Risk-stratified therapy and the intensive use of cytarabine improves the outcome in childhood acute myeloid leukemia: the AML99 trial from the Japanese Childhood AML Cooperative Study Group

PURPOSE

To improve the prognosis in children with newly diagnosed acute myeloid leukemia (AML) by introducing a dose-dense intensive chemotherapy regimen and an appropriate risk stratification system.

PATIENTS AND METHODS

Two hundred forty children with de novo AML were treated with continuous cytarabine-based induction therapy and stratified to three risk groups based on the initial treatment response, age, and WBC at diagnosis and cytogenetics. All of the patients were treated with intensive consolidation chemotherapy including three or four courses of high-dose cytarabine. Allogeneic hematopoietic stem-cell transplantation (HSCT) was indicated for only the intermediate-risk patients with matched related donors and for all the high-risk subsets.

RESULTS

Two hundred twenty-seven children (94.6%) achieved a complete remission (CR). Four children demonstrated induction death. The median follow-up of the live patients was 55 months (range, 37 to 73 months). The 5-year overall survival of all 240 children was 75.6% (95% CI, 70.3% to 81.4%) and event-free survival was 61.6% (95% CI, 55.8% to 68.1%). The 5-year disease-free survival in each risk group were 71.3% (95% CI, 63.4% to 80.2%) in the low-risk group (n = 112), 59.8% (95% CI, 50.6% to 70.7%) in the intermediate-risk group (n = 92), and 56.5% (95% CI, 39.5% to 80.9%) in the high-risk group (n = 23). Eight children died during the first CR, including four after HSCT.

CONCLUSION

A high survival rate, 75.6% at 5 years, was achieved for childhood with de novo AML in the AML99 trial. The treatment strategy was well tolerated with only 1.7% induction death rate and 3.5% remission death rate. Low-risk children were successfully treated with chemotherapy alone.

KIT mutations, and not FLT3 internal tandem duplication, are strongly associated with a poor prognosis in pediatric acute myeloid leukemia with t(8;21): a study of the Japanese Childhood AML Cooperative Study Group

Patients with t(8;21) acute myeloid leukemia (AML) are considered to have a good prognosis; however, approximately 50% of them relapse. The genetic alterations associated with a poor outcome in t(8;21) AML remain unknown. Recently, aberrations of receptor tyrosine kinases (RTKs) were frequently found in patients with AML. However, the prevalence and prognostic impact of RTK aberrations in pediatric t(8;21) AML remains undetermined. Here, we found the kinase domain mutations of the KIT gene in 8 (17.4%) of 46 patients with t(8;21) AML among newly diagnosed pediatric patients with AML treated on the AML99 protocol in Japan. Significant differences between patients with or without KIT mutations were observed in the 4-year overall survival (50.0% versus 97.4%, P = .001), disease-free survival (37.5% versus 94.7%, P < .001) and relapse rate (47.0% versus 2.7%, P < .001). Furthermore, FLT3 internal tandem duplication was found in only 2 (4.3%) patients. These results suggested that KIT mutations are strongly associated with a poor prognosis in pediatric t(8;21) AML.

Surface markers and prognostic factors in acute lymphoblastic leukemia

We investigated the surface markers on lymphoblasts from 37 patients with acute lymphoblastic leukemia. Spontaneous rosette formation with sheep erythrocytes (E rosettes) identified T cells and the presence of surface immunoglobulin identified B cells. Eight patients had T-marker lymphoblasts; 28 had no markers (null lymphoblasts), and one patient had B-marker lymphoblasts. The eight patients with T-marker acute lymphoblastic leukemia had massive leukemic infiltration, frequently a mediastinal mass, and a poor prognosis. The T-marker lymphoblasts had a weak or negative periodic acid-Schiff reaction and a very low antigenic stimulation to allogeneic lymphocytes. The association of T-marker lymphoblasts and some of the conventional poor-risk factors appears to be reliable in predicting a poor prognosis.

Risk factors for evolution of acquired aplastic anemia into myelodysplastic syndrome and acute myeloid leukemia after immunosuppressive therapy in children

Long-term survivors of acquired aplastic anemia (AA) have an increased risk of developing myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) after immunosuppressive therapy (IST). It is uncertain whether the increased survival time simply discloses the natural history of AA as a premalignant disease or whether secondary disease is related to the therapy itself. Between November 1992 and September 1997, 113 AA children with normal cytogenetics at diagnosis were treated with IST using antithymocyte globulin, cyclosporin, and danazol with or without granulocyte colony-stimulating factor (G-CSF). We assessed risk factors for developing MDS/AML by Cox proportional hazards models. Twelve of 113 patients developed MDS between 9 and 81 months following the time of diagnosis, giving a cumulative incidence of 13.7 +/- 3.9%. The following cytogenetic abnormalities were observed at the time of diagnosis of MDS: monosomy 7 (6 patients), monosomy7/trisomy21 (1 patient), trisomy 11 (1 patient), del (11) (9?:14) (1 patient), add (9q) (1 patient), add 7 (q 32) (1 patient), and trisomy 9 (1 patient). The number of days of G-CSF therapy and nonresponse to therapy at 6 months were statistically significant risk factors by multivariate analysis. The present study suggests a close relationship between long-term use of G-CSF and secondary MDS in nonresponders to IST.

Monosomy 7 and deletion 7q in children and adolescents with acute myeloid leukemia: an international retrospective study

Monosomy 7 (-7) and deletion 7q \del(7q)] are rare in childhood acute myeloid leukemia (AML). We retrospectively collected data on 258 children with AML or refractory anemia with excess blasts in transformation (RAEB-T) and -7 or del(7q) with or without other cytogenetic aberrations \+/- other]. Karyotypes included -7 (n = 90), -7 other (n = 82), del(7q) (n = 21), and del(7q) other (n = 65). Complete remission (CR) was achieved in fewer patients with -7 +/- other compared with del(7q) +/- other (61% versus 89%, P < .001). Overall, the 5-year survival rate was 39% (SE, 3%). Survival was superior in del(7q) +/- other compared with -7 +/- other (51% versus 30%, P < .01). Cytogenetic aberrations considered favorable in AML \t(8;21)(q22;q22), inv(16)(p13q22), t(15;17)(q22;q21), t(9;11)(p22;q23)] (n = 24) were strongly associated with del(7q) and a higher 5-year survival rate compared with del(7q) without favorable cytogenetics (75% versus 46%, P = .03). Patients with -7 and inv(3),-5/del(5q), or + 21 had a 5-year survival rate of 5%. Stem cell transplantation analyzed as a time-dependent variable had no impact on overall survival. However, patients not achieving CR had a 31% survival rate after stem cell transplantation. Childhood AML with chromosome 7 aberrations represents a heterogeneous group of disorders with additional cytogenetic aberrations having a major prognostic impact which should be reflected in future risk-group stratification.

Extramedullary infiltration at diagnosis and prognosis in children with acute myelogenous leukemia

BACKGROUND

Extramedullary infiltration (EMI) is an occasional clinical symptom in childhood acute myelogenous leukemia (AML), but there is considerable controversy regarding the prognostic significance of EMI in AML.

PROCEDURE

We evaluated the frequency and prognostic significance of EMI at diagnosis of AML in children.

RESULTS

Of 240 cases of de novo AML excluding children with Down syndrome and acute promyelocytic leukemia, 56 (23.3%) showed EMI at diagnosis. Patients with EMI had a higher initial WBC count and a higher proportion of M4/M5 morphological variants. The complete remission rate following induction chemotherapy was lower in patients with EMI. However, the overall survival and event-free survival did not differ between patients with and without EMI. A detailed analysis showed that patients with EMI with a WBC count at diagnosis of over 100 x 10(9)/L or infiltration into the central nervous system are likely to have a poor prognosis.

CONCLUSIONS

CNS leukemia and EMI together with a WBC count of >100 x 10(9)/L at diagnosis of AML are high risk factors for relapse, and alternative treatment approaches for patients with these characteristics should be explored.

Prospective study of a pirarubicin, intermediate-dose cytarabine, and etoposide regimen in children with Down syndrome and acute myeloid leukemia: the Japanese Childhood AML Cooperative Study Group

PURPOSE

To evaluate a less intensive chemotherapeutic regimen specifically designed for patients with Down syndrome (DS) and acute myeloid leukemia (AML), and to determine the prognostic factors for event-free survival.

PATIENTS AND METHODS

Seventy-two patients with AML-DS were treated with remission induction chemotherapy consisting of pirarubicin (25 mg/m2/d for 2 days), cytarabine (100 mg/m2/d for 7 days), and etoposide (150 mg/m2/d for 3 days). Patients received four courses of intensification therapy of the same regimen. Prophylaxis for CNS leukemia was not included.

RESULTS

All but two patients were younger than 4 years, and 67 of the 72 patients (93%) were diagnosed as acute megakaryoblastic leukemia (AMKL). Seventy of the 72 patients (97.2%) achieved a complete remission (CR), and the estimated 4-year event-free survival (EFS) rate was 83% +/- 9%. Nine patients relapsed, and one died as a result of pneumonia during CR. Multivariate analysis revealed that the presence of monosomy 7 was a greater risk factor of adverse outcome (odds ratio = 5.67; P = .027).

CONCLUSION

A less intensive chemotherapeutic regimen produces excellent outcomes in standard-risk AML-DS patient. Risk-oriented therapy should be considered for future trials in AML-DS.

An effective chemotherapeutic regimen for acute myeloid leukemia and myelodysplastic syndrome in children with Down's syndrome

In recent pediatric collaborative studies of acute myeloid leukemia (AML), patients with Down's syndrome (DS) have better outcome than other patients when they were treated according to their intensive AML protocols. This may be attributed to enhanced sensitivity of DS AML cells to selected chemotherapeutic agents. We evaluated a less intensive chemotherapeutic regimen which was specifically designed for children with AML-DS. Remission induction chemotherapy consisted of daunorubicin (25 mg/m2/day for 2 days), cytosine arabinoside (100 mg/m2/day for 7 days), and etoposide (150 mg/m2/day for 3 days). Patients received one to seven courses of consolidation therapy of the same regimen. Thirty-three patients were enrolled on the study and their clinical, hematologic and immunophenotypic features were analyzed. Of the 33 patients, all were younger than 4 years and diagnosed as having acute megakaryoblastic leukemia or myelodysplastic syndrome. All patients achieved a complete remission and estimated 8 year event-free survival rate was 80+/-7%. Three patients relapsed and two died due to cardiac toxicity and one due to septic shock. The results of our study showed that patients with AML-DS constitute a unique biologic subgroup and should be treated according to a less intensive protocol designed for AML-DS.

Antithymocyte globulin and cyclosporine for treatment of 44 children with hepatitis associated aplastic anemia

We analyzed the outcomes of 44 children with hepatitis associated aplastic anemia (HAA) who received immunosuppressive therapy (IST) with antithymocyte globulin (ATG) and cyclosporine (CsA). Fourteen (31.8%) patients achieved complete response and 17 (38.6%) achieved partial response, for an overall response rate of 70.4% after 6 months. Seven non-responders received bone marrow transplantation from an HLA-matched unrelated donor and 6 out of 7 are alive. The probability of overall survival at 10 years was 88.3+/-4.9%, which supports the role of IST with ATG and CsA as treatment of choice for children with HAA without an HLA identical sibling donor.

NUP98-NSD1 gene fusion and its related gene expression signature are strongly associated with a poor prognosis in pediatric acute myeloid leukemia

The cryptic t(5;11)(q35;p15.5) creates a fusion gene between the NUP98 and NSD1 genes. To ascertain the significance of this gene fusion, we explored its frequency, clinical impact, and gene expression pattern using DNA microarray in pediatric acute myeloid leukemia (AML) patients. NUP98-NSD1 fusion transcripts were detected in 6 (4.8%) of 124 pediatric AML patients. Supervised hierarchical clustering analyses using probe sets that were differentially expressed in these patients detected a characteristic gene expression pattern, including 18 NUP98-NSD1-negative patients (NUP98-NSD1-like patients). In total, a NUP98-NSD1-related gene expression signature (NUP98-NSD1 signature) was found in 19% (24/124) and in 58% (15/26) of cytogenetically normal cases. Their 4-year overall survival (OS) and event-free survival (EFS) were poor (33.3% in NUP98-NSD1-positive and 38.9% in NUP98-NSD1-like patients) compared with 100 NUP98-NSD1 signature-negative patients (4-year OS: 86.0%, 4-year EFS: 72.0%). Interestingly, t(7;11)(p15;p15)/NUP98-HOXA13, t(6;11)(q27;q23)/MLL-MLLT4 and t(6;9)(p22;q34)/DEK-NUP214, which are known as poor prognostic markers, were found in NUP98-NSD1-like patients. Furthermore, another type of NUP98-NSD1 fusion transcript was identified by additional RT-PCR analyses using other primers in a NUP98-NSD1-like patient, revealing the significance of this signature to detect NUP98-NSD1 gene fusions and to identify a new poor prognostic subgroup in AML.

Repetitive cycles of high-dose cytarabine are effective for childhood acute myeloid leukemia: long-term outcome of the children with AML treated on two consecutive trials of Tokyo Children's Cancer Study Group

BACKGROUND

Various methods of intensive chemotherapy have contributed to an improved survival in pediatric acute myeloid leukemia (AML). We here report the long-term results of the two consecutive trials of Tokyo Children's Cancer Study Group (TCCSG), incorporating repetitive use of high-dose cytarabine (HD-Ara-C) based combination chemotherapy in post-remission phase.

PROCEDURE

A total of 216 eligible children with newly diagnosed AML were treated in the two consecutive multi-center trials of TCCSG, M91-13 and M96-14, from August 1991 to September 1998. In M91-13 trial, patients received eight courses of intensive post-remission chemotherapy, including six HD-Ara-C containing courses, after remission-induction therapy. Autologous hematopoietic stem cell transplantation (HSCT) could be selected by physician's choice, and allogeneic HSCT was allocated if donor was available. In M96-14 trial, the last two HD-Ara-C courses were omitted from the chemotherapy arm.

RESULTS

The remission-induction rate was 88.8% and probability of 5-year Overall survival (OS) and event-free survival (EFS) were 62% (56-69% with 95% Confidence intervals (CIs)) and 56% (49-62%), respectively. Treatment-related mortality (TRM) was 7.8%. Among patients without Down syndrome (DS) or acute promyelocytic leukemia (APL), the presence of t(8;21) or inv(16) was a significant good prognostic factor both in the univariate and multivariate analyses. Children with DS (N = 10) and APL (N = 14) also showed a good survival exceeding 70% in 5 years.

CONCLUSIONS

These results suggest that repetitive use of HD-Ara-C was effective and safe for childhood AML. However, further optimization of AML therapy is required.

Tandem duplications of MLL and FLT3 are correlated with poor prognoses in pediatric acute myeloid leukemia: a study of the Japanese childhood AML Cooperative Study Group

BACKGROUND

Mixed-lineage leukemia (MLL)-partial tandem duplication (PTD) is associated with poor prognosis in adult acute myeloid leukemia (AML), but its relationship to pediatric AML is unknown.

PROCEDURE

One hundred fifty-eight newly diagnosed AML patients, including 13 FAB-M3 and 10 Down syndrome (DS) patients, who were treated on the Japanese Childhood AML Cooperative Treatment Protocol AML 99 were analyzed for MLL-PTD, as well as internal tandem duplication (ITD) and the kinase domain mutation (D835Mt) in the FLT3 gene.

RESULTS

We found MLL-PTD in 21 (13.3%) of 158 AML patients, but not in FAB-M3 or DS patients. The differences between patients with and without MLL-PTD were significant for 3-year overall survival (OS) (56.3% vs. 83.2%, P = 0.018), disease-free survival (DFS) (41.7% vs. 69.6%, P = 0.010), and relapse rate (RR) (54.3% vs. 27.6%, P = 0.0085) of 135 AML patients excluding the FAB-M3 and DS patients. Furthermore, ITD and D835Mt in the FLT3 gene were found in 17 (12.6%) and 8 (5.9%) of these 135 patients, respectively. The differences between patients with FLT3-ITD and the wild-type allele were significant for 3-year OS (35.3% and 84.3%, P < 0.0000001), DFS (40.0% and 66.9%, P < 0.003), and RR (52.4% and 30.3%, P < 0.005). Coduplication of both genes was found in only 3 (1.9%) patients.

CONCLUSION

AML patients with FLT3-ITD, but not D835Mt, showed a poor prognosis. AML patients with MLL-PTD were also correlated with poor prognosis in this study.

Long-term follow-up of childhood acute lymphoblastic leukemia in Tokyo Children's Cancer Study Group 1981-1995

The objectives were as follows: Firstly, to estimate the overall probability of event-free survival (EFS) and isolated CNS relapse in the studies for children with acute lymphoblastic leukemia (ALL) during the 1980s and 1990s. Secondly, to report the EFS according to presenting features and lineage. Thirdly, to evaluate the treatment results re-classified by the risks of NCI criteria. Four consecutive protocol studies were performed in the Tokyo Children's Cancer Study Group: L81-10 protocol (1981-1984, 189 patients), L84-11 (1984-1989, 484 patents), L89-12 (1989-1992, 418 patients) and L92-13 (1992-1995, 347 patients). Overall EFS at 5 years in each protocol was 56.5 +/- 3.8(1 s.e.)%, 71.0 +/- 2.1%, 67.8 +/- 2.3%, and 63.4 +/- 2.7%, respectively. The cumulative isolated CNS relapse rate at 5 years was 8.1 +/- 2.1%, 3.5 +/- 0.9%, 3.6 +/- 1.0%, 1.0 +/- 0.6. The EFS in SR/HR (standard risk/high risk) according to the NCI criteria in B-precursor ALL at 5 years was 61.9 +/- 4.3%/41.4 +/- 7.4% (lineage was not confirmed.), 72.5 +/- 2.6%/63.4 +/- 5.0%, 77.4 +/- 2.7%/56.3 +/- 4.7%, and 67.8 +/- 3.4%/56.7 +/- 5.4% in each protocol. Also EFSs according to NCI SR/HR at 5 years of T-ALL in protocols L84-11, L89-12 and L92-13 were 55.6 +/- 16.6%/60.9 +/- 10.1%, 72.7 +/- 13.4%/51.6 +/- 9.1%, and 77.1 +/- 14.4%/53.6/10.1%, respectively. The truncation of maintenance therapy to 6 months resulted in a decreased EFS in L92-13, particularly due to an increase of bone marrow relapse after cessation of therapy in SR and HR. The NCI risk criteria work properly even in the patients treated by different intensities, so that it makes the comparison possible among the patients in various groups. The overall EFSs in childhood ALL improved in 1980s, but it seemed stable or decreased in 1990s. The short maintenance therapy resulted in poor outcome in SR on the L92-13 protocol. Many of these late relapsers were effectively rescued and overall survival remained at a high level. The proportion of patients who received cranial irradiation reduced without any increase of the CNS events.

Superior outcome of infant acute myeloid leukemia with intensive chemotherapy: results of the Japan Infant Leukemia Study Group

This study analyzed data on 35 infants with acute myeloid leukemia (AML) who were treated with intensive chemotherapy between 1995 and 1998 in Japan. The incidence of boys, younger age (< 6 months old), and hyperleukocytosis at onset was high in patients with the M4/M5 subtype (n = 23) in the French-American-British classification, compared with the non-M4/M5 subtype (n = 12). Thirteen (56%) and 16 (70%) patients with the M4/M5 subtype also showed 11q23 translocations and MLL gene rearrangements, respectively, whereas only one patient with the non-M4/M5 subtype had this rearrangement. All 35 patients were treated with the ANLL91 protocol consisting of etoposide, high-dose cytarabine, and anthracyclines. Overall survival and the event-free survival (EFS) rates at 3 years of all patients were 76% (95% confidence interval [CI], 61.3%-90.7%) and 72% (95% CI, 56.4%-87.9%), respectively. EFS showed no significant difference between 2 subgroups divided by age, gender, presence of the MLL gene rearrangements, and white blood cell count at onset; EFS in patients with the M4/M5 subtype tended to be better than those with the non-M4/M5 subtype. Although all 6 patients who underwent allogeneic stem cell transplantation (SCT) have been in complete remission, no benefit of SCT was confirmed. These findings suggest that the intensive chemotherapy with the ANLL91 protocol might have been responsible for the observed good outcome of infant AML, even without SCT. The presence of the MLL gene rearrangements or the age at onset had no impact on the outcome of infant AML.

Hematopoietic stem cell transplantation for Diamond-Blackfan anemia: a report from the Aplastic Anemia Committee of the Japanese Society of Pediatric Hematology

Transfusion-dependent Diamond-Blackfan anemia (DBA) patients opt for allogeneic hematopoietic stem cell transplantation (HSCT) as curative therapy. Clinical outcomes of 19 transplanted Japanese patients were analyzed. Prior to HSCT, 10 patients (53%) suffered hemosiderosis with organ dysfunction, and all eight with short stature (42%) had adverse effects of prednisolone. Median age at the time of HSCT was 56 months. Transplantation sources were 13 bone marrow [six human leukocyte antigen (HLA)-matched siblings, and six HLA-matched and one HLA-mismatched unrelated donors], five cord blood (two HLA-matched siblings and three HLA-mismatched unrelated donors), and one peripheral blood from haploidentical mother. All 13 patients with bone marrow transplantation (BMT) and two with sibling cord blood transplantation (CBT) had successful engraftment. Of three patients who underwent unrelated CBT, one died after engraftment, and the other two had graft failure but succeeded in a second BMT from an HLA-disparate father and unrelated donor, respectively. One died shortly after haploidentical PBSCT. The five-yr failure-free survival rate after BMT was higher than CBT (100%: 40%, p=0.002). Platelet recovery was slower in seven unrelated BMT than in six sibling BMT (p=0.030). No other factors were associated with engraftment and survival. These results suggest that allogeneic BMT, but not unrelated CBT, is an effective HSCT for refractory DBA.

Preceding immunosuppressive therapy with antithymocyte globulin and ciclosporin increases the incidence of graft rejection in children with aplastic anaemia who underwent allogeneic bone marrow transplantation from HLA-identical siblings

The incidence of graft rejection was determined in 66 children with acquired aplastic anaemia (AA) following bone marrow transplantation (BMT) from a related donor. Eleven of 65 evaluable patients experienced either early or late rejection. Multivariate analysis identified previous immunosuppressive therapy with antithymocyte-globulin (ATG) and ciclosporin (CsA) as a risk factor for graft rejection (relative risk: 16.6, P = 0.001). Patients who received ATG and CsA had a significantly lower probability of failure-free survival than those who did not (69.7 +/- 6.2% vs. 87.9 +/- 8.0%, P = 0.044). These results suggest that BMT should be instituted immediately in children with severe AA who have human leucocyte antigen-identical siblings.

Risk-directed treatment of infant acute lymphoblastic leukaemia based on early assessment of MLL gene status: results of the Japan Infant Leukaemia Study (MLL96)

We studied the effectiveness of risk-directed therapy for infants younger than 13 months of age with acute lymphoblastic leukaemia (ALL). Fifty-five infants were assigned to different treatment programs (from December 1995 to December 1998) on the basis of their MLL gene status at diagnosis. Forty-two cases (76.3%) had a rearranged MLL gene (MLL+) and were treated with remission induction therapy followed by sequential intensive chemotherapy, including multiple genotoxic agents (MLL9601 protocol). Haematopoietic stem cell transplantation (HSCT) was attempted if suitable donors were available. Thirteen infants (23.7%) were classified as MLL- and treated for 2.5 years with intensive chemotherapy for high-risk B-ALL (MLL9602 protocol). Complete remission was induced in 38 of the 42 infants (90.5%) with MLL+ ALL and in all 13 patients (100%) with MLL- disease. In the MLL+ subgroup, the estimated event-free survival (EFS) rate at 3 years post diagnosis was 34.0% +/- 7.5%, compared with 92.3% +/- 7.4% in the MLL- subgroup (overall comparison, P = 0.001 by log-rank analysis). Both age less than 6 months (hazard ratio = 6.87, 95% CI = 0.91-52.3; P = 0.013) and central nervous system (CNS) involvement at diagnosis (hazard ratio = 2.92 95% CI = 1.29-6.63; P = 0.015) were significant independent predictors of an inferior outcome. These findings indicate a strategic advantage in classifying infant ALL as either MLL+ or MLL- early in the clinical course and selecting therapy accordingly. Standard chemotherapy for high-risk B-lineage ALL appeared adequate for MLL- cases. Novel therapeutic initiatives are warranted for infants with MLL+ disease, particularly those with initial CNS leukaemic involvement or age less than 6 months, or both.

RAS mutations are frequent in FAB type M4 and M5 of acute myeloid leukemia, and related to late relapse: a study of the Japanese Childhood AML Cooperative Study Group

Mutations in RAS are frequent in acute myeloid leukemia (AML), and are thought to contribute to leukemogenesis in a subset of patients; however, their prognostic significance has not been firmly established. One hundred and fifty-seven pediatric patients with AML were analyzed for NRAS and KRAS mutations around hot spots at codons 12, 13, and 61. Twenty-nine patients (18.5%) had an activating mutation of RAS. We found KRAS mutations to be more frequent than NRAS mutations (18/29, 62.1% of patients with RAS mutation), in contrast to previous reports (18-40%). The frequency of RAS mutation was higher in French-American-British types M4 and M5 than other types (P = 0.02). There were no significant differences in other clinical manifestations or distribution in cytogenetic subgroups, or aberrations of other genes, including KIT mutation, FLT3-ITD, and MLL-PTD, between patients with and without RAS mutations. No significant differences were observed in the 3-year overall survival and disease-free survival; however, the presence of RAS mutation was related to late relapse. The occurrence of clinical events at relatively late period should be monitored for in AML patients with mutations in RAS.

A study of rasburicase for the management of hyperuricemia in pediatric patients with newly diagnosed hematologic malignancies at high risk for tumor lysis syndrome

Tumor lysis syndrome (TLS), including hyperuricemia, is a frequent serious complication in patients with hematologic malignancies. This study in Japanese patients evaluated the efficacy, safety, and pharmacokinetic profile of rasburicase in pediatric patients with hematologic malignancies. Patients aged <18 years at high risk for TLS, with newly diagnosed hematologic malignancies, were randomized to intravenous rasburicase 0.15 mg/kg/day (n = 15) or 0.20 mg/kg/day (n = 15) for 5 days. Chemotherapy was started 4-24 h after the first rasburicase dose. Response was defined as a reduction in plasma uric acid to < or = 6.5 mg/dL (patients <13 years) or < or = 7.5 mg/dL (patients > or = 13 years) by 48 h after the first administration, lasting until 24 h after the final administration. Response rates were 93.3 and 100% with rasburicase 0.15 and 0.20 mg/kg/day, respectively. Uric acid levels declined rapidly within 4 h of starting rasburicase administration in both groups. Most adverse events were related to the underlying chemotherapy regimens. Two hypersensitivity reactions, including grade 1/2 pruritus, were considered to be related to rasburicase. Rasburicase is effective and well tolerated for the management of hyperuricemia in Japanese pediatric patients at high risk of developing TLS.

Infant leukemia in Japan: clinical and biological analysis of 48 cases

Forty-eight Japanese infants with acute lymphoid leukemia (ALL) (n = 24) and acute nonlymphoid leukemia (ANLL) (n = 24) were analyzed on the basis of clinical and laboratory data. Morphologically, 20 of the 24 infants with ALL were of the FAB L1 type, and 20 of the 24 infants with ANLL were of the M4 or M5 type. Markedly enlarged liver and spleen, and hyperleukocytosis (more than 50,000/microliters) were seen in 9, 12, and 14 infants with ALL and 10, 11, and 10 infants with ANLL, respectively. Initial CNS leukemia was evident in 2 infants. Chromosome studies of the leukemic cells showed abnormal karyotypes in 9 of the 21 infants with ALL and 19 of the 22 infants with ANLL, consisting mainly of translocation 11, 12, and inversion 16. By surface marker analysis, only 7 of the 22 infants with ALL (32%) were diagnosed as having common ALL (HLA-DR+, CD19+, CD10+). Of the 15 infants with ANLL, 12 and 5 infants also showed reactivity to HLA-DR and CD19, respectively. All of the 5 ANLL infants with lymphoid markers showed different leukemic cell features at the time of relapse. Twelve of the 19 infants with ALL (63%) who achieved a complete remission relapsed within the first 2 years; 8 of the 21 with ANLL (38%) relapsed within the first year. Analysis of event-free survival shows that the ALL infants with hyperleukocytosis have a poorer prognosis than those without hyperleukocytosis (p less than 0.05). Infant leukemia originates in a multipotent cell with lymphoid and myeloid features, and intensive multiagent chemotherapy is necessary for the treatment of infants with acute leukemia.

Clinicopathologic characteristics of leukemia in Japanese children and young adults

The aim of this study is to clarify the clinicopathologic characteristics of adolescent leukemia in Japan by retrospective analysis. Patients with acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), chronic myelogenous leukemia (CML), and myelodysplastic syndrome (MDS), consecutively diagnosed from 1986 to 1999, were enrolled. A total of 3,856 patients from 1 to 15 years of age and 1,803 patients from 15 to 29 years of age were eligible for this study. Demographically, the frequency of AML found was almost constant during the teenage years, whereas the frequency of ALL gradually decreased. The relative frequency of CML and MDS apparently started to increase in patients in their late teens. The relative frequency of M3 and t(15;17) gradually increased during adolescence. Among patients aged 1 to 4 years, M7 was the most frequent FAB subtype. Among patients aged 5 to 9 years, M2 and t(8;21) was the most frequent subtype. The percentage of T cell ALL increased in patients 5 to 9 years old, reaching 31.2% in the 20- to 24-year-old age group. The percentage of patients with hyperdiploidy over 50 chromosomes was highest (17.0%) in patients aged 1 to 4 and decreased to 3.9% in the older teens. The percentage of patients with the Ph1 chromosome increased from 9.9% in teens to 30.0% in patients in their late twenties. When comparing event-free survival (EFS) rates for ALL according to age, the estimated 7-year EFS rate was highest for patients aged 1 to 9 years (65.9%) and intermediate for patients aged 10 to 15 years (48.4%). However, the EFS rate was significantly worse for patients aged 15 to 19 years (19.4%) and 20 to 29 years (17.0%) (P = 0.024). On the other hand, the EFS rate for AML decreased with increasing age, although without statistical significance. The overall survival rates are approximate among all age groups. The results of the study indicate that there are considerable variations in biologic features of leukemia between children and young adults. The prognosis for adolescent leukemia may be improved by introducing pediatric trials, which take into account the prognostic biological features.

Prospective study of a therapeutic regimen with all-trans retinoic acid and anthracyclines in combination of cytarabine in children with acute promyelocytic leukaemia: the Japanese childhood acute myeloid leukaemia cooperative study

In childhood acute promyelocytic leukaemia (APL), the efficacy of therapy combining cytarabine with all-trans retinoic acid (ATRA) and anthracyclines remains unclear in terms of long-term prognosis. Between August 1997 and March 2004, 58 children with APL (median age: 11 years) were enrolled into an acute myeloid leukaemia (AML) study (AML99-M3) and followed up for a median time of 86 months. The regimen included ATRA and anthracyclines combined with cytarabine in both induction and consolidation. In induction, two patients died of haemorrhage and four patients developed retinoic acid syndrome. Of 58 patients, 56 (96·6%) achieved complete remission, two of whom relapsed in the bone marrow after 15 and 19 months respectively. Sepsis was a major complication, with an incidence of 5·6-10·9% in the consolidation blocks, from which all but one of patients recovered. Consequently, 7-year overall and event-free survival rates were 93·1% and 91·4% respectively, and cumulative incidence of relapse plateaued at 3·6% after 2 years. Follow-up survey of 54 patients revealed no patients with late cardiotoxicity or secondary malignancy, except one with asymptomatic prolongation of QTc interval. This study suggests that the combination of cytarabine with ATRA and anthracycline-based therapy may have useful implications in the perspective of long-term prognosis and late adverse effects for childhood APL.

Outcome of children with relapsed acute myeloid leukemia following initial therapy under the AML99 protocol

The outcomes of children with relapsed acute myeloid leukemia (AML) are known to be poor, but remain obscure. We retrospectively analyzed 71 patients who had relapsed following first-line treatment under the AML99 protocol. We investigated the time and site of recurrence, response to re-induction therapy, and performance of hematopoietic stem cell transplantation (HSCT) in relapsed cases, and performed a multivariate analysis to identify prognostic factors. The 5-year overall-survival (OS) rate after relapse was 37 %. Of 71 patients, three died without any anti-leukemic therapy and two underwent allogeneic HSCT. The remaining 66 patients received re-induction chemotherapy, and 33 (50 %) achieved second CR (CR2). Twenty-two of 25 (88 %) late relapse patients and 11 of 41 (27 %) early relapse patients achieved CR2 (P < 0.001). Twenty-nine CR2 cases and 35 non-CR2 cases underwent allogeneic HSCT. The 5-year OS rate was significantly higher in patients who underwent HSCT in CR2 than those in non-CR2 (66 vs. 17 %, P < 0.000001). Multivariate analysis indicated that early relapse (P < 0.05) and the positivity of the FMS-like tyrosine kinase 3--internal tandem duplication (P < 0.05) were adverse prognostic factors for survival. In conclusion, the etiology of relapsed pediatric AML needs to be elucidated and effective chemotherapy should be administered to obtain CR2.

Relapse of aplastic anemia in children after immunosuppressive therapy: a report from the Japan Childhood Aplastic Anemia Study Group

BACKGROUND

Although the therapeutic outcome of acquired aplastic anemia has improved markedly with the introduction of immunosuppressive therapy using antithymocyte globulin and cyclosporine, a significant proportion of patients subsequently relapse and require second-line therapy. However, detailed analyses of relapses in aplastic anemia children are limited.

DESIGN AND METHODS

We previously conducted two prospective multicenter trials of immunosuppressive therapy for children with aplastic anemia: AA-92 and AA-97, which began in 1992 and 1997, respectively. In this study, we assessed the relapse rate, risk factors for relapse, and the response to second-line treatment in children with aplastic anemia treated with antithymocyte globulin and cyclosporine.

RESULTS

From 1992 to 2007, we treated 441 children with aplastic anemia with standard immunosuppressive therapy. Among the 264 patients who responded to immunosuppressive therapy, 42 (15.9%) relapsed. The cumulative incidence of relapse was 11.9% at 10 years. Multivariate analysis revealed that relapse risk was significantly associated with an immunosuppressive therapy regimen using danazol (relative risk, 3.15; P=0.001) and non-severe aplastic anemia (relative risk, 2.51; P=0.02). Seventeen relapsed patients received additional immunosuppressive therapy with antithymocyte globulin and cyclosporine. Eight patients responded within 6 months. Seven of nine non-responders to second immunosuppressive therapy received hematopoietic stem cell transplantation and five are alive. Eleven patients underwent hematopoietic stem cell transplantation directly and seven are alive.

CONCLUSIONS

In the present study, the cumulative incidence of relapse at 10 years was relatively low compared to that in other studies mainly involving adult patients. A multicenter prospective study is warranted to establish optimal therapy for children with aplastic anemia.