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Due to the considerable success of cancer immunotherapy for leukemia, the tumor immune environment has become a focus of intense research; however, there are few reports on the dynamics of the tumor immune environment in leukemia. Here, we analyzed the tumor immune environment in pediatric B cell precursor acute lymphoblastic leukemia by analyzing serial bone marrow samples from nine patients with primary and recurrent disease by mass cytometry using 39 immunophenotype markers, and transcriptome analysis. High‐dimensional single‐cell mass cytometry analysis elucidated a dynamic shift of T cells from naïve to effector subsets, and clarified that, during relapse, the tumor immune environment comprised a T helper 1‐polarized immune profile, together with an increased number of effector regulatory T cells. These results were confirmed in a validation cohort using conventional flow cytometry. Furthermore, RNA transcriptome analysis identified the upregulation of immune‐related pathways in B cell precursor acute lymphoblastic leukemia cells during relapse, suggesting interaction with the surrounding environment. In conclusion, a tumor immune environment characterized by a T helper 1‐polarized immune profile, with an increased number of effector regulatory T cells, could contribute to the pathophysiology of recurrent B cell precursor acute lymphoblastic leukemia. This information could contribute to the development of effective immunotherapeutic approaches against B cell precursor acute lymphoblastic leukemia relapse., Tumor immune environment characterized by a T helper 1‐polarized immune profile was observed in recurrent B cell precursor acute lymphoblastic leukemia. Regulatory T cells were activated in recurrent B cell precursor acute lymphoblastic leukemia.

Detailed case reports of autologous recovery of hematopoiesis after hematopoietic stem cell transplantation with myeloablative conditioning are scarce. We present a rare case of a 3-year-old male with relapsed KMT2A -rearranged acute lymphoblastic leukemia who experienced autologous recovery following secondary engraftment failure after cord blood transplantation with myeloablative conditioning. Similar to prior reports, we detected unusual chromosomal abnormalities, which differed at each bone marrow examination. He remains alive without relapse of acute lymphoblastic leukemia 8 months after cord blood transplantation. As the rate of recurrence or late occurrence of secondary malignant neoplasm remains unclear, careful follow-up is required, especially in pediatric patients.

The prognosis of patients with relapsed osteosarcoma is extremely poor and the optimal treatment remains to be identified. Here, we retrospectively analysed the clinical outcomes of nine patients with relapsed osteosarcoma treated with temozolomide/etoposide. Of the two patients who received temozolomide/etoposide as palliative therapy for unresectable tumours, one remained alive with stable disease for >4 years. The remaining seven patients received temozolomide/etoposide as adjuvant therapy following resection of relapsed metastatic disease; of these, one was free from disease for 41 months. Potentially beneficial effects were observed in two of three O6-methylguanine-DNA methyltransferase protein-negative patients, whereas all five O6-methylguanine-DNA methyltransferase-positive patients experienced subsequent relapse. None of the patients experienced severe adverse effects requiring hospitalization. Temozolomide/etoposide is a feasible candidate as salvage therapy for relapsed osteosarcoma. Further studies are needed to verify the utility of O6-methylguanine-DNA methyltransferase protein expression as a biomarker for predicting the response to this treatment.

Shwachman–Diamond syndrome (SDS), an autosomal recessive disorder characterized by bone marrow failure, exocrine pancreatic insufficiency, and skeletal abnormalities, is caused by mutations in the Shwachman–Bodian–Diamond syndrome (SBDS) gene, which plays a role in ribosome biogenesis. Although the causative genes of congenital disorders frequently involve regulation of embryogenesis, the role of the SBDS gene in early hematopoiesis remains unclear, primarily due to the lack of a suitable experimental model for this syndrome. In this study, we established induced pluripotent stem cells (iPSCs) from patients with SDS (SDS-iPSCs) and analyzed their in vitro hematopoietic and endothelial differentiation potentials. SDS-iPSCs generated hematopoietic and endothelial cells less efficiently than iPSCs derived from healthy donors, principally due to the apoptotic predisposition of KDR+CD34+ common hemoangiogenic progenitors. By contrast, forced expression of SBDS gene in SDS-iPSCs or treatment with a caspase inhibitor reversed the deficiency in hematopoietic and endothelial development, and decreased apoptosis of their progenitors, mainly via p53-independent mechanisms. Patient-derived iPSCs exhibited the hematological abnormalities associated with SDS even at the earliest hematopoietic stages. These findings will enable us to dissect the pathogenesis of multiple disorders associated with ribosomal dysfunction.

Cryotherapy is a conventional method for preventing melphalan-induced oral mucositis (OM) in adult patients. We retrospectively examined the clinical benefits of cryotherapy in 41 pediatric patients undergoing autologous stem cell transplantation using a melphalan-etoposide-carboplatin regimen. Twenty-two patients received cryotherapy. The cumulative incidence of grade 3-4 OM was significantly lower in the cryotherapy group (57.1%) than in the noncryotherapy group (89.5%; P = .041). Multivariate analyses identified cryotherapy and the melphalan dose as independent factors for the lower occurrence of OM. The present study demonstrates the clinically significant efficacy of cryotherapy for preventing melphalan-induced OM in pediatric patients.

Growing teratoma syndrome is a well-recognized condition associated with both intracranial and extracranial nongerminomatous germ cell tumors (NGGCTs), which mostly manifest as rapid growth of cystic and solid components during or within several months after treatment. Here, we report a patient with NGGCT who experienced slow growth of intracranial growing teratoma syndrome with intraventricular lipid accumulation over 10 years without any clinical symptoms. Considering the clinicopathologic heterogeneity of this syndrome, long-term clinical and radiologic follow-up is required for all patients with intracranial NGGCT.

Intracranial germ cell tumor is sometimes associated with Down syndrome; however, no optimal treatment has been developed due to the high risk of recurrence and treatment-related mortality. Here, we report on a patient with an intracranial germinoma in the bilateral basal ganglia. The patient received 3 courses of ifosfamide-cisplatin-etoposide in combination with whole-brain irradiation (24 Gy), with no serious complications. The patient is alive and disease free 16 months after the initial diagnosis. This regimen is a feasible treatment for intracranial germ cell tumor associated with Down syndrome, although careful attention must be paid to the increased risk for severe infection.

Inversion of chromosome 16 (inv(16)) generates a fusion gene CBFB-MYH11, which is a driver mutation for acute myeloid leukemia (AML). Gene expression profiling suggests that Gata2, a hematopoietic transcription factor, is a top upregulated genes in preleukemic Cbfb-MYH11 knockin mice and is expressed in human inv(16) AML. On the other hand, we have also identified recurrent monoallelic deletions of GATA2 in relapsed human CBF-AML patients. To clarify the role of Gata2 in leukemogenesis by Cbfb-MYH11, we generated conditional Cbfb-MYH11 knockin mice with Gata2 heterozygous knockout. Gata2 heterozygous knockout reduced abnormal myeloid progenitors, which are capable of inducing leukemia in the Cbfb-MYH11 mice. Consequently, Cbfb-MYH11 mice with Gata2 heterozygous knockout developed leukemia with longer latencies than those with intact Gata2. Interestingly, leukemic cells with Gata2 heterozygous knockout gained higher number of mutations and showed more aggressive phenotype in both primary and transplanted mice. Moreover, leukemic cells with Gata2 heterozygous knockout showed higher repopulating capacity in competitive transplantation experiments. In summary, reduction of Gata2 activity affects mutational dynamics of leukemia with delayed leukemia onset in Cbfb-MYH11 knockin mice, but paradoxically results in a more aggressive leukemia phenotype, which may be correlated with leukemia relapse or poor prognosis in human patients.

Malignant rhabdoid tumor (MRT) is a rare, highly aggressive pediatric malignancy that primarily develops during infancy and early childhood. Despite the existing standard of intensive multimodal therapy, the prognosis of patients with MRT is dismal; therefore, a greater understanding of the biology of this disease is required to establish novel therapies. In this study, we identified a highly tumorigenic sub-population in MRT, based on the expression of CD146 (also known as melanoma cell adhesion molecule), a cell adhesion molecule expressed by neural crest cells and various derivatives. CD146+ cells isolated from four MRT cell lines by cell sorting exhibited enhanced self-renewal and invasive potential in vitro. In a xenograft model using immunodeficient NOD/Shi-scid IL-2Rγ-null mice, purified CD146+ cells obtained from MRT cell lines or a primary tumor exhibited the exclusive ability to form tumors in vivo. Blocking of CD146-related mechanisms, either by short hairpin RNA knockdown or treatment with a polyclonal antibody against CD146, effectively suppressed tumor growth of MRT cells both in vitro and in vivo via induction of apoptosis by inactivating Akt. Furthermore, CD146 positivity in immunohistological analysis of 11 MRT patient samples was associated with poor patient outcomes. These results suggest that CD146 defines a distinct sub-population in MRT with high tumorigenic capacity and that this marker represents a promising therapeutic target.

We report on three cases of pediatric acute lymphoblastic leukemia presenting with bone pain and arthralgia as initial symptoms. At the first visit, their primary signs were recurrent bone pain and arthralgia, without significant peripheral blood abnormalities. It took 2-4 months to confirm the diagnosis from the onset of arthralgia due to this atypical presentation of the disease. Definitive diagnosis was obtained by bone marrow examination, and in all cases, complete remission was achieved by chemotherapy. As a feature of imaging, MRI exhibited diffuse bone marrow signal changes in T1-weighted images, and FDG-PET showed extensive abnormal bone marrow uptakes. In cases 2 and 3, it was difficult to diagnose by bone marrow aspiration from the iliac bone, but definitive diagnosis was obtained by bone marrow aspiration from the tibia, in which FDG-PET showed increased uptake. FDG-PET was therefore considered useful for the selection of bone marrow aspiration sites. In cases presenting with recurrent migratory bone pain and arthralgia, we need to consider performing bone marrow aspiration and imaging, such as MRI and FDG-PET, for early diagnosis and treatment of leukemia.

A 16-year-old boy was incidentally found to have hyperleukocytosis during a school physical examination. He was diagnosed with atypical chronic myeloid leukemia in chronic phase. Although treatment with hydoxyurea was started, his white blood cell count increased and he eventually developed lethal intracranial hemorrhage. Although very rare, intracranial hemorrhage should be considered as a possible complication in patients with atypical chronic myeloid leukemia, even in chronic phase, if they have hyperleukocytosis and thrombocytopenia.

LT has contributed to an elevation in cure rates for patients with unresectable HB; however, patients with recurrent HB after LT have poor prognosis. To analyze the prognostic and therapeutic factors that influence the clinical outcome of patients with HB receiving LT, we retrospectively analyzed 24 patients with HB who underwent LT between 1997 and 2015. The 5-year OS rate of all patients was 69.6±9.7%. The 5-year OS rate of 11 patients receiving salvage LT for recurrent tumor after a primary resection was comparable to that of 13 patients receiving primary LT. Among 12 evaluable patients receiving primary LT, six of 10 patients with a decline of serum AFP >95% at LT are currently alive and in remission, whereas two patients with a decline of AFP ≤95% experienced post-LT relapse. Among 9 evaluable patients receiving salvage LT, all three patients with any decline of AFP at LT are currently alive in remission, and three of six patients with no response to pre-LT salvage chemotherapy are also alive and in remission. Response to chemotherapy may be a reliable marker for prediction of post-LT relapse, even for patients receiving salvage LT.

Mucosal-associated invariant T (MAIT) and invariant natural killer T (iNKT) cells are T cell subpopulations that possess innate-like properties. We examined the impact of post-hematopoietic stem cell transplantation (HSCT) MAIT and iNKT cell recovery on the clinical outcomes of 69 patients who underwent allogeneic HSCT at Kyoto University Hospital. Multivariate analyses identified the absolute number of MAIT cells (

HAX1 was identified as the gene responsible for the autosomal recessive type of severe congenital neutropenia. However, the connection between mutations in the HAX1 gene and defective granulopoiesis in this disease has remained unclear, mainly due to the lack of a useful experimental model for this disease. In this study, we generated induced pluripotent stem cell lines from a patient presenting for severe congenital neutropenia with HAX1 gene deficiency, and analyzed their in vitro neutrophil differentiation potential by using a novel serum- and feeder-free directed differentiation culture system. Cytostaining and flow cytometric analyses of myeloid cells differentiated from patient-derived induced pluripotent stem cells showed arrest at the myeloid progenitor stage and apoptotic predisposition, both of which replicated abnormal granulopoiesis. Moreover, lentiviral transduction of the HAX1 cDNA into patient-derived induced pluripotent stem cells reversed disease-related abnormal granulopoiesis. This in vitro neutrophil differentiation system, which uses patient-derived induced pluripotent stem cells for disease investigation, may serve as a novel experimental model and a platform for high-throughput screening of drugs for various congenital neutrophil disorders in the future.

There are few reports on the clinical significance of MRD before HSCT in pediatric ALL. We retrospectively analyzed the clinical significance of FCM-based detection of MRD (FCM-MRD) before allogeneic HSCT in pediatric ALL. Of 38 pediatric patients who underwent allogeneic HSCT for the first time between 1998 and 2014, 33 patients were in CR and five patients were in non-CR. The CR group was further divided into two groups based on the pretransplant FCM-MRD level: the MRD(neg) (

Parosteal osteosarcoma (POS) is conventionally a low-grade sarcoma with limited metastatic potential; however, the tumor occasionally transforms into a high-grade dedifferentiated POS, which commonly metastasizes to distant organs. The present report describes a rare pediatric case of conventional POS with no dedifferentiated component yet had multiple pulmonary metastases at initial diagnosis. Following limb-sparing surgery and osteosarcoma-oriented neoadjuvant chemotherapy, the patient received total resection of pulmonary metastases. Despite no treatment for pulmonary recurrence 1 year after adjuvant chemotherapy, the patient is alive with stable disease 4 years and 6 months after the initial diagnosis.

A 13-yr-old boy bearing lymphedema and congenital deafness had distinct hematological abnormalities consisting of reduced monocytes, B cells, and dendritic cells in the peripheral blood as well as MDS with normal karyotype in the bone marrow. The patient was diagnosed with Emberger syndrome by sequencing of GATA2 DNA, and underwent RIST from an HLA-matched unrelated donor. Prompt engraftment and immunological reconstitution were observed without any severe RRT. As most patients with GATA2 anomaly died due to the development of AML or active infections, RIST could be a promising treatment option before progression of advanced MDS.

Acute gastrointestinal graft-versus-host disease (GI-GVHD) is a major cause of morbidity and mortality after hematopoietic stem cell transplantation (HSCT). There are very few studies on specific endoscopic findings in pediatric acute GI-GVHD. The aim of this retrospective case-control study was to elucidate the characteristic endoscopic findings in pediatric acute GI-GVHD that improve the diagnostic accuracy of endoscopy.All consecutive patients under 18 years of age who underwent allogeneic HSCT in Kyoto University Hospital from May 2003 to October 2014 were identified retrospectively. Patients who underwent GI endoscopy as a result of sustained GI symptoms were identified. Intestinal villous patterns were evaluated by magnification endoscopy with the water-immersion technique. The patients were diagnosed with acute GI-GVHD and non-GVHD on the basis of biopsy histology. Endoscopic findings of the two groups were compared.Of the 171 patients who underwent HSCT, 30 underwent GI endoscopy. Of these, 17 and nine were diagnosed with acute GI-GVHD and non-GVHD, respectively. Compared with non-GVHD, acute GI-GVHD was associated significantly more often with short blunt villi in the duodenum (P = 0.013), variable defect villi and short blunt villi in the ileum (P = 0.009 and 0.035, respectively), and edema, erosion, and tortoiseshell-like mucosae in the colon (P = 0.017, 0.023, and 0.017, respectively).Pediatric acute GI-GVHD was associated with several characteristic features on magnifying endoscopy with the water-immersion technique. These features will be useful for endoscopic diagnosis of pediatric acute GI-GVHD.

A five-month-old male infant with familial hemophagocytic lymphohistiocytosis underwent cord blood transplantation using reduced-intensity conditioning. Methylprednisolone (mPSL) pulse administration was performed for marked pulmonary edema during the early phase of transplantation, followed by GVHD treatment with mPSL until day 100. CMV antigenemia was detected on days 27 and 55, but serum became negative with 2- to 3-week ganciclovir (GCV) treatment on both occasions. On day 120, ophthalmological findings included multiple bilateral white spots and a positive PCR study using anterior chamber fluid confirmed the diagnosis of CMV retinitis affecting both eyes, although CMV antigenemia was negative. Re-treatment with GCV had a minimal effect on the ophthalmological findings, while foscarnet administration markedly improved the retinitis and decreased the CMV-DNA level. Considering that a substantial proportion of patients develop CMV retinitis even when CMV antigenemia is not present, routine monitoring involving ophthalmological examinations should be conducted for hematopoietic transplant patients, especially infants, who cannot complain of ocular symptoms.

The incidence of HHV-6 encephalitis during hematopoietic stem cell transplantation (HSCT) in children is thought to be less than that in adults and risk factors, prognosis and complications are virtually unknown. Herein, we report a pediatric case developing epileptic encephalopathy following HHV-6 encephalitis after a second cord blood transplantation (CBT). A 7-year-old boy with relapsed B-precursor acute lymphoblastic leukemia in second remission underwent CBT. However, he received a second CBT due to graft failure. On day 25 after the second CBT, he developed short-term memory defects and seizures. He was diagnosed with HHV-6 encephalitis because HHV-6 DNA was detected in his blood and cerebrospinal fluid and abnormal hippocampal signals were seen on cranial magnetic resonance imaging (MRI). After treatment with foscarnet, HHV-6 DNA levels and MRI findings improved; however, he developed epileptic encephalopathy five months after the onset of encephalitis. There are very few reports on pediatric epileptic encephalopathy associated with HHV-6 encephalitis after HSCT. Detailed studies are needed to analyze risk factors, prognosis, and complications.

This retrospective study examined the clinical significance of FCM-MRD in 36 patients with ALL and 29 patients with AML after their first allogeneic HSCT. Hematological (FCM-MRD ≥5.0%) and molecular relapse (FCM-MRD

A 5-year-old boy with glioblastoma relapsed soon after postoperative irradiation in combination with temozolomide. Second-line chemotherapy was also ineffective; therefore, the bevacizumab and irinotecan were given after a third gross-total resection of the tumor. Treatment was interrupted for 1 month due to development of posterior reversible encephalopathy syndrome, but was re-initiated at a lower dose of bevacizumab with prolonged intervals between treatments. The patient was alive and disease free 2 years after initial diagnosis. Bevacizumab and irinotecan are a promising regimen for pediatric cases of recurrent glioblastoma after gross-total resection, although the optimal treatment schedule must be determined on a patient-by-patient basis.

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) was performed as a diagnostic procedure for two pediatric patients with intra-abdominal tumors. Case 1 was an 8-year-old boy with a huge tumor in the portal-hepatic region. Case 2 was a 17-year-old girl with a history of diabetes and recurrent relapse of Burkitt lymphoma, who had a newly developing tumor in the pancreatic body. In both cases, EUS-FNA was performed as a less invasive diagnostic procedure than open biopsy or total resection of the tumor. Tumor cells were determined to be of the B cell lineage by flow cytometric and immunostaining analyses. Both cases were diagnosed as having Burkitt lymphoma based on detection of IgH/C-MYC translocation by FISH. The aspiration was successfully conducted without severe complications, and both patients were immediately given chemotherapy. EUS-FNA is a safe and minimally invasive procedure with high diagnostic value for pediatric cases with intra-abdominal tumors.

Transient abnormal myelopoiesis (TAM) is a clonal preleukemic disorder that progresses to myeloid leukemia of Down syndrome (ML-DS) through the accumulation of genetic alterations. To investigate the mechanism of leukemogenesis in this disorder, a xenograft model of TAM was established using NOD/Shi-scid, interleukin (IL)-2Rγ(null) mice. Serial engraftment after transplantation of cells from a TAM patient who developed ML-DS a year later demonstrated their self-renewal capacity. A GATA1 mutation and no copy number alterations (CNAs) were detected in the primary patient sample by conventional genomic sequencing and CNA profiling. However, in serial transplantations, engrafted TAM-derived cells showed the emergence of divergent subclones with another GATA1 mutation and various CNAs, including a 16q deletion and 1q gain, which are clinically associated with ML-DS. Detailed genomic analysis identified minor subclones with a 16q deletion or this distinct GATA1 mutation in the primary patient sample. These results suggest that genetically heterogeneous subclones with varying leukemia-initiating potential already exist in the neonatal TAM phase, and ML-DS may develop from a pool of such minor clones through clonal selection. Our xenograft model of TAM may provide unique insight into the evolutionary process of leukemia.

Hepatoblastoma is a rare childhood malignant tumor that originates from immature hepatic cells. Aminopeptidase-N(CD13), an ectopeptidase that promotes tumor invasion and metastasis, is expressed in fetal stage hepatic progenitor cells, although its role in hepatoblastoma remains unclear.The expression pattern of CD13 was investigated on immunohistochemistry in 30 tissue samples from 27 hepatoblastoma patients (16 with predominantly embryonal [pE] histology and 14 with predominantly fetal [pF] histology). Immunoreactive score (IRS) was used to quantify staining data, and the relationship between CD13 expression, clinicopathological factors, and clinical outcome was investigated. The biological function of CD13 was also examined in the hepatoblastoma cell lines Huh6 and HepG2.All specimens stained positive for CD13, with higher CD13 expression in pE than in pF hepatoblastoma samples (median IRS, 4; range, 2-9 vs 2; range, 1-4). Strong CD13 expression was correlated with vascular invasion. Five year event-free survival and overall survival were better in patients with CD13(low) than in those with CD13(high) tumors (100% vs 51.0%, P = 0.026; and 100% vs 74.0%, P = 0.114, respectively). A CD13-neutralizing antibody and the potent CD13 inhibitor, Ubenimex, suppressed invasive activity in HepG2 cells in vitro.CD13 expression is associated with hepatoblastoma invasiveness and could be a novel prognostic marker for hepatoblastoma.

The opacity of the maxillary sinuses on X-ray film in Waters' view in patients with nasal allergy was evaluated by a microdensitometer. The patients with nasal allergy were diagnosed with the positive results of the following; 1) eosinophilia in nasal secretion, 2) nasal provocation test, 3) intradermal skin test or radioallergosorbent test (RAST). The ratio of density of the maxillary sinuses and orbits was determined by a microdensitometer, and the ratio of the average degree of the opacity of the maxillary sinus to that of the ipsilateral orbit was designated as the M/O ratio. The normal range of the M/O ratio was set over the mean value -2 standard deviations in the normal group. The results are followings. 1) The abnormal shadows in the maxillary sinuses were found out to be 36.9% in patients with nasal allergy. 2) Patients under 15 years old had significantly higher incidence of abnormal shadows, especially in the bilateral sinuses compared with patients over 15 years old. 3) Polyps in the maxillary sinus were recognized in 5.0% of all the sinuses. 4) There were no significant differences for the incidence of abnormal shadow among the patients with nasal allergy caused by different antigens.

Nasal mucociliary clearance was measured before and after treatment in patients with chronic sinusitis. Nasal mucociliary transit time before the study was greater than 36 min in 8 out of 14 patients who were treated with S-carboxymethylcysteine, and in 9 out of 22 patients who were treated by repeated antral lavage. The nasal mucociliary clearance was significantly improved by both treatment regimens. This may indicate that the malfunction of the nasal mucociliary system is not the cause of chronic sinusitis but an effect of chronic inflammation of the respiratory mucosa.