Sequential use of second-generation tyrosine kinase inhibitors following imatinib therapy in pediatric chronic myeloid leukemia: A report from the Japanese Pediatric Leukemia/Lymphoma Study Group.

BACKGROUND: The details of the sequential use of imatinib for first-line treatment followed by second-generation tyrosine kinase inhibitors (2G-TKIs) for pediatric chronic myeloid leukemia (CML) are still unknown. This study analyzed clinical responses and adverse effects of the use of 2G-TKIs following imatinib in pediatric chronic phase (CP)-CML. PROCEDURES: The Japanese Pediatric Leukemia/Lymphoma Study Group conducted a retrospective study of patients with newly diagnosed CML from 1996 to 2011. A total of 152 cases that received imatinib as first-line therapy were analyzed. RESULTS: Excluding 46 cases treated with hematopoietic stem cell transplantation before nilotinib and dasatinib became available, 31 of 106 patients changed to 2G-TKIs. The primary reason for changing from imatinib was poor response, followed by intolerance, with the main reason for the latter being musculoskeletal events. Switches from imatinib to 2G-TKIs with intolerance occurred significantly earlier than switches with poor response. Sixteen and 15 patients were treated with nilotinib and dasatinib, respectively, following imatinib therapy. After switching to 2G-TKIs, the response status improved in 63% of evaluable patients. The adverse effect profiles of nilotinib and dasatinib tended to be different, with hyperbilirubinemia observed in 33% of nilotinib-treated patients, but in none of the cases with dasatinib. CONCLUSION: This retrospective study represents the first series of children and adolescents in whom sequential use of imatinib followed by 2G-TKIs was reported. These data provide useful insights into the selection of 2G-TKIs as first-line treatment for children and adolescents with CP-CML.

Necrotizing Ulcer After BCG Vaccination in a Girl With Leukocyte-adhesion Deficiency Type 1.

Leukocyte-adhesion deficiency-1 is a recessively inherited disorder associated with recurrent bacterial infections, severe periodontitis, peripheral leukocytosis, and impaired wound healing. We diagnosed moderate-type leukocyte-adhesion deficiency-1 in a 7-year-old girl who developed a necrotizing ulcer after Bacillus Calmette-Guerin vaccination. The patient showed moderate expression of CD18 in neutrophils with a homozygous splice mutation with c.41_c.58+2dup20 of ITGB2 and experienced recurrent severe infections complicated with systemic lupus erythematosus. She received hematopoietic stem cell transplantation from a matched elder brother with heterozygous mutation of ITGB2, and has since remained free of infection and systemic lupus erythematosus symptoms without immunosuppression therapy.

Allogeneic Hematopoietic Stem Cell Transplantation for Leukocyte Adhesion Deficiency.

The clinical outcome of allogeneic hematopoietic stem cell transplantation (HSCT) was retrospectively analyzed in 6 patients with leukocyte adhesion deficiency. Of 3 patients transplanted with myeloablative conditioning, 2 patients had complete chimerism and 1 patient had mixed chimerism. By contrast, all 3 patients transplanted with reduced-intensity conditioning (RIC) had mixed chimerism, one of whom progressed to secondary graft failure. All patients with low-level mixed chimerism and secondary graft failure were rescued by donor lymphocyte infusion or a second HSCT. RIC-HSCT is feasible for leukocyte adhesion deficiency, although further refinement/modification of conditioning is required to achieve higher donor chimerism levels.

ZNF384-related fusion genes define a subgroup of childhood B-cell precursor acute lymphoblastic leukemia with a characteristic immunotype.

Fusion genes involving ZNF384 have recently been identified in B-cell precursor acute lymphoblastic leukemia, and 7 fusion partners have been reported. We further characterized this type of fusion gene by whole transcriptome sequencing and/or polymerase chain reaction. In addition to previously reported genes, we identified BMP2K as a novel fusion partner for ZNF384 Including the EP300-ZNF384 that we reported recently, the total frequency of ZNF384-related fusion genes was 4.1% in 291 B-cell precursor acute lymphoblastic leukemia patients enrolled in a single clinical trial, and TCF3-ZNF384 was the most recurrent, with a frequency of 2.4%. The characteristic immunophenotype of weak CD10 and aberrant CD13 and/or CD33 expression was revealed to be a common feature of the leukemic cells harboring ZNF384-related fusion genes. The signature gene expression profile in TCF3-ZNF384-positive patients was enriched in hematopoietic stem cell features and related to that of EP300-ZNF384-positive patients, but was significantly distinct from that of TCF3-PBX1-positive and ZNF384-fusion-negative patients. However, clinical features of TCF3-ZNF384-positive patients are markedly different from those of EP300-ZNF384-positive patients, exhibiting higher cell counts and a younger age at presentation. TCF3-ZNF384-positive patients revealed a significantly poorer steroid response and a higher frequency of relapse, and the additional activating mutations in RAS signaling pathway genes were detected by whole exome analysis in some of the cases. Our observations indicate that ZNF384-related fusion genes consist of a distinct subgroup of B-cell precursor acute lymphoblastic leukemia with a characteristic immunophenotype, while the clinical features depend on the functional properties of individual fusion partners.

Flow cytometric analysis as an additional predictive tool of treatment response in children with chronic-phase chronic myeloid leukemia treated with imatinib.

Bone marrow samples of newly diagnosed children with chronic-phase chronic myeloid leukemia (CML) were obtained at diagnosis and after imatinib initiation and stained with anti-human CD34, CD38, CD123, CD45RA, cMpl, and lineage antibodies. Flow cytometric analysis revealed that granulocyte macrophage progenitor predominance in CML progenitors at diagnosis and elevated cMpl expression in bone marrow progenitors at 3 months may predict poor outcome in children with chronic-phase CML treated with imatinib. We recommend flow cytometric analysis of bone marrow in the early phase of treatment, as it is a convenient tool that may predict treatment response and guide CML management.

Fludarabine, cytarabine, granulocyte colony-stimulating factor and idarubicin for relapsed childhood acute myeloid leukemia.

BACKGROUND: The combination of fludarabine (Flu), high-dose cytarabine (Ara-C) and granulocyte colony-stimulating factor (G-CSF; FLAG), with anthracyclines has become standard chemotherapy for refractory acute myeloid leukemia (AML) in European children and adults. To clarify the efficacy and the safety of FLAG-idarubicin (IDA) for children prospectively, we planned a multicenter phase II study (AML-R11) by the Japanese Pediatric Leukemia/Lymphoma Study Group. METHODS: Patients with AML aged between 2 and 20 years old, who had the first bone marrow (BM) relapse or induction failure, were enrolled. The FLAG-IDA regimen consisted of Flu 30 mg/m2 for 5 days, Ara-C 2 g/m2 for 5 days, G-CSF (lenograstim) 5 µg/kg for 6 days and IDA 10 mg/m2 for 3 days. The primary endpoint was remission rate after therapy. RESULTS: Due to drug supply issues, the trial was suspended after the inclusion of seven eligible patients. There were six cases of early relapse within 1 year of the first remission. All seven patients completed the therapy and no early death was observed. Hematological toxicity was common, and one patient developed grade 4 non-hematological toxicity of bacterial meningitis. Although only one patient with late relapse achieved complete remission, minimal residual disease was positive on both flow cytometry and Wilms' tumor 1 mRNA. Two patients were alive in remission following hematopoietic stem cell transplantation, whereas the other five patients died of either the disease or treatment-related causes. CONCLUSION: FLAG-IDA might be tolerable for children with refractory AML although the efficacy should be further investigated.

Leukostasis in Children and Adolescents with Chronic Myeloid Leukemia: Japanese Pediatric Leukemia/Lymphoma Study Group.

BACKGROUND: The details of leukostasis in children and adolescents with chronic myeloid leukemia (CML) are unknown. This study determined the characteristics of leukostasis in children and adolescents with CML. PROCEDURE: A total of 256 cases from a retrospective study of patients with CML conducted by the Japanese Pediatric Leukemia/Lymphoma Study Group from 1996 to 2011 were analyzed, and of these, 238 cases were evaluated in this study. RESULTS: Leukostasis was diagnosed in 23 patients (9.7%). The median leukocyte count and spleen size below the left costal margin in cases with leukostasis were significantly higher and larger when compared to those in cases without leukostasis (458.5 × 10(9) /l vs. 151.8 × 10(9) /l (P < 0.01), and 13 vs. 5 cm (P < 0.01), respectively). Leukostasis occurred with ocular symptoms in 14 cases, priapism in four cases, and dyspnea, syncope, headache, knee pain, difficulty hearing, and aseptic necrosis of the femoral head in one case each. One case had two leukostasis symptoms simultaneously. Three cases were diagnosed before imatinib became available. Five cases received special treatment, and in the remaining 15 cases, all of these symptoms resolved after treatment with imatinib. CONCLUSIONS: This retrospective study represents the largest series of children and adolescents in which leukostasis of CML has been reported. Our data provide useful insight into the characteristics of leukostasis in recent cases of children and adolescents with CML.

Comparison of chemotherapeutic agents as a myeloablative conditioning with total body irradiation for pediatric acute lymphoblastic leukemia: A study from the pediatric ALL working group of the Japan Society for Hematopoietic Cell Transplantation.

BACKGROUND: As a partner of total body irradiation (TBI) in hematopoietic stem cell transplantation (HSCT) for pediatric acute lymphoblastic leukemia (ALL), various cytotoxic agents are used, but the optimal combination is still unclear. PROCEDURE: We retrospectively analyzed 767 children who received TBI-based myeloablative allogeneic HSCT in complete remission (CR), using nationwide registry data of the Japan Society for Hematopoietic Cell Transplantation. Combinations of chemotherapy were categorized as follows: cyclophosphamide (CY) (n = 74), melphalan (L-PAM) (n = 139), CY + etoposide (VP16) (n = 408), CY + cytarabine (AraC) (n = 73), and others (n = 73). RESULTS: Event-free survival (EFS) at 5 years after HSCT was 62.2% for CY, 71.4% for L-PAM, 67.6% for CY + VP16, 52.6% for CY + AraC, and 59.1% for others (P = 0.009). Further detailed comparison of LPAM and CY + VP16 demonstrated superior EFS for LPAM (83.2 ± 6.7%), with a marked difference compared with CY + VP16 (66.7 ± 4.9%) when limited to HSCT from a matched related donor (MRD), and this result was reproduced regardless of disease status (CR1 or CR2). However, EFS for CY + VP16 (68.3 ± 2.8%) was comparable to that for LPAM (64.5 ± 5.7%, P = 0.37) in HSCT from alternative donors, because higher non-relapse mortality attenuated the advantage of LPAM. CONCLUSIONS: For pediatric ALL in remission, LPAM could provide superior EFS for HSCT from MRD; however, compared to LPAM, CY + VP16 has similar EFS for HSCT from an alternative donor.

Salvage allogeneic stem cell transplantation in patients with pediatric myelodysplastic syndrome and myeloproliferative neoplasms.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curable approach for myelodysplastic syndrome (MDS) and myeloproliferative neoplasms (MPN); however, the event-free survival rate of patients with pediatric MDS and MPN is still only approximately 60%. Although salvage HSCT is the only curative approach for patients with the failure of previous HSCT, its safety and efficacy have yet to be determined. PROCEDURES: We retrospectively analyzed 51 pediatric MDS or MPN who received salvage HSCT for relapse or graft failure following HSCT using registry data of the Japan Society for Hematopoietic Cell Transplantation. The indications used for salvage HSCT were relapse in 22 patients and graft failure in 29 patients. RESULTS: The overall survival (OS) rate for salvage HSCT in relapsed patients was 49.0 ± 10.8% at 3 years. The cumulative incidence of relapse following salvage HSCT was 29.8 ± 10.7% at 3 years, whereas the incidence of non-relapse mortality (NRM) was 28.6 ± 10.2%. No significant differences were observed in the OS after salvage HSCT between disease types. Twenty-four of 29 patients who received salvage HSCT for graft failure achieved engraftment, resulting in an engraftment probability of 81.5 ± 8.0% on day 100. The OS rate after salvage HSCT for graft failure was 56.8 ± 9.6% at 3 years. CONCLUSIONS: Second HSCT should be considered as a valuable option for the patients with relapse and graft failure in patients with pediatric MDS or MPN after HSCT, but high NRM is an important issue that needs to be addressed.

Necessary stem cell transplantation using myeloablative therapy for myelodysplastic syndrome with progression of genotypic abnormalities and TP53 dysfunction in a young adult.

A 14-yr-old male was admitted to our hospital with MDS and the chromosomal abnormality 45,XY,der(5;17)(p10;q10). He rapidly developed karyotype abnormalities, accompanied by the loss of tumor suppressor gene TP53 function. He suffered an early relapse after reduced-intensity-conditioning SCT and ultimately required myeloablative therapy before a second SCT. We consider that the analysis of TP53 mutations is essential when planning the treatment of patients with MDS.

[Acute monoblastic leukemia with MLL/AF9 rearrangement which developed 18 months after myeloid sarcoma onset].

We describe a 36-month-old boy with acute monoblastic leukemia (AMoL M5a) and mixed-lineage leukemia (MLL)-AF9 rearrangement. At 18 months of age, he presented with swelling on the back of his hand that was considered to be an inflammatory change, but no hematological abnormalities were found. However, blasts with MLL-AF9 rearrangement were detected in biopsied tissue taken at the time and in peripheral blood samples taken 18 months later. These findings indicate that myeloid sarcoma with MLL-AF9 rearrangement may ultimately, though slowly, progress to AMoL.

Aberrant induction of LMO2 by the E2A-HLF chimeric transcription factor and its implication in leukemogenesis of B-precursor ALL with t(17;19).

LMO2, a critical transcription regulator of hematopoiesis, is involved in human T-cell leukemia. The binding site of proline and acidic amino acid-rich protein (PAR) transcription factors in the promoter of the LMO2 gene plays a central role in hematopoietic-specific expression. E2A-HLF fusion derived from t(17;19) in B-precursor acute lymphoblastic leukemia (ALL) has the transactivation domain of E2A and the basic region/leucine zipper domain of HLF, which is a PAR transcription factor, raising the possibility that E2A-HLF aberrantly induces LMO2 expression. We here demonstrate that cell lines and a primary sample of t(17;19)-ALL expressed LMO2 at significantly higher levels than other B-precursor ALLs did. Transfection of E2A-HLF into a non-t(17;19) B-precursor ALL cell line induced LMO2 gene expression that was dependent on the DNA-binding and transactivation activities of E2A-HLF. The PAR site in the LMO2 gene promoter was critical for E2A-HLF-induced LMO2 expression. Gene silencing of LMO2 in a t(17;19)-ALL cell line by short hairpin RNA induced apoptotic cell death. These observations indicated that E2A-HLF promotes cell survival of t(17;19)-ALL cells by aberrantly up-regulating LMO2 expression. LMO2 could be a target for a new therapeutic modality for extremely chemo-resistant t(17;19)-ALL.

Up-regulation of survivin by the E2A-HLF chimera is indispensable for the survival of t(17;19)-positive leukemia cells.

The E2A-HLF fusion transcription factor generated by t(17;19)(q22;p13) translocation is found in a small subset of pro-B cell acute lymphoblastic leukemias (ALLs) and promotes leukemogenesis by substituting for the antiapoptotic function of cytokines. Here we show that t(17;19)+ ALL cells express Survivin at high levels and that a dominant negative mutant of E2A-HLF suppresses Survivin expression. Forced expression of E2A-HLF in t(17;19)(-) leukemia cells up-regulated Survivin expression, suggesting that Survivin is a downstream target of E2A-HLF. Analysis using a counterflow centrifugal elutriator revealed that t(17;19)+ ALL cells express Survivin throughout the cell cycle. Reporter assays revealed that E2A-HLF induces survivin expression at the transcriptional level likely through indirect down-regulation of a cell cycle-dependent cis element in the promoter region. Down-regulation of Survivin function by a dominant negative mutant of Survivin or reduction of Survivin expression induced massive apoptosis throughout the cell cycle in t(17;19)+ cells mainly through caspase-independent pathways involving translocation of apoptosis-inducing factor (AIF) from mitochondria to the nucleus. AIF knockdown conferred resistance to apoptosis caused by down-regulation of Survivin function. These data indicated that reversal of AIF translocation by Survivin, which is induced by E2A-HLF throughout the cell cycle, is one of the key mechanisms in the protection of t(17;19)+ leukemia cells from apoptosis.

Distinct impact of imatinib on growth at prepubertal and pubertal ages of children with chronic myeloid leukemia.

OBJECTIVE: To determine the extent of growth impairment resulting from imatinib treatment in children with chronic myeloid leukemia (CML). STUDY DESIGN: Clinical records of 48 chronic-phase CML children administered imatinib as the first-line therapy between 2001 and 2006 were analyzed retrospectively. Cumulative change in height was assessed using the height height-SDS and converted height data from age- and sex-adjusted Japanese norms. RESULTS: A decrease in height-SDS was observed in 72.9% of children, with a median maximum reduction in height-SDS of 0.61 during imatinib treatment. Median follow-up time was 34 months (range, 10-88 months). Growth impairment was seen predominantly in children who started imatinib at a prepubertal age compared with those who started at pubertal age. Growth velocity tended to recuperate in prepubertal children with growth impairment, as they reached pubertal age, suggesting that imatinib had little impact on growth during puberty. CONCLUSIONS: Growth impairment was a major adverse effect of long-term imatinib treatment in children with CML. We report the distinct inhibitory effect of imatinib on growth in prepubertal and pubertal children with CML. We should be aware of growth deceleration in children, especially in young children given imatinib before puberty and subjected to prolonged exposure.

Viridans streptococcal bacteremia-related encephalopathy in childhood with malignancy.

Viridans streptococcal bacteremia is a prognostic factor in pediatric patients with malignant disease accompanied by severe neutropenia. Here the authors describe 4 patients with viridans streptococcal bacteremia-related encephalopathy who showed serious complications, which included seizures and loss of consciousness. Therapy for relief of brain edema on seizures was started quickly, and included the administration of midazolam, dexamethasone, and mannitol with antimicrobial therapy. The treatment was successfully completed without sequelae. The authors registered 28 episodes of viridans streptococcal bacteremia in their hospital. The peak of serum C-reaction protein was higher in viridans streptococcal bacteremia patients with encephalopathy than in those without encephalopathy. The authors concluded that viridans streptococcal bacteremia can induce encephalopathy in pediatric patients with malignancy and that it is crucial to establish an accurate diagnosis and initiate therapy as soon as possible.

Outcome of 125 children with chronic myelogenous leukemia who received transplants from unrelated donors: the Japan Marrow Donor Program.

Because of a small number of patients, only a few studies have addressed the outcome of bone marrow transplantation (BMT) in children with Philadelphia chromosome-positive (Ph+) chronic myelogenous leukemia (CML), who receive graft from a volunteer-unrelated donor (VUD), especially after practical application of imatinib mesylate. The outcomes of BMT from a VUD in 125 children with Ph+ CML were retrospectively reviewed. Patients were identified through the Japan Marrow Donor Program as having undergone BMT between 1993 and 2005 and were aged 1-19 years at the time of transplant (median age, 14 years). The probabilities of 5-year overall survival (OS) and leukemia-free survival (LFS) were 59.3% and 55.5%, respectively. Multivariate analysis identified the following unfavorable survival factors: infused total nucleated cell dose<314 x 10(6) /kg (relative risk [RR]=2.43; 95% confidence interval [CI]=1.33-4.44; P=.004), advanced phase (RR=2.43; 95% CI=1.37-4.31; P=.004), and no major cytogenetic response (MCyR) at the time of BMT (RR=6.55; 95% CI=1.98-21.6; P=.002). Of the 17 patients treated with imatinib, 15 (88%) achieved MCyR at the time of BMT, and this group had an excellent 5-year OS of 81.9%. Disease phase, infused total nucleated cell dose, and cytogenetic response were independent risk factors for survival of unrelated BMT. These findings provide important information for assessing the indications for and improving outcome in unrelated BMT for the treatment of pediatric CML.

Chronic active Epstein-Barr virus infection with mosquito allergy successfully treated with reduced-intensity unrelated allogeneic bone marrow transplantation in a boy.

EBV-infected T-/NK cells play an important role in the pathogenesis of mosquito allergy, and the prognosis of most patients with mosquito allergy is poor without proper treatment. We describe a 13-yr-old boy who had CAEBV with mosquito allergy and was successfully treated with BMT from an unrelated donor after reduced-intensity preconditioning. Because combination chemotherapy failed to achieve CR, we performed unrelated BMT to reconstitute normal immunity and eradicate any residual EBV-infected cells. To reduce complications after BMT, we selected a reduced-intensity preconditioning regimen consisting of fludarabine, l-phenylalanine mustard, and antithymocyte Ig instead of a conventional myeloablative preconditioning. Although grade II acute GVHD developed, it was successfully controlled with immunosuppressive therapy. After 27 months, the patient has been well without any signs of CAEBV, and the EBV DNA has been undetectable with real-time PCR analysis. We conclude that RIST from the bone marrow of an unrelated donor is indicated for some patients who have CAEBV that is refractory to chemotherapy and who have no HLA-matched related donors or cord blood as a source of stem cells.

JAK2V617F mutation-positive childhood essential thrombocythemia associated with cerebral venous sinus thrombosis.

Myeloproliferative diseases (MPDs) in childhood are quite rare. Although pediatric and adult MPDs exhibit similar hematologic findings, JAK2V617F mutations and clonality status of MPDs in the DNA of neutrophils are evaluated less frequently in children than in adults. Increased incidence of venous thrombosis at uncommon sites is associated with JAK2V617F mutation in MPDs and thrombotic complications are more common in essential thrombocythemia (ET). Here, we describe 6-year-old girl with clonal myelopoiesis and JAK2V617F-positive ET associated with cerebral venous sinus thrombosis. To our knowledge, this is the first report of pediatric monoclonal and JAK2V617F-positive ET with cerebral venous sinus thrombosis.