Transcriptional features of low-grade neuroepithelial tumors with the BRAF V600E mutation associated with epileptogenicity.

Low-grade neuroepithelial tumors are major causes of drug-resistant focal epilepsy. Clinically, these tumors are defined as low-grade epilepsy-associated neuroepithelial tumors (LEATs). The BRAF V600E mutation is frequently observed in LEAT and linked to poor seizure outcomes. However, its molecular role in epileptogenicity remains elusive. To understand the molecular mechanism underlying the epileptogenicity in LEAT with the BRAF V600E genetic mutation (BRAF V600E-LEAT), we conducted RNA sequencing (RNA-seq) analysis using surgical specimens of BRAF V600E-LEAT obtained and stored at a single institute. We obtained 21 BRAF V600E-LEAT specimens and 4 control specimens, including 24 from Japanese patients and 1 from a patient of Central Asian origin, along with comprehensive clinical data. We submitted the transcriptome dataset of 21 BRAF V600E-LEAT plus 4 controls, as well as detailed clinical information, to a public database. Preliminary bioinformatics analysis using this dataset identified 2134 differentially expressed genes between BRAF V600E-LEAT and control. Additionally, gene set enrichment analysis provided novel insights into the association between estrogen response-related pathways and the epileptogenicity of BRAF V600E-LEAT patients. Our datasets and findings will contribute toward the understanding of the pathology of epilepsy caused by LEAT and the identification of new therapeutic targets.

Flexible use of copula-type model for dose-finding in drug combination clinical trials.

Identification of the maximum tolerated dose combination (MTDC) of cancer drugs is an important objective in phase I oncology trials. Numerous dose-finding designs for drug combination have been proposed over the years. Copula-type models exhibit distinctive advantages in this task over other models used in existing competitive designs. For example, their application enables the consideration of dose-limiting toxicities attributable to one of two agents. However, if a particular combination therapy demonstrates extremely synergistic toxicity, copula-type models are liable to induce biases in toxicity probability estimators due to the associated Fréchet-Hoeffding bounds. Consequently, the dose-finding performance may be worse than those of other competitive designs. The objective of this study is to improve the performance of dose-finding designs based on copula-type models while maintaining their advantageous properties. We propose an extension of the parameter space of the interaction term in copula-type models. This releases the Fréchet-Hoeffding bounds, making the estimation of toxicity probabilities more flexible. Numerical examples in various scenarios demonstrate that the performance (e.g., the percentage of correct MTDC selection) of the proposed method is better than those exhibited by existing copula-type models and comparable with those of other competitive designs, irrespective of the existence of extreme synergistic toxicity. The results obtained in this study could motivate the real-world application of the proposed method in cases requiring the utilization of the properties of copula-type models.

Efficacy and safety of abatacept in biologic-naïve patients with active rheumatoid arthritis by background methotrexate dose: post hoc analysis of a randomized, placebo-controlled, phase 4 study.

OBJECTIVES: The objective of this study is to evaluate efficacy and safety of abatacept in biologic-naïve, anti-citrullinated protein antibody (ACPA)-positive Japanese patients with active rheumatoid arthritis (RA) by background methotrexate (MTX) dose. METHODS: In this post hoc analysis of a randomized, double-blind, placebo-controlled phase 4 study (NCT01758198), patients received intravenous abatacept (∼10 mg/kg) or placebo both with MTX (≥6 mg/week). Efficacy (Disease Activity Score 28 using C-reactive protein [DAS28 (CRP)] and Health Assessment Questionnaire-Disability Index [HAQ-DI]) was assessed by baseline MTX dosage (≤8 and >8 mg/week) to week 16; safety was assessed by MTX dosage ≤8 and >8 mg/week. Change from baseline in DAS28 (CRP) and HAQ-DI was assessed using longitudinal repeated measures analysis. RESULTS: Overall, 101 and 102 patients received abatacept + MTX ≤8 and >8 mg/week, while 96 and 106 patients received placebo + MTX ≤8 and >8 mg/week, respectively. Regardless of baseline MTX dose received, mean changes from baseline in DAS28 (CRP) and HAQ-DI in abatacept groups were similar; repeated measures analysis showed similar trends in changes from baseline in DAS28 (CRP) and HAQ-DI. Abatacept safety profile was consistent with previous observations. CONCLUSIONS: Post hoc analysis demonstrated similar efficacy and safety of abatacept in biologic-naïve ACPA-positive Japanese patients with RA regardless of baseline MTX dose.

Potential involvement of DSCAML1 mutations in neurodevelopmental disorders.

The molecular mechanisms underlying neurodevelopmental disorders (NDDs) remain unclear. We previously identified Down syndrome cell adhesion molecule like 1 (Dscaml1) as a responsible gene for Ihara epileptic rat (IER), a rat model for human NDDs with epilepsy. However, the relationship between NDDs and DSCAML1 in humans is still elusive. In this study, we screened databases of autism spectrum disorders (ASD), intellectual disability (ID)/developmental disorders (DD) and schizophrenia for genomic mutations in human DSCAML1. We then performed in silico analyses to estimate the potential damage to the mutated DSCAML1 proteins and chose three representative mutations (DSCAML1C729R , DSCAML1R1685* and DSCAML1K2108Nfs*37 ), which lacked a cysteine residue in the seventh Ig domain, the intracellular region and the C-terminal PDZ-binding motif, respectively. In overexpression experiments in a cell line, DSCAML1C729R lost its mature N-glycosylation, whereas DSCAML1K2108Nfs*37 was abnormally degraded via proteasome-dependent protein degradation. Furthermore, in primary hippocampal neurons, the ability of the wild-type DSCAML1 to regulate the number of synapses was lost with all mutant proteins. These results provide insight into understanding the roles of the domains in the DSCAML1 protein and further suggest that these mutations cause functional changes, albeit through different mechanisms, that likely affect the pathophysiology of NDDs.

Down syndrome cell adhesion molecule like-1 (DSCAML1) links the GABA system and seizure susceptibility.

The Ihara epileptic rat (IER) is a mutant model with limbic-like seizures whose pathology and causative gene remain elusive. In this report, via linkage analysis, we identified Down syndrome cell adhesion molecule-like 1(Dscaml1) as the responsible gene for IER. A single base mutation in Dscaml1 causes abnormal splicing, leading to lack of DSCAML1. IERs have enhanced seizure susceptibility and accelerated kindling establishment. Furthermore, GABAergic neurons are severely reduced in the entorhinal cortex (ECx) of these animals. Voltage-sensitive dye imaging that directly presents the excitation status of brain slices revealed abnormally persistent excitability in IER ECx. This suggests that reduced GABAergic neurons may cause weak sustained entorhinal cortex activations, leading to natural kindling via the perforant path that could cause dentate gyrus hypertrophy and epileptogenesis. Furthermore, we identified a single nucleotide substitution in a human epilepsy that would result in one amino acid change in DSCAML1 (A2105T mutation). The mutant DSCAML1A2105T protein is not presented on the cell surface, losing its homophilic cell adhesion ability. We generated knock-in mice (Dscaml1A2105T) carrying the corresponding mutation and observed reduced GABAergic neurons in the ECx as well as spike-and-wave electrocorticogram. We conclude that DSCAML1 is required for GABAergic neuron placement in the ECx and suppression of seizure susceptibility in rodents. Our findings suggest that mutations in DSCAML1 may affect seizure susceptibility in humans.

DSCAM regulates delamination of neurons in the developing midbrain.

For normal neurogenesis and circuit formation, delamination of differentiating neurons from the proliferative zone must be precisely controlled; however, the regulatory mechanisms underlying cell attachment are poorly understood. Here, we show that Down syndrome cell adhesion molecule (DSCAM) controls neuronal delamination by local suppression of the RapGEF2-Rap1-N-cadherin cascade at the apical endfeet in the dorsal midbrain. Dscam transcripts were expressed in differentiating neurons, and DSCAM protein accumulated at the distal part of the apical endfeet. Cre-loxP-based neuronal labeling revealed that Dscam knockdown impaired endfeet detachment from ventricles. DSCAM associated with RapGEF2 to inactivate Rap1, whose activity is required for membrane localization of N-cadherin. Correspondingly, Dscam knockdown increased N-cadherin localization and ventricular attachment area at the endfeet. Furthermore, excessive endfeet attachment by Dscam knockdown was restored by co-knockdown of RapGEF2 or N-cadherin Our findings shed light on the molecular mechanism that regulates a critical step in early neuronal development.

Abatacept in combination with methotrexate in Japanese biologic-naive patients with active rheumatoid arthritis: a randomised placebo-controlled phase IV study.

OBJECTIVES: To evaluate efficacy and safety of abatacept+methotrexate (MTX) in biologic-naive, anticitrullinated protein antibody (ACPA)-positive Japanese patients with active rheumatoid arthritis (RA) and early erosion versus placebo+MTX. METHODS: In this phase IV, multicentre, double-blind study (NCT01758198), patients were randomised (1:1) to receive intravenous abatacept (~10 mg/kg) or placebo, plus MTX (≥6 mg/week). Primary efficacy objectives were to compare American College of Rheumatology 20 (ACR20) response rates at week 16 and mean change from baseline in van der Heijde-modified total Sharp score (vdH-mTSS) at week 24 between abatacept+MTX and placebo+MTX groups. RESULTS: Overall, 203 and 202 patients received abatacept+MTX and placebo+MTX, respectively. At week 16, ACR20 response rates were higher in the abatacept (75.4%) versus placebo group (27.7%; p<0.001). Mean change from baseline in vdH-mTSS at week 24 was 0.84 in the abatacept and 1.26 in the placebo group (p=0.017). Radiographic non-progression rates (change in vdH-mTSS≤smallest detectable change (2.4)) were 88.1% and 75.4% in abatacept and placebo groups, respectively. Adjusted mean change from baseline in Disease Activity Score 28 (C-reactive protein) (DAS28 (CRP)) at week 16 demonstrated a numerically greater reduction in the abatacept versus placebo group. Proportions of patients with DAS28 (CRP), Simplified Disease Activity Index and Clinical Disease Activity Index remission up to week 52 were higher in the abatacept versus placebo group. The abatacept safety profile was consistent with previous observations. CONCLUSIONS: Compared with MTX alone, abatacept+MTX improved clinical symptoms and inhibited structural damage progression in ACPA-positive, Japanese patients with RA, early erosion and inadequate response to MTX.