Keizo Horibe

Childhood Acute Lymphoblastic Leukemia: Progress Through Collaboration

PURPOSE To review the impact of collaborative studies on advances in the biology and treatment of acute lymphoblastic leukemia (ALL) in children and adolescents. METHODS A review of English literature on childhood ALL focusing on collaborative studies was performed. The resulting article was reviewed and revised by the committee chairs of the major ALL study groups. RESULTS With long-term survival rates for ALL approaching 90% and the advent of high-resolution genome-wide analyses, several international study groups or consortia were established to conduct collaborative research to further improve outcome. As a result, treatment strategies have been improved for several subtypes of ALL, such as infant, MLL-rearranged, Philadelphia chromosome-positive, and Philadelphia chromosome-like ALL. Many recurrent genetic abnormalities that respond to tyrosine kinase inhibitors and multiple genetic determinants of drug resistance and toxicities have been identified to help develop targeted therapy. Several genetic polymorphisms have been recognized that show susceptibility to developing ALL and that help explain the racial/ethnic differences in the incidence of ALL. CONCLUSION The information gained from collaborative studies has helped decipher the heterogeneity of ALL to help improve personalized treatment, which will further advance the current high cure rate and the quality of life for children and adolescents with ALL.

Prognostic value of internal tandem duplication of the FLT3 gene in childhood acute myelogenous leukemia.

BACKGROUND Recently, an internal tandem duplication of the FLT3 gene (FLT3/ITD) was found in 20% of adult cases of acute myelogenous leukemia (AML), and this length abnormality was suggested to be associated with leukemic progression. PROCEDURE We examined the mRNA expression of the FLT3 gene by using reverse transcription-polymerase chain reaction (RT-PCR) in 64 children with AML, and further abnormal transcripts were cloned and sequenced. RESULTS An unexpected longer product was found in seven patients (11%) by RT-PCR of the FLT3 gene. Sequence analysis of these abnormal products revealed the presence of tandemly duplicated fragments in all seven patients. Three factors were identified to be associated with high incidence of FLT3/ITD; older patients (> or = 10 years) (P = 0.049), high WBC count (> or = 50,000/microl) at presentation (P = 0.002), and M3 in FAB subtypes (P = 0.002). Induction failure was observed in 3 (43%) of 7 patients with FLT3/ITD. Only FLT3/ITD was identified as a significant risk factor for induction failure by univariate analysis (P = 0.013), although it was not significant by multivariate analysis (P = 0.11). The Kaplan-Meier estimate of event-free survival rate at 5 years was 14% for patients with FLT3/ITD, which was significantly lower in comparison with 69% for patients without FLT3/ITD (P = 0.003). This finding was also identified by multivariate analysis (P = 0.01). CONCLUSIONS In this study, FLT3/ITD was observed in 11% of childhood AML and identified to be associated with poor prognosis. A large prospective study with uniform treatment is necessary to confirm our results.

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.

Human herpesvirus 6 viremia in bone marrow transplant recipients: clinical features and risk factors.

Human herpesvirus 6 (HHV-6) infection was studied in 82 bone marrow transplant (BMT) recipients (72 allogeneic, 10 autologous). All recipients and 30 donors were seropositive for HHV-6 antibody at the time of bone marrow transplantation. Thirty-one recipients (37.8%) had HHV-6 viremia 2-4 weeks after transplantation. The incidence of HHV-6 viremia was significantly higher among allogeneic BMT recipients than in autologous BMT recipients (P=.011). Therefore, the following analyses of allogeneic BMT recipients were carried out (n=72). Geometric mean antibody titers (log(10)) were significantly higher in recipients without viremia than in those with viremia (1.84+/-0.39 vs. 1.61+/-0.42; P=.022). Logistic regression analysis demonstrated that leukemia or lymphoma is an independent risk factor (P=.031) for HHV-6 viremia. Rash occurring within 1 month after transplantation was observed in 17 (54.8%) of 31 recipients with HHV-6 viremia but in only 8 (19.5%) of 41 recipients without HHV-6 viremia (P=.001).

Outcomes after Induction Failure in Childhood Acute Lymphoblastic Leukemia

BACKGROUND Failure of remission-induction therapy is a rare but highly adverse event in children and adolescents with acute lymphoblastic leukemia (ALL). METHODS We identified induction failure, defined by the persistence of leukemic blasts in blood, bone marrow, or any extramedullary site after 4 to 6 weeks of remission-induction therapy, in 1041 of 44,017 patients (2.4%) 0 to 18 years of age with newly diagnosed ALL who were treated by a total of 14 cooperative study groups between 1985 and 2000. We analyzed the relationships among disease characteristics, treatments administered, and outcomes in these patients. RESULTS Patients with induction failure frequently presented with high-risk features, including older age, high leukocyte count, leukemia with a T-cell phenotype, the Philadelphia chromosome, and 11q23 rearrangement. With a median follow-up period of 8.3 years (range, 1.5 to 22.1), the 10-year survival rate (±SE) was estimated at only 32±1%. An age of 10 years or older, T-cell leukemia, the presence of an 11q23 rearrangement, and 25% or more blasts in the bone marrow at the end of induction therapy were associated with a particularly poor outcome. High hyperdiploidy (a modal chromosome number >50) and an age of 1 to 5 years were associated with a favorable outcome in patients with precursor B-cell leukemia. Allogeneic stem-cell transplantation from matched, related donors was associated with improved outcomes in T-cell leukemia. Children younger than 6 years of age with precursor B-cell leukemia and no adverse genetic features had a 10-year survival rate of 72±5% when treated with chemotherapy only. CONCLUSIONS Pediatric ALL with induction failure is highly heterogeneous. Patients who have T-cell leukemia appear to have a better outcome with allogeneic stem-cell transplantation than with chemotherapy, whereas patients who have precursor B-cell leukemia without other adverse features appear to have a better outcome with chemotherapy. (Funded by Deutsche Krebshilfe and others.).

Clinical Outcome of Children With Newly Diagnosed Philadelphia Chromosome–Positive Acute Lymphoblastic Leukemia Treated Between 1995 and 2005

PURPOSE In a previous analysis of 326 children with Philadelphia chromosome (Ph) -positive acute lymphoblastic leukemia (ALL) treated between 1986 and 1996, hematopoietic stem-cell transplantation from HLA-matched related donors, but not from unrelated donors, offered a superior outcome than chemotherapy alone. To evaluate the impact of recent improvements in chemotherapy and transplantation, we performed a similar analysis on patients treated in the following decade. PATIENTS AND METHODS We analyzed 610 patients with Ph-positive ALL treated between 1995 and 2005 without tyrosine kinase inhibitor therapy. The median follow-up duration was 6.3 years. RESULTS Complete remission was achieved in 89% of patients. The 7-year event-free survival and overall survival rates were superior in the present cohort compared with the previous cohort (32.0% ± 2.0% v 25.0% ± 3.0, respectively, P = .007; and 44.9% ± 2.2% v 36.0% ± 3.0%, respectively, P = .017). Compared with chemotherapy alone, transplantation with matched related donors or unrelated donors in first remission (325 patients) showed an advantage with increasing follow-up, suggesting greater protection against late relapses (hazard ratio at 5 years, 0.37; P < .001). In the multivariate Cox regression analysis accounting for treatment (transplantation v no transplantation), age, leukocyte count, and early response had independent impact on treatment outcome. CONCLUSION Clinical outcome of children and adolescents with Ph-positive ALL has improved with advances in transplantation and chemotherapy. Transplantations with matched related donors and unrelated donors were equivalent and offered better disease control compared with chemotherapy alone. Age, leukocyte count, and early treatment response were independent prognostic indicators. The results of this study will serve as a historical reference to evaluate the therapeutic impact of tyrosine kinase inhibitors on the outcome of Ph-positive ALL.

Impact of the Methotrexate Administration Dose on the Need for Intrathecal Treatment in Children and Adolescents With Anaplastic Large-Cell Lymphoma: Results of a Randomized Trial of the EICNHL Group

PURPOSE To compare the efficacy and safety of two methotrexate doses and administration schedules in children with anaplastic large-cell lymphoma (ALCL). PATIENTS AND METHODS This randomized trial for children with ALCL was based on the Non-Hodgkins Lymphoma-Berlin-Frankfurt-Muenster 90 (NHL-BFM90) study protocol and compared six courses of methotrexate 1 g/m2 over 24 hours and an intrathecal injection (IT) followed by folinic acid rescue at 42 hours (MTX1 arm) with six courses of methotrexate 3 g/m2 over 3 hours followed by folinic acid rescue at 24 hours without IT (MTX3 arm). This trial involved most European pediatric/lymphoma study groups and a Japanese group. RESULTS Overall, 352 patients (96% ALK positive) were recruited between 1999 and 2005; 175 were randomly assigned to the MTX1 arm, and 177 were assigned to the MTX3 arm. Ninety-two percent of patients received protocol treatment. Median follow-up time is 3.7 years. Event-free survival (EFS) curves were superimposed with 2-year EFS rates (73.6% and 74.5% in the MTX1 and MTX3 arms, respectively; hazard ratio = 0.98; 91.76% CI, 0.69 to 1.38). Two-year overall survival rates were 90.1% and 94.9% in MTX1 and MTX3, respectively. Only two CNS relapses occurred (both in the MTX1 arm). Toxicity was assessed after 2,050 courses and included grade 4 hematologic toxicity after 79% and 64% of MTX1 and MTX3 courses, respectively (P < .0001); infection after 50% and 32% of courses, respectively (P < .0001); and grade 3 to 4 stomatitis after 21% and 6% of courses, respectively (P < .0001). CONCLUSION The results of the NHL-BFM90 study were reproduced in this large international trial. The methotrexate schedule of the NHL-BFM90 protocol including IT therapy can be safely replaced by a less toxic schedule of methotrexate 3 g/m2 in a 3-hour infusion without IT therapy.

Long‐term outcome of acquired aplastic anaemia in children: comparison between immunosuppressive therapy and bone marrow transplantation

A total of 100 children under the age of 17 years with acquired aplastic anaemia (AA) were initially treated with immunosuppressive therapy (IST) (n = 63) or bone marrow transplantation (BMT) (n = 37) from an HLA‐matched family donor. The projected 10‐year survival rates were 55 ± 8% and 97 ± 3% respectively (P = 0·004). Because the IST group included 11 non‐responders who were salvaged by BMT from an HLA‐matched unrelated donor, we compared failure‐free survival (FFS) between the groups. The probability of FFS at 10 years was 97 ± 3% for the BMT group, compared with 40 ± 8% for the IST group (P = 0·0001). Seven patients evolved to myelodysplastic syndrome (MDS) with monosomy 7 and the estimated cumulative incidence of MDS 10 years after diagnosis was 20 ± 7% in the IST group. We compared the outcome of children treated with IST during the two consecutive periods of 1983–91 (group A, n = 40) and 1991–8 (group B, n = 23) to assess the impact of combined therapy with anti‐thymocyte globulin and cyclosporin. The probability of FFS at 7 years follow‐up was the same in the two groups (50 ± 8% vs. 40 ± 15%, P = 0·40). We recommend BMT as first‐line therapy in paediatric severe AA patients with an HLA‐matched family donor. Alternative donor BMT is recommended as salvage therapy in patients who relapse or do not respond to initial IST.

Detection of neuroblastoma cells in bone marrow and peripheral blood at diagnosis by the reverse transcriptase‐polymerase chain reaction for tyrosine hydroxylase mRNA

Background. Bone marrow metastasis often occurs in patients with neuroblastoma; therefore, a sensitive assay to detect occult neuroblastoma cells in bone marrow (BM) and peripheral blood (PB) is needed. The feasibility and clinical value of using the reverse transcriptase‐ (RT) polymerase chain reaction (PCR) to amplify mRNA for tyrosine hydroxylase (TH), the first enzyme of catecholamine synthesis, was evaluated to detect neuroblastoma cells in patient samples.

Alterations of the p53, p21, p16, p15 and RAS genes in childhood T-cell acute lymphoblastic leukemia

We investigated the alterations of the p53, p21, p16, p15 and RAS genes in childhood T-cell acute lymphoblastic leukemia (T-ALL) and T-ALL cell lines by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing. Mutations of the p53 gene were found in three of 57 (5%) patients at diagnosis, one of 14 (7%) patients at relapse and in 12 of 18 (67%) cell lines. In these 12 cell lines, four had more than two mutations of the p53 gene. The p53 mutations were found in four of five cell lines whose original fresh leukemic cells were simultaneously examined original fresh leukemic cells. However, only one of the four fresh leukemic cells had the same mutation. All patients with p53 mutations in the course of disease died. Mutations of the p21 gene were not identified in 71 fresh samples and in 18 cell lines. N-RAS mutations were found in two of 57 (4%) fresh T-ALL patients at diagnosis, and four of 18 cell lines (22%), whereas no mutations were detected in any samples at relapse. Alterations of the p16 gene were found in 18 of 47 (38%) patients at diagnosis and in seven of 14 (50%) at relapse. These differences were not statistically significant. There were no differences in the frequency of alteration of the p16 and p15 genes between event-free patients and the remaining patients. Furthermore, we found the methylation of p16 gene in three of seven patients lacking homozygous deletions, suggesting higher frequency of p16 inactivation than previous reports in T-ALL. Interestingly, we found that one allele is inactivated by methylation and another allele had nonsense mutation in one cell line (KOPT-KI), resulting in loss of protein expression of p16. This type of p16 inactivation has not been so far reported in leukemia. We conclude that, (1) p53 mutations are infrequent at diagnosis but tend to be associated with poor clinical outcome; (2) RAS and p21 mutations may not be involved in the pathogenesis of T-ALL; (3) not only frequent alterations of p16 and p15 genes but also methylation of p16 gene are involved in initiating the leukemogenesis of T-ALLs, and (4) these 5 genes are independently involved in T-ALL.