Myeloid/natural killer (NK) cell precursor acute leukemia as a distinct leukemia type.

Myeloid/natural killer (NK) cell precursor acute leukemia (MNKPL) has been described on the basis of its unique immunophenotype and clinical phenotype. However, there is no consensus on the characteristics for identifying this disease type because of its rarity and lack of defined distinctive molecular characteristics. In this study, multiomics analysis revealed that MNKPL is distinct from acute myeloid leukemia, T cell acute lymphoblastic leukemia, and mixed-phenotype acute leukemia (MPAL), and NOTCH1 and RUNX3 activation and BCL11B down-regulation are hallmarks of MNKPL. Although NK cells have been classically considered to be lymphoid lineage-derived, the results of our single-cell analysis using MNKPL cells suggest that NK cells and myeloid cells share common progenitor cells. Treatment outcomes for MNKPL are unsatisfactory, even when hematopoietic cell transplantation is performed. Multiomics analysis and in vitro drug sensitivity assays revealed increased sensitivity to l-asparaginase and reduced levels of asparagine synthetase (ASNS), supporting the clinically observed effectiveness of l-asparaginase.

Enhanced osteoclastogenesis in patients with MSMD due to impaired response to IFN-γ.

BACKGROUND: Patients with Mendelian susceptibility to mycobacterial disease (MSMD) experience recurrent and/or persistent infectious diseases associated with poorly virulent mycobacteria. Multifocal osteomyelitis is among the representative manifestations of MSMD. The frequency of multifocal osteomyelitis is especially high in patients with MSMD etiologies that impair cellular response to IFN-γ, such as IFN-γR1, IFN-γR2, or STAT1 deficiency. OBJECTIVES: This study sought to characterize the mechanism underlying multifocal osteomyelitis in MSMD. METHODS: GM colonies prepared from bone marrow mononuclear cells from patients with autosomal dominant (AD) IFN-γR1 deficiency, AD STAT1 deficiency, or STAT1 gain of function (GOF) and from healthy controls were differentiated into osteoclasts in the presence or absence of IFN-γ. The inhibitory effect of IFN-γ on osteoclastogenesis was investigated by quantitative PCR, immunoblotting, tartrate-resistant acid phosphatase staining, and pit formation assays. RESULTS: Increased osteoclast numbers were identified by examining the histopathology of osteomyelitis in patients with AD IFN-γR1 deficiency or AD STAT1 deficiency. In the presence of receptor activator of nuclear factor kappa-B ligand and M-CSF, GM colonies from patients with AD IFN-γR1 deficiency, AD STAT1 deficiency, or STAT1 GOF differentiated into osteoclasts, similar to GM colonies from healthy volunteers. IFN-γ concentration-dependent inhibition of osteoclast formation was impaired in GM colonies from patients with AD IFN-γR1 deficiency or AD STAT1 deficiency, whereas it was enhanced in GM colonies from patients with STAT1 GOF. CONCLUSIONS: Osteoclast differentiation is increased in AD IFN-γR1 deficiency and AD STAT1 deficiency due to an impaired response to IFN-γ, leading to excessive osteoclast proliferation and, by inference, increased bone resorption in infected foci, which may underlie multifocal osteomyelitis.

Azacitidine successfully maintained the second remission in an infant with KMT2A-rearranged acute lymphoblastic leukemia who relapsed after unrelated cord blood transplantation.

The outcome for infants with KMT2A (MLL)-rearranged acute lymphoblastic leukemia (MLL-r ALL) is dismal despite intensive therapy, including hematopoietic stem cell transplantation (HSCT). Epigenetic dysregulation is considered a key driver of MLL-r leukemogenesis, which theoretically supports the use of epigenetic modifiers as a treatment option. We report an infant MLL-r ALL case with post-HSCT relapse. After achieving a second remission, which was maintained for 10 months using only the DNA methyltransferase inhibitor, azacitidine, the patient successfully received the second HSCT. This report describes the clinical effectiveness of azacitidine for the treatment of infant MLL-r ALL.

Comparison of second transplantation and donor lymphocyte infusion for donor mixed chimerism after allogeneic stem cell transplantation for nonmalignant diseases.

BACKGROUND: Donor mixed chimerism (MC) is an increasing problem after hematopoietic stem cell transplantation (HSCT) for nonmalignant diseases. PROCEDURE: In this study, a self-administered questionnaire was used to retrospectively compare efficacy and safety in 49 patients undergoing second HSCT (n = 13) or donor lymphocyte infusion (DLI; n = 36) as treatment for MC. RESULTS: The response rate to DLI of patients with secondary graft failure (GF) (25.0%) was significantly lower than that of patients without secondary GF (81.3%; P = 0.041). Among patients undergoing DLI, the rates of successful response were significantly higher in patients having at least 30% donor chimerism (94.1%) than in patients having less than 30% donor chimerism (61.1%; P = 0.041). Furthermore, the rates of successful response were significantly higher in patients receiving larger first or maximum doses of DLI. Sixteen (50.0%) of 32 patients without secondary GF attained complete chimerism after DLI. The cumulative incidence of grade II-IV acute graft-versus-host disease and cytopenia was 37.6 and 26.1%, respectively. CONCLUSIONS: DLI yields promising response rates in most patients with higher donor chimerism levels, whereas second HSCT is more likely to benefit patients with lower donor chimerism levels.

Effective Treatment of a Childhood Blastic Plasmacytoid Dendritic Cell Neoplasm with a Cutaneous Tumor Alone by Stem Cell Transplantation with Reduced Intensity Conditioning.

Pediatric blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematological malignancy that has an extremely poor prognosis despite the use of intensive chemotherapy. Recently, treatment of BPDCN with bone marrow transplantation (BMT) using myeloablative conditioning has been reported to increase survival in adults. We report a 9-year-old girl with cutaneous BPDCN who was successfully treated with combination chemotherapy followed by BMT using reduced intensity conditioning (RIC), without any adverse complications. The success of this treatment regimen suggests that BMT with RIC may be a feasible option for treating children with cutaneous BPDCN.

Early eradication of factor VIII inhibitor in patients with congenital hemophilia A by immune tolerance induction with a high dose of immunoglobulin.

The production of factor VIII (FVIII) inhibitory antibodies is a serious problem in patients with hemophilia A. Immune tolerance induction (ITI) is the only strategy proven to eradicate persistent inhibitors and has been shown to be successful in 70 % of patients with hemophilia A. However, a minority of hemophilia patients present life-long inhibitors. To eliminate such inhibitors, we designed an intravenous immunoglobulin (IVIG) strategy in combination with high dose recombinant FVIII for ITI in hemophilia A children with inhibitors. Four previously untreated patients produced inhibitors within 16 exposures to FVIII. The peak inhibitor titers in these patients ranged from 3 to 14 BU/mL. The patients received ITI combined with IVIG within 1.5 months after the inhibitors were detected. All patients showed a negative titer for inhibitors by 28 days, with no anamnestic responses. The recovery of FVIII in the plasma concentration was normalized within three months after initiation of ITI. An additional course of IVIG administration led to induction of complete tolerance by 20 months after initiation of ITI therapy in all patients. ITI treatment with high-dose FVIII combined with IVIG may be effective for the early elimination of inhibitors.

Hematopoietic stem cell transplantation for patients with acute lymphoblastic leukemia and Down syndrome.

BACKGROUND: Hematopoietic stem cell transplantation (HSCT) is one curable option for high-risk acute lymphoblastic leukemia (ALL); however, transplant-related toxicities might be severe in patients with Down syndrome and ALL (DS-ALL). PROCEDURE: HSCTs performed in patients with DS-ALL were identified in the Japan Society for Hematopoietic Cell Transplantation registry. RESULTS: In the registry data, 11 patients with DS-ALL were identified. The median age at HSCT was 9 years (range: 6-22 years). Six patients underwent HSCT at non-remission status. Allogeneic grafts were utilized in all patients, including eight patients who received HSCT from unrelated donors. Reduced intensity conditioning regimens were used in three patients. All patients achieved neutrophil engraftment by a median of day 18 (range: day 11-61). Ten patients experienced grade 3 or more infectious episodes. Six patients experienced complications of the respiratory system. The incidences of II-IV or III-IV acute GVHD were nine (81.8%) or seven patients (63.6%), respectively. Chronic GVHD was observed in five (55.6%) out of nine evaluable patients. Seven patients died at a median of 6 months (range: 0-24 months) after HSCT. Two-year relapse-free and overall survival were 33.3% (95% CI: 2.5-64.1%) or 37.5% (95% CI: 5.9-69.1%), respectively. The causes of death were relapse (n = 2), infection (n = 2), bleeding (n = 1), thrombotic microangiopathy (n = 1), and chronic GVHD (n = 1). CONCLUSIONS: Therapy-related mortality accounted for five out of seven deceased patients in this case series. Attempts to reduce toxicities should be considered in HSCT for patients with DS-ALL.

Detection of Mucor velutinosus in a blood culture after autologous peripheral blood stem cell transplantation : a pediatric case report.

Filamentous fungi were detected in the blood culture of a one-year-old boy after autologous peripheral blood stem cell transplantation. The patient was suspected to have aspergillosis and received micafungin. Fungi were isolated on potato dextrose agar medium and incubated at 37℃ for 2-5 days. Grayish, cottony colonies formed. A slide culture showed a spherical sporangium at the tips of the sporangiophores. The fungus could have been a zygomycete. The zygomycete was isolated from three blood cultures. The antifungal drug was changed from micafungin to liposomal amphotericin B, which resulted in an improvement in the patient's symptoms. Growth was observed at 37℃, but not 42℃ in a growth temperature test. Gene sequence analysis identified the fungus as Mucor velutinosus. To the best of our knowledge, this is the first time M. velutinosus has been detected in Japan, and this case is very rare. Zygomycetes are known to be pathogens that cause fungal infections in immunodeficient patients such as those with leukemia. They are difficult to identify by culture and are identified at autopsy in many cases. Therefore, culture examinations should be performed for immunodeficient patients with the consideration of zygomycetes.

Management of advanced-stage neuroblastoma in a patient with 21-hydroxalase deficiency.

A 2-year-old boy presented with a 21-hydroxylase deficiency, associated with advanced-stage neuroblastoma primarily occurring in the left adrenal gland. He required intensive chemotherapy with polypharmacy, followed by cord blood stem cell transplantation to treat the neuroblastoma. The precise adjustment of cortisol levels was crucial in this patient to prevent adrenal crisis. We administered hydrocortisone by continuous infusion while monitoring blood cortisol levels. As there are no published reports on the target cortisol levels for children, we used two control infants with advanced-stage neuroblastoma, also undergoing chemotherapy and cord blood stem cell transplantation, to guide the continuous hydrocortisone therapy. The daily dose of hydrocortisone during chemotherapy required about threefold the normal treatment to avoid adrenal insufficiency. Continuous hydrocortisone therapy is feasible for preventing adrenal crisis and this report may provide an effective management for hydrocortisone replacement in 21-hydroxylase-deficient patients undergoing chemotherapy and hematopoietic stem cell transplantation.

Heterozygosity for the Y701C STAT1 mutation in a multiplex kindred with multifocal osteomyelitis.

Heterozygosity for dominant-negative STAT1 mutations underlies autosomal dominant Mendelian susceptibility to mycobacterial diseases. Mutations conferring Mendelian susceptibility to mycobacterial diseases have been identified in the regions of the STAT1 gene encoding the tail segment, DNA-binding domain and SH2 domain. We describe here a new heterozygous mutation, Y701C, in a Japanese two-generation multiplex kindred with autosomal dominant Mendelian susceptibility to mycobacterial diseases. This mutation affects precisely the canonical STAT1 tyrosine phosphorylation site. The Y701C STAT1 protein is produced normally, but its phosphorylation is abolished, resulting in a loss-of-function for STAT1-dependent cellular responses to interferon-γ or interferon-α. In the patients' cells, the allele is dominant-negative for γ-activated factor-mediated responses to interferon-γ, but not for interferon-stimulated gene factor-3-mediated responses to interferon-α/ß, accounting for the clinical phenotype of Mendelian susceptibility to mycobacterial diseases without severe viral diseases. Interestingly, both patients displayed multifocal osteomyelitis, which is often seen in patients with Mendelian susceptibility to mycobacterial diseases with autosomal dominant partial IFN-γR1 deficiency. Multifocal osteomyelitis should thus prompt investigations of both STAT1 and IFN-γR1. This experiment of nature also confirms the essential role of tyrosine 701 in human STAT1 activity in natura.

Identification of the integrin ß3 L718P mutation in a pedigree with autosomal dominant thrombocytopenia with anisocytosis.

αIIbß3 integrin mutations that result in the complete loss of expression of this molecule on the platelet surface cause Glanzmann thrombasthenia. This is usually autosomal recessive, while other mutations are known to cause dominantly inherited macrothrombocytopenia (although such cases are rare). Here, we report a 4-generation pedigree including 10 individuals affected by dominantly inherited thrombocytopenia with anisocytosis. Six individuals, whose detailed clinical and laboratory data were available, carried a non-synonymous ITGB3 gene alteration resulting in mutated integrin ß3 (ITGB3)-L718P. This mutation causes partial activation of the αIIbß3 complex, which promotes the generation of abnormal pro-platelet-like protrusions through downregulating RhoA (RHOA) activity in transfected Chinese Hamster Ovary cells. These findings suggest a model whereby the integrin ß3-L718P mutation contributes to thrombocytopenia through gain-of-function mechanisms.

Population pharmacokinetics and pharmacodynamics of meropenem in Japanese pediatric patients.

The aims of this study were to develop a population pharmacokinetic model for meropenem in Japanese pediatric patients, and to use this model to assess the pharmacodynamics of meropenem regimens against common bacterial populations. Pharmacokinetic data were pooled from nine separate studies (229 plasma samples and 61 urine samples from 40 infected children), modeled using the NONMEM program, and used for a pharmacodynamic simulation to estimate the probabilities of attaining the bactericidal target (40% of the time above the MIC for the bacterium). In the final population pharmacokinetic model, body weight (BW, kg) was the most significant covariate: Cl(r) (l/h) = 0.254 x BW, Cl(nr) (l/h) = 3.45, V (c) (l) = 0.272 x BW, Q (l/h) = 1.65, and V (p) (l) = 0.228 x BW, where Cl(r) and Cl(nr) are the renal and non-renal clearances, V (p) and V (c) are the volumes of distribution of the central and peripheral compartments, and Q is the intercompartmental (central-peripheral) clearance. In most typical patients (BW = 10, 20, and 30 kg), the approved regimens of 10-40 mg/kg, three times a day (0.5-h infusions), achieved a target attainment probability of >80% against Escherichia coli, Streptococcus pneumoniae, methicillin-susceptible Staphylococcus aureus, Haemophilus influenzae, and Pseudomonas aeruginosa isolates. The results of this study provide a better understanding of the pharmacokinetics and pharmacodynamics of meropenem in Japanese pediatric patients.

Deficiency of regulatory T cells in children with autoimmune neutropenia.

CD4+ 25+ regulatory T cells (Tregs) play a role in controlling the development and progression of autoimmunity. The transcription factors Foxp3 and NFATC2 (NFAT1) play key roles in regulating the development and function of Tregs. The present study examined the involvement of Tregs in the pathophysiology of autoimmune neutropenia in children. Tregs were analysed by flow cytometry, based on the expressions of CD4, CD25, and intracellular Foxp3. The expressions of FOXP3 and NFATC2 mRNA in the CD4+ 25+ cells were determined by quantitative real-time polymerase chain reaction. The percentage of CD4+ 25(high) Tregs in patients with autoimmune neutropenia was significantly lower than that in age-matched healthy subjects. The intracellular expression of Foxp3 of CD4+ 25+ cells in patients similarly decreased in comparison to that in healthy subjects. The expression of FOXP3 and NFATC2 mRNA of CD4+ 25+ cells in patients also significantly decreased in comparison to that in healthy subjects. These results suggest that the deficiency of Tregs might thus play an important role in the immunopathophysiology of autoimmune neutropenia in children.

[Dosing regimen rationalization of biapenem in pediatric patients: use of Monte Carlo simulation].

Biapenem has been used in pediatric patients as well as adult patients; however, little information is available on dosing regimens for pediatric patients. This study examined biapenem pharmacokinetics in pediatric population and performed pharmacokinetic-pharmacodynamic analysis. Biapenem plasma concentrations from 10 pediatric patients were pharmacokinetically analyzed. A multi-regression analysis showed the pharmacokinetic parameters were affected by body weight and creatinine clearance of the patients. Using the pharmacokinetic parameters, a Monte Carlo simulation predicted the probabilities of attaining the pharmacodynamic target (40% of the time above the minimum inhibitory concentration for the bacterium). In the case of about 20 kg, biapenem regimens of 5 mg/kg b.i.d. and 10 mg/kg b.i.d. provided sufficient target attainment probabilities against Streptococcus pneumoniae and Pseudomonas aeruginosa isolates, respectively. Our results should provide a PK-PD-based guidance for rationalizing biapenem regimen according to the body weight and renal function of a pediatric patient and the specific bacterium suspected.

High-performance liquid chromatography with ultraviolet detection for real-time therapeutic drug monitoring of meropenem in plasma.

A simple, rapid, and precise high-performance liquid chromatography (HPLC) method using ultrafiltration to remove plasma protein was developed to determine meropenem concentrations in human plasma in a clinical setting. Plasma was separated by centrifugation at 4 degrees C from blood collected in heparinized vacuum tubes, and meropenem was stabilized by immediately mixing the plasma with 1M 3-morpholinopropanesulfonic acid buffer (pH 7.0) (1:1). Ultrafiltration was used for plasma deproteinization. Meropenem was detected by ultraviolet absorbance at 300 nm with no interfering plasma peak. The calibration curve of meropenem in human plasma was linear from 0.05 to 100 microg/mL. Intraday and interday precision was less than 7.17% (CV), and accuracy was between 97.7% and 106.3% over 0.05 microg/mL. The limit of detection was 0.01 microg/mL. The assay has been clinically applied to a real-time therapeutic drug monitoring in pediatric patients and pharmacokinetic studies.

A severe case of neonatal toxic shock syndrome-like exanthematous disease with superantigen-induced high T cell response.

Most newborn patients with a neonatal type of toxic shock syndrome (TSS), called neonatal TSS-like exanthematous disease (NTED), exhibit mild clinical symptoms. We present the case of a patient with NTED who exhibited exceptionally severe clinical symptoms and an adult-type T cell response to the causative toxin TSS toxin-1.