Tsc2 mutation rather than Tsc1 mutation dominantly causes a social deficit in a mouse model of tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that is associated with neurological symptoms, including autism spectrum disorder. Tuberous sclerosis complex is caused by pathogenic germline mutations of either the TSC1 or TSC2 gene, but somatic mutations were identified in both genes, and the combined effects of TSC1 and TSC2 mutations have been unknown.

METHODS

The present study investigated social behaviors by the social interaction test and three-chambered sociability tests, effects of rapamycin treatment, and gene expression profiles with a gene expression microarray in Tsc1 and Tsc2 double heterozygous mutant (TscD^+/-) mice.

RESULTS

TscD^+/- mice exhibited impairments in social behaviors, and the severity of impairments was similar to Tsc2^+/- mice rather than Tsc1^+/- mice. Impairments in social behaviors were rescued by rapamycin treatment in all mutant mice. Gene expression profiles in the brain were greatly altered in TscD^+/- mice more than in Tsc1^+/- and Tsc2^+/- mice. The gene expression changes compared with wild type (WT) mice were similar between TscD^+/- and Tsc2^+/- mice, and the overlapping genes whose expression was altered in mutant mice compared with WT mice were enriched in the neoplasm- and inflammation-related canonical pathways. The "signal transducer and activator of transcription 3, interferon regulatory factor 1, interferon regulatory factor 4, interleukin-2R α chain, and interferon-γ" signaling pathway, which is initiated from signal transducer and activator of transcription 4 and PDZ and LIM domain protein 2, was associated with impairments in social behaviors in all mutant mice.

LIMITATIONS

It is unclear whether the signaling pathway also plays a critical role in autism spectrum disorders not caused by Tsc1 and Tsc2 mutations.

CONCLUSIONS

These findings suggest that TSC1 and TSC2 double mutations cause autistic behaviors similarly to TSC2 mutations, although significant changes in gene expression were attributable to the double mutations. These findings contribute to the knowledge of genotype-phenotype correlations in TSC and suggest that mutations in both the TSC1 and TSC2 genes act in concert to cause neurological symptoms, including autism spectrum disorder.

First-line osimertinib in patients with epidermal growth factor receptor-mutant non-small-cell lung cancer and with a coexisting low allelic fraction of Thr790Met

AIM OF THE STUDY

The AZENT (NCT02841579) study aimed to assess the efficacy and safety of first-line osimertinib in patients with epidermal growth factor receptor(EGFR)mutation-positive advanced non-small-cell lung cancer (NSCLC) and with a coexisting low allelic fraction of Thr790Met.

METHODS

In this multicentre, single-arm, open-label, phase IIa study, patients with locally advanced or metastatic NSCLC harbouring centrally confirmedEGFR Thr790Met mutation received 80 mg osimertinib daily. The primary end-point was objective response rate (ORR). The secondary end-points included disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and safety. Efficacy was assessed as per Response Evaluation Criteria in Solid Tumours, version 1.1. Blood samples collected at baseline, end of week 2 and disease progression were analysed using next-generation sequencing. As osimertinib was approved as a first-line therapy during the trial, this led to early termination of phase II; thus, analysis is considered exploratory.

RESULTS

Twenty-two patients were enrolled and received osimertinib. All 22 patients were included in the efficacy and safety analysis. At the data cutoff, 10 (50%) patients remained on treatment. The median duration of follow-up was 24.4 months (interquartile range 12.9 to 26.0). The ORR was 77.3% (17/22 [95% confidence interval {CI} 54.6 to 89.3]). The DCR was 86.4% (19/22, [95% CI 65.1 to 97.1]). The median PFS was 23.1 months (95% CI 14.1 to NE). The median OS was 28·4 months (95% CI 25.6 to NE).

CONCLUSION

Despite early study termination, osimertinib first-line therapy yields an overall PFS of 23.1 months in EGFR-mutant patients harbouring a coexisting low allelic fraction of EGFR Thr790Met mutation.

A long-term survivor of pediatric midline glioma with H3F3A K27M and BRAF V600E double mutations

We report a case of 2-year-old female with lateral ventricular glioma harboring both H3F3A K27M and BRAF V600E mutations. By the methylation analysis, the tumor was classified as a diffuse midline glioma H3 K27M mutant, WHO grade IV. However, the tumor was pathologically low-grade and likely localized rather than diffusely infiltrating. Further, the patient has survived more than 8 years after gross total resection of the tumor. Whereas both H3F3A K27M and BRAF V600E have been reported as poor prognostic markers in pediatric glioma, our case, along with several other reported cases, suggests that the coexistence of these two mutations might not indicate poor prognosis. The case emphasizes the importance of comprehensive assessment based on pathological, genetic and clinical findings and calls for further investigations of non-diffuse glioma with H3F3A K27M and glioma with H3F3A K27M and BRAF V600E.

Nonsquamous, Non-Small-Cell Lung Cancer Patients Who Carry a Double Mutation of EGFR, EML4-ALK or KRAS: Frequency, Clinical-Pathological Characteristics, and Response to Therapy

BACKGROUND

Epidermal growth factor receptor (EGFR) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations, and echinoderm microtubule-associated protein-like 4 (EML4) anaplastic lymphoma kinase (ALK) translocation are generally considered to be mutually exclusive. However, concomitant mutations are found in a small number of patients and the effect of these on response to targeted therapy is still unknown.

PATIENTS AND METHODS

We considered 380 non-small-cell lung cancer (NSCLC) patients who underwent nonsequential testing for EGFR and EML4-ALK translocation. KRAS mutation analysis was also performed on 282 patients.

RESULTS

We found 1.6%, 1.1%, and 2.5% of patients who showed a double mutation comprising EGFR and EML4-ALK, EGFR and KRAS, and EML4-ALK and KRAS, respectively. Twenty-eight patients with EGFR mutation underwent first-line therapy with a tyrosine kinase receptor; a clinical benefit was observed in 81.8% of patients with EGFR mutations only and in 67% of those who also showed an EML4-ALK translocation. Twelve patients with an EML4-ALK translocation received crizotinib and 7 of these had disease progression within 3 months (2 had a concomitant KRAS mutation and 1 had a concomitant EGFR mutation). Two patients showed stable disease, 1 of whom also had a KRAS mutation. Two patients obtained a partial response and 1 had a complete response; all harbored an EML4-ALK translocation only. The median overall survival of patients who carried an EML4-ALK translocation alone or concomitant with a KRAS mutation was 57.1 (range, 10.7-not reached) and 10.7 (range, 4.6-not reached) months, respectively.

CONCLUSION

Concomitant EGFR, EML4-ALK, or KRAS mutations can occur in NSCLC. Concomitant KRAS mutation and EML4-ALK translocation represents the most common double alteration and confers a poor prognosis.

Somatic mosaicism of a CDKL5 mutation identified by next-generation sequencing

INTRODUCTION

CDKL5-related encephalopathy is an X-linked dominantly inherited disorder that is characterized by early infantile epileptic encephalopathy or atypical Rett syndrome. We describe a 5-year-old Japanese boy with intractable epilepsy, severe developmental delay, and Rett syndrome-like features. Onset was at 2 months, when his electroencephalogram showed sporadic single poly spikes and diffuse irregular poly spikes.

METHODS

We conducted a genetic analysis using an Illumina® TruSight™ One sequencing panel on a next-generation sequencer.

RESULTS

We identified two epilepsy-associated single nucleotide variants in our case: CDKL5 p.Ala40Val and KCNQ2 p.Glu515Asp. CDKL5 p.Ala40Val has been previously reported to be responsible for early infantile epileptic encephalopathy. In our case, the CDKL5 heterozygous mutation showed somatic mosaicism because the boy's karyotype was 46,XY. The KCNQ2 variant p.Glu515Asp is known to cause benign familial neonatal seizures-1, and this variant showed paternal inheritance.

CONCLUSIONS

Although we believe that the somatic mosaic CDKL5 mutation is mainly responsible for the neurological phenotype in the patient, the KCNQ2 variant might have some neurological effect. Genetic analysis by next-generation sequencing is capable of identifying multiple variants in a patient.