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No previous research papers have reported a comparative survey of local radiologic diagnoses and central review in children with hepatoblastoma.To evaluate the utility of central review of children with hepatoblastoma enrolled in a clinical trial.The study included 91 children enrolled in a clinical trial conducted by the Japanese Study Group for Pediatric Liver Tumor. We compared the results of the initial pre-treatment extent of tumor (PRETEXT) disease staging performed at local sites with the results obtained on central review to determine the concurrence rates for tumor staging and additional criteria.The concurrence rate for PRETEXT staging was 70%. As the stage increased, the concurrence rate decreased. Using additional criteria, central review identified 143 lesions (157.1%), about 1.8 times higher than the number identified for the local site diagnoses. The additional criterion found most often on central review was "multifocal lesion" (n=19). The concurrence rate for lung metastases was high. However, our central review found many false-positive assertions of hepatic vein lesions, portal vein invasion and extrahepatic lesions among the local site diagnoses.In a clinical trial of hepatoblastoma, central review provided a more precise diagnosis than local site diagnoses with respect to severe PRETEXT stages III and IV cases and other cases including hepatic and portal vein invasion. The central review process appears to be effective and essential for improving the quality of clinical trials.

Hepatoblastoma (HB) is the most common paediatric liver tumour, and epigenetic aberrations may be important in HB development. Recently, the Children's Hepatic Tumors International Collaboration-Hepatoblastoma Stratification (CHIC-HS) developed risk stratification based on clinicopathological factors. This study aimed to construct a more accurate model by integrating CHIC-HS with molecular factors based on DNA methylation.HB tumour specimens (N = 132) from patients treated with the Japanese Pediatric Liver Tumors Group-2 protocol were collected and subjected to methylation analysis by bisulfite pyrosequencing. Associations between methylation status and clinicopathological factors, overall survival (OS), and event-free survival (EFS) were retrospectively analysed. We investigated the effectiveness of the evaluation of methylation status in each CHIC-HS risk group and generated a new risk stratification model.Most specimens (82%) were from post-chemotherapy tissue. Hypermethylation in ≥2 of the four genes (RASSF1A, PARP6, OCIAD2, and MST1R) was significantly associated with poorer OS and EFS. Multivariate analysis indicated that ≥2 methylated genes was an independent prognostic factor (hazard ratios of 6.014 and 3.684 for OS and EFS, respectively). Two or more methylated genes was also associated with poorer OS in the CHIC-very low (VL)-/low (L)-risk and CHIC-intermediate (I) risk groups (3-year OS rates were 83% vs. 98% and 50% vs. 95%, respectively). The 3-year OS rates of the VL/L, I, and high-risk groups in the new stratification model were 98%, 90%, and 62% (vs. CHIC-HS [96%, 82%, and 65%, respectively]), optimising CHIC-HS.Our proposed stratification system considers individual risk in HB and may improve patient clinical management.

Background The SIOPEL-4 study has demonstrated that dose-dense cisplatin-based chemotherapy dramatically improves outcome in children with high-risk hepatoblastoma in western countries. However, the feasibility and safety of this regimen have not been clarified in Japanese patients. Methods A pilot study, JPLT3-H, was designed to evaluate the safety profile of the SIOPEL-4 regimen in Japanese children with newly diagnosed hepatoblastoma with either metastatic disease or low alpha-fetoprotein. Results A total of 15 patients (three female) were enrolled. Median age was 2 years (range, 0-14). Three patients were PRETEXT II (where PRETEXT is PRETreatment EXTent of disease), six PRETEXT III, and six PRETEXT IV. All patients had lung metastasis, none had low alpha-fetoprotein. Eight patients completed the prescribed treatment, and seven patients discontinued therapy prematurely, four due to progressive disease and three due to causes other than severe toxicity. Grade 4 neutropenia was documented in most patients in preoperative cycles A1-3 (11/15 in A1, 9/11 in A2, and 7/11 in A3) and in all considering all cycles. Grade 3-4 thrombocytopenia and grade 3 anemia were also frequently observed. Patients experienced several episodes of grade 3 febrile neutropenia, but none had grade 4 febrile neutropenia or severe infections. One patient had grade 3 heart failure only in the first cycle. Other grade 3 or 4 toxicities were hypomagnesemia, anorexia, nausea, mucositis, liver enzyme elevation, fever, infection, and fatigue. There were no unexpected severe toxicities. Conclusion The toxicity profile of JPLT3-H was comparable to that of SIOPEL-4. Dose-dense cisplatin-based chemotherapy may be feasible among Japanese patients with high-risk hepatoblastoma.

Hepatoblastoma (HB) is the most common pediatric liver malignancy; however, hereditary predisposition and acquired molecular aberrations related to HB clinicopathological diversity are not well understood. Here, we perform an integrative genomic profiling of 163 pediatric liver tumors (154 HBs and nine hepatocellular carcinomas) based on the data acquired from a cohort study (JPLT-2). The total number of somatic mutations is precious low (0.52/Mb on exonic regions) but correlated with age at diagnosis. Telomerase reverse transcriptase (TERT) promoter mutations are prevalent in the tween HBs, selective in the transitional liver cell tumor (TLCT, > 8 years old). DNA methylation profiling reveals that classical HBs are characterized by the specific hypomethylated enhancers, which are enriched with binding sites for ASCL2, a regulatory transcription factor for definitive endoderm in Wnt-pathway. Prolonged upregulation of ASCL2, as well as fetal-liver-like methylation patterns of IGF2 promoters, suggests their “cell of origin” derived from the premature hepatoblast, similar to intestinal epithelial cells, which are highly proliferative. Systematic molecular profiling of HB is a promising approach for understanding the epigenetic drivers of hepatoblast carcinogenesis and deriving clues for risk stratification., While hepatoblastoma is the most common pediatric liver cancer, its molecular background has not been fully characterised. Here, the authors perform genomic and epigenomic profiling of 163 untreated pediatric liver tumours and suggest the upregulation of ASCL2 and methylation patterns of IGF2 promoters in driving hepatoblast carcinogenesis.

Background Although irinotecan hydrochloride (IRI) is a promising chemotherapeutic agent for pediatric solid tumors, its indications had been off-label in the USA, EU and Japan. Therefore, we conducted a phase 1/2 trial of IRI monotherapy in a registration-directed setting. Methods Children aged 2-18 years with solid tumors who were either refractory to or relapsed after standard chemotherapy were enrolled. Phase 1 was a conventional dose escalation study to determine the dose-limiting toxicity (DLT) and the recommended dose. IRI was given i.v. on days 1, 2, 3 and 8, 9, 10 in up to eight, 21 day cycles. Results The starting dose (40 mg/m2 /day) was determined to be the recommended dose because the next higher dose level (45 mg/m2 /day) resulted in two cases of DLT. Seventeen children (11 in phase 1 and six in phase 2) with a refractory solid tumor received IRI. Of the 12 patients treated with 40 mg/m2 /day, seven (58.3%) achieved a stable disease condition for >8 weeks. Conclusions The RD of IRI in this treatment schedule was 40 mg/m2 /day. IRI did not cause tumor shrinkage but might help to stabilize refractory pediatric solid tumors. Based on the accumulating evidence from international studies of the efficacy of IRI against refractory pediatric solid tumors, the Japanese regulatory authority approved its use for this indication in 2011.

PURPOSEWe report here the outcomes and late effects of the Japanese Study Group for Pediatric Liver Tumors (JPLT)-2 protocol, on the basis of cisplatin-tetrahydropyranyl-adriamycin (CITA) with risk stratification according to the pretreatment extent of disease (PRETEXT) classification for hepatoblastoma (HB).PATIENTS AND METHODSFrom 1999 to 2012, 361 patients with untreated HB were enrolled. PRETEXT I/II patients were treated with up-front resection, followed by low-dose CITA (stratum 1) or received low-dose CITA, followed by surgery and postoperative chemotherapy (stratum 2). In the remaining patients, after 2 cycles of CITA, responders received the CITA regimen before resection (stratum 3), and nonresponders were switched to ifosfamide, pirarubicin, etoposide, and carboplatin (ITEC; stratum 4). Intensified chemotherapeutic regimens with autologous hematopoietic stem-cell transplantation (SCT) after resection were an optional treatment for patients with refractory/metastatic disease.RESULTSThe 5-year event-free and overall survival rates of HB patients were 74.2% and 89.9%, respectively, for stratum 1, 84.8% and 90.8%%, respectively, for stratum 2, 71.6% and 85.9%%, respectively, for stratum 3, and 59.1% and 67.3%%, respectively, for stratum 4. The outcomes for CITA responders were significantly better than those for nonresponders, whose outcomes remained poor despite salvage therapy with a second-line ITEC regimen or SCT. The late effects, ototoxicity, cardiotoxicity, and delayed growth, occurred in 61, 18, and 47 patients, respectively. Thirteen secondary malignant neoplasms (SMNs), including 10 leukemia, occurred, correlating with higher exposure to pirarubicin and younger age at diagnosis.CONCLUSIONThe JPLT-2 protocol achieved up-front resectability in PRETEXT I/II patients with no annotation factors, and satisfactory survival in patients who were CITA responders in the remaining patients. However, outcomes for CITA nonresponders were unsatisfactory, despite therapy intensification with ITEC regimens and SCT. JPLT-2 had a relatively low incidence of cardiotoxicity but high rates of SMNs.

Background/purpose The purpose of this study was to clarify the role of pulmonary metastasectomy in hepatoblastomas with lung metastasis at diagnosis. We reviewed cases enrolled in the JPLT-2 study. Methods A total of 360 cases with hepatoblastoma were enrolled. The clinical courses and outcome of 60 cases with pulmonary metastasis at diagnosis were reviewed, focusing on metastasectomy. Results Induction chemotherapy resulted in eradication of nodules in 26, residual nodules in 33, and early treatment-related death in one. Of the 33 cases with residual nodules, 11 underwent complete resection of the lung lesions, and among these, progression was reported in five. Complete resection of the liver tumor was not achieved in two of these. Three underwent incomplete resection of lung nodules, eventually leading to progression. Twelve cases with incomplete or no liver tumor resection progressed regardless of the status of lung lesions. Contrarily, among patients who underwent complete resection of the liver tumor, half were cured without metastasectomy. Conclusions Metastasectomy for residual pulmonary nodules after induction chemotherapy is effective provided that the liver tumor could be completely resected. Type of study Prospective Cohort Study. Level of evidence Level II.

Background Von Willebrand disease (VWD) is the most common inherited bleeding disorder in humans. Coagulopathies such as VWD are evidently risk factors for post-surgical bleeding. Perioperative management of patients with VWD remains controversial and is a major clinical concern. Case presentation A 5-year-old girl was scheduled for tonsillectomy under general anesthesia. Preoperative laboratory tests revealed prolongation of activated partial thromboplastin time and a mild decrease in von Willebrand factor (VWF) activity. Prophylactic administration of desmopressin or VWF was not performed. During tonsillectomy, oozing from the surgical wound was uncontrollable by conventional hemostasis techniques, but complete hemostasis was ensured by plasma-derived coagulation factor VIII concentrate containing VWF. Conclusion Pediatric patients with mild abnormalities in preoperative laboratory tests may have coagulopathies. Prophylactic intervention and/or the preparation of a sufficient amount of coagulation factor VIII concentrate containing VWF may be required in patients suspected of having VWD or with mild VWF deficiency.

Background Returning to school after a cancer diagnosis can be socially challenging for children with cancer. This study investigated the form of support for school reentry and the associations with social support from peers and teachers. Methods This was a multicenter cross-sectional study. Children with cancer and their guardians completed questionnaires. Their guardians also underwent a semi-structured interview to describe the background of support for school reentry. Results Thirty-nine children with cancer and guardian dyads completed questionnaires and three guardians underwent semi-structured interview. Peer visits and their understanding of hospital experiences and how to interact with children were related to social support from peers. Teachers’ understanding of physical appearance, academic performance, hospital experience and of how to interact with children was related to social support from peers. Teachers’ understanding of diagnosis/treatment, academic performance and their status as the liaison between doctors/nurses in hospitals and teachers in local schools were also related to social support from teachers. Furthermore, children with cancer were also encouraged to establish supportive relationships with peers and teachers as a result of school reentry support that (i) helped children to feel that they are still members of the local school; (ii) improved peer and teacher understanding of the long-term recovery process of children with cancer; and (iii) facilitated the children's own awareness that they are fighting the disease. Conclusions The multidisciplinary team consisting of the children with cancer, their families, doctors, nurses and teachers in the local school need to communicate with peers regarding positive experiences of fighting, and overcoming, severe disease.

Background: The aim of this study was to clarify the degree of information provision to children with brain tumors, factors influencing this provision, and the relationship between this provision and psychosocial consequences. Methods: A total of 157 parents completed a questionnaire on the degree of information provision to their children and sociodemographic and medical characteristics. Parents and their children completed subscales of the Pediatric Quality of Life Inventory (PedsQL) Cancer Module. Relevant factors were investigated using ordinal logistic regression analysis and compared with PedsQL scores by degree of information provision with adjustment for age. Results: The majority of children aged 2 - 4 years received a low level of information only in regard to medical procedure and preparation. The majority of children aged 5 - 11 years were provided information regarding disease symptoms and treatment, but not actual diagnosis. Approximately half of children aged 12 - 18 years were provided detailed information including their actual diagnosis. Older children generally received more information regarding their disease (odds ratio [OR] = 1.3 per 1 year old, P < 0.001), while children with intellectual disability received less (OR = 0.2, P = 0.006). The provision of information did not worsen scores for Procedural Anxiety, Treatment Anxiety, Worry, or Communication. Conclusions: To our knowledge, this is the first report on the degree of information provision to children with brain tumors. Parents of children with brain tumors in Japan provide information dependent on age and intellectual level. The disclosure of information to children regarding their disease might affect their trust of medical and health care professionals.

Chemotherapy-induced leukopenia has been shown to be associated with the outcomes of several types of cancer, but the association with childhood acute lymphoblastic leukemia (ALL) remains unknown. To elucidate the association of chemotherapy-induced leukopenia with the clinical outcome of childhood ALL, retrospective analysis was performed on 19 child patients with ALL treated according to the ALL-BFM 95 high-risk (HR) protocol. The mean minimum leukocyte count over the first three courses of the consolidation phase was used as the measure of hematological toxicity and ranged between 200 and 1,167/μl. The risk of relapse was significantly higher in patients with a mean minimum leukocyte count above the median of 433/μl (hazard ratio, 6.61; P=0.047). In conclusion, chemotherapy-induced leukopenia was found to correlate with relapse-free survival in childhood HR ALL. Dose escalation based on hematologic toxicity must be prospectively studied.

10043 Background: This study focused on late toxicities, especially second malignancies (SMNs), experienced by patients with hepatoblastoma (HB) treated with CITA (cisplatin and pirarubicin) in the Japanese Study Group for Pediatric Liver Tumor protocol-2 (JPLT-2). Methods: In the JPLT-2, 361 children with HB were eligible for inclusion. We evaluated late effects including ototoxicity, cardiotoxicity and SMN in these patients. PRETEXT I/II patients were typically treated by initial resection at diagnosis followed by CITA. Otherwise, patients received preoperative CITA, followed by surgery and postoperative chemotherapy. Non-responders to CITA received ITEC (ifosfamide, pirarubicin, etoposide, and carboplatin) or intensified chemotherapeutic regimens. In 267 patients whose germline DNA samples were available, genotyping analysis was performed using the Illumina Human Omni Express Exome-8 v.1.3 BeadChip. Associations between single nucleotide polymorphisms (SNPs) and toxicities were assessed using logistic regression analysis. Results: Among the patients (n = 300) who survived more than 5 years, ototoxicity was detected in 61 and cardiotoxicity in 18. The presence of ototoxicity was associated with a significantly higher dose of cisplatin, and the Brock grade of ototoxicity was correlated with the total dose of cisplatin (P < 0.01). SMNs occurred in 13 patients (9 leukemia, 1 myelodysplastic disease, 1 lymphoma, 1 Ewing sarcoma and 1 thyroid tumor). The total dose of pirarubicin in SMN cases was significantly higher than those without SMNs (P = 0.035). The mean age at onset of HB was 13 months in the patients with SMNs and 23.3 months in the other patient (P = 0.12). However, two-way analysis of variance showed that SMN occurrence was significantly correlated with the age of HB onset and the total dose of pirarubicin (P < 0.0001). We identified ten inherited SNPs, including six SNPs associated with ototoxicity such as ACYP2, two SNPs associated with cardiotoxicity and two candidate SNPs associated with SMNs. Conclusions: The total dose of cisplatin was significantly associated with ototoxicity development. A low incidence of cardiotoxicity but high rates of SMTs, which were correlated with a high dose of pirarubicin and younger age at diagnosis, were found in this study. We also identified SNPs associated with SMNs in HB. Our study provides strong evidence that germline mutation may modify the effect of chemotherapy for childhood cancers on late toxicities, especially during early childhood. Clinical trial information: UMIN000001116.

We present two cases of bacteremia caused by Leptotrichia trevisanii: a 12-year-old girl with recurrent myeloid leukemia of the mandible and a 66-year-old man with esophageal carcinoma. As this filamentous bacillus showed indefinite Gram staining and the identification based on biochemical enzymatic reactions was not definitive, identification required 16s rRNA analysis. For this organism, drug sensitivity testing showed susceptiblity to each β-lactam antibiotics and clindamycin, but resistance to fluoroquinolone and erythromycin. This filamentous bacillus needs careful identification and appropriate antibiotic treatment.

We aimed to clarify whether surgical resectability and tumor response after preoperative chemotherapy (preCTx) represented prognostic factors for patients with hepatoblastoma (HBL) in the JPLT-2 study (1999-2012).Patients (N=342) with HBL who underwent preCTx were eligible. PRETEXT, CHIC risk stratification (standard [SR], intermediate [IR] and high risk [HR]) at diagnosis, POST-TEXT, and tumor resectability were evaluated by imaging. Tumor response was classified into responders (CR or PR) and nonresponders (NC or PD) according to RECIST criteria.There were 7 PRETEXT I, 106 II, 143 III, and 86 IV, including 71 metastatic HBLs. In POST-TEXT, 12 PRETEXT II, 42 III, and 58 IV were down-staged. The 5-year EFS/OS rates of 198 SR, 73 IR, and 71 HR-HBLs were 82/94%, 49/64%, and 28/34%, respectively. In 198 SR, 154 of 160 responders and 24 of 38 nonresponders survived event-free (P0.01). In 73 IR, 12 of 24 whose tumors remained unresectable experienced recurrence, 9 of whom were nonresponders (P0.01). In 71 HR, chemoresponders and tumor resectability after preCTx correlated with favorable outcomes (P0.05).Evaluation of response and tumor resectability after preCTx is useful for predicting prognosis in HBLs. To improve outcomes, we should reconsider surgical procedures according to resectability and chemoresponsiveness.Level II.

Health-related quality of life (HRQOL) is not only a degree of health but also reflects patient perceptions and expectations of health. For children with brain tumors, better understanding of HRQOL requires the use of complementary reports from parents and interviewer-administered reports for children. Here, we aimed to test whether or not the trait anxiety of children and the psychological distress of their parents influence children's and parents' responses to HRQOL questionnaires, and whether or not the report-administration method for children influences children's responses to HRQOL questionnaires.One hundred and thirty-four children aged 5-18 with brain tumors and one of their parents completed the Pediatric Quality of Life Inventory(™) (PedsQL(™)) Brain Tumor Module questionnaires. In addition, the children also completed the State-Trait Anxiety Inventory for Children (STAIC), and the parents also completed the Kessler-10 (K10) and health and sociodemographic characteristics questionnaires. The child questionnaires were administered either by the child (self-administered) or an interviewer. Rater-dependent perceptions about HRQOL were derived from the subscales scores of the PedsQL(™) Brain Tumor Module using structural equation modeling based on a multitrait-multimethod model. The STAIC trait-anxiety score, K10 score, report-administration method, and other health and sociodemographic factors related to each child's or parent's perceptions were identified through multiple linear regression analyses of the questionnaire responses. We used a path analysis to estimate the change in a PedsQL(™) child-reported score that occurs when interviewer-administration changes the child's perception about HRQOL.Surveys for 89 children were self-administered while those for 45 were interviewer-administered. The perceptions of the children and parents were calculated by fitting data to the model (chi-squared P = 0.087, normed fit index = 0.932, comparative fit index = 0.978, standardized root mean squared residual = 0.053, and root mean square error of approximation = 0.054). The children's perception of HRQOL was affected by their STAIC trait-anxiety score (b = -0.43, 95% CI [-0.60, -0.25]). The parent's perception was affected by their child's treatment status (b = 0.26, 95% CI [0.09, 0.43]), the parent's K10 score (b = -0.21, 95% CI [-0.37, -0.04]), and by education level (b = 0.17, 95% CI [0.00, 0.34]). The change in the child-reported PedsQL(™) score in relation to the method of administration ranged from -1.1 (95% CI: -3.5, 1.3) on the procedural anxiety subscale to -2.5 (95% CI: -7.6, 2.6) on the movement and balance subscale.Child-reporting of HRQOL is little influenced by the method of administration. Children's perception about HRQOL tended to be influenced by their trait anxiety, while parents' perception was influenced by their psychological distress, academic background, and their child's treatment status.

The present study describes a unique pediatric case with multiple bone invasions of acute lymphoblastic leukemia (ALL) during remission. An eight-year-old male with a history of ALL was admitted complaining of intermittent and migrating pain in the limb 2 years following complete remission. Magnetic resonance imaging and whole-body positron emission tomography with 18F-fluorodeoxyglucose revealed abnormal multifocal involvement in the bones and corresponding soft tissues. Repeated bone marrow (BM) aspiration indicated normal cellular marrow without leukemic cells, and marked leukemic cell infiltration in different sections of the ilium, respectively. These findings suggested isolated bone relapse, and it is probable that systematic BM relapse occurred as a consequence.

In the recent years, surgical resection with pre- and/or postoperative chemotherapy has markedly improved the survival rate of hepatoblastoma patients. We herein report the results of patients treated with the current protocol of the Japanese Study Group for Pediatric Liver Tumor, JPLT-2. A total of 279 patients with malignant liver tumor were enrolled in JPLT-2. Data from 212 hepatoblastoma cases were analyzed. PRETEXT I patients were treated with primary resection followed by low doses of cisplatin–pirarubicin (tetrahydropyranyl-adriamycin). Otherwise, patients received preoperative cisplatin–pirarubicin (CITA), followed by surgery and postoperative chemotherapy. Ifosfamide, pirarubicin, etoposide, and carboplatin (ITEC) were given as a salvage treatment. High-dose chemotherapy with hematopoietic stem cell transplantation (SCT) was reserved for patients with metastatic diseases. The 5-year overall survival rate (OS) in non-metastatic cases was 100% for PRETEXT I, 87.1% for PRETEXT II, 89.7% for PRETEXT III, and 78.3% for PRETEXT IV. The 5-year OS in metastatic cases was 43.9%. The outcome in non-metastatic PRETEXT IV cases was markedly improved, while the results of metastatic tumors remained poor. JPLT-2 protocol achieved satisfactory survival among children with non-metastatic hepatoblastoma. New approaches are needed for patients with metastatic diseases.

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma of childhood. The simultaneous loss of Ink4a/Arf function and disruption of Met signaling in Ink4a/Arf-/- mice transgenic for hepatocyte growth factor/scatter factor (HGF/SF) induces RMS with extremely high penetrance and short latency. To address the roles of MET and CDKN2A (p16INK4A/p14ARF) in human RMS, we performed mutational analyses in 39 samples of RMS by PCR-SSCP. No mutations were detected in exons 14-21 of MET whereas a nonsense mutation at codon 80 of p16(INK4A) was identified in an alveolar RMS cell line. We also quantified the relative expression levels and DNA copy numbers of these genes in seven cell lines and 17 fresh tumors by real-time quantitative PCR. Expression of MET was detected in all samples; however, more than 10-fold difference was found in the samples with higher or lower expression level, despite a normal DNA copy number. The protein expression level was consistent with that of mRNA, and in cell lines with a higher expression level, MET was constitutively activated. Notably, the expression level of MET was significantly higher in patients who died (P = 0.02), in patients with stage IV (P = 0.04), as well as in patients with PAX3-FKHR chimeric transcript (P = 0.04). On the other hand, reduced or absent expression of p16INK4A and/or p14(ARF) showed no significant correlation with the clinicopathological parameters, except for the age at diagnosis. Our data suggest that MET plays a role in the progression of RMS.

Residual disease (RD) after induction chemotherapy may predict clinical outcome in acute myeloid leukemia (AML). In the present study, we investigated the prognostic significance of RD detected by multidimensional flow cytometry (MDF) among 34 children treated for AML in a clinical trial (JPLSG AML-05) in Japan. Bone marrow samples were analyzed at the points of the end of the first induction course (BMA-1) and second induction course (BMA-2) by MDF. RD was evaluated by detecting the immature cells showing abnormal antigen expression pattern; CD34(+), CD15(+), CD7(+). Thirteen (39.4 %) of 34 patients at BMA-1 and 8 (27.6 %) of 34 at BMA-2 had RD levels ≥0.1 %. There was no significant difference in 3y-EFS and 3y-OS between patients with RD levels ≥0.1 % and those with RD levels

Background In the Japanese Study Group for Pediatric Liver Tumor (JPLT) protocols (JPLT-1 and 2) for evaluating the cure rate of risk-stratified hepatoblastoma, primary resection was permitted in PRETEXT I and II cases, followed by postoperative chemotherapy. Methods In approximately 500 enrolled cases, resection was performed as the initial treatment in 60 cases, including all 18 PRETEXT I, 30 PRETEXT II, and 12 ruptured cases. The clinical features, surgical procedures, complications, and survival rates were compared in these three groups. Results All 18 PRETEXT I cases underwent complete resection by lobectomy or segmentectomy (n=14) or nonanatomical partial hepatectomy (NPH) (n=4). The 30 PRETEXT II cases underwent primary resection by right or left lobectomy (n=16), NPH (n=10), or other procedures (n=4). Of these 30 cases, operational death occurred in 1 newborn, and recurrence occurred in 7 cases (14.6%), including 6 NPH cases and 4 older cases (aged >3years). Of the 12 ruptured cases, 7 (58.3%) showed recurrence. Event-free survival rates at 5years in the 3 groups were 88%, 70%, and 32%, respectively. Conclusions Primary resection for PRETEXT I or II HB cases should be performed by anatomical resection according to strict surgical guidelines. More intensified chemotherapy is required for primary resected cases whose tumors have ruptured.

Returning to school after a cancer diagnosis can be socially challenging for children with cancer. This study investigated the form of support for school reentry and the associations with social support from peers and teachers.This was a multicenter cross-sectional study. Children with cancer and their guardians completed questionnaires. Their guardians also underwent a semi-structured interview to describe the background of support for school reentry.Thirty-nine children with cancer and guardian dyads completed questionnaires and three guardians underwent semi-structured interview. Peer visits and their understanding of hospital experiences and how to interact with children were related to social support from peers. Teachers' understanding of physical appearance, academic performance, hospital experience and of how to interact with children was related to social support from peers. Teachers' understanding of diagnosis/treatment, academic performance and their status as the liaison between doctors/nurses in hospitals and teachers in local schools were also related to social support from teachers. Furthermore, children with cancer were also encouraged to establish supportive relationships with peers and teachers as a result of school reentry support that (i) helped children to feel that they are still members of the local school; (ii) improved peer and teacher understanding of the long-term recovery process of children with cancer; and (iii) facilitated the children's own awareness that they are fighting the disease.The multidisciplinary team consisting of the children with cancer, their families, doctors, nurses and teachers in the local school need to communicate with peers regarding positive experiences of fighting, and overcoming, severe disease.

Imatinib, the ABL kinase inhibitor, is used not only for Philadelphia chromosome-positive (Ph + ) chronic myelogenous leukemia, but also for Ph + acute lymphoblastic leukemia (ALL), although resistance to the drug tends to develop in an early stage of the clinical course. We describe a childhood refractory Ph + ALL patient in whom progressive resistance to imatinib was correlated with the appearance of a mutation in the BCR-ABL kinase domain and in vitro drug resistance to imatinib as determined by the methyl-thiazol-tetrazolium (MTT) assay. A missense mutation of T to C (Y253H) of the ABL gene was identified in the resistant clone, suggesting that this mutation may play an etiological role in the rapid loss of drug sensitivity.

Point mutations of D835/I836 of the FLT3 gene have been reported in adult acute myeloid leukemia (AML), but not in pediatric AML or acute lymphoblastic leukemia (ALL). FLT3 -D835/I836 mutations were found in 6 (5.4%) of 112 children with ALL older than 1 year and in 8 (16.0%) of 50 infants with ALL. Missense mutations were found in 11 patients, 3-base pair deletions in 2 patients, and a deletion/insertion in 1 patient. Remarkably, FLT3 -D835/I836 mutations were found in 8 (18.2%) of 44 infants with ALL with MLL rearrangements and in 4 (21.5%) of 19 patients with hyperdiploid ALL, but they were not found in any patients older than 1 year who had TEL-AML1 (n = 11), E2APBX1 (n = 4), or BCR-ABL (n = 6) fusion genes. Although infant ALL patients with mutations had poorer prognoses than did those without mutations, pediatric ALL patients with mutations who were older than 1 year had good prognoses. We also found FLT3 -D835 mutations in 2 of 11 leukemic cell lines with MLL rearrangements. FLT3 was highly phosphorylated in these cell lines with FLT3 -D835 mutations, leading to constitutive activation of downstream targets such as signal transducer and activator of transcription 5 (STAT5) without FLT3 ligand stimulation. These results suggested that FLT3 -D835/I836 mutations are one of the second genetic events in infant ALL with MLL rearrangements or pediatric ALL with hyperdiploidy. (Blood. 2004;103:1085-1088)

The nucleoporin gene NUP98 has been reported to be fused to 9 partner genes in hematologic malignancies with 11p15 translocations. The NUP98-HOXA9 fusion gene has been identified in acute myeloid leukemia (AML) and chronic myelogenous leukemia with t(7;11)(p15;p15). We report here a novel NUP98 partner gene, HOXA13, in a patient with de novo AML having t(7;11)(p15;p15). The HOXA13 gene is part of the HOXA cluster genes and contains 2 exons, encoding a protein of 338 amino acids with a homeodomain. The NUP98-HOXA13 fusion protein consists of the N-terminal phenylalanine-glycine repeat motif of NUP98 and the C-terminal homeodomain of HOXA13, similar to the NUP98-HOXA9 fusion protein. Reverse transcriptase–polymerase chain reaction (RT-PCR) analysis in various leukemic cell lines showed that the HOXA13 gene was expressed significantly more frequently in acute monocytic leukemic cell lines than in other leukemic cell lines (P = 0.039). HOXA13 and three HOXA cluster genes (A9, A10, A11) located at the 5′ end of the HOXA9 gene were frequently expressed in myeloid leukemic cell lines. Our results revealed that t(7;11)(p15;p15) was not a single chromosomal abnormality at the molecular level. The protein encoded by the NUP98-HOXA13 fusion gene is similar to that encoded by NUP98-HOXA9, and the expression pattern of the HOXA13 gene in leukemic cell lines is similar to that of the HOXA9 gene, suggesting that the NUP98-HOXA13 fusion protein may play a role in leukemogenesis through a mechanism similar to that of the NUP98-HOXA9 fusion protein. © 2002 Wiley-Liss, Inc.

Nephrotic syndrome (NS) associated with hematopoietic stem cell transplantation (HSCT) is usually related to chronic graft-versus-host disease (GVHD) and invariably occurs later than 100 days after transplantation. Here, we report the case of a 6-year-old boy who presented with NS only 61 days after cord blood stem cell transplantation (CBSCT). At 4 years old he was diagnosed with acute lymphoblastic leukemia and underwent bone marrow transplantation. Six months later, a recurrence was noted in the thymus, which required CBSCT at the age of 6. Acute GVHD and hemophagocytic syndrome occurred on day +13 and day +15, respectively, and were successfully treated with tacrolimus and a steroid. After tacrolimus was switched from intravenous infusion to oral administration, NS occurred on day +61. Complete remission was achieved in 3 weeks by resuming steroid treatment. Dry erythema with pigmentation and elevation of Th2 cytokine level suggest that NS in this case was also related to chronic GVHD. To our knowledge, this is the earliest occurrence of NS after HSCT. Hematologists and nephrologists should be aware that this condition may occur even in early periods after HSCT.

The expression of the p73 gene and the methylation status was examined in 61 acute lymphoblastic leukemia (ALL) cell lines and lymphocytes from seven healthy individuals. p73 mRNA was not expressed in 19 (31.1%) of 61 ALL cell lines, including 11 (31.4%) of 35 B-precursor ALL cell lines, 2 (16.7%) of 12 B-ALL/Burkitt lymphoma (BL) cell lines (totally 27.7% of B-lineage cell lines), 6 (42.9%) of 14 T-ALL cell lines, and expressed in all of normal lymphocytes, by reverse transcriptase-polymerase chain reaction (RT-PCR). Restriction-enzyme related PCR (REP) and methylation-specific PCR (MSP) revealed that the cell lines lacking p73 mRNA expression were hypermethylated. In contrast, normal lymphocytes and most cell lines that expressed detectable p73 mRNA were not hypermethylated with the exception of five cell lines. Furthermore, bisulfite genomic sequencing confirmed the results obtained by REP and MSP. Our results suggest that p73 inactivation may be involved in the pathogenesis of both T- and B-ALLs, and that hypermethylation is the predominant mechanism of inactivation of the p73 gene in ALL.

p300, which was originally cloned as a nuclear binding target of the adenovirus E1A oncoprotein, forms a family with cyclic-AMP response element binding protein (CREB)-binding protein (CBP). p300/CBP are considered to be transcriptional coactivators that connect the basal transcriptional machinery to various DNA-binding transcriptional factors. p300/CBP are implicated in both cell differentiation and regulation of cell-cycle. We identify here that the p300 gene is fused to the MLL gene and that in-frame MLL-p300 fusion protein is generated in acute myeloid leukemia (AML) with t(11; 22)(q23; q13). These findings suggest that the basis for the leukemogenesis of t(11; 22)-AML is the inability of p300 to regulate cell-cycle and cell differentiation after fusion with MLL.

p16 and p15 genes are putative tumor suppressor genes located on chromosome 9p21. In acute leukemias, alterations of p16 and p15 genes have been reported to occur exclusively in lymphoid lineage. We analyzed alterations of p16 and p15 genes in 46 acute leukemias with MLL gene rearrangements by Southern blot analysis, and investigated the association with clinical characteristics. We identified homozygous deletion of p16 and p15 genes in five (19%) of 27 acute lymphoblastic leukemias (ALLs) and in two (11%) of 19 acute myeloid leukemias (AMLs). Patients with homozygous deletion of p16 and p15 genes showed higher average leukocyte counts (343 x 10(9)/l vs 271 x 10(9)/l) and lower estimated 2-year survival rates than those with normal p16 and p15 genes (14.3 vs 30.7%), although the differences were not statistically significant. In addition, we investigated mutation of p16 gene by polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) in 31 patients, but no mutation was found in the patients tested. Our results suggest that alterations of p16 and p15 genes are involved in a subset of acute leukemias with MLL gene rearrangement not only of lymphoid but also of myeloid phenotype. Homozygous deletion of p16 and p15 genes may be a possible adverse prognostic factor, although further analysis would be needed to confirm it.

Recurrent translocations involving chromosome band 11q23 are often found in human acute leukemias. Recently, the MLL gene on 11q23 and 10 partner genes involved in these translocations have been cloned and characterized. We performed a reverse transcriptase-polymerase chain reaction (RT-PCR) to detect the resultant der(11) chimeric mRNAs of the 3 types of 11q23 translocations including t(4;11), t(9;11), or t(11;19), in 14 leukemia patients with MLL gene rearrangements. At diagnosis or relapse, chimeric mRNA could be detected in all of the 4 patients with t(4;11), 2 of 3 with t(9;11), 2 of 3 with t(11;19), and 1 of 4 with unsuccessful karyotype. In 5 patients, we could monitor minimal residual disease (MRD) serially through the clinical course. One patient, in whom chi-meric mRNA was detected during complete remission (CR) just after the induction chemotheraphy, relapsed within 2 months and died, while 2 patients in which chimeric mRNA was not detected remained in CR from 10–23 months. These findings suggest that RT-PCR is a useful approach for detecting which partner gene is involved in the translocation and monitoring MRD in patients with MLL gene rearrangement. Nonetheless, the clinical relevance of MRD evaluation by RT-PCR monitoring remains controversial. Long-term and prospective investigation of a larger series of patients is needed to confirm the clinical significance of monitoring MRD by RT-PCR method. Med. Pediatr. Oncol. 28:325–332, 1997. © 1997 Wiley-Liss, Inc.

Graft-versus-host disease (GVHD) is one of the most important complications in allogeneic hematopoietic stem cell transplantation. Intensity of conditioning regimen is one of the risk factors, which is associated with acute GVHD, and some studies have shown that alteration of the administration order from busulfan to cyclophosphamide to cyclophosphamide to busulfan could decrease cytokine levels and organ toxicity.To investigate whether the order of total body irradiation (TBI) and chemotherapy is associated with the incidence of GVHD, we reviewed the charts of 124 consecutive hematopoietic stem cell transplantation, which was performed in Saitama Children's Medical Centre and University of Tokyo Hospital between 1995 and 2010.TBI performed before chemotherapy (TBI-CT) showed an increased risk for grades II to IV acute GVHD (61.6±7.8%) compared with the TBI performed after chemotherapy (CT-TBI) (42.8±7.2%) (P=0.048), whereas the incidence of grades III and IV GVHD were similar between TBI-CT and CT-TBI. Multivariate analysis showed that TBI-CT was associated with a higher risk of grades II to IV acute GVHD. However, overall survival probability of TBI-CT cohort was similar to that of CT-TBI cohort.Our results provided a novel risk factor for acute GVHD, which can be easily controlled by the physician.

Thde t( 11;22)(q24;q 12) and t(21;22)(q22;q 12) are specific chromosomal translocations found in the Ewinhd family of tumors including ES, PNET and Askin tumors. In these translocations, the amino-terminal portion of the EWS gene located in 22q 12 fuses to the carboxyl-terminal portion of the FLI-I gene located in 11 q24 or the ERG gene located in 21 q22, which belong to the ets oncogene super-family of transcription activators. We investigated the chimeric mRNAs of 15 ESs (7 cell lines and 8 tumor samples) and 7 PNETs (3 cell lines and 4 tumor samples) using the RT-PCR method and sequencing. We detected 2 types of EWS-ERG chimeric mRNA in 2 ES cell lines and I PNET tumor sample in addition to 4 types of EWS-FU-1 chimeric mRNA in 11 ESs (4 cell lines and 7 tumor samples) and 4 PNETs (2 cell lines and 2 tumor samples). There seemed to be no association between the type of chimeric mRNA and clinical features such as sex, age, primary site and histopathology of the patients. All of the chimeric mRNAs are generated from in-frame junctions and are thought to encode fusion proteins that may be the molecular mechanism involved in the Ewing family of tumors.

Fifty-six primary childhood T-cell acute lymphoblastic leukemia (T-ALL) samples and 17 T-ALL cell lines were examined for mutations and homozygous deletions of the p16/MTS1 gene using polymerase chain reaction single-strand conformation polymorphism and Southern blot analysis. Homozygous deletions were found in 22 primary samples (39%) and in 10 cell lines (59%). In contrast, mutations including small deletions and/or insertions were identified in only 4 primary samples (7%) and in 2 cell lines (12%). Mutations included samples (7%) and in 2 cell lines (12%). Mutations included one nonsense mutation at codon 72, one missense mutation at codon 58, one deletion (29 bp from codon 52–61), one insertion (7 bp into codon 50), and two deletion/insertions (codon 63 and intron 1). Four of the six mutations caused subsequent stop codon and presumably produced truncated p16 protein. Our results suggest that p16 gene alterations are involved in the development of T- ALLs and that the inactivation of the p16 gene occurs mainly through homozygous deletions rather than mutations.

Background The Pediatric Quality of Life Inventory™ (PedsQL™) is a widely-used modular instrument for measuring health-related quality of life in children aged 2 to 18 years. The PedsQL™ Brain Tumor Module is comprised of six scales: Cognitive Problems, Pain and Hurt, Movement and Balance, Procedural Anxiety, Nausea, and Worry. In the present study, we developed the Japanese version of the PedsQL™ Brain Tumor Module and investigated its feasibility, reliability, and validity among Japanese children and their parents. Methods Translation equivalence and content validity were verified using the standard back-translation method and cognitive debriefing tests. Participants were recruited from 6 hospitals in Japan and the Children's Cancer Association of Japan, and questionnaires were completed by 137 children with brain tumors and 166 parents. Feasibility of the questionnaire was determined based on the amount of time required to complete the form and the percentage of missing values. Internal consistency was assessed using Cronbach's coefficient alpha. Test-retest reliability was assessed by retesting 22 children and 27 parents. Factorial validity was verified by exploratory factor analyses. Known-groups validity was described with regard to whole brain irradiation, developmental impairment, infratentorial tumors, paresis, and concurrent chemotherapy. Convergent and discriminant validity were determined using Generic Core Scales and State-Trait Anxiety Inventory for children. Results Internal consistency was relatively high for all scales (Cronbach's coefficient alpha > 0.70) except the Pain and Hurt scale for the child-report, and sufficient test-retest reliability was demonstrated for all scales (intraclass correlation coefficient = 0.45-0.95). Factorial validity was supported through exploratory factor analysis (factor-item correlation = 0.33-0.96 for children, 0.55-1.00 for parents). Evaluation of known-groups validity confirmed that the Cognitive Problems scale was sensitive for developmental impairment, the Movement and Balance scale for infratentorial tumors or paresis, and the Nausea scale for a patient currently undergoing chemotherapy. Convergent and discriminant validity with the PedsQL™ Generic Core Scales and State-Trait Anxiety Inventory for children were acceptable. Conclusions The Japanese version of the PedsQL™ Brain Tumor Module is suitable for assessing health-related quality of life in children with brain tumors in clinical trials and research studies.

Mixed-lineage leukemia (MLL) rearrangements are commonly observed in childhood acute lymphoblastic and myeloid leukemia, as well as therapy-related leukemia. However, the occurrence of MLL rearrangements in acute megakaryoblastic leukemia (AMKL) is very rare. We report a pediatric case of AMKL with the MLL-AF4 fusion transcript. MLL-AF4 is derived from t(4;11)(q21:q23) and occurs exclusively in B-cell lineage leukemia. To our knowledge, MLL-AF4 as well as t(4;11)(q21:q23) has not been reported in adult and childhood AMKL. Thus, our case provides new insight into the molecular mechanisms of MLL-AF4-associated leukemia.

We report a case of hepatoblastoma that developed in a child with Sotos syndrome, an overgrowth syndrome with an increased risk of neoplasms. Genome-wide analysis of copy number alterations showed a gain of chromosome 2, uniparental disomy of 18q, and microdeletion of 5q35.

The p300 protein shows a striking homology with cyclic-AMP-response-element-binding-protein binding protein (CBP) and both proteins form a family of DNA-binding transcriptional coactivators/histone acetyltransferases. The authors, herein, report a therapy-related acute myeloid leukemia with MLL-p300 fusion gene. Spectral karyotyping clarified that chromosome 11 is involved in complex t(1;22;11)(q44;q13;q23), and is fused to the chromosome 22, and direct sequencing revealed the fusion of exon 8 of MLL and exon 15 of p300 in this case. This is only the second reported case of leukemia with an MLL-p300 fusion gene, and the other case with MLL-p300 was also a therapy-related leukemia. Considering that the MLL-CBP fusion gene is also found almost exclusively in therapy-related leukemia, the association of MLL-p300 and MLL-CBP with therapy-related leukemia rather than de novo leukemia is thereby suggested.

In pediatric solid tumors, such as neuroblastoma (NB), it has been reported that the frequency of TP53 gene alterations is lower than that in adult tumors, suggesting that other tumor suppressor genes may play more important roles in the development of pediatric solid tumors. The CHK2 gene, whose product is a checkpoint kinase that plays a central role in DNA damage response and acts upstream of TP53, has been found to be mutated in a subset of Li-Fraumeni syndrome without mutations of TP53 and in some other sporadic human tumors, earmarking this serine/threonine kinase as a candidate tumor suppressor gene. Thus, we analyzed the CHK2 gene to address whether it is a candidate tumor suppressor gene for pediatric solid tumors. We screened for mutations of the CHK2 gene in 25 NB, 8 rhbdomyosarcoma, 12 Ewing sarcoma, and 26 other pediatric solid tumor cell lines as well as 77 fresh tumors including two cases of multiple cancers. Using polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis and reverse transcriptase (RT)-PCR-SSCP followed by direct sequence analysis, we detected only one missense mutation (S505T) in one NB cell line and two silent mutations in one NB cell line and one NB fresh tumor, respectively. Through RT-PCR and subcloning analysis, we detected a similar expression of the CHK2 gene in all of the NB cell lines and fresh tumors; however, we identified at least three isoforms of the CHK2 gene, two of which have not been reported previously. These results suggest that aberrations of the CHK2 gene are rare in pediatric solid tumors.

Interstitial cells of Cajal (ICC) are known to be essential regulators of gastrointestinal (GI) motility. Here, we report the clinical course and abnormalities of intestinal ICC distribution in a 5-year-old patient with congenital fiber type disproportion myopathy who demonstrated long-term GI dismotility. Full thickness biopsies of the small intestine and colon showed a normal enteric muscle layer and myenteric plexus. However, the density of ICC was strikingly decreased around the myenteric plexus compared to that in autopsied cases without GI tract disease. These findings suggest that a decline in ICC may contribute to disturbed GI motility in our patient with congenital myopathy.

AML1/RUNX1, located on chromosome band 21q22, is one of the most important hematopoietic transcription factors. AML1 is frequently affected in leukemia and myelodysplastic syndrome with 21q22 translocations. Recently, AML1 mutations were found in adult hematologic malignancies, especially acute myeloid leukemia (AML)–M0 or leukemia with acquired trisomy 21, and familial platelet disorder with a predisposition toward AML. Through the use of polymerase chain reaction–single-strand conformation polymorphism analysis, we examined the AML1 gene for mutations in 241 patients with pediatric hematologic malignancies, and we detected AML1 mutations in seven patients (2.9%). Deletion was found in one patient, and point mutations in four patients, including three missense mutations, two silent mutations, and one mutation within an intron resulting in an abnormal splice acceptor site. All of the mutations except for one were heterozygous. Mutations within the runt domain were found in six of seven patients. Six of seven patients with AML1 mutations were diagnosed with AML, and one had acute lymphoblastic leukemia. In three of these seven patients, AML evolved from other hematologic disorders. AML1 mutations were found in two of four AML-M0 and two of three patients with acquired trisomy 21. Patients with AML1 mutations tended to be older children. Three of four patients with AML1 mutations who received stem cell transplantation (SCT) are alive, whereas the remaining three patients with mutations without SCT died. These results suggest that AML1 mutations in pediatric hematologic malignancies are infrequent, but are possibly related to AML-M0, acquired trisomy 21, and leukemic transformation. These patients may have a poor clinical outcome. © 2003 Wiley-Liss, Inc.

We showed that the LAF4 gene on 2q11.2–12 was fused to the MLL gene on 11q23 in a pediatric patient with CD10 positive acute lymphoblastic leukemia (ALL) having t(2;11)(q11;q23). The LAF4 gene, which encodes a lymphoid nuclear protein of 1227 amino acids with transactivation potential, is thought to have a role in early lymphoid development. The LAF4 protein was homologous to AF4 and AF5q31 proteins that are fused to MLL in infant early pre-B ALL and the breakpoint of LAF4 was located within the region homologous to the transactivation domain of AF4 and AF5q31. Expression of the 8.5-kb LAF4 transcript was detected in the adult heart, brain, and placenta and in the fetal brain. LAF4 expression was found to be higher in ALL cell lines than in AML and Epstein–Barr virus-transformed B-lymphocyte cell lines. These findings suggest that LAF4, AF4 and AF5q31 might define a new family particularly involved in the pathogenesis of 11q23-associated ALL.

The nucleoporin gene NUP98 has been reported to be fused to 9 partner genes in hematologic malignancies with 11p15 translocations. The NUP98-HOXA9 fusion gene has been identified in acute myeloid leukemia (AML) and chronic myelogenous leukemia with t(7;11)(p15;p15). We report here a novel NUP98 partner gene, HOXA13, in a patient with de novo AML having t(7;11)(p15;p15). The HOXA13 gene is part of the HOXA cluster genes and contains 2 exons, encoding a protein of 338 amino acids with a homeodomain. The NUP98-HOXA13 fusion protein consists of the N-terminal phenylalanine-glycine repeat motif of NUP98 and the C-terminal homeodomain of HOXA13, similar to the NUP98-HOXA9 fusion protein. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis in various leukemic cell lines showed that the HOXA13 gene was expressed significantly more frequently in acute monocytic leukemic cell lines than in other leukemic cell lines (P = 0.039). HOXA13 and three HOXA cluster genes (A9, A10, A11) located at the 5' end of the HOXA9 gene were frequently expressed in myeloid leukemic cell lines. Our results revealed that t(7;11)(p15;p15) was not a single chromosomal abnormality at the molecular level. The protein encoded by the NUP98-HOXA13 fusion gene is similar to that encoded by NUP98-HOXA9, and the expression pattern of the HOXA13 gene in leukemic cell lines is similar to that of the HOXA9 gene, suggesting that the NUP98-HOXA13 fusion protein may play a role in leukemogenesis through a mechanism similar to that of the NUP98-HOXA9 fusion protein.

Background Response to induction chemotherapy is one of the most important predictors of outcome in acute myeloid leukemia (AML) as well as cytogenetics and molecular genetics. Measurement of minimal residual disease (MRD) by flow cytometry is an informative method for assessment of initial treatment response, but the heterogeneity of leukemia-associated antigens and antigen shifts during treatment limit its sensitivity and specificity. We prospectively evaluated the prognostic prevalence of MRD monitoring using multi-color flow cytometry in children with AML treated on the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) AML-05 trial. Patients and methods From January 2007 to October 2010, 34 children with newly diagnosed de novo AML were enrolled on the AML-MRD study conducted by the Tokyo Children's Cancer Study Group. The median age at the diagnosis was 8 years (1 month- 15 years), and 17 patients were boys and 17 were girls. They were all treated with the JPLSG AML-05 trial. In AML-05, enrolled patients received two induction courses and those achieving a complete remission (CR) were treated according to risk classification at which all the core binding factor-AML cases and good initial response based on morphology after induction 1 were assigned to low risk (LR) group, cases presented with FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD), unfavorable cytogenetics including monosomy7, 5q-,t(16;21), and with poor initial response were assigned to high risk (HR) group, the others were assigned to intermediate risk (IR) group. Allogeneic hematopoietic stem cell transplantation (HSCT) was indicated for the HR patients after the third or later treatment courses. Among the 34 patients enrolled on the AML-MRD study, 8 presented with LR, 22 with IR, and 4 with HR regarding the cytogenetics and FLT3-ITD status. MRD of 63 bone marrow samples were analyzed after induction 1 (BMA-2) and induction 2 (BMA-3) by four-color flow cytometry using 9 AML-associated antigens. A threshold level for MRD-positivity was set at the point of 0.1%. Results Sixty-two (98.4%) of 63 bone marrow samples were evaluable for MRD. Thirteen (39.4%) of 33 samples and 8 (27.6%) of 29 showed MRD-positivity at BMA-2 and BMA-3 respectively. Among the patients with MRD-positivity, 12 at BMA-2 and 7 at BMA-3 were diagnosed as achieving CR by morphology. MRD was associated neither specific FAB subtype nor white blood cell count at diagnosis, but all 3 patients with FLT3-ITD showed the MRD-positivity at BMA-2. Although 3-year probability of event free survival (3-yr EFS) at BMA-2 or BMA-3 was similar between patients with and without MRD; 53.8% (n= 13) vs 70.0% (n= 20) (p=0.30) and 50.0% (n= 8)vs 62.0%(n= 21) (p=0.36), respectively, 3-yr EFS of those with MRD at BMA-2 or BMA-3 was significantly worse compared to those without MRD; 33.3% (n= 9) vs 83.3% (n= 12) (p=0.02) and 20.0%(n= 5) vs 76.9% (n= 13) (p=0.04), respectively, in the group of the IR cytogenetics and negative FLT3-ITD. Multivariate analysis indicated that the MRD detected by multi-color flow cytometry was solely associated with worse outcome in this group. Conclusion Highly sensitive detection of MRD by multi-color flow cytometry was possible in children with AML. The present study suggests that MRD monitoring may have a prognostic relevance in childhood AML with the IR cytogenetics and negative FLT3-ITD. Disclosures: No relevant conflicts of interest to declare.

The AML1-CBFbeta transcription factor complex is essential for the definitive hematopoiesis of all lineages and is the most frequent target of chromosomal rearrangements in human leukemia. In the t(8;21) translocation associated with acute myeloid leukemia (AML), the AML1(CBFA2/PEBP2alphaB) gene is juxtaposed to the MTG8(ETO/CDR) gene. We show here that the resultant AML1-MTG8 gene product specifically and strongly interacts with an 85-kDa phosphoprotein. Molecular cloning of cDNA indicated that the AML1-MTG8-binding protein (MTGR1) is highly related to MTG8 and similar to Drosophila Nervy. Comparison of amino acid sequences among MTGR1, MTG8, and Nervy revealed four evolutionarily conserved regions (NHR1 to NHR4). Ectopic expression of AML1-MTG8 in L-G murine myeloid progenitor cells inhibits differentiation to mature neutrophils and induces cell proliferation in response to granulocyte colony-stimulating factor (G-CSF). Analysis with C-terminal deletion mutants of AML1-MTG8 indicated that the region of 51 residues (488 to 538), which contains NHR2, is essential for the induction of G-CSF-dependent cell proliferation. Immunoprecipitation analysis indicates that this region is required for AML1-MTG8 to form a stable complex with MTGR1. Overexpression of MTGR1 stimulates AML1-MTG8 to induce G-CSF-dependent proliferation of L-G cells and to interfere with AML1-dependent transcription. These results suggest that AML1-MTG8 could function as a complex with MTGR1 and that the complex might be important in promoting leukemogenesis.