Showing papers by "Susumu Kobayashi published in 2020"

EGFR-A763_Y764insFQEA Is a Unique Exon 20 Insertion Mutation That Displays Sensitivity to Approved and In-Development Lung Cancer EGFR Tyrosine Kinase Inhibitors.

Abstract: Introduction The EGFR-A763_Y764insFQEA is a unique exon 20 insertion mutation (∼5% to 6% of exon 20 insertions), which, at the structural and enzyme kinetic level, more closely resembles EGFR tyrosine kinase inhibitor (TKI)–sensitizing mutants, such as EGFR exon 19 indels and L858R. A limited number of preclinical models and clinical reports have studied the response of this mutant to EGFR TKIs. Methods We used models of EGFR-A763_Y764insFQEA and more typical EGFR exon 20 insertion mutations to probe representative first- (gefitinib, erlotinib), second- (afatinib), third-generation (osimertinib), and in-development EGFR exon 20–specific (poziotinib, mobocertinib [TAK-788]) TKIs. We also compiled outcomes of EGFR-A763_Y764insFQEA-mutated lung cancers treated with EGFR TKIs. Results Cells driven by EGFR-A763_Y764insFQEA were consistently sensitive to EGFR TKIs (as opposed to those driven by typical EGFR exon 20 insertions [A767_V769dupASV, D770_N771insSVD and H773_V774insH]), which were only inhibited by in-development EGFR TKIs at doses below those affecting wild-type EGFR. Most case instances (62.5% [95% confidence interval: 39%–86%], n = 16) with lung cancers harboring EGFR-A763_Y764insFQEA responded to clinically available EGFR TKIs (including osimertinib) and to in-development EGFR exon 20-specific TKIs (including mobocertinib) with prolonged periods of progression-free survival in some cases. Median overall survival for EGFR TKI–treated cases was 22 months (95% confidence interval: 16–25). Mechanisms of acquired TKI resistance of this mutant remain underreported, but do seem to align with those of common mutations. Conclusions To our knowledge, this is the largest report to confirm that the EGFR-A763_Y764insFQEA mutation is sensitive to clinically available first-, second-, third-generation, and in-development EGFR TKIs.

Combination treatment with a PI3K/Akt/mTOR pathway inhibitor overcomes resistance to anti-HER2 therapy in PIK3CA-mutant HER2-positive breast cancer cells.

Abstract: Amplification and/or overexpression of human epidermal growth factor receptor 2 (HER2) are observed in 15-20% of breast cancers (HER2+ breast cancers), and anti-HER2 therapies have significantly improved prognosis of patients with HER2+ breast cancer. One resistance mechanism to anti-HER2 therapies is constitutive activation of the phosphoinositide 3-kinase (PI3K) pathway. Combination therapy with small-molecule inhibitors of AKT and HER2 was conducted in HER2+ breast cancer cell lines with or without PIK3CA mutations, which lead to constitutive activation of the PI3K pathway. PIK3CA mutations played important roles in resistance to single-agent anti-HER2 therapy in breast cancer cell lines. Combination therapy of a HER2 inhibitor and an AKT inhibitor, as well as other PI3K pathway inhibitors, could overcome the therapeutic limitations associated with single-agent anti-HER2 treatment in PIK3CA-mutant HER2+ breast cancer cell lines. Furthermore, expression of phosphorylated 4E-binding protein 1 (p4EBP1) following the treatment correlated with the antiproliferative activities of the combination, suggesting that p4EBP1 may have potential as a prognostic and/or efficacy-linking biomarkers for these combination therapies in patients with HER2+ breast cancer. These findings highlight potential clinical strategies using combination therapy to overcome the limitations associated with single-agent anti-HER2 therapies in patients with HER2+ breast cancer.

Iron leakage owing to blood-brain barrier disruption in small vessel disease CADASIL.

Abstract: Objective: To assess the relationship between iron accumulation, blood-brain barrier (BBB) damage, and cognitive function in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) Methods: We enrolled 21 patients with NOTCH3 mutations and 21 age-matched healthy controls in this cross-sectional study All participants underwent global physical and cognitive assessments and brain MRI, using voxel-based quantitative susceptibility mapping (QSM; iron deposition measure) and dynamic contrast enhanced MRI (DCE-MRI; BBB permeability measure) We compared behavioral and imaging data between the groups and analyzed the correlations in each group Results: Among 21 NOTCH3 mutation carriers, 10 were symptomatic and 11 asymptomatic Montreal Cognitive Assessment scores were significantly different among the groups (symptomatic Conclusions: This study showed that cerebral iron burden was associated with regional BBB permeability and cognitive dysfunction in patients with CADASIL, highlighting the potential of these imaging techniques as auxiliary biomarkers to monitor the course of small vessel disease

Magnetic Susceptibility Associates With Dopaminergic Deficits and Cognition in Parkinson's Disease

Abstract: OBJECTIVE The objective of this study was to assess the relationship between nigrostriatal magnetic susceptibility and dopamine transporter abnormality and their associations with behavioral and cognitive impairments in patients with Parkinson's disease (PD). METHODS For this case-control study, we enrolled 41 patients with PD and 20 age-matched healthy controls. All participants underwent global physical and cognitive assessments, 3-Tesla brain magnetic resonance imaging including quantitative susceptibility mapping (QSM; iron deposition measure), and 123 I-N-v-fluoropropyl-2b-carbomethoxy-3b-(4-iodophenyl) nortropane single-photon emission computed tomography (dopamine transporter measure). We subdivided the striatum into the putamen, caudate nucleus, and nucleus accumbens and measured the nigrostriatal QSM values and dopamine transporter-specific binding ratios using an atlas-based approach. RESULTS The patients with PD had higher QSM values in the substantia nigra and subdivisions of the striatum than did the healthy controls. The striatal dopamine transporter-specific binding ratios were not correlated with the QSM values of the substantia nigra but were inversely correlated with those of the striatum (putamen, r = -0.478, P = 0.009; caudate nucleus, r = -0.462, P = 0.011). The QSM values of the putamen were positively correlated with motor parkinsonism scores (Movement Disorder Society Unified Parkinson's Disease Rating Scale, r = 0.505, P = 0.003), and those of the caudate nucleus were negatively correlated with cognitive impairment scores (Montreal Cognitive Assessment, r = -0.525, P < 0.001). CONCLUSIONS This study showed that striatal iron accumulations were correlated with dopaminergic deficits and neurophysiological signs in patients with PD, highlighting the potential of QSM as an auxiliary biomarker for parkinsonism and cognitive dysfunction. © 2020 International Parkinson and Movement Disorder Society.

Long-read sequencing for non-small-cell lung cancer genomes.

Abstract: Here, we report the application of a long-read sequencer, PromethION, for analyzing human cancer genomes. We first conducted whole-genome sequencing on lung cancer cell lines. We found that it is possible to genotype known cancerous mutations, such as point mutations. We also found that long-read sequencing is particularly useful for precisely identifying and characterizing structural aberrations, such as large deletions, gene fusions, and other chromosomal rearrangements. In addition, we identified several medium-sized structural aberrations consisting of complex combinations of local duplications, inversions, and microdeletions. These complex mutations occurred even in key cancer-related genes, such as STK11, NF1, SMARCA4, and PTEN The biological relevance of those mutations was further revealed by epigenome, transcriptome, and protein analyses of the affected signaling pathways. Such structural aberrations were also found in clinical lung adenocarcinoma specimens. Those structural aberrations were unlikely to be reliably detected by conventional short-read sequencing. Therefore, long-read sequencing may contribute to understanding the molecular etiology of patients for whom causative cancerous mutations remain unknown and therapeutic strategies are elusive.

Acquired Resistance to Osimertinib Plus Savolitinib Is Mediated by MET-D1228 and MET-Y1230 Mutations in EGFR-Mutated MET-Amplified Lung Cancer.

Abstract: Acquired Resistance to Osimertinib Plus Savolitinib Is Mediated by MET-D1228 and MET-Y1230 Mutations in EGFR-Mutated MET-Amplified Lung Cancer Andrew J. Piper-Vallillo, MD, Brian T. Halbert, MD, Deepa Rangachari, MD, Susumu S. Kobayashi, MD, PhD, Daniel B. Costa, MD, PhD* Department of Medicine, Division of Medical Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts Division of Translational Genomics, Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Kashiwa, Chiba, Japan

Formal Total Synthesis of Atropurpuran.

Abstract: Atropurpuran, isolated from the roots of Aconitum hemsleyanum, is a non-alkaloidal diterpene which possesses a unique pentacyclic skeleton that contains an unprecedented tetracyclo[5.3.3.04,9.04,12]tridecane unit. We report herein the formal total synthesis of atropurpuran. The key features of our synthetic route are a high diastereoselective construction of the tri- and tetrasubstituted carbons (i.e., C4, C5, C10, and C20) through an Yb-catalyzed Mukaiyama aldol reaction in an aqueous medium and a one-pot operation including an intramolecular Diels-Alder reaction/ring-closing metathesis to construct the unique pentacyclic skeleton of atropurpuran.

NAD modulates DNA methylation and cell differentiation

Abstract: Nutritional intake impacts the human epigenome by directing epigenetic pathways in normal cell development via as yet unknown molecular mechanisms. Consequently, imbalance in the nutritional intake is able to dysregulate the epigenetic profile and drive cells towards malignant transformation. Herein, we present a novel epigenetic effect of the essential nutrient, NAD. We demonstrate that impairment of DNMT1 enzymatic activity by NAD-promoted ADP-ribosylation, leads to demethylation and transcriptional activation of CEBPA gene, suggesting the existence of an unknown NAD-controlled region within the locus. In addition to the molecular events, NAD treated cells exhibit significant morphological and phenotypical changes that correspond to myeloid differentiation. Collectively, these results delineate a novel role for NAD in cell differentiation and indicate novel nutri-epigenetic strategy to regulate and control gene expression in human cells.

Alternative splicing of APOBEC3D generates functional diversity and its role as a DNA mutator

Abstract: The apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like (APOBEC) protein family members have cytidine deaminase activity and can induce cytosine to uracil transition in nucleic acid. The main function of APOBEC3 (A3) proteins is to trigger an innate immune response to viral infections. Recent reports have shown that several APOBEC family proteins such as A3B can induce somatic mutations into genomic DNA and thus promote cancer development. However, the role of A3D on somatic mutations is unclear. Here, we identified the alternative splicing of A3D, and investigated each splice variant's subcellular localization and role in DNA mutagenesis. We identified four A3D variants, which all have one or two cytidine deaminase domains. The full-length form of A3D (variant 1) and truncated forms of A3D (variant 2, 6, 7) showed the ability to induce C/G to T/A transitions in foreign DNA and genomic DNA and retained antiretroviral activity. Furthermore, we demonstrated that A3D and A3B could induce deletions that are possibly repaired by microhomology-mediated end joining (MMEJ). Taken together, our experiments illustrated that alternative splicing generates functional diversity of A3D, and some variants can act as DNA mutators in genomic DNA.

Understanding and therapeutic targeting of aberrant mRNA splicing mechanisms in oncogenesis

Abstract: Splicing factor 3b subunit 1 (SF3B1) is the most commonly mutated RNA splicing factor identified in myelodysplastic syndrome (MDS), chronic lymphocytic leukemia, and uveal melanoma. The mechanisms by which SF3B1 mutations promote malignancy are poorly understood. Here, we integrated pan-cancer RNA sequencing to identify mutant SF3B1-dependent aberrant splicing events with a positive CRISPR screen to prioritize alterations that functionally promote oncogenesis. Our results indicated that diverse, recurrent SF3B1 mutations converge on the repression of bromodomain containing 9 (BRD9), a core component of the recently described non-canonical barrier-to-autointegration factor complex (ncBAF). Mutant SF3B1 recognizes intronic sequences within BRD9 as exons, thereby permitting inclusion of aberrant sequence (i.e., poison exon) that will result in the degradation of BRD9 mRNA. BRD9 depletion results in significant loss of ncBAF at CCCTC-binding factor (CTCF)-binding loci but has no impact on the localization of canonical BAF. These actions resulted in disturbed myeloid/erythroid differentiation and promoted the development of MDS and melanoma. Of note, correcting BRD9 mis-splicing in SF3B1-mutant cells with antisense oligonucleotides (ASOs), by targeting the poison exon with CRISPR-directed mutagenesis, or via the use of spliceosomal inhibitors are all potential therapeutic options. Our results implicate disruption of ncBAF as a critical factor promoting the development of the diverse array of cancers that carry SF3B1 mutations and suggest a mechanism-based therapeutic approach for treating these malignancies.

Preclinical characterization of mobocertinib highlights the putative therapeutic window of this novel EGFR inhibitor to EGFR exon 20 insertion mutations

Abstract: Background Epidermal growth factor receptor (EGFR) exon 20 insertion mutations account for 10% of all EGFR mutations and are mostly insensitive to approved EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Novel EGFR-TKIs have been developed or repurposed for these mutants. A limited number of preclinical studies have detailed these EGFR-TKIs. We sought to use commercially available mobocertinib (TAK-788) to characterize the preclinical therapeutic window of this EGFR-TKI against EGFR mutations and to probe possible on-target mechanisms of resistance (EGFR-C797S). Methods We used models of EGFR mutations to probe representative 1st, 2nd, 3rd generation, and in-development EGFR exon 20-active (poziotinib, mobocertinib) TKIs. We also introduced EGFR-C797S to these models to identify mechanisms of resistance. Results Cells driven by the most common EGFR exon 20 insertion mutations (A767_V769dupASV, D770_N771insSVD, H773_V774insH and others) were inhibited by in-development EGFR TKIs at doses below those affecting EGFR-wildtype; albeit more common EGFR mutations (exon 19 deletions and L858R) were inhibited more readily by mobocertinib and poziotinib. Mobocertinib was able to inhibit phosphorylation of EGFR in multiple preclinical models. The presence of EGFR-C797S led to >200-fold resistance in proliferation assays probing mobocertinib and osimertinib. Review of clinical studies of mobocertinib disclosed responses that could be lasting. Conclusions This is one of the initial reports to characterize the novel EGFR TKI mobocertinib and highlights its broad activity against EGFR mutants plus the therapeutic window to EGFR exon 20 insertion mutations; as well as EGFR-C797S as a possible mechanism of resistance. Further clinical development of mobocertinib merits continuation.

A young male of hemorrhagic cerebral infarction associated with finasteride and minoxidil

Abstract: A young male of hemorrhagic cerebral infarction associated with finasteride and minoxidil Tomoyuki Kuno, M.D., Yuto Uchida, M.D., Toshihiko Usami, M.D., Susumu Kobayashi, M.D., Koji Takada, M.D., Ph.D., Masahiro Oomura, M.D., Ph.D., and Noriyuki Matsukawa, M.D., Ph.D. Department of Neurology, Toyokawa City Hospital Department of Neurology, Nagoya City University Graduate School of Medical Sciences Department of Radiology, Toyokawa City Hospital We report a young male of hemorrhagic cerebral infarction associated with finasteride and minoxidil. He had undertaken 0.4 mg of finasteride and 4 mg of minoxidil daily for 8 months. During his exercising, he suddenly presented with a headache, followed by visual disorder. On admission, his brain MRI showed hemorrhagic cerebral infarction in the right occipital lobe. However, our examinations that revealed the cause of his cerebral infarction showed no abnormalities. Thereafter, we suspected adverse effects of finasteride and minoxidil and discontinued these medications. He never had recurrent stroke since then. We emphasize the importance of a detailed interview including unusual medications to investigate the cause of cerebral infarction.