Outcomes following induction failure in Japanese children with acute lymphoblastic leukemia.

The characteristics and prognosis of Japanese children with acute lymphoblastic leukemia (ALL) who fail to achieve complete remission after remission induction chemotherapy (i.e., experience induction failure) are poorly understood. Therefore, we retrospectively analyzed data of patients enrolled in Japanese clinical trials for newly diagnosed ALL between 1996 and 2009. Among 4956 participants, 89 (1.8%) experienced induction failure. With a 6.0-year median follow-up, the 5-year overall survival rate of the entire cohort was 43.0% ± 5.5%. Survival rates did not differ between patients with B-cell precursor ALL (BCP-ALL) and T-cell ALL (T-ALL). In multivariate analysis, day 15 M3 marrow (bone marrow blast count ≥ 25%) was significantly correlated with poorer survival in the whole or BCP-ALL cohorts. In T-ALL, age < 6 years was significantly associated with poor survival. However, due to the small sample size, this correlation must be further investigated. Most T-ALL and BCR-ABL-positive BCP-ALL patients underwent allogeneic stem cell transplantation (allo-SCT). Survival rates did not differ between BCR-ABL-negative BCP-ALL patients who did and did not undergo allo-SCT, possibly due to the inclusion of lower-risk patients in the latter group. In conclusion, the induction failure rate and survival after diagnosis of induction failure in our study were comparable to previously reported figures.

Reduced-intensity conditioning is effective for allogeneic hematopoietic stem cell transplantation in infants with MECOM-associated syndrome.

Mutations in the MECOM encoding EVI1 are observed in infants who have radioulnar synostosis with amegakaryocytic thrombocytopenia. MECOM-associated syndrome was proposed based on clinical heterogeneity. Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for progressive bone marrow failure. However, data regarding allogeneic HSCT for this rare disease are limited. We retrospectively assessed overall survival, conditioning regimen, regimen-related toxicities and long-term sequelae in six patients treated with allogeneic HSCT. All patients received a reduced-intensity conditioning (RIC) regimen consisting of fludarabine, cyclophosphamide or melphalan, and rabbit anti-thymocyte globulin and/or low-dose total body/thoracic-abdominal/total lymphoid irradiation, followed by allogeneic bone marrow or cord blood transplantation from unrelated donors between 4 and 18 months of age. All patients survived and achieved stable engraftment and complete chimerization with the donor type. Moreover, no patient experienced severe regimen-related toxicities, and only lower grades of acute graft-versus-host disease were observed. Three patients treated with low-dose irradiation had relatively short stature compared to three patients not treated with irradiation. Therefore, allogeneic HSCT with RIC is an effective and feasible treatment for infants with MECOM-associated syndrome. Future studies are needed to evaluate the use of low-dose irradiation to avoid risks of other long-term sequelae.

Stage M Infantile Neuroblastoma With Involvement of Falx Cerebri: Case Report and Literature Review.

Neuroblastoma is the most common extracranial solid tumor in children. When metastasis to the falx cerebri is present, it is classified as stage M; however, its behavior has not been well characterized. Here we present a case of stage M infantile neuroblastoma (NB) with involvement of the falx cerebri, and also summarize the clinical profiles of previously reported cases. Notably, all of the tumors resolved with low-dose chemotherapy alone. Although further study is needed to distinguish NBs presenting at these different intracranial locations, NB with metastasis to the falx cerebri may be categorized as MS when diagnosed at less than 18 months of age.

Intraoperative Placement of an Absorbable Spacer Prior to Radiation Therapy for a Malignant Peripheral Nerve Sheath Tumor.

A 7-year-6-month-old female was diagnosed with a pelvic malignant peripheral nerve sheath tumor and lymph node metastases. Tumorectomy was performed after four cycles of chemotherapy. A 33-mm cystic lesion was observed around the left iliac muscle after three cycles of postoperative chemotherapy, and proton beam therapy (PBT) was recommended. She was referred for absorbable spacer (AS) placement. The left ovarian appendage (OA) was resected due to the direct tumor infiltration. The right OA was fixed to the uterosacral ligament. The AS was fixed to the lateral pelvis. The PBT (70.3 Gy relative biological effectiveness) was performed successfully with the AS, and she also had the reproducing possibility due to prevention of severe irradiation damage of the right OA. AS eliminated the surgical removal of spacers and enabled us high-dose PBT for residual tumor without severe irradiation damage including infertility.

The incidence of symptomatic osteonecrosis is similar between Japanese children and children in Western countries with acute lymphoblastic leukaemia treated with a Berlin-Frankfurt-Münster (BFM)95-based protocol.

In this study, we performed a retrospective analysis of a cohort of Japanese paediatric patients with B-cell precursor (BCP)-acute lymphoblastic leukaemia (ALL) treated with a Berlin-Frankfurt-Münster (BFM)95-based protocol, to clarify the incidence, clinical characteristics, and risk factors of osteonecrosis (ON) in comparison to the ALL-02 protocol. We identified a high frequency of ON with the BFM95-based protocol compared to the ALL-02 protocol. The incidence of symptomatic ON with the BFM95-based protocol is comparable to previous studies in Western countries. We believe that the type of treatment regimen has more impact on the incidence of symptomatic ON in paediatric ALL than ethnicity.

Clofarabine monotherapy in two patients with refractory Langerhans cell histiocytosis.

BACKGROUND: Better therapeutic options other than conventional chemotherapy for pediatric patients with refractory Langerhans cell histiocytosis (LCH) remain undetermined. CASE: We successfully treated two patients with refractory and risk organ negative LCH with clofarabine (CLO) monotherapy after recurrence. We administered total 23 courses of CLO monotherapy in patient 1 and 4 courses in patient 2. Both patients had distinct clinical manifestations but achieved a durable complete response with acceptable adverse effects of transient myelosuppression. CLO monotherapy was still effective when he had the second recurrent lesion after first completion of CLO in patient 1. We could discontinue prednisolone to control his refractory inflammation of LCH after completing CLO chemotherapy in patient 2. CONCLUSION: Although large-scale studies are warranted, CLO monotherapy could be a therapeutic option for high efficacy and feasibility besides other intensive combination chemotherapies or allogeneic hematopoietic stem cell transplantation for refractory LCH without risk organ involvement in children.

Refractory T-cell/histiocyte-rich large B-cell lymphoma in a patient with ataxia-telangiectasia caused by novel compound heterozygous variants in ATM.

Ataxia-telangiectasia (A-T) is an autosomal recessive chromosomal breakage syndrome caused by mutation of the ATM (A-T mutated) gene, which encodes a protein kinase that has a major role in the cellular response to DNA damage. Approximately, 10% of A-T patients develop lymphoid malignancies. Deaths caused by extreme sensitivity to chemotherapy for malignancy have been reported, and cancer treatment in A-T is extraordinarily difficult, needing careful monitoring and individualized protocols. We report the case of a 12-year-old girl with A-T diagnosed at the age of 3 in association with IgA deficiency and recurrent pulmonary infections. Sanger sequencing revealed compound heterozygosity of the ATM gene, which bore two novel mutations. At the age of 12, she developed stage IV T-cell/histiocyte-rich large B-cell lymphoma. The tumor was resistant to chemotherapy, and she unfortunately died of cardiac insufficiency and multiple organ failure induced by rapid progression of the disease. The treatment approach for children with A-T and advanced-stage B-non-Hodgkin lymphoma must be refined.

Case Report: Infantile-Onset Fulminant Type 1 Diabetes Mellitus Caused by Novel Compound Heterozygous LRBA Variants.

Lipopolysaccharide-responsive beige-like anchor (LRBA) deficiency is a subtype of common variable immune deficiency (CVID). Numerous case reports and cohort studies have described a broad spectrum of clinical manifestations and variable disease phenotypes, including immune dysregulation, enteropathy, and recurrent infections. Although LRBA deficiency is an autosomal recessive primary immunodeficiency resulting in a phenotype similar to CVID, it is a monogenic disease and separate from CVID. Recently, in a report of monogenic primary immunodeficiency disorder associated with CVID and autoimmunity, the most common mutated gene was LRBA. We report the case of a girl who presented with fulminant type 1 diabetes at age 7 months. She later experienced recurrent bacterial infections with neutropenia and idiopathic thrombocytopenic purpura. Clinical genome sequencing revealed compound heterozygosity of the LRBA gene, which bore two novel mutations. A genetic basis should be considered in the differential diagnosis for very young patients with fulminant autoimmunity, and the diagnostic work-up should include evaluation of markers of immunodeficiency.

EVI1 and GATA2 misexpression induced by inv(3)(q21q26) contribute to megakaryocyte-lineage skewing and leukemogenesis.

Chromosomal rearrangements between 3q21 and 3q26 elicit high-risk acute myeloid leukemia (AML), which is often associated with elevated platelet and megakaryocyte (Mk) numbers. The 3q rearrangements reposition a GATA2 enhancer near the EVI1 (or MECOM) locus, which results in both EVI1 overexpression and GATA2 haploinsufficiency. However, the mechanisms explaining how the misexpression of these 2 genes individually contribute to leukemogenesis are unknown. To clarify the characteristics of differentiation defects caused by EVI1 and GATA2 misexpression and to identify the cellular origin of leukemic cells, we generated a system to monitor both inv(3) allele-driven EVI1 and Gata2 expression in 3q-rearranged AML model mice. A cell population in which both EVI1 and Gata2 were highly induced appeared in the bone marrows before the onset of frank leukemia. This population had acquired serial colony-forming potential. Because hematopoietic stem/progenitor cells (HSPCs) and Mks were enriched in this peculiar population, we analyzed the independent EVI1 and GATA2 contributions to HSPC and Mk. We found that inv(3)-driven EVI1 promotes accumulation of Mk-biased and myeloid-biased progenitors, Mks, and platelets, and that Gata2 heterozygous deletion enhanced Mk-lineage skewing of EVI1-expressing progenitors. Notably, inv(3)-directed EVI1 expression and Gata2 haploinsufficient expression cooperatively provoke a leukemia characterized by abundant Mks and platelets. These hematological features of the mouse model phenocopy those observed in human 3q AML. On the basis of these results, we conclude that inv(3)-driven EVI1 expression in HSPCs and Mks collaborates with Gata2 haploinsufficiency to provoke Mk-lineage skewing and leukemogenesis with excessive platelets, thus mimicking an important feature of human AML.

Ruxolitinib treatment of a patient with steroid-dependent severe autoimmunity due to STAT1 gain-of-function mutation.

Signal transducer and activator of transcription 1 gain-of-function (STAT1 GOF) mutations are the most common cause of chronic mucocutaneous candidiasis (CMC). We report the effect of oral ruxolitinib, an inhibitor of Janus kinase (JAK) family tyrosine kinases, on the clinical and immune status of a 3-year-old male with steroid-dependent severe autoimmunity due to a STAT1 GOF T385M mutation. The patient's susceptibility to infection improved with antimicrobial prophylaxis and immunoglobulin replacement therapy, but he continued to exhibit severely disabling symptoms of autoimmunity. More than one-third of patients with STAT1 GOF mutations present with autoimmune manifestations, and this patient's mutation was reported to cause CMC with autoimmunity. We analyzed the interleukin (IL)-17A and IFN-γ levels and immunophenotype by flow cytometry before and during treatment with ruxolitinib. The peripheral IL-17A level did not increase, but the IFN-γ level decreased after 4 months of therapy. The STAT1 phosphorylation level decreased significantly upon stimulation of patient cells with IFN-γ. Clinically, cytomegalovirus reactivation occurred, but was controlled. No other adverse effect was noted. We report the potential of JAK1/2 inhibition with ruxolitinib for both CMC and steroid-dependent autoimmunity. However, long-term administration is necessary, as the effect is not sustained after treatment is discontinued.

Two effects of GATA2 enhancer repositioning by 3q chromosomal rearrangements.

Chromosomal inversion and translocation between 3q21 and 3q26 [inv (3)(q21.3q26.2) and t(3;3)(q21.3;q26.2), respectively] give rise to acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), which have poor prognoses. The chromosomal rearrangements reposition a GATA2 distal hematopoietic enhancer from the original 3q21 locus to the EVI1 (also known as MECOM) locus on 3q26. Therefore, the GATA2 enhancer from one of two GATA2 alleles drives EVI1 gene expression in hematopoietic stem and progenitor cells, which promotes the accumulation of abnormal progenitors and induces leukemogenesis. On the other hand, one allele of the GATA2 gene loses its enhancer, which results in reduced GATA2 expression. The GATA2 gene encodes a transcription factor critical for the generation and maintenance of hematopoietic stem and progenitor cells. GATA2 haploinsufficiency has been known to cause immunodeficiency and myeloid leukemia. Notably, reduced GATA2 expression suppresses the differentiation but promotes the proliferation of EVI1-expressing leukemic cells, which accelerates EVI1-driven leukemogenesis. A series of studies have shown that the GATA2 enhancer repositioning caused by the chromosomal rearrangements between 3q21 and 3q26 provokes misexpression of both the EVI1 and GATA2 genes and that these two effects coordinately elicit high-risk leukemia.

GATA2 haploinsufficiency accelerates EVI1-driven leukemogenesis.

Chromosomal rearrangements between 3q21 and 3q26 induce inappropriate EVI1 expression by recruiting a GATA2-distal hematopoietic enhancer (G2DHE) to the proximity of the EVI1 gene, leading to myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). The acquisition of G2DHE by the EVI1 gene reciprocally deprives this enhancer of 1 of the 2 GATA2 alleles, resulting in a loss-of-function genetic reduction in GATA2 abundance. Because GATA2 haploinsufficiency is strongly associated with MDS and AML, we asked whether EVI1 misexpression and GATA2 haploinsufficiency both contributed to the observed leukemogenesis by using a 3q21q26 mouse model that recapitulates the G2DHE-driven EVI1 misexpression, but in this case, it was coupled to a Gata2 heterozygous germ line deletion. Of note, the Gata2 heterozygous deletion promoted the EVI1-provoked leukemic transformation, resulting in early onset of leukemia. The 3q21q26 mice suffered from leukemia in which B220+ cells and/or Gr1+ leukemic cells occupied their bone marrows. We found that the B220+Gr1-c-Kit+ population contained leukemia-initiating cells and supplied Gr1+ leukemia cells in the 3q21q26 leukemia. When Gata2 expression levels in the B220+Gr1-c-Kit+ cells were decreased as a result of Gata2 heterozygous deletion or spontaneous phenomenon, myeloid differentiation of the B220+Gr1-c-Kit+ cells was suppressed, and the cells acquired induced proliferation as well as B-lymphoid-primed characteristics. Competitive transplantation analysis revealed that Gata2 heterozygous deletion confers selective advantage to EVI1-expressing leukemia cell expansion in recipient mice. These results demonstrate that both the inappropriate stimulation of EVI1 and the loss of 1 allele equivalent of Gata2 expression contribute to the acceleration of leukemogenesis.

Derepression of the DNA Methylation Machinery of the Gata1 Gene Triggers the Differentiation Cue for Erythropoiesis.

GATA1 is a critical regulator of erythropoiesis. While the mechanisms underlying the high-level expression of GATA1 in maturing erythroid cells have been studied extensively, the initial activation of the Gata1 gene in early hematopoietic progenitors remains to be elucidated. We previously identified a hematopoietic stem and progenitor cell (HSPC)-specific silencer element (the Gata1 methylation-determining region [G1MDR]) that recruits DNA methyltransferase 1 (Dnmt1) and provokes methylation of the Gata1 gene enhancer. In the present study, we hypothesized that removal of the G1MDR-mediated silencing machinery is the molecular basis of the initial activation of the Gata1 gene and erythropoiesis. To address this hypothesis, we generated transgenic mouse lines harboring a Gata1 bacterial artificial chromosome in which the G1MDR was deleted. The mice exhibited abundant GATA1 expression in HSPCs, in a GATA2-dependent manner. The ectopic GATA1 expression repressed Gata2 transcription and induced erythropoiesis and apoptosis of HSPCs. Furthermore, genetic deletion of Dnmt1 in HSPCs activated Gata1 expression and depleted HSPCs, thus recapitulating the HSC phenotype associated with GATA1 gain of function. These results demonstrate that the G1MDR holds the key to HSPC maintenance and suggest that release from this suppressive mechanism is a fundamental requirement for subsequent initiation of erythroid differentiation.

Amelioration of inflammation and tissue damage in sickle cell model mice by Nrf2 activation.

Sickle cell disease (SCD) is an inherited disorder caused by a point mutation in the ß-globin gene, leading to the production of abnormally shaped red blood cells. Sickle cells are prone to hemolysis and thereby release free heme into plasma, causing oxidative stress and inflammation that in turn result in damage to multiple organs. The transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2) is a master regulator of the antioxidant cell-defense system. Here we show that constitutive Nrf2 activation by ablation of its negative regulator Keap1 (kelch-like ECH-associated protein 1) significantly improves symptoms in SCD model mice. SCD mice exhibit severe liver damage and lung inflammation associated with high expression levels of proinflammatory cytokines and adhesion molecules compared with normal mice. Importantly, these symptoms subsided after Nrf2 activation. Although hemolysis and stress erythropoiesis did not change substantially in the Nrf2-activated SCD mice, Nrf2 promoted the elimination of plasma heme released by sickle cells' hemolysis and thereby reduced oxidative stress and inflammation, demonstrating that Nrf2 activation reduces organ damage and segregates inflammation from prevention of hemolysis in SCD mice. Furthermore, administration of the Nrf2 inducer CDDO-Im (2-cyano-3, 12 dioxooleana-1, 9 diene-28-imidazolide) also relieved inflammation and organ failure in SCD mice. These results support the contention that Nrf2 induction may be an important means to protect organs from the pathophysiology of sickle cell-induced damage.

Mesenchymal chondrosarcoma diagnosed on FISH for HEY1-NCOA2 fusion gene.

Mesenchymal chondrosarcoma (MC) is an extremely rare subtype of chondrosarcoma that has a small round-cell sarcoma with focal cartilaginous differentiation, often with a pericytomatous vascular pattern. The non-cartilaginous components are usually dominant, and such lesions might be confused with other small round-cell tumors. Recently, a tumor-specific HEY1-NCOA2 fusion gene was identified in MC. Here we report the case of a 9-year-old boy who was diagnosed with MC by detection of HEY1-NCOA2 fusion signals in almost 50% of tumor cells in tissue sections on fluorescence in situ hybridization (FISH). In this way, the tumor was definitively diagnosed as MC. This case suggests that the detection of the HEY1-NCOA2 fusion gene on FISH is of diagnostic value for MC.

A case series of CAEBV of children and young adults treated with reduced-intensity conditioning and allogeneic bone marrow transplantation: a single-center study.

BACKGROUND: Epstein-Barr virus (EBV)-infected T or NK cells cause chronic active EBV infection (CAEBV). Allogeneic hematopoietic stem cell transplantation (HSCT) is curative treatment for CAEBV patients. However, chemotherapy prior to HSCT and optimal conditioning regimen for allogeneic HSCT are still controversial. PATIENTS AND METHODS: We retrospectively analyzed five patients with CAEBV treated with reduced-intensity conditioning (RIC) consisted of fludarabine, cyclophosphamide, and low-dose total-body irradiation followed by allogeneic bone marrow transplantation in a single institute. Only one of five patients received chemotherapy prior to transplantation. We analyzed EBV-infected cells in a patient whose EBV load increased after HSCT by T-cell repertoire assay, separation of T-cell subpopulations, in situ hybridization and microsatellite analysis. RESULTS: All five patients achieved engraftment, complete chimera, and eradication of EBV load. All patients have been alive without any serious regimen-related toxicity for more than 16 months following HSCT. However, one patient transplanted from HLA-matched sibling donor developed clonal proliferation of CD4+ Vß3+ T cells caused by monoclonal EBV infection on day 99 after transplantation. Further analysis revealed that the CD4+ Vß3+ T cells selectively harbored EBV genome, and these infected cells were derived from donor T cells. CONCLUSIONS: Allogeneic HSCT with RIC is a safe and effective treatment for better overall survival and less regimen-related toxicity in patients with CAEBV. Our first pediatric case reported in the literature suggests that we should consider the possibility of persistent EBV infection in donor T cells as well as the relapse in recipient cells if EBV load increases after allogeneic HSCT.