Search

Introduction Graft‐versus‐host disease (GVHD) is frequent and fatal complication following allogeneic hematopoietic stem cell transplantation (HSCT) and characteristically involves skin, gut, and liver. Macrophages promote tissue regeneration and mediate immunomodulation. Macrophages are divided into two different phenotypes, classically activated M1 (pro‐inflammatory or immune‐reactive macrophages) and alternatively activated M2 (anti‐inflammatory or immune‐suppressive macrophages). The anti‐inflammatory effect of M2 macrophage led us to test its effect in the pathophysiology of GVHD. Methods GVHD was induced in lethally irradiated BALB/c mice. M2 macrophages derived from donor bone marrow (BM) were administered intravenously, while controls received donor BM‐mononuclear cells and splenocytes. Animals were monitored for clinical GVHD and analyzed. Results We confirmed that administering donor BM‐derived M2 macrophages attenuated GVHD severity and prolonged survival after HSCT. Moreover, donor BM‐derived M2 macrophages significantly suppressed donor T cell proliferation by cell‐to‐cell contact in vitro. Conclusions We showed the protective effects of donor‐derived M2 macrophages on GVHD and improved survival in a model of HSCT. Our data suggest that donor‐derived M2 macrophages offer the potential for cell‐based therapy to treat GVHD., Adoptive transferred M2 macrophages prolong the survival of GVHD mice.

BACKGROUND The quality of end-of-life (Q-EOL) care is influenced by various factors such as resources for palliative care (PC). We introduced a multi-professional expert team (MET) in 2014, which provides home-based care for children and adolescents with incurable cancer. This study investigated the impacts of the outreach activities by the MET on Q-EOL care of pediatric oncology patients. METHODS This observational study retrospectively examined 112 patients receiving end-of-life care between 1989 and 2018 at a pediatric cancer center in Japan. Some of the indicators of Q-EOL care before and after the introduction of the outreach activities by the MET were compared. The subjects were 92 in pre-MET and 20 in post-MET periods. RESULTS The median number of days for which the patients stayed at home during the final seven or 30 days were significantly prolonged in the post-MET period (0.0 vs 1.5 days, P = 0.020, 3.0 vs 12.0 days, P = 0.042). The change was more significant in hematologic malignancies than solid and central nervous system tumors. Patients receiving longer PC before their deaths could stay at home longer during the last 7 days. The ratio of patients receiving PC for more than 2 months was significantly increased in post-MET period (60.9 vs 90.0%, P = 0.014). More patients also greeted their deaths at home in the post-MET period (3.3 vs 25.0%, P < 0.001). CONCLUSIONS The activities of the MET transformed the end-of-life care of children and adolescents with incurable cancer. Earlier transitions to PC from curative treatment were associated with longer home-based care and more deaths at home.

Respiratory gas analyzers to measure functions such as ventilation volume respiratory rate are expensive, and patients with severe motor and intellectual disabilities (SMID) often remove the devices, increasing contact risk and making them difficult to use in institutions. We propose here an inexpensive, non-contact method of measuring respiratory function using the depth camera introduced in our previous study. The method includes an algorithm that differentiates between body tremors, and between movements peculiar to patients with SMID and those caused by respiration, while further detecting appropriate respiration. However, the previous region of interest (ROI) was limited to a simple rectangular area from the navel to the xiphoid process, and we did not compare measurements using the geometry of the thorax and the abdomen as the ROI. In this study, we performed non-contact respiratory measurement using the geometric shape of the upper body of patients as the ROI, and investigated the improvement of measurement accuracy when the ROI was set according to the individual patient’s body. The results indicated that the values from the new method approached those of the respiratory gas analyzer more closely than the conventional method, and its measurement performance was sufficient for respiratory rehabilitation evaluation. We also found that the measured respiratory signal correlated with the ventilation rate in respiration with large ventilation rate fluctuations, and that the respiratory rhythm abnormalities associated with ventilation rate changes could be measured by the respiratory rate per min and apnea time per min evaluation indices.

Neuroblastoma is a highly malignant disease with a poor prognosis and few treatment options. Despite conventional chemotherapy for neuroblastoma, resistance, invasiveness, and metastatic mobility limit the treatment efficacy. Therefore, it is necessary to develop new strategies for treating neuroblastoma. The present study aimed to evaluate the anticancer effects of nafamostat mesylate, a previously known serine protease inhibitor, on neuroblastoma cells. Effects of nafamostat mesylate on neuroblastoma cell migration and proliferation were analyzed by wound healing assay and WST-8 assay, respectively. To elucidate the mechanisms underlying the effects of nafamostat mesylate on neuroblastoma, the expression levels of NF-κB were measured via western blotting, and the production of the cytokine vascular endothelial growth factor (VEGF) in the cell culture supernatants was determined via ELISA. In addition, a mouse model of hematogenous metastasis was used to investigate the effects of nafamostat mesylate on neuroblastoma. It was determined that nafamostat mesylate significantly inhibited migration and invasion of Neuro-2a cells, but it had no effect on cell proliferation at 24 h after treatment. Exposure of Neuro-2a cells to nafamostat mesylate resulted in decreased vascular endothelial growth factor production, which could be a pivotal mechanism underlying the inhibitory effects of neuroblastoma metastasis. The results of the present study suggest that nafamostat mesylate may be an effective treatment against neuroblastoma invasion and metastasis.

Myeloid leukemia of Down syndrome (ML-DS) is associated with good response to chemotherapy, resulting in favorable outcomes. However, no universal prognostic factors have been identified to date. To clarify a subgroup with high risk of relapse, the role of minimal residual disease (MRD) was explored in the AML-D11 trial by the Japanese Pediatric Leukemia/Lymphoma Study Group. MRD was prospectively evaluated at after induction therapy and at the end of all chemotherapy, using flow cytometry (FCM-MRD) and GATA1-targeted deep sequencing (GATA1-MRD). A total of 78 patients were eligible and 76 patients were stratified to the standard risk (SR) group by morphology. In SR patients, FCM-MRD and GATA1-MRD after induction were positive in 5/65 and 7/59 patients, respectively. Three-year event-free survival (EFS) and overall survival (OS) rates were 93.3% and 95.0% in the FCM-MRD-negative population, and 60.0% and 80.0% in the positive population. Three-year EFS and OS rates were both 96.2% in the GATA1-MRD-negative population, and 57.1% and 71.4% in the positive population. Adjusted hazard ratios for associations of FCM-MRD or GATA1-MRD with EFS were 10.98 (p = 0.01) and 27.68 (p < 0.01), respectively. Detection of MRD by either FCM or GATA1 after initial induction therapy represents a significant prognostic factor for predicting ML-DS relapse.

Identification of genetic variants associated with glucocorticoids (GC) sensitivity of leukaemia cells may provide insight into potential drug targets and tailored therapy. In the present study, within 72 leukaemic cell lines derived from Japanese patients with B‐cell precursor acute lymphoblastic leukaemia (ALL), we conducted genome‐wide genotyping of single nucleotide polymorphisms (SNP) and attempted to identify genetic variants associated with GC sensitivity and NR3C1 (GC receptor) gene expression. IC50 measures for prednisolone (Pred) and dexamethasone (Dex) were available using an alamarBlue cell viability assay. IC50 values of Pred showed the strongest association with rs904419 (P = 4.34 × 10−8), located between the FRMD4B and MITF genes. The median IC50 values of prednisolone for cell lines with rs904419 AA (n = 13), AG (n = 31) and GG (n = 28) genotypes were 0.089, 0.139 and 297 µmol/L, respectively. For dexamethasone sensitivity, suggestive association was observed for SNP rs2306888 (P = 1.43 × 10−6), a synonymous SNP of the TGFBR3 gene. For NR3C1 gene expression, suggestive association was observed for SNP rs11982167 (P = 6.44 × 10−8), located in the PLEKHA8 gene. These genetic variants may affect GC sensitivity of ALL cells and may give rise to opportunities in personalized medicine for effective and safe chemotherapy in ALL patients.

Minimal residual disease of leukemia may reside in the bone marrow (BM) microenvironment and escape the effects of chemotherapeutic agents. This study investigated interactions between B cell precursor (BCP)-acute lymphoblastic leukemia (ALL) cells and BM mesenchymal stromal cells (BM-MSCs) in vitro. Five BCP-ALL cell lines established from pediatric patients and primary samples from a BCP-ALL patient were examined by flow cytometry and immunocytochemistry for expression of specific cell surface markers and cell adhesion proteins. The cell lines developed chemoresistance to commonly used anti-leukemic agents through adhesion to MSC-TERT cells in long-term culture. The change in chemosensitivity after adhering to BM-MSCs was associated with the expression of CD34, CD133, P-glycoprotein and BCRP/ABCG2, and downregulation of CD38. Similar phenotypic changes were observed in primary samples obtained by marrow aspiration or biopsy from a BCP-ALL patient. BM-MSC-adhering leukemia cells also showed deceleration of cell proliferation and expressed proteins in the Cadherin and Integrin pathways. These results suggest that BCP-ALL cells residing in the BM microenvironment may acquire chemoresistance by altering their phenotype to resemble that of cancer stem cells. Our results indicate that cell adhesion could be potentially targeted to improve the chemosensitivity of residual BCP-ALL cells in the BM microenvironment.

Li-Fraumeni syndrome (LFS) is a rare inherited disease characterized by a high and early-onset cancer risk. A cancer surveillance program is important to reduce cancer-related morbidity and mortality in individuals with LFS. We report 2 pediatric cases with LFS-related malignancy in a family. Eight-year-old elder brother was diagnosed with adrenocortical carcinoma and was found to have a heterozygous missense germline mutation c.736A>G: p.Met246Val in the TP53 gene. Cancer screening led to the diagnosis of rhabdomyosarcoma at a curable stage in his 2-year-old younger brother. Comprehensive surveillance resulted in early tumor detection and improved survival.

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

The purpose of this study is to establish a treatment with appropriate intensity for children (

Myeloid leukemia associated with Down syndrome (ML-DS) is characterized by a predominance of acute megakaryoblastic leukemia, the presence of GATA1 mutations and a favorable outcome. Because DS children can also develop conventional acute myeloid leukemia with unfavorable outcome, detection of GATA1 mutations is important for diagnosis of ML-DS. However, myelofibrosis and the significant frequency of dry taps have hampered practical screening of GATA1 mutations using bone marrow (BM) samples. In response to those problems, 82 patients were enrolled in the Japanese Pediatric Leukemia/Lymphoma Study Group AML-D11 study. GATA1 mutations were analyzed by Sanger sequencing (SS) using genomic DNA (gDNA) from BM and cDNA from peripheral blood (PB) followed by targeted next-generation sequencing (NGS) using pooled diagnostic samples. BM and PB samples were obtained from 71 (87%) and 82 (100%) patients, respectively. GATA1 mutations were detected in 46 (56%) and 58 (71%) patients by SS using BM gDNA and PB cDNA, respectively. Collectively, GATA1 mutations were identified in 73/82 (89%) patients by SS. Targeted NGS detected GATA1 mutations in 74/82 (90%) patients. Finally, combining the results of SS with those of targeted NGS, GATA1 mutations were identified in 80/82 (98%) patients. These results indicate that SS using BM gDNA and PB cDNA is a rapid and useful method for screening for GATA1 mutations in ML-DS patients. Thus, a combination of SS and targeted NGS is a sensitive and useful method to evaluate the actual incidence and clinical significance of GATA1 mutations in ML-DS patients.

Patient: Female, 14 Final Diagnosis: Nasopharyngeal carcinoma Symptoms: Fever • neck swelling • trismus Medication: — Clinical Procedure: Biopsy Specialty: Oncology Objective: Challenging differential diagnosis Background: Clinical presentation of nasopharyngeal carcinoma (NPC) is correlated with the extent of primary and nodal disease. Hence, depending on the anatomical structures affected, the clinical presentation varies accordingly, ranging from non-specific symptoms of epistaxis, unilateral nasal obstruction, and auditory complaints, to cranial nerve palsies. Nodal metastasis in the neck is a frequent clinical finding in nasopharyngeal carcinoma. Case Report: A female was admitted to the hospital because of fever and trismus with painful swelling in the right neck. Computed tomography (CT) revealed a mass in the nasopharynx with heterogeneous enhancement and multiple swollen lymph nodes in the corresponding neck. Initial biopsies of nasopharyngeal mass and lymph node of the neck revealed nonspecific lymphoid hyperplasia; we administered antibiotics with the provisional diagnosis of bacterial infection, including Lemierre syndrome that is typically defined by the constellation of septic internal jugular vein thrombophlebitis, pulmonary and other septic emboli, and sterile site bacterial infection. However, the patient was refractory to antibiotics over a month of treatments. The third biopsy of the throat lesion revealed NPC and bacterial cultures using the biopsy specimen were negative. She received intensity-modulated radiation therapy and chemotherapy for NPC stage II (TNM staging: T2N1M0). She never developed Lemierre syndrome-like symptoms after chemoradiotherapy. Conclusions: We report a unique case of NPC presenting with Lemierre syndrome-like symptoms, including prior sore throat, trismus, painful swollen neck, and high fever. Since these symptoms have not been reported in NPC, we included NPC as a differential diagnosis.

Transient hypogammaglobulinemia of infancy may be associated with chromosome del (16)(p11.2) that has reportedly been associated with other forms of primary immunodeficiency (Clin Immunol, 2009, 131, 24; J Allergy Clin Immunol, 2015;135, 1569)., Transient hypogammaglobulinemia of infancy may be associated with chromosome del (16)(p11.2) that has reportedly been associated with other forms of primary immunodeficiency1,2.

Glucocorticoid (GC) is a key drug in the treatment of B-cell precursor acute lymphoblastic leukemia (BCP-ALL), and the initial GC response is an important prognostic factor. GC receptors play an essential role in GC sensitivity, and somatic mutations of the GC receptor gene, NR3C1, are reportedly identified in some BCP-ALL cases, particularly at relapse. Moreover, associations of somatic mutations of the CREB-binding protein (CREBBP) and Wolf-Hirschhorn syndrome candidate 1 (WHSC1) genes with the GC-resistance of ALL have been suggested. However, the significance of these mutations in the GC sensitivity of BCP-ALL remains to be clarified in the intrinsic genes. In the present study, we sequenced NR3C1, WHSC1, and CREBBP genes in 99 BCP-ALL and 22 T-ALL cell lines (32 and 67 cell lines were known to be established at diagnosis and at relapse, respectively), and detected their mutations in 19 (2 cell lines at diagnosis and 15 cell lines at relapse), 26 (6 and 15), and 38 (11 and 15) cell lines, respectively. Of note, 14 BCP-ALL cell lines with the NR3C1 mutations were significantly more resistant to GC than those without mutations. In contrast, WHSC1 and CREBBP mutations were not associated with GC resistance. However, among the NR3C1 unmutated BCP-ALL cell lines, WHSC1 mutations tended to be associated with GC resistance and lower NR3C1 gene expression. Finally, we successfully established GC-resistant sublines of the GC-sensitive BCP-ALL cell line (697) by disrupting ligand binding and DNA binding domains of the NR3C1 gene using the CRISPR/Cas9 system. These observations demonstrated that somatic mutations of the NR3C1 gene, and possibly the WHSC1 gene, confer GC resistance in BCP-ALL.

Patients with SMID (severe motor and intellectual disabilities) have severe limb disorders and severe mental disabilities. More than half of their deaths are due to respiratory disorders. Therefore, respiratory rehabilitation is important. The effect of respiratory rehabilitation is generally determined by measuring respiratory volume and rate with an expired gas analyzer. However, the equipment is expensive and requires direct contact, making it difficult to use. The purpose of this research is to develop a non-contact measurement system for respiratory function to assess the effect of respiratory rehabilitation in patients with SMID. The proposed method detects respiration by depth change of the abdomen measured using a three-dimensional camera designed to identify body tremor /motion and respiration based on respiratory parameters and individually adapted parameters. Finally, we verify the rehabilitation effect of an RTX respirator on patients with SMID and the effectiveness of the proposed method in an experiment.

Background The genetic variants of the ARID5B gene have recently been reported to be associated with disease susceptibility and treatment outcome in childhood acute lymphoblastic leukemia (ALL). However, few studies have explored the association of ARID5B with sensitivities to chemotherapeutic agents. Methods We genotyped susceptibility-linked rs7923074 and rs10821936 as well as relapse-linked rs4948488, rs2893881, and rs6479778 of ARDI5B by direct sequencing of polymerase chain reaction (PCR) products in 72 B-cell precursor-ALL (BCP-ALL) cell lines established from Japanese patients. We also quantified their ARID5B expression levels by real-time reverse transcription PCR, and determined their 50% inhibitory concentration (IC50) values by alamarBlue assays in nine representative chemotherapeutic agents used for ALL treatment. Results No significant associations were observed in genotypes of the susceptibility-linked single nucleotide polymorphisms (SNPs) and the relapsed-linked SNPs with ARID5B gene expression levels. Of note, IC50 values of vincristine (VCR) (median IC50: 39.6 ng/ml) in 12 cell lines with homozygous genotype of risk allele (C) in the relapse-linked rs4948488 were significantly higher (p = 0.031 in Mann–Whitney U test) than those (1.04 ng/ml) in 60 cell lines with heterozygous or homozygous genotypes of the non-risk allele (T). Furthermore, the IC50 values of mafosfamide [Maf; active metabolite of cyclophosphamide (CY)] and cytarabine (AraC) tended to be associated with the genotype of rs4948488. Similar associations were observed in genotypes of the relapse-linked rs2893881 and rs6479778, but not in those of the susceptibility-linked rs7923074 and rs10821936. In addition, the IC50 values of methotrexate (MTX) were significantly higher (p = 0.023) in 36 cell lines with lower ARID5B gene expression (median IC50: 37.1 ng/ml) than those in the other 36 cell lines with higher expression (16.9 ng/ml). Conclusion These observations in 72 BCP-ALL cell lines suggested that the risk allele of the relapse-linked SNPs of ARID5B may be involved in a higher relapse rate because of resistance to chemotherapeutic agents such as VCR, CY, and AraC. In addition, lower ARID5B gene expression may be associated with MTX resistance.

BACKGROUND The prognosis of children with acute myeloid leukemia (AML) has improved with the efficacy of hematopoietic cell transplantation (HCT) as a second-line therapy and improvements in supportive care following anthracycline- and cytarabine-based chemotherapy; however, the outcomes of children with relapsed AML still remain unsatisfactory. PROCEDURE In order to identify prognostic factors and improve their prognosis, we analyzed 111 patients who relapsed after treatment with the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) AML-05 protocol and who were registered in the retrospective JPLSG AML-05R study. RESULTS The 5-year overall survival rate was 36.1%. The major determinant of survival was duration from the diagnosis to relapse. The mean duration in the nonsurviving group (10.1 ± 4.1 months) was shorter than that in the surviving group (16.3 ± 8.3 months) (P

The variability in myelosuppression after chemotherapy for acute myeloid leukaemia (AML) can affect its prognosis; however, the underlying mechanism remains controversial. In the Japanese Paediatric Leukaemia/Lymphoma Study Group AML-05 study, we showed that prolonged neutropenia was associated with high overall survival (P = 0·011) and low frequency of relapse (P = 0·042) in patients without granulocyte-colony stimulating factor (G-CSF) who completed the indicated treatment protocol. Our data indicate that predisposition to prolonged neutropenia after chemotherapy is correlated with a better outcome of AML treatment. Our results promote the usage of individualised drug dosing strategies to improve the therapeutic outcome in AML patients.

In this study, we performed genetic analysis of 83 B cell precursor acute lymphoblastic leukemia (B-ALL) cell lines. First, we performed multiplex ligation-dependent probe amplification analysis to identify copy number abnormalities (CNAs) in eight genes associated with B-ALL according to genetic subtype. In Ph+ B-ALL cell lines, the frequencies of IKZF1, CDKN2A/2B, BTG1, and PAX5 deletion were significantly higher than those in Ph− B-ALL cell lines. The frequency of CDKN2A/2B deletion in KMT2A rearranged cell lines was significantly lower than that in non-KMT2A rearranged cell lines. These findings suggest that CNAs are correlated with genetic subtype in B-ALL cell lines. In addition, we determined that three B-other ALL cell lines had IKZF1 deletions (YCUB-5, KOPN49, and KOPN75); we therefore performed comprehensive genetic analysis of these cell lines. YCUB-5, KOPN49, and KOPN75 had P2RY8-CRLF2, IgH-CRLF2, and PAX5-ETV6 fusions, respectively. Moreover, targeted capture sequencing revealed that YCUB-5 had JAK2 R683I and KRAS G12D, and KOPN49 had JAK2 R683G and KRAS G13D mutations. These data may contribute to progress in the field of leukemia research.

Acute myeloid leukemia harboring internal tandem duplication of FMS-like tyrosine kinase 3 (AMLFLT3-ITD) is associated with poor prognosis. We evaluated the results of the AML-05 study, in which all AMLFLT3-ITD patients were assigned to receive hematopoietic stem cell transplantation (HSCT) in the first remission (1CR). We also investigated the effects of additional genetic alterations on FLT3-ITD. The 5-year overall survival (OS) and event-free survival (EFS) rates among the 47 AMLFLT3-ITD patients were 42.2 and 36.8%, respectively. The 5-year disease-free survival rate among 29 patients without induction failure was 58.4%. We defined the allelic ratio (AR) of FLT3-ITD to WT > 0.7 as high. Significant differences were found in OS (AR-high, 20% vs. AR-low, 66%, p 0.7 and expression of the NUP98-NSD1 chimera strongly impacted OS and EFS. Although all the AMLFLT3-ITD patients received HSCT at 1CR, the treatment outcome of AMLFLT3-ITD patients did not improve compared with those in a previous study. Heterogeneity was observed among AMLFLT3-ITD patients.

A deletion polymorphism in the BIM gene was identified as an intrinsic mechanism for resistance to tyrosine kinase inhibitor in chronic myeloid leukemia patients in East Asia. BIM is also involved in the responses to glucocorticoid and chemotherapy in acute lymphoblastic leukemia (ALL), suggesting a possible association between deletion polymorphism of BIM and the chemosensitivity of ALL. Thus, we analyzed 72 B-cell precursor (BCP)-ALL cell lines established from Japanese patients. Indeed, higher BIM gene expression was associated with good in vitro sensitivities to glucocorticoid and chemotherapeutic agents used in induction therapy. We also analyzed the methylation status of the BIM gene promoter by next generation sequencing of genome bisulfite PCR products, since genetic polymorphism could be insignificant when epigenetically inactivated. Hypermethylation of the BIM gene promoter was associated with lower BIM gene expression and poorer sensitivity to vincristine. Of note, however, the prevalence of a deletion polymorphism was not associated with the BIM gene expression level or drug sensitivities in BCP-ALL cell lines, in which the BIM gene was unmethylated. These observations suggest that an association of a deletion polymorphism of BIM and the response to induction therapy in BCP-ALL may be clinically minimal.

Although prognosis in patients with localized osteosarcoma has been dramatically improved by the introduction of multiple chemotherapy agents known as combination chemotherapy, there is growing concern about the development of secondary malignant neoplasms. We report the case of a 13-year-old girl in whom the diagnosis of Ewing sarcoma of bone localized on the shaft of left femur was made 2 years after successful treatment without radiotherapy for osteosarcoma of right proximal femur. EWS-FLI1 fusion gene was detected by reverse transcriptase-polymerase chain reaction. To our knowledge, this is the first case with Ewing sarcoma of the bone as a secondary malignant neoplasm developed in osteosarcoma survivor. We collected 15 cases, included this case, with secondary Ewing sarcoma family of tumor by utilizing the PubMed search and might consider the causes of this secondary cancer.

We previously reported that risk-stratified therapy and intensive postremission chemotherapy (PRC) contributed to the improved survival of childhood acute myeloid leukemia (AML) in the AML99 study, which led us to consider a reduction in the number of PRC courses with more restrictive indications for stem cell transplantation (SCT) in the successor AML-05 study. We here report the outcome of AML patients without core-binding factor mutation (non-CBF AML) in the AML-05 study. Two-hundred eighty-nine children (age < 18 years old) with non-CBF AML were eligible. Patients with unfavorable cytogenetics and/or poor bone marrow response to the first induction course were candidates for SCT in the AML-05 study. After two courses of induction, a further three courses of PRC were given in AML-05, while four courses were given in the AML99 study. The 3-year event-free survival (EFS) rate in the AML-05 study (46.7%, 95% CI: 40.6-52.6%) was comparable to that of non-CBF AML in the AML99 study (51.5%, 95% CI: 42.7-59.6%) (P = .16). However, the 3-year overall survival (OS) rate in the AML-05 study (62.9%, 95% CI: 56.3-68.8%) was slightly lower than that in the AML99 study (71.6%, 95% CI: 63.2-78.5%) (P = .060), mainly due to decreased remission induction rate and increased nonrelapsed mortality. In conclusion, reductions in the number of PRC courses from four to three, together with repetitive cycles of high-dose cytarabine, were acceptable for non-CBF childhood AML.

Karyotype is an important prognostic factor in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL), but the underlying pharmacogenomics remain unknown. Asparaginase is an integral component in current chemotherapy for childhood BCP-ALL. Asparaginase therapy depletes serum asparagine. Normal hematopoietic cells can produce asparagine by asparagine synthetase (ASNS) activity, but ALL cells are unable to synthesize adequate amounts of asparagine. The ASNS gene has a typical CpG island in its promoter. Thus, methylation of the ASNS CpG island could be one of the epigenetic mechanisms for ASNS gene silencing in BCP-ALL. To gain deep insights into the pharmacogenomics of asparaginase therapy, we investigated the association of ASNS methylation status with asparaginase sensitivity. The ASNS CpG island is largely unmethylated in normal hematopoietic cells, but it is allele-specifically methylated in BCP-ALL cells. The ASNS gene is located at 7q21, an evolutionally conserved imprinted gene cluster. ASNS methylation in childhood BCP-ALL is associated with an aberrant methylation of the imprinted gene cluster at 7q21. Aberrant methylation of mouse Asns and a syntenic imprinted gene cluster is also confirmed in leukemic spleen samples from ETV6-RUNX1 knockin mice. In 3 childhood BCP-ALL cohorts, ASNS is highly methylated in BCP-ALL patients with favorable karyotypes but is mostly unmethylated in BCP-ALL patients with poor prognostic karyotypes. Higher ASNS methylation is associated with higher L-asparaginase sensitivity in BCP-ALL through lower ASNS gene and protein expression levels. These observations demonstrate that silencing of the ASNS gene as a result of aberrant imprinting is a pharmacogenetic mechanism for the leukemia-specific activity of asparaginase therapy in BCP-ALL.