECC1L variants. Homozygous variants in CDH11 truncating the transmembrane and intracellular domains have been implicated in Elsahy-Waters syndrome (EWS; OMIM 211380) with hypertelorism. We report THS due to CDH11 heterozygous missense variants on 19 subjects from 9 families. All affected residues in the extracellular region of Cadherin-11 (CHD11) are highly conserved across vertebrate species and classical cadherins. Six of the variants that cluster around the EC2-EC3 and EC3-EC4 linker regions are predicted to affect Ca2+ binding that is required for cadherin stability. Two of the additional variants [c.164G > C, p.(Trp55Ser) and c.418G > A, p.(Glu140Lys)] are also notable as they are predicted to directly affect trans-homodimer formation. Immunohistochemical study demonstrates that CDH11 is strongly expressed in human facial mesenchyme. Using multiple functional assays, we show that five variants from the EC1, EC2-EC3 linker, and EC3 regions significantly reduced the cell-substrate trans adhesion activity and one variant from EC3-EC4 linker results in changes in cell morphology, focal adhesion, and migration, suggesting dominant negative effect. Characteristic features in this cohort included depressed nasal root, cardiac and umbilical defects. These features distinguished this phenotype from that seen in SPECC1L-related hypertelorism syndrome and CDH11-related EWS. Our results demonstrate heterozygous variants in CDH11, which decrease cell-cell adhesion and increase cell migratory behavior, cause a form of THS, as termed CDH11-related THS.

Phenotypic spectrum of the RBM10-mediated intellectual disability and congenital malformation syndrome beyond classic TARP syndrome features.

Pathogenic variants in the RBM10 gene cause a rare X-linked disorder described as TARP (Talipes equinovarus, Atrial septal defect, Robin sequence, and Persistent left vena cava superior) syndrome. We report two novel patients with truncating RBM10 variants in view of the literature, presenting a total of 26 patients from 15 unrelated families. Our results illustrate the highly pleiotropic nature of RBM10 pathogenic variants, beyond the classic TARP syndrome features. Major clinical characteristics include severe developmental delay, failure to thrive, brain malformations, neurological symptoms, respiratory issues, and facial dysmorphism. Minor features are growth retardation, cardiac, gastrointestinal, limb, and skeletal abnormalities. Additional recurrent features include genital and renal abnormalities as well as hearing and visual impairment. Thus, RBM10 loss of function variants typically cause an intellectual disability and congenital malformation syndrome that requires assessment of multiple organ systems at diagnosis and for which provided clinical features might simplify diagnostic assessment. Furthermore, evidence for an RBM10-related genotype-phenotype correlation is emerging, which can be important for prognosis.

IQSEC2 disorder: A new disease entity or a Rett spectrum continuum?

IQSEC2 mutations are associated with IQSEC2-related intellectual disability (ID). Phenotypic spectrum has been better defined in the last few years by the increasing number of reported cases although the genotype-phenotype relationship for IQSEC2 remains overall complex. As for IQSEC2-related ID a wide phenotypic diversity has been described in Rett syndrome (RTT). Several patients harboring IQSEC2 mutations present with clinical symptoms similar to RTT and some cases meet most of the criteria for classic RTT. With the aim of establishing a genotype-phenotype correlation, we collected data of 16 patients harboring IQSEC2 point mutations (15 of them previously unreported) and of five novel patients carrying CNVs encompassing IQSEC2. Most of our patients surprisingly shared a moderate-to-mild phenotype. The similarities in the clinical course between our mild cases and patients with milder forms of atypical RTT reinforce the hypothesis that also IQSEC2 mutated patients may lay under the wide clinical spectrum of RTT and thus IQSEC2 should be considered in the differential diagnosis. Our data confirm that position, type of variant and gender are crucial for IQSEC2-associated phenotype delineation.

Phenotyping nocturnal polyuria: circadian and age-related variations in diuresis rate, free water clearance and sodium clearance.

BACKGROUND: this study compares diuresis rate, sodium clearance and free water clearance (FWC) by age and time of day (nighttime vs. daytime) in subjects with and without nocturnal polyuria (NP) to determine whether these variables affect the phenotype of NP. METHODS: post hoc analysis of two prospective observational studies. Eight urine samples collected at 3-h intervals and a single blood sample were used to calculate daytime (10a/1p/4p/7p/10p) and nighttime (1a/4a/7a) diuresis rates, sodium clearance and FWC. Three mixed linear models were constructed for diuresis rate, sodium clearance and FWC using four predictor variables: NP status (present [nocturnal urine production >90 ml/h] vs. absent [≤90 ml/h]), time of day, age and study identification. RESULTS: subjects with NP experienced higher nighttime versus daytime diuresis rates, sodium clearance and FWC. Regardless of NP status, increased age was accompanied by an increase in the ratio of nighttime/daytime diuresis rate, nighttime sodium clearance and daytime sodium clearance. FWC showed a complex age effect, which was independent of time of day or NP status. CONCLUSIONS: age-related increases in nighttime/daytime diuresis rate, 24-h sodium clearance and 24-h FWC are not specific to subjects with NP. The age-related surge in either nocturnal sodium clearance or nocturnal FWC may represent the relevant substrate for behavioural or pharmacologic interventions targeting sodium diuresis or free water diuresis, respectively. Increases in FWC in older age groups may reflect impaired circadian rhythmicity of endogenous AVP or changes in responsiveness of the aged nephron to water clearance.

The ETS transcription factor ETV5 is a target of activated ALK in neuroblastoma contributing to increased tumour aggressiveness.

Neuroblastoma is an aggressive childhood cancer arising from sympatho-adrenergic neuronal progenitors. The low survival rates for high-risk disease point to an urgent need for novel targeted therapeutic approaches. Detailed molecular characterization of the neuroblastoma genomic landscape indicates that ALK-activating mutations are present in 10% of primary tumours. Together with other mutations causing RAS/MAPK pathway activation, ALK mutations are also enriched in relapsed cases and ALK activation was shown to accelerate MYCN-driven tumour formation through hitherto unknown ALK-driven target genes. To gain further insight into how ALK contributes to neuroblastoma aggressiveness, we searched for known oncogenes in our previously reported ALK-driven gene signature. We identified ETV5, a bona fide oncogene in prostate cancer, as robustly upregulated in neuroblastoma cells harbouring ALK mutations, and show high ETV5 levels downstream of the RAS/MAPK axis. Increased ETV5 expression significantly impacted migration, invasion and colony formation in vitro, and ETV5 knockdown reduced proliferation in a murine xenograft model. We also established a gene signature associated with ETV5 knockdown that correlates with poor patient survival. Taken together, our data highlight ETV5 as an intrinsic component of oncogenic ALK-driven signalling through the MAPK axis and propose that ETV5 upregulation in neuroblastoma may contribute to tumour aggressiveness.

Nocturnal voiding frequency does not describe nocturia-related bother.

AIM: Nocturia frequency has been used as a measure of treatment efficacy for nocturia even though fluctuation of the symptom over time has been well described in the literature. Additionally, given the multifactorial causal pathway and clinically relevant comorbidities, frequency alone may be an insufficient marker of treatment direction. The aim of this study was to investigate factors associated with nocturia-related bother to identify additional variables that may capture the impact of nocturia, direct clinical care and have potential to quantify treatment outcome. METHODS: Prospective data from tertiary hospital Urology and Continence cohorts were matched for identical variables to generate a sample of 204 datasets. Descriptive statistics were obtained to describe the two cohorts. Characteristics of patients were evaluated across levels of nocturia frequency and nocturia-related bother using nonparametric methods; statistically significant differences between groups in each cohort were established. RESULTS: Nocturia frequency alone does not comprehensively reflect attributable bother. Five sleep variables (poor quality sleep, short time to first awakening to void, less than 7 hours of total sleep, primary sleep latency, and daytime sleepiness) and daily urinary urgency were significantly associated with high nocturia-related bother. Attributable bother, despite high-frequency nocturia, was minimized by male gender, lack of daily urinary urgency and good sleep quality. Poor health status, urinary urgency and sleep latency were associated with nocturia frequency. CONCLUSIONS: Items of importance to individuals with nocturia have been identified from patient data. These variables have the potential to sit alongside change in nocturia frequency as potential markers of treatment response.

Smart diapers for nursing home residents with dementia: a pilot study.

Objectives: The objective of the study is to evaluate the use of an experimental smart diaper as an indicator of saturation for diaper change in persons with dementia living in nursing homes. Methods: A multicenter prospective study was conducted in 3 nursing homes amongst 18 residents with dementia. For each resident, a frequency-volume urine chart (FVUC) was kept for 24 h including voided volume and diaper weights, wearing smart diapers. A comparative study was set up between results obtained by smart diapers and data registered in FVUCs. Results: Analysis based on quantification of the agreement between saturation calculated by smart diaper and determined by FVUC indicates that measurements reported by sensor do not correspond with measurements based on FVUC. For the regular diaper, the saturation measured by sensor may be 26% below or 39% above saturation based on FVUC and for the super diaper, respectively, 34% below or 30% above. Discussion: This study indicates that the sensor detects and notifies wetness but is not sensitive enough for using it as an indicator for diaper change in people with severe dementia.

ALK positively regulates MYCN activity through repression of HBP1 expression.

ALK mutations occur in 10% of primary neuroblastomas and represent a major target for precision treatment. In combination with MYCN amplification, ALK mutations infer an ultra-high-risk phenotype resulting in very poor patient prognosis. To open up opportunities for future precision drugging, a deeper understanding of the molecular consequences of constitutive ALK signaling and its relationship to MYCN activity in this aggressive pediatric tumor entity will be essential. We show that mutant ALK downregulates the 'HMG-box transcription factor 1' (HBP1) through the PI3K-AKT-FOXO3a signaling axis. HBP1 inhibits both the transcriptional activating and repressing activity of MYCN, the latter being mediated through PRC2 activity. HBP1 itself is under negative control of MYCN through miR-17~92. Combined targeting of HBP1 by PI3K antagonists and MYCN signaling by BET- or HDAC-inhibitors blocks MYCN activity and significantly reduces tumor growth, suggesting a novel targeted therapy option for high-risk neuroblastoma.

Prognostic and Therapeutic Implications of Circulating Androgen Receptor Gene Copy Number in Prostate Cancer Patients Using Droplet Digital Polymerase Chain Reaction.

BACKGROUND: Resistance mechanisms in the androgen receptor (AR) signaling pathway remain key drivers in the progression to castration-resistant prostate cancer (CRPC) and relapse under antihormonal therapy. MATERIALS AND METHODS: We evaluated the circulating AR gene copy number (CN) gain using droplet digital polymerase chain reaction in 21 control and 91 prostate cancer serum samples and its prognostic and therapeutic implications in prostate cancer. RESULTS: In CRPC, AR CN gain was associated with faster progression to CRPC (P = .026), a greater number of previous treatments (P = .045), and previous chemotherapy (P = .016). Comparing patients with and without CN gain, the median progression-free survival (PFS) in the abiraterone subgroup was 1.7 months versus not reached (P = .004), and the median overall survival (OS) was 7 months versus 20.9 months (P = .020). In the enzalutamide subgroup, PFS was 1.7 versus 10.8 months (P = .006), and OS was 6.1 versus 16.5 months (P = .042). In the taxane subgroup, PFS was 3.2 versus 6.5 months (P = .093), and OS was 3.9 months versus not reached (P = .026). The presence of more AR copies correlated with shorter androgen deprivation (P = .002), abiraterone (P = .022), enzalutamide (P = .008), and taxane (P = .039) therapy. CONCLUSION: Circulating AR CN gain predicts for a poor prognosis in CRPC. It is a promising biomarker predetermining rapid CRPC progression and predicting worse abiraterone and enzalutamide outcomes. Furthermore, it is associated with multiple previous treatments and previous chemotherapy.

Clean Intermittent Self-Catheterization as a Treatment Modality for Urinary Retention: Perceptions of Urologists.

PURPOSE: Clean intermittent self-catheterization (CISC) is now considered the gold standard for the management of urinary retention. In the literature, several articles on patients' perspectives on CISC and adherence to this technique have been published. No studies have yet explored the points of view of professional caregivers, such as nurses and doctors. The aim of this study was to explore the opinions of urologists about CISC and to evaluate the need for dedicated nurses specialized in CISC through a self-administered questionnaire. METHODS: A questionnaire was developed to explore the opinions of professional caregivers about self-catheterization and to evaluate the need to provide nurses with specialized education in CISC. Questionnaires were sent to 244 urologists through email. We received 101 completed questionnaires. The response rate was 41.4%. RESULTS: Hand function, the presence or absence of tremor, and visual acuity were rated as the most important determinants for proposing CISC to a patient. Twenty-five percent of the urologists reported that financial remuneration would give them a greater incentive to propose CISC. The lack of dedicated nurses was reported by half of the urologists as a factor preventing them from proposing CISC. A meaningful number of urologists thought that patients perceive CISC as invasive and unpleasant. Although most urologists would choose CISC as a treatment option for themselves, almost 1 urologist out of 5 would prefer a permanent catheter. CONCLUSIONS: This questionnaire gave valuable insights into urologists' perceptions of CISC, and could serve as the basis for a subsequent broader international study. Further research should also focus on the opinions of nurses and other caregivers involved in incontinence management. Apart from financial remuneration, it is also clear that ensuring sufficient expertise and time for high-quality CISC care is important. This could be a potential role for dedicated nurses.

Pathophysiology of nocturnal lower urinary tract symptoms in older patients with urinary incontinence.

OBJECTIVES: To explore the mismatch between functional bladder capacity and nocturnal urine production, and to study the pathophysiology of an increased nocturnal urine production in older patients with urinary incontinence. METHODS: The present prospective observational study included adults aged ≥65 years with urinary incontinence. Participants completed questionnaires, frequency volume charts and renal function profiles. The nocturnal lower urinary tract symptom index was defined as nocturnal urine output/maximum voided volume; the nocturnal polyuria index as nocturnal/24 h urine output. RESULTS: The median age (n = 95) was 74 years (69-79), 87% were women and 73% had nocturnal lower urinary tract symptoms (nocturnal urinary incontinence or nocturia ≥2). Participants with nocturnal lower urinary tract symptoms had a significantly higher nocturnal urine output (809 mL vs 650 mL; P = 0.001) and no significant difference in maximum voided volume (350 mL vs 437 mL; P = 0.079) compared with participants without nocturnal lower urinary tract symptoms. Participants (nocturnal polyuria index >33% [n = 56], nocturnal polyuria index >40% [n = 42], nocturnal lower urinary tract symptom index >1.87 [n = 51]) showed higher night-time diuresis rates, free water and sodium clearance compared with during the daytime. Controls (nocturnal polyuria index ≤33% [n = 26], nocturnal polyuria index ≤40% [n = 40], nocturnal lower urinary tract symptom index ≤1.87 [n = 44]) had no circadian rhythm in their diuresis rate or sodium clearance, but more nocturnal free water clearance compared with during the daytime. CONCLUSIONS: The majority of older adults with urinary incontinence present nocturnal lower urinary tract symptoms. An increased nocturnal sodium diuresis seems to be the only mechanism differentiating patients with nocturnal lower urinary tract symptoms from controls.

The independent oncological role for cytoreductive nephrectomy in metastatic renal cell carcinoma: Prognostic features in the era of targeted therapies.

OBJECTIVES: To describe the effects of cytoreductive nephrectomy (CN) on the natural course of metastatic renal cell carcinoma (mRCC). CN appears to stabilize metastatic lesions in mRCC in a subgroup of patients and we hypothesize that systemic treatment might be deferred in these patients with stable disease after CN. SUBJECTS AND METHODS: Overall, 45 patients with mRCC who underwent CN and subsequent oncologic follow-up were included in this retrospective, single-center analysis. After CN, patients were followed at least every 3 months with clinical evaluation, contrast-enhanced computerized tomography scan of chest and abdomen, with additional imaging if needed. At 3 months, patients were radiographically evaluated and categorized into nonresponders (death or progression) or responders (stable disease or remission). Kaplan-Meier and Cox proportional hazards regression statistics were used to describe prognostic factors for overall survival (OS) and systemic therapy-free survival (STFS). RESULTS: Median OS was 31(3-121) months. Further, 24 (53.3%) and 21 (46.7%) patients were classified as responders and nonresponders at 3 months, respectively. Responders had a significant better 2-year OS compared with nonresponders (81.7% vs. 26.5%, P = 0.005). Responders also had a better 2-year STFS (40.3% vs. 6.3%, P = 0.005). On Cox regression analysis, worse OS was found to be associated with low preoperative hemoglobin levels, the absence of postoperative radiographical response, and the presence of non-clear cell pathology. The presence of postoperative radiographical response, normal preoperative lactate dehydrogenase levels, the presence of a single metastasis, and performing metastasis-directed therapy was found to be associated with a longer systemic therapy-free period. CONCLUSION: A beneficial oncologic response is observed in approximately half of the patients undergoing CN. Absence of radiographic progression at 3 months is an important marker for OS and STFS. Therefore, systemic treatment might be postponed in selected patients.

Circadian Variation in Post Void Residual in Nursing Home Residents With Moderate Impairment in Activities of Daily Living.

BACKGROUND: Despite the conflicting evidence about postvoid residual (PVR) and its variation in time and corresponding voided volume (VV), studies with urinary diaries and systematic measurements of PVR after each void have never been conducted in nursing home (NH) residents. OBJECTIVE: To describe the circadian rhythm of PVR and residual fraction (RF, the net quantity of PVR) and to identify the time window with the highest PVR and RF. DESIGN, SETTING, AND PARTICIPANTS: A multicentre prospective study conducted between 2014 and 2015 in 5 Belgian NHs. A convenience sample of cognitively intact residents completed a 24-hour frequency volume chart with PVR. RESULTS: Participants (n = 73) had a median age of 84 years (interquartile range 82-89) and moderate impairment of activities of daily living; 69% were women. In residents with nocturia, mean PVR was higher during the night [45 mL (26-80)] than during the day [36 mL (18-61)]. In residents without nocturia no difference was detected. In spite of the variation between diurnal and nocturnal VV and PVR in residents with nocturia, all residents emptied their bladder as effectively during daytime as during nighttime [mean RF = 20% (12-32)]. Maximum PVR and RF in residents with nocturia (n = 57) showed a circadian variation. The highest PVR and RF were found during the day. The PVR and RF of the first morning void were an indicator of the maximum nocturnal PVR and RF. CONCLUSIONS: PVR and VV should be measured in NH residents during the waking hours (first morning void excepted) to detect the clinically relevant maximum PVR and RF.

Androgen Receptor Gene Copy Number and Protein Expression in Treatment-Naïve Prostate Cancer.

OBJECTIVES: To evaluate the androgen receptor (AR) gene copy number in androgen deprivation therapy (ADT) treatment-naïve prostate cancer (PCa) patients and to evaluate the corresponding AR protein expression and assess the association between these features and prognostic factors. MATERIALS AND METHODS: Chromosome X and AR gene copy number, using fluorescence-in-situ-hybridization, and epithelial-stromal AR expression, using AR immunohistochemistry, were analyzed in 62 ADT treatment-naïve PCa patients and 8 castration-refractory patients. RESULTS: In ADT treatment-naïve PCa patients, the AR expression was higher in tumor epithelial cells versus surrounding stromal cells (p < 0.001) and versus normal epithelium in the same patient (p = 0.043). The difference between tumoral AR expression and expression in normal epithelium was higher in patients with ≥15% of tumor cells with increased AR copy number (p = 0.019). Peritumoral stroma had lower AR expression in patients with lymph-node or distant metastases compared to those without metastases (p = 0.038). CONCLUSIONS: This research evaluates the link between AR gene status, expression profile, and possible prognostic factors. Furthermore, it highlights the importance of the peritumoral environment in PCa. Additional research is needed to further clarify the role of stromal AR in PCa dissemination and identify possible therapeutic strategies to target this mechanism.

Early and late effects of pharmacological ALK inhibition on the neuroblastoma transcriptome.

BACKGROUND: Neuroblastoma is an aggressive childhood malignancy of the sympathetic nervous system. Despite multi-modal therapy, survival of high-risk patients remains disappointingly low, underscoring the need for novel treatment strategies. The discovery of ALK activating mutations opened the way to precision treatment in a subset of these patients. Previously, we investigated the transcriptional effects of pharmacological ALK inhibition on neuroblastoma cell lines, six hours after TAE684 administration, resulting in the 77-gene ALK signature, which was shown to gradually decrease from 120 minutes after TAE684 treatment, to gain deeper insight into the molecular effects of oncogenic ALK signaling. AIM: Here, we further dissected the transcriptional dynamic profiles of neuroblastoma cells upon TAE684 treatment in a detailed timeframe of ten minutes up to six hours after inhibition, in order to identify additional early targets for combination treatment. RESULTS: We observed an unexpected initial upregulation of positively regulated MYCN target genes following subsequent downregulation of overall MYCN activity. In addition, we identified adrenomedullin (ADM), previously shown to be implicated in sunitinib resistance, as the earliest response gene upon ALK inhibition. CONCLUSIONS: We describe the early and late effects of ALK inhibitor TAE684 treatment on the neuroblastoma transcriptome. The observed unexpected upregulation of ADM warrants further investigation in relation to putative ALK resistance in neuroblastoma patients currently undergoing ALK inhibitor treatment.

Upregulation of MAPK Negative Feedback Regulators and RET in Mutant ALK Neuroblastoma: Implications for Targeted Treatment.

PURPOSE: Activating ALK mutations are present in almost 10% of primary neuroblastomas and mark patients for treatment with small-molecule ALK inhibitors in clinical trials. However, recent studies have shown that multiple mechanisms drive resistance to these molecular therapies. We anticipated that detailed mapping of the oncogenic ALK-driven signaling in neuroblastoma can aid to identify potential fragile nodes as additional targets for combination therapies. EXPERIMENTAL DESIGN: To achieve this goal, transcriptome profiling was performed in neuroblastoma cell lines with the ALK(F1174L) or ALK(R1275Q) hotspot mutations, ALK amplification, or wild-type ALK following pharmacologic inhibition of ALK using four different compounds. Next, we performed cross-species genomic analyses to identify commonly transcriptionally perturbed genes in MYCN/ALK(F1174L) double transgenic versus MYCN transgenic mouse tumors as compared with the mutant ALK-driven transcriptome in human neuroblastomas. RESULTS: A 77-gene ALK signature was established and successfully validated in primary neuroblastoma samples, in a neuroblastoma cell line with ALK(F1174L) and ALK(R1275Q) regulable overexpression constructs and in other ALKomas. In addition to the previously established PI3K/AKT/mTOR, MAPK/ERK, and MYC/MYCN signaling branches, we identified that mutant ALK drives a strong upregulation of MAPK negative feedback regulators and upregulates RET and RET-driven sympathetic neuronal markers of the cholinergic lineage. CONCLUSIONS: We provide important novel insights into the transcriptional consequences and the complexity of mutant ALK signaling in this aggressive pediatric tumor. The negative feedback loop of MAPK pathway inhibitors may affect novel ALK inhibition therapies, whereas mutant ALK induced RET signaling can offer novel opportunities for testing ALK-RET oriented molecular combination therapies.

Activated Alk triggers prolonged neurogenesis and Ret upregulation providing a therapeutic target in ALK-mutated neuroblastoma.

Activating mutations of the ALK (Anaplastic lymphoma Kinase) gene have been identified in sporadic and familial cases of neuroblastoma, a cancer of early childhood arising from the sympathetic nervous system (SNS). To decipher ALK function in neuroblastoma predisposition and oncogenesis, we have characterized knock-in (KI) mice bearing the two most frequent mutations observed in neuroblastoma patients. A dramatic enlargement of sympathetic ganglia is observed in AlkF1178L mice from embryonic to adult stages associated with an increased proliferation of sympathetic neuroblasts from E14.5 to birth. In a MYCN transgenic context, the F1178L mutation displays a higher oncogenic potential than the R1279Q mutation as evident from a shorter latency of tumor onset. We show that tumors expressing the R1279Q mutation are sensitive to ALK inhibition upon crizotinib treatment. Furthermore, our data provide evidence that activated ALK triggers RET upregulation in mouse sympathetic ganglia at birth as well as in murine and human neuroblastoma. Using vandetanib, we show that RET inhibition strongly impairs tumor growth in vivo in both MYCN/KI AlkR1279Q and MYCN/KI AlkF1178L mice. Altogether, our findings demonstrate the critical role of activated ALK in SNS development and pathogenesis and identify RET as a therapeutic target in ALK mutated neuroblastoma.