Genome-wide assessment of genetic risk loci for childhood acute lymphoblastic leukemia in Japanese patients

Not available.

Involvement of BCR::ABL1 in laminin adhesion of Philadelphia chromosome-positive acute lymphoblastic leukemia through upregulation of integrin α6

BACKGROUND

Adhesion of cancer cells to extracellular matrix laminin through the integrin superfamily reportedly induces drug resistance. Heterodimers of integrin α6 (CD49f) with integrin β1 (CD29) or β4 (CD104) are major functional receptors for laminin. Higher CD49f expression is reportedly associated with a poorer response to induction therapy in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Moreover, a xenograft mouse model transplanted with primary BCP-ALL cells revealed that neutralized antibody against CD49f improved survival after chemotherapy.

AIMS

Considering the poor outcomes in Philadelphia chromosome (Ph)-positive ALL treated with conventional chemotherapy without tyrosine kinase inhibitors, we sought to investigate an involvement of the laminin adhesion.

METHODS AND RESULTS

Ph-positive ALL cell lines expressed the highest levels of CD49f among the BCP-ALL cell lines with representative translocations, while CD29 and CD104 were ubiquitously expressed in BCP-ALL cell lines. The association of Ph-positive ALL with high levels of CD49f gene expression was also confirmed in two databases of childhood ALL cohorts. Ph-positive ALL cell lines attached to laminin and their laminin-binding properties were disrupted by blocking antibodies against CD49f and CD29 but not CD104. The cell surface expression of CD49f, but not CD29 and CD104, was downregulated by imatinib treatment in Ph-positive ALL cell lines, but not in their T315I-acquired sublines. Consistently, the laminin-binding properties were disrupted by the imatinib pre-treatment in the Ph-positive ALL cell line, but not in its T315I-acquired subline.

CONCLUSION

BCR::ABL1 plays an essential role in the laminin adhesion of Ph-positive ALL cells through upregulation of CD49f.

Mother-child correlation of kidney function: data from the Yamanashi Adjunct Study of Japan Environment and Children's Study (JECS)

BACKGROUND

Individual variation in kidney function can be affected by both congenital and acquired factors, and kidney function in children is possibly correlated with that in their mothers. However, the mother-child correlation in kidney function remains directly unconfirmed.

METHODS

We conducted a cross-sectional study of 655 healthy pairs of 7- or 8-year-old children and their mothers as an adjunct study of a nationwide epidemiological study (Japan Environment and Children's Study).

RESULTS

Both serum creatinine level (all children, r = 0.324, p < 0.001; girls, r = 0.365, p < 0.001; boys, r = 0.278, p < 0.001) and estimated glomerular filtration rate (eGFR) (r = 0.274, p < 0.001; r = 0.352, p < 0.001; r = 0.195, p < 0.001, respectively) in children were weakly associated with their maternal values. In the single linear regression analyses, maternal values of serum creatinine and eGFR were significantly associated with the children's values. Moreover, several body composition values in children, such as weight-SDS, fat (%), and predicted muscle weight, were also significantly associated with kidney function values in children. In the multiple linear regression analysis for serum creatinine levels in children, in which weight-SDS and predicted muscle weight in children were selected as adjustment factors, maternal serum creatinine level showed a significant positive association (B = 0.214, p < 0.001 in the adjusted model). Moreover, in the multiple linear regression analysis for eGFR value in children, in which fat (%) and predicted muscle weight in children were selected as adjustment factors, maternal eGFR values showed a significant positive association (B = 0.319, p < 0.001).

CONCLUSIONS

We directly confirmed mother-child correlations in both serum creatinine levels and eGFR values, particularly in girls. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information.

NAA10 gene expression is associated with mesenchymal transition, dedifferentiation, and progression of clear cell renal cell carcinoma

INTRODUCTION

We aimed to investigate the expression and prognostic role of NAA10 in clear cell renal cell carcinoma (ccRCC).

MATERIAL AND METHODS

We performed a gene expression and survival analysis based on the human cancer genome atlas database of ccRCC patients (TCGA-KIRC).

RESULTS

The patients in the TCGA-KIRC (n = 537) were divided into two subgroups: NAA10-low and NAA10-high expression groups. NAA10-high ccRCC exhibited higher T stages (p = 0.002), a higher frequency of distant metastasis (p = 0.018), more advanced AJCC stages (p < 0.001), a lower overall survival time (p = 0.036), and a lower survival rate (p < 0.001). NAA10-high ccRCC was associated with increased activity of non-specific oncogenic pathways, including oxidative phosphorylation (p < 0.001) and cell cycle progression [G2 to M phase transition (p = 0.045) and E2F targets (p < 0.001)]. Additionally, the NAA10-high tumors showed reduced apoptosis via TRIAL pathways (p < 0.001) and increased levels of activity that promoted epithelial-mesenchymal transition (p = 0.026) or undifferentiation (p = 0.01). In ccRCC, NAA10 expression was found to be a negative prognostic factor in both non-metastatic (p < 0.001) and metastatic tumors (p = 0.032).

CONCLUSIONS

In ccRCC, NAA10 expression was shown to be a negative prognostic factor related to tumor progression rather than tumor initiation, and high NAA10 expression promoted epithelial-mesenchymal transition and undifferentiation.

Canonical BAF complex regulates the oncogenic program in human T-cell acute lymphoblastic leukemia

ABSTRACT

Acute leukemia cells require bone marrow microenvironments, known as niches, which provide leukemic cells with niche factors that are essential for leukemic cell survival and/or proliferation. However, it remains unclear how the dynamics of the leukemic cell-niche interaction are regulated. Using a genome-wide CRISPR screen, we discovered that canonical BRG1/BRM-associated factor (cBAF), a variant of the switch/sucrose nonfermenting chromatin remodeling complex, regulates the migratory response of human T-cell acute lymphoblastic leukemia (T-ALL) cells to a niche factor CXCL12. Mechanistically, cBAF maintains chromatin accessibility and allows RUNX1 to bind to CXCR4 enhancer regions. cBAF inhibition evicts RUNX1 from the genome, resulting in CXCR4 downregulation and impaired migration activity. In addition, cBAF maintains chromatin accessibility preferentially at RUNX1 binding sites, ensuring RUNX1 binding at these sites, and is required for expression of RUNX1-regulated genes, such as CDK6; therefore, cBAF inhibition negatively impacts cell proliferation and profoundly induces apoptosis. This anticancer effect was also confirmed using T-ALL xenograft models, suggesting cBAF as a promising therapeutic target. Thus, we provide novel evidence that cBAF regulates the RUNX1-driven leukemic program and governs migration activity toward CXCL12 and cell-autonomous growth in human T-ALL.

Novel TRPS1 frameshift variant in tricho-rhino-phalangeal syndrome type I accompanied by zinc deficiency

Tricho-rhino-phalangeal syndrome type I (TRPS1), caused by pathogenic variants in the transcriptional repressor GATA-binding 1 gene (TRPS1), is characterized by ectodermal and skeletal anomalies including short stature and sparse scalp hair during infancy. TRPS1 encodes a zinc finger protein transcription factor that contributes to bone homeostasis by regulating perichondral mineralization, chondrocyte proliferation, and apoptosis. Here, a male infant aged 14 months presented with sparse scalp hair, deformed nails, fused teeth, and postnatal growth retardation without neurodevelopmental disorder. As endocrinological measurements revealed low serum zinc levels, he was treated with zinc acetate hydrate, which improved his growth velocity and scalp hair. Whole-exome sequencing revealed that this patient harbored a novel pathogenic de novo heterozygous TRPS1 frameshift variant, c.2819_2822del, p.(His940Argfs*6). Zinc deficiency induces zinc finger protein dysfunction via effects on protein folding and assembly, affecting target gene transcription and apoptosis. The symptoms of TRPS1 are similar to those caused by inadequate levels of zinc, an essential trace element with important roles in tissue growth and repair. Accompanying zinc deficiency may have affected the function of important zinc finger proteins, resulting in phenotypic deterioration. Analysis of zinc metabolism in patients harboring TRPS1 variants will enhance understanding the variety of phenotypes of TRPS1.

Prenatal Torsion of Radial Polydactyly: A Gangrenous Mass at the Base of the Thumb

A patient was born with a mass at the base of the thumb approximately 1.5 cm in diameter on the radial side of the fingers. The mass had globular swelling filled with hemorrhagic fluid and was dark red. X-rays and histology of the excised specimen suggested the diagnosis of gangrene and torsion of polydactyly. Prenatal torsion of polydactyly is not a common occurrence; moreover, prenatal torsion of polydactyly has only been found in ulnar polydactyly. Our case is a novel case of radial polydactyly that was gangrenous at birth owing to prenatal torsion. Diagnosing such a mass at the base of the thumb is important.

Utility of ASNS gene methylation evaluated with the HPLC method as a pharmacogenomic biomarker to predict asparaginase sensitivity in BCP-ALL

Asparaginase is an important agent for the treatment of acute lymphoblastic leukaemia (ALL), but it is occasionally associated with severe adverse events. Thus, for safer and more efficacious therapy, a clinical biomarker predicting asparaginase sensitivity is highly anticipated. Asparaginase depletes serum asparagine by deaminating asparagine into aspartic acid, and ALL cells are thought to be sensitive to asparaginase due to reduced asparagine synthetase (ASNS) activity. We have recently shown that allele-specific methylation of the ASNS gene is highly involved in asparaginase sensitivity in B-precursor ALL (BCP-ALL) by using next-generation sequence (NGS) analysis of bisulphite PCR products of the genomic DNA. Here, we sought to confirm the utility of methylation status of the ASNS gene evaluated with high-performance liquid chromatography (HPLC) analysis of bisulphite PCR products for future clinical applications. In the global methylation status of 23 CpG sites at the boundary region of promoter and exon 1 of the ASNS gene, a strong positive correlation was confirmed between the mean percent methylation evaluated with the HPLC method and that with the NGS method in 79 BCP-ALL cell lines (R2 = 0.85, p = 1.3 × 10-33) and in 63 BCP-ALL clinical samples (R2 = 0.84, p = 5.0 × 10-26). Moreover, methylation status of the ASNS gene evaluated with the HPLC method was significantly associated with in vitro asparaginase sensitivities as well as gene and protein expression levels of ASNS. These observations indicated that the ASNS gene methylation status evaluated with the HPLC method is a reliable biomarker for predicting the asparaginase sensitivity of BCP-ALL.

Factors associated with the development of epilepsy in very low birth weight infants

BACKGROUND

The survival rate of very low birth weight (VLBW) infants has recently improved. However, the occurrence of and factors associated with epilepsy in VLBW infants remain unknown. This study aimed to clarify the incidence, characteristics, and factors associated with epilepsy development in VLBW infants.

METHODS

All VLBW infants admitted to our hospital between 2012 and 2017 were included in this study. VLBW infants with a follow-up period of <1 year were excluded. Chromosomal abnormalities, brain anomalies, severe intraventricular hemorrhage (IVH), cystic periventricular leukomalacia (PVL), and hypoxic ischemic encephalopathy (HIE) were considered to be risk factors.

RESULTS

Epilepsy occurred in 21/526 (4.0%) VLBW infants. Chromosomal abnormalities, brain anomalies, severe IVH, cystic PVL, HIE, neonatal seizures, advanced maternal age, maternal diabetes mellitus, no administration of antenatal corticosteroids, and low Apgar scores at 1 and 5 min were associated with a risk of epilepsy. The median time to epilepsy onset was 8 months (range: 0-59 months), and the onset occurred within 2 years in 15/21 patients (71.4%) and within 4 years in 18/21 patients (85.7%). VLBW infants with risk factors developed epilepsy earlier and at a significantly higher rate than those without risk factors. Among infants who had risk factors and who developed epilepsy, 86.7% did so within 2 years of age, compared to 33.3% of those who developed epilepsy but did not have risk factors.

CONCLUSION

These findings regarding factors associated with a risk of development of epilepsy and temporal feature of epilepsy may contribute to the development of monitoring and treatment protocols for epilepsy in VLBW infants.

Targeting Poly(ADP)ribose polymerase in BCR/ABL1-positive cells

BCR/ABL1 causes dysregulated cell proliferation and is responsible for chronic myelogenous leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph1-ALL). In addition to the deregulatory effects of its kinase activity on cell proliferation, BCR/ABL1 induces genomic instability by downregulating BRCA1. PARP inhibitors (PARPi) effectively induce cell death in BRCA-defective cells. Therefore, PARPi are expected to inhibit growth of CML and Ph1-ALL cells showing downregulated expression of BRCA1. Here, we show that PARPi effectively induced cell death in BCR/ABL1 positive cells and suppressed colony forming activity. Prevention of BCR/ABL1-mediated leukemogenesis by PARP inhibition was tested in two in vivo models: wild-type mice that had undergone hematopoietic cell transplantation with BCR/ABL1-transduced cells, and a genetic model constructed by crossing Parp1 knockout mice with BCR/ABL1 transgenic mice. The results showed that a PARPi, olaparib, attenuates BCR/ABL1-mediated leukemogenesis. One possible mechanism underlying PARPi-dependent inhibition of leukemogenesis is increased interferon signaling via activation of the cGAS/STING pathway. This is compatible with the use of interferon as a first-line therapy for CML. Because tyrosine kinase inhibitor (TKI) monotherapy does not completely eradicate leukemic cells in all patients, combined use of PARPi and a TKI is an attractive option that may eradicate CML stem cells.

Rare TCF3 variants associated with pediatric B cell acute lymphoblastic leukemia

Germline genetic variants influence development of pediatric B cell acute lymphoblastic leukemia (B-ALL). Genome-wide association studies (GWAS) have identified several pediatric B-ALL susceptibility loci. IKZF1 and PAX5, transcription factors involved in B cell development, have been reported as susceptibility genes for B-ALL development. Therefore, we hypothesized that rare variants of genes involved in B cell development would be candidate susceptibility loci for pediatric B-ALL. Thus, we sequenced TCF3, a key transcription factor gene involving in B cell development. Saliva DNA from 527 pediatric patients with pediatric B-ALL in remission who were registered with the Tokyo Children's Cancer Study Group (TCCSG) were examined. As a TCF3 gene-based evaluation, the numbers of rare deleterious germline TCF3 sequence variants in patients with pediatric B-ALL were compared with those in cancer-free individuals using data in public databases. As a TCF3 single-variant evaluation, the frequencies of rare deleterious germline TCF3 sequence variants in patients with pediatric B-ALL were also compared with those in control data. TCF3 gene-based analysis revealed significant associations between rare deleterious variants and pediatric B-ALL development. In addition, TCF3 variant-based analysis showed particularly strong association between variant rs372168347 (three in 521 TCCSG and three in the 15780 gnomAD whole genome analysis cohort, p = 0.0006) and pediatric B-ALL development. TCF3 variants are known to influence B cell maturation and may increase the risk of preleukemic clone emergence.

A simple scoring model based on machine learning predicts intravenous immunoglobulin resistance in Kawasaki disease

INTRODUCTION

In Kawasaki disease (KD), accurate prediction of intravenous immunoglobulin (IVIG) resistance is crucial to reduce a risk for developing coronary artery lesions.

OBJECTIVE

To establish a simple scoring model predicting IVIG resistance in KD patients based on the machine learning model.

METHODS

A retrospective cohort study of 1002 KD patients diagnosed at 12 facilities for 10 years, in which 22.7% were resistant to initial IVIG treatment. We performed machine learning with diverse models using 30 clinical variables at diagnosis in 801 and 201 cases for training and test datasets, respectively. SHAP was applied to identify the variables that influenced the prediction model. A scoring model was designed using the influential clinical variables based on the Shapley additive explanation results.

RESULTS

Light gradient boosting machine model accurately predicted IVIG resistance (area under the receiver operating characteristic curve (AUC), 0.78; sensitivity, 0.50; specificity, 0.88). Next, using top three influential features (days of illness at initial therapy, serum levels of C-reactive protein, and total cholesterol), we designed a simple scoring system. In spite of its simplicity, it predicted IVIG resistance (AUC, 0.72; sensitivity, 0.49; specificity, 0.82) as accurately as machine learning models. Moreover, accuracy of our scoring system with three clinical features was almost identical to that of Gunma score with seven clinical features (AUC, 0.73; sensitivity, 0.53; specificity, 0.83), a well-known logistic regression scoring model.

CONCLUSION

A simple scoring system based on the findings in machine learning seems to be a useful tool to accurately predict IVIG resistance in KD patients.

Eighteen-years follow-up of congenital hypothyroidism by TSHR gene p.Arg109Gln and p.Arg450His variants

Congenital hypothyroidism (CH) is a common heterogeneous endocrine disorder. The thyroid-stimulating hormone receptor gene (TSHR) is one of the major candidate genes associated with CH. Studies have investigated the possible correlations between the specific clinical features and the presence of TSHR variants. However, only a few reports have focused on the long-term follow-up of patients with CH. Here we present a case of CH-associated TSHR p.Arg109Gln and p.Arg450His rare compound heterozygous variants, with a follow-up performed until adolescence. The patient had high serum TSH levels during newborn screening. Oral administration of levothyroxine (l-T4) was initiated at 1 month of age. The ultrasonogram revealed normal thyroid morphology and blood flow. Reduced uptake of I-123 and negative perchlorate test was observed. A small amount of l-T4 remained needed although l-T4 could be steadily reduced by puberty. The patient was diagnosed with orthotopic, nongoitrous, and permanent CH. He had no nonclassical TSH resistance. Patients with the TSHR p.Arg109Gln compound heterozygous variant exhibit permanent CH with high TSH levels and normal or slightly lower fT4 levels. In the future, genotype identification could help predict the long-term prognosis and reduce the requirement for detailed examinations. More case studies are needed to determine the relationship between genetic variants and clinical features in CH.

Evaluating Dysfunction in Fever-Induced Paroxysmal Weakness and Encephalopathy

Heterozygous variants in the ATP1A3 gene are linked to well-known neurological phenotypes. There has been growing evidence for a separate phenotype associated with variants in residue Arg756-fever-induced paroxysmal weakness and encephalopathy (FIPWE) or relapsing encephalopathy with cerebellar ataxia (RECA). With only about 20 cases being reported, the clinical features associated with mutations at Arg756 have not been fully elucidated. We report a case of FIPWE with a p.Arg756Cys change in the ATP1A3 gene and a comparison of the clinical features, including electrophysiological examination, with previous cases. The 3-year-old male patient had normal psychomotor development, presenting with recurrent symptoms of generalized hypotonia with loss of gait, mutism, and dystonic movements only during febrile illnesses since 19 months of age. At 2.7 years of age, a third neurological decompensation episode occurred, during which electroencephalography (EEG) did not reveal high voltage slow waves or epileptiform discharge. Nerve conduction studies (NCS) also did not show latency delay or amplitude reduction. ATP1A3 exon sequencing showed a heterozygous p.Arg756Cys mutation. While the patient experienced repeated encephalopathy-like episodes, including severe hypotonia during febrile illness, EEG and NCS did not reveal any obvious abnormalities. These electrophysiological findings may represent an opportunity to suspect FIPWE and RECA.

CRISPR/Cas9-Mediated Induction of Relapse-Specific NT5C2 and PRPS1 Mutations Confers Thiopurine Resistance as a Relapsed Lymphoid Leukemia Model

6-Mercaptopurine (6-MP) is a key component in maintenance therapy for childhood acute lymphoblastic leukemia (ALL). Recent next-generation sequencing analysis of childhood ALL clarified the emergence of the relapse-specific mutations of the NT5C2 and PRPS1 genes, which are involved in thiopurine metabolism. In this scenario, minor clones of leukemia cells could acquire the 6-MP-resistant phenotype as a result of the NT5C2 or PRPS1 mutation during chemotherapy (including 6-MP treatment) and confer disease relapse after selective expansion. Thus, to establish new therapeutic modalities overcoming 6-MP resistance in relapsed ALL, human leukemia models with NT5C2 and PRPS1 mutations in the intrinsic genes are urgently required. Here, mimicking the initiation process of the above clinical course, we sought to induce two relapse-specific hotspot mutations (R39Q mutation of the NT5C2 gene and S103N mutation of the PRPS1 gene) into a human lymphoid leukemia cell line by homologous recombination (HR) using the CRISPR/Cas9 system. After 6-MP selection of the cells transfected with Cas9 combined with single-guide RNA and donor DNA templates specific for either of those two mutations, we obtained the sublines with the intended NT5C2-R39Q and PRPS1-S103N mutation as a result of HR. Moreover, diverse in-frame small insertion/deletions were also confirmed in the 6-MP-resistant sublines at the target sites of the NT5C2 and PRPS1 genes as a result of nonhomologous end joining. These sublines are useful for molecular pharmacological evaluation of the NT5C2 and PRPS1 gene mutations in the 6-MP sensitivity and development of therapy overcoming the thiopurine resistance of leukemia cells. SIGNIFICANCE STATEMENT: Mimicking the initiation process of relapse-specific mutations of the NT5C2 and PRPS1 genes in childhood acute lymphoblastic leukemia treated with 6-mercaptopurine (6-MP), this study sought to introduce NT5C2-R39Q and PRPS1-S103N mutations into a human lymphoid leukemia cell line by homologous recombination using the CRISPR/Cas9 system. In the resultant 6-MP-resistant sublines, the intended mutations and diverse in-frame small insertions/deletions were confirmed, indicating that the obtained sublines are useful for molecular pharmacological evaluation of the NT5C2 and PRPS1 gene mutations.

Creation of Philadelphia chromosome by CRISPR/Cas9-mediated double cleavages on BCR and ABL1 genes as a model for initial event in leukemogenesis

The Philadelphia (Ph) chromosome was the first translocation identified in leukemia. It is supposed to be generated by aberrant ligation between two DNA double-strand breaks (DSBs) at the BCR gene located on chromosome 9q34 and the ABL1 gene located on chromosome 22q11. Thus, mimicking the initiation process of translocation, we induced CRISPR/Cas9-mediated DSBs simultaneously at the breakpoints of the BCR and ABL1 genes in a granulocyte-macrophage colony-stimulating factor (GM-CSF) dependent human leukemia cell line. After transfection of two single guide RNAs (sgRNAs) targeting intron 13 of the BCR gene and intron 1 of the ABL1 gene, a factor-independent subline was obtained. In the subline, p210 BCR::ABL1 and its reciprocal ABL1::BCR fusions were generated as a result of balanced translocation corresponding to the Ph chromosome. Another set of sgRNAs targeting intron 1 of the BCR gene and intron 1 of the ABL1 gene induced a factor-independent subline expressing p190 BCR::ABL1. Both p210 and p190 BCR::ABL1 induced factor-independent growth by constitutively activating intracellular signaling pathways for transcriptional regulation of cell cycle progression and cell survival that are usually regulated by GM-CSF. These observations suggested that simultaneous DSBs at the BCR and ABL1 gene breakpoints are initiation events for oncogenesis in Ph+ leukemia. (200/200 words).

Synergistic effect of combined PI3 kinase inhibitor and PARP inhibitor treatment on BCR/ABL1-positive acute lymphoblastic leukemia cells

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) function by inhibiting base excision repair and inducing synthetic lethality in homologous recombination repair-deficient cells, such as BRCA1/2-mutated cancer cells. The BCR/ABL1 fusion protein causes dysregulated cell proliferation and is responsible for chronic myelogenous leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph⁺ALL). BCR/ABL1 also induces genomic instability by downregulating BRCA1. We investigated the effect of the PARPi, olaparib, against Ph⁺ALL cell lines and found that they show variable sensitivity, presumably due to cancer-associated genetic alterations other than BCR/ABL1. To investigate the reasons for the variable responses of Ph⁺ALL cells to PARPi treatment, we analyzed the transcriptomes of olaparib-sensitive and -resistant Ph⁺ALL cell lines, which revealed that activation of the phosphatidylinositol 3-kinase (PI3K) pathway was a hallmark of PARPi resistance. Based on these findings, we examined the effects of adding a PI3K inhibitor (PI3Ki) to PARPi treatment to overcome PARPi insensitivity in Ph⁺ALL cell lines. Combination with PI3Ki increased PARPi cytotoxicity in PARPi-resistant Ph⁺ALL cell lines. Tyrosine kinase inhibitor (TKI) therapy is the gold standard for Ph⁺ALL, and, based on our findings, we propose that PARPi combined with TKI and PI3K inhibition could be a novel therapeutic strategy for Ph⁺ALL.

Low NUDT15 expression levels due to biallelic NUDT15 variants and 6-mercaptopurine intolerance

6-Mercaptopurine (6-MP) is widely used for the treatment of paediatric leukaemia and lymphoma. Recently, germline variants in the NUDT15 gene have been identified as one of the major genetic causes for 6-MP-associated adverse effects such as myelosuppression. Patients with hypomorphic NUDT15 variants accumulate excessive levels of DNA-incorporated thioguanine in white blood cells, resulting in severe myelosuppression. Although preclinical studies suggest that these variants may influence the protein stability of NUDT15, this has not been directly characterised in patients. In this study, we report the development of a series of novel monoclonal antibodies against NUDT15, using which we quantitatively assessed NUDT15 protein levels in 37 patients with acute lymphoblastic leukaemia treated with 6-MP, using sandwich enzyme-linked immunosorbent assay (ELISA). The NUDT15 genotype was highly correlated with its protein levels (p < 0.0001), with homozygous and compound heterozygous patients showing exceedingly low NUDT15 expression. There was a positive correlation between NUDT15 protein level and 6-MP tolerance (r = 0.631, p < 0.0001). In conclusion, our results point to low NUDT15 protein abundance as the biochemical basis for NUDT15-mediated 6-MP intolerance, thus providing a phenotypic readout of inherited NUDT15 deficiency.

Introduction of the T315I gatekeeper mutation of BCR/ABL1 into a Philadelphia chromosome-positive lymphoid leukemia cell line using the CRISPR/Cas9 system

Imatinib and second-generation tyrosine kinase inhibitors (TKIs) have dramatically improved the prognosis of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). However, overcoming TKI resistance due to the T315I gatekeeper mutation of BCR/ABL1 is crucial for further improving the prognosis. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system is appropriate for establishing a human model of Ph+ ALL with the T315I mutation, because it can induce specific mutations via homologous recombination (HR) repair in cells with intact endogenous HR pathway. Here we used CRISPR/Cas9 to introduce the T315I mutation into the Ph+ lymphoid leukemia cell line KOPN55bi, which appeared to have an active HR pathway based on its resistance to a poly (ADP-Ribose) polymerase-1 inhibitor. Single-guide RNA targeting at codon 315 and single-strand oligodeoxynucleotide containing ACT to ATT nucleotide transition at codon 315 were electroporated with recombinant Cas9 protein. Dasatinib-resistant sublines were obtained after one-month selection with the therapeutic concentration of dasatinib, leading to T315I mutation acquisition through HR. T315I-acquired sublines were highly resistant to imatinib and second-generation TKIs but moderately sensitive to the therapeutic concentration of ponatinib. This authentic human model is helpful for developing new therapeutic strategies overcoming TKI resistance in Ph+ ALL due to T315I mutation.

BCL6 inhibition ameliorates resistance to ruxolitinib in CRLF2-rearranged acute lymphoblastic leukemia

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is an intractable disease and most cases harbor genetic alterations that activate JAK or ABL signaling. The commonest subtype of Ph-like ALL exhibits a CRLF2 gene rearrangement that brings about JAK1/2-STAT5 pathway activation. However, JAK1/2 inhibition alone is insufficient as a treatment, so combinatorial therapies targeting multiple signals are needed. To better understand the mechanisms underlying the insufficient efficacy of JAK inhibition, we explored gene expression changes upon treatment with a JAK1/2 inhibitor (ruxolitinib) and found that elevated BCL6 expression was one such mechanism. Upregulated BCL6 suppressed the expression of TP53 along with its downstream cell cycle inhibitor p21 (CDKN2A) and pro-apoptotic molecules, such as FAS, TNFRSF10B, BID, BAX, BAK, PUMA, and NOXA, conferring cells some degree of resistance to therapy. BCL6 inhibition (with FX1) alone was able to upregulate TP53 and restore the TP53 expression that ruxolitinib had diminished. In addition, ruxolitinib and FX1 concertedly downregulated MYC. As a result, FX1 treatment alone had growth-inhibitory and apoptosis- sensitizing effects, but the combination of ruxolitinib and FX1 more potently inhibited leukemia cell growth, enhanced apoptosis sensitivity, and prolonged the survival of xenografted mice. These findings provide one mechanism for the insufficiency of JAK inhibition for the treatment of CRLF2-rearranged ALL and indicate BCL6 inhibition as a potentially helpful adjunctive therapy combined with JAK inhibition.

Prominence of NUDT15 genetic variation associated with 6-mercaptopurine tolerance in a genome-wide association study of Japanese children with acute lymphoblastic leukaemia

Inherited genetic variation is associated with 6-mercaptopurine (6-MP) dose reduction and frequent toxicities induced by 6-MP. However, the tolerable dose for 6-MP is not fully predicted by the known variation in NUDT15 and TPMT among Asian children with acute lymphoblastic leukaemia (ALL). We performed a genome-wide association study (GWAS) related to 6-MP dose among Japanese children with ALL. This GWAS comprised 224 patients previously enrolled in Tokyo Children's Cancer Study Group clinical studies with replication attempted in 55 patients. Genome-wide single nucleotide polymorphism (SNP) genotypes were evaluated for association with average 6-MP dose during the initial 168 days of maintenance therapy. Possible associations were observed across five gene-coding regions, among which only variants at 13q14.2 were significant and replicated genome-wide (rs116855232, NUDT15, β = -10.99, p = 3.7 × 10^-13 ). Notable findings were observed for variants in AFF3 (rs75364948, p = 2.05 × 10^-6 ) and CHST11 (rs1148407, p = 2.09 × 10^-6 ), but were not replicated possibly due to small numbers. A previously reported candidate SNP in MTHFR was associated with higher average 6-MP dose (rs1801133, p = 0.045), and FOLH1 (rs12574928) was associated in an evaluation of candidate regions (p_adjust  = 0.013). This study provides strong evidence that rs116855232 in NUDT15 is the genetic factor predominantly associated with 6-MP tolerable dose in children in Japan.

Impairment of autonomic emotional response for executive function in children with ADHD: A multi-modal fNIRS and pupillometric study during the Wisconsin Card Sorting Test

OBJECTIVE

Children with attention deficit hyperactivity disorder (ADHD) often experience difficulties with emotional control and a consequent inability to perform tasks. To clarify the effects of emotional behavior on cognitive functions, we aimed to determine the association between emotional changes and executive functions in children with ADHD by measuring the pupil diameter changes associated with emotional changes.

PARTICIPANTS AND METHODS

This study included 14 children with ADHD and 10 typically developing children (TDC) aged between 10 and 16 years. During the Wisconsin Card Sorting Test (WCST), which is related to context formation and task switching among executive functions, changes in pupil diameter and frontal oxygenated hemoglobin (oxy-Hb) using functional near-infrared spectroscopy (fNIRS) were recorded simultaneously. Pupil diameter changes during "cognitive shift" and "consecutive correction" were compared between both groups.

RESULTS

During cognitive shift, the pupils of children with ADHD contracted, whereas those of the TDC were mydriatic. During consecutive correction, the pupils of children with ADHD were mydriatic, whereas those of the TDC tended to contract. These results correlated with WCST performance. Moreover, during cognitive shifts, changes in bilateral frontal blood flow were increased in TDC, but not in children with ADHD.

CONCLUSION

The locus coeruleus-norepinephrine (LC-NE) system plays an important role in pupillary diameter response. These results suggest that the LC-NE system may be dysfunctional in children with ADHD, and the system's abnormality may lead to affective abnormalities in such patients, which results in poor performance on WCST (i.e., impaired executive functions).

Idiopathic central precocious puberty with Prader-Willi syndrome: pubertal development with discontinuation of gonadotropin-releasing hormone analog

Summary

Prader-Willi syndrome (PWS) is a genetic imprinting disorder that is characterized by obesity, short stature, and hypogonadism. Hypogonadism is characterized by normal luteinizing hormone (LH), high follicle-stimulating hormone (FSH), low testosterone, low inhibin B, and relatively low anti-Müllerian hormone (AMH). Only a few cases of central precocious puberty (CPP) have been reported in PWS, and follow-up for CPP with PWS is not established. Hence, we present a boy with PWS accompanied by CPP. Gonadotropin-releasing hormone analog (GnRHa) therapy was started at 7 years of age, CPP was adequately arrested, and GnRHa therapy was discontinued at 11.3 years of age. Growth hormone (GH) therapy was started at 12 years of age due to inadequate growth. He grew close to his final height, and his testes developed with normal LH, increased FSH, normal testosterone, and reduced AMH corresponding to puberty at 13.5 years of age. The features of 16 patients with PWS with CPP, including our patient, were summarized. Out of seven male patients, five were treated with GnRHa, as well as four out of nine female patients. Out of 16 patients, 6 were assessed with pubertal development over 13 years of age. Pubertal development was considered to be restored in four patients who had GnRHa therapy discontinuation. We should carefully follow-up on pubertal development in CPP. GnRHa therapy is useful for adequate puberty blockage, and pubertal development could be restored with GnRHa therapy discontinuation.

Learning points

Pubertal development in Prader-Willi syndrome (PWS) varies from hypogonadism to precocious puberty. Pubertal development assessment based on clinical features and hormone levels is needed in central precocious puberty (CPP) treatment with PWS. Gonadotropin-releasing hormone analog (GnRHa) therapy is useful for CPP with PWS, and pubertal development can be restored with GnRHa therapy discontinuation.

Compound heterozygous variants of the NARS2 gene in siblings with developmental delay, epilepsy, and neonatal diabetes syndrome

Neonatal diabetes mellitus (NDM) with developmental delay and epilepsy is classified as developmental delay, epilepsy, and neonatal diabetes (DEND) syndrome. The majority of DEND syndrome are due to severely damaging variants of K-ATP channels, and few mitochondria-related genes have been reported. We report here two Japanese siblings who were clinically diagnosed with DEND syndrome in whom NARS2 compound heterozygous variants were detected. Patient 1 was a 3-year-old girl and presented with diabetes ketoacidosis at 3 months old. Patient 2 was a 1-year-old boy who presented with severe hyperglycemia and started insulin therapy at 3 days old. After the first episodes, they both presented with severe developmental delay, hearing loss and treatment-resistant epilepsy accompanied by progressive brain atrophy. Whole-exome sequencing revealed compound heterozygous NARS2 p.R159C and p.L217V variants, and the GATA4 p.P407Q variant in both patients. They were treated by mitochondrial supportive therapy of vitamin B1, L-carnitine, and coenzyme Q10. Patient 2 was withdrawn from insulin therapy at 6 months old. This is the first report of NDM in which variants of the NARS2 gene coding mitochondrial protein were detected. Genetic analysis including mitochondrial genes should be considered in patients with neonatal onset diabetes associated with neurogenic symptoms.

Arterial spin labeling perfusion imaging in an infant with anti-N-methyl-D-aspartate receptor encephalitis: A case report

BACKGROUND

Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is an autoimmune encephalitis characterized by complex neuropsychiatric syndromes and the presence of cerebrospinal fluid (CSF) antibodies against NMDAR. The characteristics of anti-NMDAR encephalitis in children, particularly infants, are unclear due to difficulties in neurologic assessment such as psychiatric symptoms. Additionally, subtle or non-specific findings of conventional magnetic resonance imaging (MRI) make early diagnosis even more difficult. Herein, we present the first case of infant anti-NMDAR encephalitis in which perfusion imaging demonstrated marked abnormalities and the absence of conventional MRI findings.

CASE PRESENTATION

The patient was an 11-month-old boy who was admitted because of seizure and prolonged fever. He presented with involuntary movements of the mouth and tongue. Brain MRI showed no morphological abnormalities, but three-dimensional arterial spin labeling (ASL) perfusion imaging showed reduced blood flow in the left temporal and frontal regions and the right cerebellum. After that, a positive anti-NMDAR antibody test result was received. Despite treatment with IVIG and methylprednisolone, the involuntary movements and autonomic dysfunction gradually became more prominent. After rituximab administration, the clinical symptoms improved slightly, and follow-up MRI revealed diffuse brain atrophy and improvement in the balance of brain perfusion.

CONCLUSIONS

To the best of our knowledge, this is the first case report of infantile anti-NMDAR encephalitis in which cerebral blood flow was evaluated using three-dimensional ASL perfusion imaging. Indeed, our case, which showed abnormalities only in ASL perfusion imaging, suggests that CBF assessment could aid in the early diagnosis of anti-NMDAR encephalitis in infants.

Glucocorticoid receptor gene mutations confer glucocorticoid resistance in B-cell precursor acute lymphoblastic leukemia

Glucocorticoid (GC) is a key drug in the treatment of B-cell precursor acute lymphoblastic leukemia (BCP-ALL), and the initial GC response is an important prognostic factor. GC receptors play an essential role in GC sensitivity, and somatic mutations of the GC receptor gene, NR3C1, are reportedly identified in some BCP-ALL cases, particularly at relapse. Moreover, associations of somatic mutations of the CREB-binding protein (CREBBP) and Wolf-Hirschhorn syndrome candidate 1 (WHSC1) genes with the GC-resistance of ALL have been suggested. However, the significance of these mutations in the GC sensitivity of BCP-ALL remains to be clarified in the intrinsic genes. In the present study, we sequenced NR3C1, WHSC1, and CREBBP genes in 99 BCP-ALL and 22 T-ALL cell lines (32 and 67 cell lines were known to be established at diagnosis and at relapse, respectively), and detected their mutations in 19 (2 cell lines at diagnosis and 15 cell lines at relapse), 26 (6 and 15), and 38 (11 and 15) cell lines, respectively. Of note, 14 BCP-ALL cell lines with the NR3C1 mutations were significantly more resistant to GC than those without mutations. In contrast, WHSC1 and CREBBP mutations were not associated with GC resistance. However, among the NR3C1 unmutated BCP-ALL cell lines, WHSC1 mutations tended to be associated with GC resistance and lower NR3C1 gene expression. Finally, we successfully established GC-resistant sublines of the GC-sensitive BCP-ALL cell line (697) by disrupting ligand binding and DNA binding domains of the NR3C1 gene using the CRISPR/Cas9 system. These observations demonstrated that somatic mutations of the NR3C1 gene, and possibly the WHSC1 gene, confer GC resistance in BCP-ALL.

Successful treatment of intractable gastrointestinal tract graft-vs-host disease with oral beclomethasone dipropionate in pediatric and young adult patients: Case reports

RATIONALE

The gastrointestinal (GI) tract is a common target organ of graft-vs-host disease (GVHD) in hematopoietic stem cell transplantation (HSCT) patients, and GI tract GVHD is often resistant to standard treatments such as corticosteroids. Moreover, longterm use of systemic corticosteroids sometimes induces adverse events such as infection. Beclomethasone dipropionate (BDP) is a potent, topically active corticosteroid, which is metabolized to an active derivative in the intestinal mucosa. Oral BDP therapy is reportedly effective against GI tract GVHD in adult HSCT patients, but its efficacy and safety in pediatric patients remain undefined. Here, we report three pediatric and young adult cases who were treated with oral BDP.

PATIENT CONCERNS

Three (6-, 7-, and 18-year-old) patients developed stage 2 to 4 lower GI tract GVHD, which was resistant to standard immunosuppressive therapies.

DIAGNOSIS

Lower GI tract GVHD in these patients was histopathologically proven by endoscopic biopsy.

INTERVENTIONS

Oral administration of enteric-coated capsules of BDP (3-8 mg/day) was started for the treatment of lower GI tract GVHD.

OUTCOMES

With the introduction of oral BDP therapy, their GI tract symptoms promptly resolved (abdominal pain, within 3-7 days; diarrhea, within 2-3 weeks). Subsequently, systemic immunosuppressive agents such as corticosteroids and mycophenolate mofetil were successfully tapered off. During oral BDP therapy, although cytomegalovirus antigenemia and Acinetobacter Iwoffii sepsis developed in 2 cases, both were curable with conventional treatments. In a young adult case, concomitant BK virus-associated hemorrhagic cystitis resolved after oral BDP was introduced and systemic immunosuppressive agents were reduced. Transient growth restriction was observed in a pediatric case who was treated with oral BDP for approximately 300days.

LESSONS

Our experiences suggest that oral BDP therapy is an effective approach for GI tract GVHD that is resistant to standard immunosuppressive therapies. Of clinical importance, our case suggests the possibility that oral BDP therapy may improve the immunosuppressive condition in GI tract GVHD patients by contributing to the reduction of systemic immunosuppressive medications as a result of prompt improvement of GI tract GVHD symptoms.

Genome-wide CRISPR-Cas9 screen identifies rationally designed combination therapies for CRLF2-rearranged Ph-like ALL

Acute lymphoblastic leukemia (ALL) harboring the IgH-CRLF2 rearrangement (IgH-CRLF2-r) exhibits poor clinical outcomes and is the most common subtype of Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL). While multiple chemotherapeutic regimens, including ruxolitinib monotherapy and/or its combination with chemotherapy, are being tested, their efficacy is reportedly limited. To identify molecules/pathways relevant for IgH-CRLF2-r ALL pathogenesis, we performed genome-wide CRISPR-Cas9 dropout screens in the presence or absence of ruxolitinib using 2 IgH-CRLF2-r ALL lines that differ in RAS mutational status. To do so, we employed a baboon envelope pseudotyped lentiviral vector system, which enabled, for the first time, highly efficient transduction of human B cells. While single-guide RNAs (sgRNAs) targeting CRLF2, IL7RA, or JAK1/2 significantly affected cell fitness in both lines, those targeting STAT5A, STAT5B, or STAT3 did not, suggesting that STAT signaling is largely dispensable for IgH-CRLF2-r ALL cell survival. We show that regulators of RAS signaling are critical for cell fitness and ruxolitinib sensitivity and that CRKL depletion enhances ruxolitinib sensitivity in RAS wild-type (WT) cells. Gilteritinib, a pan-tyrosine kinase inhibitor that blocks CRKL phosphorylation, effectively killed RAS WT IgH-CRLF2-r ALL cells in vitro and in vivo, either alone or combined with ruxolitinib. We further show that combining gilteritinib with trametinib, a MEK1/2 inhibitor, is an effective means to target IgH-CRLF2-r ALL cells regardless of RAS mutational status. Our study delineates molecules/pathways relevant for CRLF2-r ALL pathogenesis and could suggest rationally designed combination therapies appropriate for disease subtypes.

CN470 is a BET/CBP/p300 multi-bromodomain inhibitor and has an anti-tumor activity against MLL-rearranged acute lymphoblastic leukemia

Acute lymphoblastic leukemia with chromosomal rearrangements involving the mixed-lineage leukemia (MLL) gene (MLL-r ALL) remains an incurable disease. Thus, development of a safe and effective therapeutic agent to treat this disease is crucial to address this unmet medical need. BRD4, a member of the bromodomain and extra-terminal domain (BET) protein family, and cyclic AMP response element binding protein binding protein (CBP) and p300, two paralogous histone acetyltransferases, are all considered cancer drug targets and simultaneous targeting of these proteins may have therapeutic advantages. Here, we demonstrate that a BET/CBP/p300 multi-bromodomain inhibitor, CN470, has anti-tumor activity against MLL-r ALL in vitro and in vivo. CN470, potently inhibited ligand binding to the bromodomains of BRD4, CBP, and p300 and suppressed the growth of MLL-r ALL cell lines and patient-derived cells with MLL rearrangements. CN470 suppressed mRNA and protein expression of MYC and induced apoptosis in MLL-r ALL cells, following a cell cycle arrest in the G1 phase. Moreover, CN470 reduced BRD4 binding to acetylated histone H3. The in vivo effects of CN470 were investigated using SEM^Luc/GFP cells expressing luminescent markers in an orthotopic mouse model. Mice administered CN470 daily had prolonged survival compared to the vehicle group. Further, CN470 also showed anti-tumor effects against an MLL-r ALL patient-derived xenograft model. These findings suggest that inhibition of BET/CBP/p300 by the multi-bromodomain inhibitor, CN470, represents a promising therapeutic approach against MLL-r ALL.

Screening of frequent variants associated with congenital hypothyroidism: a comparison with next generation sequencing

Congenital hypothyroidism (CH) is considered the most common congenital endocrine disorder of genetic origin. Next generation sequencing (NGS) is the standard method for identifying genetic mutations, but it is an expensive and complex technique. Therefore, we propose to use Sanger sequencing to identify selected variants of the four most common CH-causative genes: DUOX2, TG, TSHR, and PAX8. To analyze the performance of Sanger sequencing, we compared its variant detection ability with that of a CH NGS panel containing 53 genes. We performed Sanger sequencing of selected variants and panel NGS analysis of 25 Japanese patients with CH. Sanger sequencing identified nine variants in seven patients, while NGS identified 24 variants in 14 patients. Of these, eight, five, eight, two, and one were found to be potentially pathogenic in DUOX2, TSHR, TG, UBR1, and TPO genes, respectively. The percentage of detectable variants using Sanger sequencing compared with NGS was 37.5% (9/24 variants), whereas the percentage of detectable cases carrying variants using Sanger sequencing compared with NGS was 50% (7/14 patients). We proposed a system for screening commonly identified CH-related variants by Sanger sequencing. Sanger sequencing could therefore identify about a third of CH-causative variants, so is considered an effective and efficient form of pre-screening before NGS.

Prevention Measures for COVID-19 and Changes in Kawasaki Disease Incidence

BACKGROUND

Kawasaki disease is suspected to be triggered by previous infection. The prevention measures for coronavirus disease 2019 (COVID-19) have reportedly reduced transmission of certain infectious diseases. Under these circumstances, the prevention measures for COVID-19 may reduce the incidence of Kawasaki disease.

METHODS

We conducted a retrospective study using registration datasets of patients with Kawasaki disease who were diagnosed in all 11 inpatient pediatric facilities in Yamanashi Prefecture. The eligible cases were 595 cases that were diagnosed before the COVID-19 pandemic (from January 2015 through February 2020) and 38 cases that were diagnosed during the COVID-19 pandemic (from March through November 2020). Incidence of several infectious disease were evaluated using data from the Infectious Disease Weekly Report conducted by the National Institute of Infectious Diseases.

RESULTS

Epidemics of various infectious diseases generally remained at low levels during the first 9 months (March through November 2020) of the COVID-19 pandemic. Moreover, the incidence of COVID-19 was 50-80 times lower than the incidence in European countries and the United States. The total number of 38 cases with Kawasaki disease for the 9 months during the COVID-19 pandemic was 46.3% (-3.5 standard deviations [SDs] of the average [82.0; SD, 12.7 cases] for the corresponding 9 months of the previous 5 years. None of the 38 cases was determined to be triggered by COVID-19 based on their medical histories and negative results of severe acute respiratory syndrome coronavirus 2 testing at admission.

CONCLUSION

These observations provide a new epidemiological evidence for the notion that Kawasaki disease is triggered by major infectious diseases in children.

NUDT15 polymorphism and NT5C2 and PRPS1 mutations influence thiopurine sensitivity in acute lymphoblastic leukaemia cells

In chemotherapy for childhood acute lymphoblastic leukaemia (ALL), maintenance therapy consisting of oral daily mercaptopurine and weekly methotrexate is important. NUDT15 variant genotype is reportedly highly associated with severe myelosuppression during maintenance therapy, particularly in Asian and Hispanic populations. It has also been demonstrated that acquired somatic mutations of the NT5C2 and PRPS1 genes, which are involved in thiopurine metabolism, are detectable in a portion of relapsed childhood ALL. To directly confirm the significance of the NUDT15 variant genotype and NT5C2 and PRPS1 mutations in thiopurine sensitivity of leukaemia cells in the intrinsic genes, we investigated 84 B‐cell precursor‐ALL (BCP‐ALL) cell lines. Three and 14 cell lines had homozygous and heterozygous variant diplotypes of the NUDT15 gene, respectively, while 4 and 2 cell lines that were exclusively established from the samples at relapse had the NT5C2 and PRPS1 mutations, respectively. Both NUDT15 variant genotype and NT5C2 and PRPS1 mutations were significantly associated with DNA‐incorporated thioguanine levels after exposure to thioguanine at therapeutic concentration. Considering the continuous exposure during the maintenance therapy, we evaluated in vitro mercaptopurine sensitivity after 7‐day exposure. Mercaptopurine concentrations lethal to 50% of the leukaemia cells were comparable to therapeutic serum concentration of mercaptopurine. Both NUDT15 variant genotype and NT5C2 and PRPS1 mutations were significantly associated with mercaptopurine sensitivity in 83 BCP‐ALL and 23 T‐ALL cell lines. The present study provides direct evidence to support the general principle showing that both inherited genotype and somatically acquired mutation are crucially implicated in the drug sensitivity of leukaemia cells.

KIR3DL1 Allotype-Dependent Modulation of NK Cell Immunity against Chronic Myeloid Leukemia

Tyrosine kinase inhibitor (TKI)-treated chronic myeloid leukemia (CML) patients with increased NK cell number have a better prognosis, and thus, NK cells may suppress CML. However, the efficacy of TKIs varies for reasons yet to be fully elucidated. As NK cell activity is modulated by interactions between their killer cell Ig-like receptors (KIRs) and HLAs of target cells, the combination of their polymorphisms may have functional significance. We previously showed that allelic polymorphisms of KIR3DL1 and HLAs were associated with the prognosis of TKI-treated CML patients. In this study, we focus on differential NK cell activity modulation through KIR3DL1 allotypes. KIR3DL1 expression levels varied according to their alleles. The combination of KIR3DL1 expression level and HLA-Bw4 motifs defined NK cell activity in response to the CML-derived K562 cell line, and Ab-mediated KIR3DL1 blocking reversed this activity. The TKI dasatinib enhanced NK cell activation and cytotoxicity in a KIR3DL1 allotype-dependent manner but did not significantly decrease effector regulatory T cells, suggesting that it directly activated NK cells. Dasatinib also enhanced NK cell cytotoxicity against K562 bearing the BCR-ABL1 T315I TKI resistance-conferring mutation, depending on KIR3DL1/HLA-Bw4 allotypes. Transduction of KIR3DL1*01502 into the NK cell line NK-92 resulted in KIR3DL1 expression and suppression of NK-92 activity by HLA-B ligation, which was reversed by anti-KIR3DL1 Ab. Finally, KIR3DL1 expression levels also defined activation patterns in CML patient-derived NK cells. Our findings raise the possibility of a novel strategy to enhance antitumor NK cell immunity against CML in a KIR3DL1 allotype-dependent manner.

IMiDs uniquely synergize with TKIs to upregulate apoptosis of Philadelphia chromosome-positive acute lymphoblastic leukemia cells expressing a dominant-negative IKZF1 isoform

The long-term prognosis of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL) is still unsatisfactory even after the emergence of tyrosine kinase inhibitors (TKIs) against chimeric BCR-ABL, and this is associated with the high incidence of genetic alterations of Ikaros family zinc finger 1 (IKZF1), most frequently the hemi-allelic loss of exons 4–7 expressing a dominant-negative isoform Ik6. We found that lenalidomide (LEN), a representative of immunomodulatory drugs (IMiDs), which have been long used for the treatment of multiple myeloma, specifically induced accumulation of Ik6 with the disappearance of functional isoforms within 24 h (i.e., abrupt and complete shut-down of the IKZF1 activity) in Ik6-positive Ph+ALL cells in a neddylation-dependent manner. The functional IKZF3 isoforms expression was also abruptly and markedly downregulated. The LEN treatment specifically suppressed proliferation of Ik6-positive-Ph+ALL cells by inducing cell cycle arrest via downregulation of cyclins D3 and E and CDK2, and of importance, markedly upregulated their apoptosis in synergy with the TKI imatinib (IM). Apoptosis of IM-resistant Ph+ALL cells with T315I mutation of BCR-ABL was also upregulated by LEN in the presence of the newly developed TKI ponatinib. Analyses of flow cytometry, western blot, and oligonucleotide array revealed that apoptosis was caspase-/p53-dependent and associated with upregulation of pro-apoptotic Bax/Bim, enhanced dephosphorylation of BCR-ABL/Akt, and downregulation of oncogenic helicase genes HILLS, CDC6, and MCMs4 and 8. Further, the synergism of LEN with IM was clearly documented as a significant prolongation of survival in the xenograft mice model. Because this synergism was further potentiated in vitro by dexamethasone, a key drug for ALL treatment, the strategy of repositioning IMiDs for the treatment of Ik6-positive Ph+ALL patients certainly shed new light on an outpatient-based treatment option for achieving their long-term durable remission and higher QOL, particularly for those who are not tolerable to intensified therapeutic approaches.

Clinically Mild Encephalopathy With a Reversible Splenial Lesion Type 2 Caused by Human Herpesvirus 6 Infection

BACKGROUND

Clinically mild encephalopathy with a reversible splenial lesion (MERS) is the second commonest cause of encephalopathy. Several pathogens have been detected in patients with MERS type 2, such as influenza A and B, but little is known about the proportion of cases of MERS type 2 with this pathogenesis. Human herpesvirus 6 (HHV6) is the second commonest pathogen causing acute encephalopathy. However, HHV6 has not been previously reported in patients with MERS type 2.

PATIENT DESCRIPTION

In this report, we describe a five-year-old boy with MERS type 2 caused by HHV6 infection. The present case was diagnosed with MERS type 2 caused by HHV6 infection based on the characteristic clinical course, the results of the virus testing, and imaging findings.

DISCUSSION

This is the first description of MERS type 2 caused by HHV6 infection. Although there is a report of MERS type 1 caused by HHV6 infection, there are no detailed reports in the literature about MERS type 2 associated with HHV6 infection. Thus the clinical findings associated with MERS type 2 caused by HHV6 infection are poorly understood. This report indicates that HHV6 can cause MERS type 2.

Assessment of MGMT methylation status using high-performance liquid chromatography in newly diagnosed glioblastoma

BACKGROUND

The utility of O⁶-methylguanine-DNA methyltransferase (MGMT) gene promoter methylation status as a prognostic marker in patients with glioblastoma (GBM) has been established. However, the number of CpG sites that must be methylated to cause transcriptional silencing remains unclear, and no significant consensus exists on the optimal method of assessing MGMT methylation. We developed a new high-performance liquid chromatography (HPLC) method that enables accurate analysis of DNA methylation levels using long PCR products. In the present study, we analyzed the MGMT methylation status of 28 isocitrate dehydrogenase-wild-type GBMs treated with temozolomide using ion-exchange HPLC and set the optimal cutoff values.

RESULTS

We designed three primers for separate regions (regions 1-3) that had 21 to 38 CpGs for PCR and validated the MGMT promoter methylation status using frozen samples. There was a strong correlation between HPLC and bisulfite sequencing results (R = 0.794). The optimal cutoff values for MGMT methylation in HPLC were determined to allow differentiation of patient prognosis by receiver operating characteristic curve analysis. The cutoff values were 34.15% for region 1, 8.84% for region 2, and 36.72% for region 3. Kaplan-Meyer curve analysis estimated that the most differentiated prognosis was enabled in the setting of 8.84% methylation of MGMT in region 2. Progression-free survival and overall survival were significantly longer for patients in this setting of region 2 methylation (p = 0.00365 and p = 0.00258, respectively).

CONCLUSIONS

The combination of our HPLC method and the original primer setting provides a new standard method for determination of MGMT methylation status in patients with GBM and is useful for refining MGMT-based drug selection.

Inherited genetic variants associated with glucocorticoid sensitivity in leukaemia cells

Identification of genetic variants associated with glucocorticoids (GC) sensitivity of leukaemia cells may provide insight into potential drug targets and tailored therapy. In the present study, within 72 leukaemic cell lines derived from Japanese patients with B-cell precursor acute lymphoblastic leukaemia (ALL), we conducted genome-wide genotyping of single nucleotide polymorphisms (SNP) and attempted to identify genetic variants associated with GC sensitivity and NR3C1 (GC receptor) gene expression. IC50 measures for prednisolone (Pred) and dexamethasone (Dex) were available using an alamarBlue cell viability assay. IC50 values of Pred showed the strongest association with rs904419 (P = 4.34 × 10^-8 ), located between the FRMD4B and MITF genes. The median IC50 values of prednisolone for cell lines with rs904419 AA (n = 13), AG (n = 31) and GG (n = 28) genotypes were 0.089, 0.139 and 297 µmol/L, respectively. For dexamethasone sensitivity, suggestive association was observed for SNP rs2306888 (P = 1.43 × 10^-6 ), a synonymous SNP of the TGFBR3 gene. For NR3C1 gene expression, suggestive association was observed for SNP rs11982167 (P = 6.44 × 10^-8 ), located in the PLEKHA8 gene. These genetic variants may affect GC sensitivity of ALL cells and may give rise to opportunities in personalized medicine for effective and safe chemotherapy in ALL patients.

Apparent Life-Threatening Event in an Infant with SARS-CoV-2 Infection

The 2019 novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a global outbreak of infection. In general, children with coronavirus disease-2019 have been reported to show milder respiratory symptoms than adult patients. Here, we have described a case of a SARS-CoV-2-infected infant who presented to our hospital with a severe episode of an apparent life-threatening event (ALTE). An 8-month-old, otherwise healthy female infant presented to our hospital because of a sudden cardiopulmonary arrest. Approximately 1 h before this episode, the patient showed no symptoms, except a worse humor than usual. On arrival at our hospital, the patient had severe acidosis, but there were no clear signs of inflammatory response. Chest computed tomography showed weak consolidations in the upper right lung and atelectasis in the lower left lung. No signs of congenital heart disease or cardiomyopathy were observed on echocardiography, and no significant arrhythmia was observed during the clinical course. However, SARS-CoV-2 RNA was detected by real-time reverse transcription polymerase chain reaction in tracheal aspirate and urine samples. Although the assessment of further similar cases is indispensable, this case suggests that SARS-CoV-2 infection may be an underlying factor in the pathophysiology of ALTE.

Association of relapse-linked ARID5B single nucleotide polymorphisms with drug resistance in B-cell precursor acute lymphoblastic leukemia cell lines

Background

The genetic variants of the ARID5B gene have recently been reported to be associated with disease susceptibility and treatment outcome in childhood acute lymphoblastic leukemia (ALL). However, few studies have explored the association of ARID5B with sensitivities to chemotherapeutic agents.

Methods

We genotyped susceptibility-linked rs7923074 and rs10821936 as well as relapse-linked rs4948488, rs2893881, and rs6479778 of ARDI5B by direct sequencing of polymerase chain reaction (PCR) products in 72 B-cell precursor-ALL (BCP-ALL) cell lines established from Japanese patients. We also quantified their ARID5B expression levels by real-time reverse transcription PCR, and determined their 50% inhibitory concentration (IC50) values by alamarBlue assays in nine representative chemotherapeutic agents used for ALL treatment.

Results

No significant associations were observed in genotypes of the susceptibility-linked single nucleotide polymorphisms (SNPs) and the relapsed-linked SNPs with ARID5B gene expression levels. Of note, IC50 values of vincristine (VCR) (median IC50: 39.6 ng/ml) in 12 cell lines with homozygous genotype of risk allele (C) in the relapse-linked rs4948488 were significantly higher (p = 0.031 in Mann–Whitney U test) than those (1.04 ng/ml) in 60 cell lines with heterozygous or homozygous genotypes of the non-risk allele (T). Furthermore, the IC50 values of mafosfamide [Maf; active metabolite of cyclophosphamide (CY)] and cytarabine (AraC) tended to be associated with the genotype of rs4948488. Similar associations were observed in genotypes of the relapse-linked rs2893881 and rs6479778, but not in those of the susceptibility-linked rs7923074 and rs10821936. In addition, the IC50 values of methotrexate (MTX) were significantly higher (p = 0.023) in 36 cell lines with lower ARID5B gene expression (median IC50: 37.1 ng/ml) than those in the other 36 cell lines with higher expression (16.9 ng/ml).

Conclusion

These observations in 72 BCP-ALL cell lines suggested that the risk allele of the relapse-linked SNPs of ARID5B may be involved in a higher relapse rate because of resistance to chemotherapeutic agents such as VCR, CY, and AraC. In addition, lower ARID5B gene expression may be associated with MTX resistance.

Abstract 1745: Application of BET/CBP/p300 multi-bromodomain inhibitors as a novel therapeutic strategy for MLL-rearranged acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common form of childhood leukemia. While the prognosis of patients with ALL has improved significantly, ALL with chromosomal rearrangements involving mixed-lineage leukemia (MLL) gene remains an incurable disease. Thus, development of a safe and efficacious therapeutic agent based on the biology of MLL rearrangement is of high importance to address this unmet medical need.

Bromodomains are protein motifs that bind to acetylated histones and are recognized as new epigenetic drug targets in recent years. Bromodomain and extra-terminal motif proteins (“BET proteins”) are epigenetic ‘reader' proteins that are characterized by containing two of such bromodomains. BRD4, a member of BET protein family, is a key component of multi-protein complex that induce oncogene transcription at Super-Enhancers. Currently, small-molecule BET inhibitors are being investigated in the clinic as potential therapeutics for hematological cancers. CBP and p300, two paralogous histone acetyltransferases, also contain bromodomains and are considered as drug targets for cancer. Because BET and CBP/p300 proteins are key components of the etiology of MLL-rearranged (MLL-r) leukemia, an agent that simultaneously target both classes of proteins may have therapeutic advantages.

We previously demonstrated that a novel BET inhibitor, CG13250, suppressed multiple myeloma cell proliferation in vitro and in vivo (Biochem Biophys Res Commun, 484:262-268, 2017) and subsequently synthesized additional BET inhibitors (Bioorg Med Chem Lett, 29:1220-1226, 2019). In the present study, we demonstrate that some of our BET inhibitors can also inhibit bromodomains of CBP/p300 proteins. One such compound, CN470, potently suppresses BRD4, CBP, and p300 with BROMOscan KD values of 33, 32, and 20 nM, respectively, and suppressed mRNA and protein expression of c-MYC as expected. CN470 potently inhibited the growth of MLL-r ALL cell lines in a dose-dependent manner and flow cytometric analyses showed that CN470 caused apoptosis in MLL-r ALL cells following a cell cycle arrest at the G1 phase. Moreover, co-immunoprecipitation assay demonstrated that CN470 reduced the binding of BRD4 to acetylated H3 (H3K27), an effect absent with a reference BET inhibitor, OTX-015. Taken together, CN470 may represent an effective strategy against MLL-r ALL cells.

As a confirmatory study, we investigated the in vivo effects of CN470 by using SEMLuc/GFP cells in an orthotopic mouse model of MLL-AF4 leukemia. Mice were orally administered with CN470 (10 mg/kg) once daily resulting in a prolonged survival compared to vehicle control group (mean 37 days vs. 28 days; p=0.0246).

In conclusion, simultaneous inhibition of BET/CBP/p300 with a multi-bromodomain inhibitor represents a promising novel therapeutic approach against MLL-r ALL.

Citation Format: Natsuki Imayoshi, Makoto Yoshioka, Shyh-Ming Yang, Koshi Akahane, Yuki Toda, Shigekuni Hosogi, Takeshi Inukai, Seiji Okada, David J. Maloney, Jefferey W. Strovel, Eishi Ashihara. Application of BET/CBP/p300 multi-bromodomain inhibitors as a novel therapeutic strategy for MLL-rearranged acute lymphoblastic leukemia [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1745.