ALBERT

Beschreibung: Introduction: Anthracyclines (Atc) are the key drugs in the treatment of acute promyelocytic leukemia (APL) combined with all-trans retinoic acid (ATRA), however, dose-dependent risk of long-term cardiac toxicity is sometimes problematic especially in pediatric patients. To evaluate efficacy of the treatment with reduced cumulative doses of Atc in childhood APL, we conducted a nationwide non-randomized prospective study, AML-P05, in the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG). Patients & Methods: Between April 2006 and March 2011, forty-six children with newly diagnosed APL were enrolled in this study. All patients received at least 3-day precedence of ATRA monotherapy (45mg/m2/d for 35 days in total), followed by chemotherapeutic agents consisted of cytarabine (200mg/m2/d for 7 days) and daunorubicin (DNR, 45mg/m2/d for 3 days) as the first induction therapy. The second induction therapy and subsequent 3 courses of consolidation therapy consisted of ATRA, either high- or intermediate-dose of cytarabine, triple intrathecal injection, and single dose of Atc; 10mg/m2 of mitoxantrone (MIT) in the first 2 courses and 45mg/m2 of pirarubicin (THP) in the last 2 courses. Finally, patients received one-year maintenance therapy with ATRA for 15 days every 3 months. Results: Among the 46 patients registered in this study, 3 were excluded because of PML/RARA negativity, and the remaining 43 patients including 2 with molecular variants were evaluated. The median age at diagnosis was 9 years (range, 11 months to 15 years old). The median follow up period was 4.47 years (0.00-7.45 years). FLT3-ITD was positive in 6 out of 40 patients examined. Two patients died during induction therapies; one of coagulopathy in first course and the other of infection in second course. Two patients developed differentiation syndrome but resolved with temporary cessation of ATRA and supportive therapies. Three patients did not achieve complete remission (CR) after 2 courses of induction therapy, and overall CR rate was 85.7% (36/42, 95%CI: 71.5-94.6%). Neither cardiac adverse events nor treatment-related death were observed during consolidation and maintenance therapies. Three patients exhibited relapse during or after maintenance therapy, and another one developed secondary acute myeloid leukemia. Consequently, the 3-year event-free (EFS) and overall survival rate were 83.6% (95%CI: 68.6-91.8%) and 90.7% (95%CI: 77.1-96.4%), respectively. Age less than 4 years old at diagnosis and non-M1 marrow after first induction therapy were associated with lower EFS. High WBC count (〉10,000/μL), low platelet count (

Beschreibung: Although tyrosine kinase inhibitor (TKI) is popular in controlling chronic myeloid leukemia in the chronic phase (CML-CP), its long-term adverse effects in children are an issue of concern. One such concern is the negative impact on growth in these children. We previously demonstrated that growth impairment was a major adverse effect in imatinib-treated CML children. However, severity of impairment was not completely elucidated because of the short follow-up period. The Japanese Pediatric Leukemia/Lymphoma Study Group CML committee reviewed the clinical records of 107 Japanese children diagnosed with CML-CP (1 SD in 21 children (27.2%). Decrease in height-SDS was more severe in prepubertal children than in pubertal children (0.85 vs. 0.36, p〈 0.01). However, in prepubertal children median annual change in height-SDS significantly decreased 2 years after TKI initiation, and was

Beschreibung: 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.

Beschreibung: [Background] Acute promyelocytic leukemia (APL) cells induce dysregulation of coagulation and fibrinolysis, and most of the cases are complicated with disseminated intravascular coagulopathy (DIC) at the time of diagnosis. Administration of all-trans retinoic acid (ATRA) rapidly corrects dysregulation and improves DIC. But in some cases, management of DIC with ATRA alone is very difficult because addition of chemotherapeutic agents may reactivate fibrinolytic state. Thus the control of DIC is still an issue for the initial management of APL even in the ATRA era. Recombinant thrombomodulin (rTM) improves DIC by inhibiting excessive coagulation through the activation of protein C cascade (Saito H, et al. J Thromb Haemost 2007), and was approved in Japan for the treatment of DIC induced by severe infection or hematological malignancy in 2008. However, because activated protein C also facilitate fibrinolytic pathway by inhibiting plasminogen activator inhibitor-I, administration of rTM may lead to severe hemorrhage complication in patients with APL. Therefore, we retrospectively analyzed its efficacy and safety in pediatric APL. [Object & Methods] This study included 45 cases; 42 who registered to the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) AML-P05 study (UMIN Clinical Trials Registry, # UMIN000000645) and responded to the questionnaire and 3 cases outside the study. Questionnaire regarding the use of rTM and efficacy and safety issues, such as “Worst DIC score according to the diagnostic criteria of the Japanese Ministry of Health and Welfare (worst DIC score)” and “Days until resolution of DIC score from diagnosis of DIC (DIC duration)” were investigated. [Results] Among 45 cases analyzed, 38 (84%) were diagnosed to complicate with DIC, and 9 (24%) among them used rTM by physician’s decision. In these 9 cases (rTM+ group), mean duration of rTM administration was 13.8 days (7–24 days). WBC count and FDP level at diagnosis of APL were not different between rTM+ group and rTM-NOT used group (rTM- group). In rTM+ group, mean value of “Worst DIC score” was 5.8 and mean “DIC duration” from diagnosis was 16.8 days, both of them were not statistically significant with those in rTM- group (5.4 and 13.0 days, respectively). However, median “DIC duration” from commencement of rTM (11.5 days) seems shorter than “DIC duration” from diagnosis of DIC in rTM- group (13.0 days), although the difference was not statistically significant. Regarding safety issues, there was no death or severe hemorrhage in rTM+ group, while 3 cases (10%) of severe hemorrhage due to uncontrolled DIC were reported in rTM- group, with fatal brain hemorrhage in 1 case (3%) among them. There was no significant difference of induction rate between rTM+ group (1 case, 11%) and rTM- group (3 cases, 10%), although 2 cases of ATRA-refractory APL in rTM+ group who were additionally treated with arsenic trioxide. [Conclusions] In this retrospective analysis investigating efficacy and safety of rTM in the management of pediatric APL-related DIC, there were no significant differences regarding the efficacy of rTM because of the limited cases of rTM+ group. However, it is notable that there was no severe hemorrhage or death in rTM+ group. rTM seems to be safely used for the management of pediatric APL-related DIC. Disclosures No relevant conflicts of interest to declare.

Beschreibung: Background: The Japan Pediatric Leukemia/Lymphoma Study Group (JPLSG) CML-08 prospective study was designed to determine the efficacy and tolerability of tyrosine kinase inhibitor (TKI) in children and adolescents with newly diagnosed CML in chronic phase (CP). Methods: Monitoring of response to TKI and the treatment were conducted according to the modified ELN-2009 guidelines. Results: From October 2009 until September 2014, 78 patients (49 males and 29 females) from age 1 to 17 years (median: 11 years) were enrolled in 45 hospitals in Japan. As of May 2015, the median observation period was 31 months (662 months). Median WBC, Hb and platelet counts were 275x109/L (8 to 765), 9.6g/dL (5.8 to 14.6) and 560x109/L (110 to 2875), respectively. Splenomegaly was found in 76%. High scores of Sokal, Hasford and EUTOS were observed in 21, 13 and 27%, respectively. Clonal chromosome abnormalities in Ph-positive cells occurred in 3 patients at diagnosis. Imatinib, dasatinib and nilotinib were used as a first-line treatment in 69 (88%), 7 (9%) and 2 (3%) patients, respectively. The median initial dose of imatinib, dasatinib and nilotinib was 276, 63 and 262mg/m2, respectively. Of 69 patients with a first-line imatinib, 30 (43%) have been continued imatinib treatment, and the others were switched to second TKI (dasatinib or nilotinib) or hematopoietic stem cell transplantation (HSCT) due to poor response or intolerance to imatinib. The most common cause of intolerance to imatinib was musculoskeletal events. At the last observation, HSCT had been conducted in 8 patients (10%). 4y-PFS and 4y-OS was 97.1% (95%CI, 88.7 to 99.3%) and 97.8% (95%CI, 85.3 to 99.7%), respectively. One patient was dead because of blast crisis followed by transplant-related complications. CHR was achieved in 96.2% at 3 months, CCyR in 76.8% at 12 months, MMR in 40.8% at 18 months, and CMR4.0 in 22.4% at 24 months. Cumulative incidence of CMR4.0 by 24 months was 27.8% and 7.5% in patients with BCR-ABL (IS) of ≤ 10% and 〉 10% at 3 months with a first-line imatinib, respectively (P=0.0435). In patients with a first-line imatinib, age and WBC count at diagnosis were found to be potential prognostic factors for cumulative incidence of molecular response. Patients with a first-line second TKI had a higher 12-months cumulative incidence of MMR (60.0% vs 21.7%, P = 0.0460) and CMR4.0 (35.1% vs 6.3%, P = 0.0061) than patients with a first-line imatinib. There were no significant differences between their clinical characteristics including sex, WBC count, Hb, platelet count, Sokal score, Hasford score, and EUTOS score, except for age. Second TKI was used as a first-line treatment only for patients ≥ 9 years of age. In this study, the follow-up is planned to continue until 2019. Conclusion: A first-line second TKI was more effective than imatinib for inducing molecular responses also in pediatric CML-CP, as reported in adult CML-CP. Discontinuation of TKI after achieving CMR is a desirable strategy especially for children and adolescents. Thus, considering prognosis factors including age and WBC count, pediatric CML patients with unfavorable prognosis should be treated by second TKI rather than imatinib as a first-line treatment. Disclosures No relevant conflicts of interest to declare.

Beschreibung: Scrutiny of the human genome through evaluation of common genetic variants has revealed hundreds of disease susceptibility loci. In childhood acute lymphoblastic leukemia (ALL), six regions that have replicated in several populations are now considered known susceptibility loci (ARID5B, IKZF1, CEBPE, CDKN2A, PIP4K2A, and GATA3), but their effects have yet to be fully confirmed in populations of non-European ancestry. Targeted validation attempts based on the same SNPs originally identified in European ancestral populations have been performed in East Asians, but findings have been inconsistent. This may be due to differences in linkage disequilibrium patterns, allele frequency, and/or magnitude of effect between Europeans and East Asians; thus a comprehensive characterization of genetic variation across the targeted genetic loci is required for an appropriate validation attempt in different populations. Using a large network of hospitals within the Tokyo Children's Cancer Study Group, saliva samples from previously diagnosed childhood ALL patients (aged 0-19 years) were collected between December 2012 and May 2015. Genome-wide single nucleotide polymorphism (SNP) genotyping was performed and resulted in the inclusion of a total of 570 ALL patients, with genetic data available for up to about 500,000 SNPs after quality control exclusions. Control genome-wide data were available for 2,712 previously genotyped samples from the Nagahama Study Group and Aichi Cancer Center Study, Japan. SNP imputation was performed on the combined case-control dataset using ShapeIT and Minimac3, and the 1000 Genomes Project Phase I Version 3 as the reference population. Tests of association between childhood ALL and all available SNP genotypes across the six genes (mentioned above) implicated in previous genome-wide association studies was performed using logistic regression and assuming a log-additive model of inheritance. Of the six genomic regions examined, SNPs within the IKZF1, ARID5B, and PIP4K2A genes showed a statistically significant association with childhood ALL risk after Bonferroni correction. SNPs with the strongest evidence of association for these three genes included rs7090445 (ARID5B, OR=1.75, P =3.7x10-17), rs12533431 (IKZF1, OR=1.43, P =4.3x10-5), and rs11013045 (PIP4K2A, OR=0.76, P =9.5x10-5). Further examination of these regions indicated a second independently associated locus within ARID5B. Furthermore, we observed that the same previously reported primary ALL susceptibility SNPs for IKZF1 (e.g. rs4132601, rs11978267) and PIP4K2A (e.g. rs10828317, rs7088318) were not associated in Japanese. This highlights the importance of considering regional genetic variation comprehensively when testing the role of previously implicated candidate regions in a different racial/ethnic population. Characterization of the role of CEBPE, CDKN2A, and GATA3 genetic variation in Japanese may benefit from greater statistical power and potentially additional coverage of SNPs within these regions. Disclosures No relevant conflicts of interest to declare.

Beschreibung: Background: Tyrosine kinase inhibitor (TKI) has now enabled patients with chronic myeloid leukemia (CML) to live a normal lifespan. However, its long-term side effects such as growth impairment are an issue of concern especially for children. Recent clinical trials in adults have suggested that a subset of CML patients with deep molecular response on TKI therapy may have chance to discontinue TKI without molecular relapse (Saussele et al. Lancet Oncol. 2018). However, the biology of CML in children may differ from adults with more aggressive presentation, and data of TKI discontinuation in CML children are limited (Hijiya et al. Blood. 2019; Bruijn et al. British Journal of Haematol. 2019). Methods: The Japan Pediatric Leukemia/Lymphoma Study Group (JPLSG) CML committee recruited 22 Japanese patients diagnosed with CML-chronic or accelerated phase at 〈 20 years of age, treated with TKI for ≥ 3 years, and sustained molecular response (MR4.0) for ≥ 2 preceding years. Patients who relapsed after hematopoietic stem cell transplantation (HSCT) were included if total duration of TKI treatment was ≥ 3 years after rejection and relapse, and also met the criteria mentioned above. We prospectively analyzed treatment-free remission rate (TFR) at 12 months. Molecular relapse was defined as at least one loss of major molecular response (MMR), and TKI treatment was restarted as prescribed before discontinuation. Results: All the patients were diagnosed with CML-chronic phase. Median age at diagnosis of CML was 9 years (range, 1 to 14 years), and median age at discontinuation of TKI was 16 years (range, 5 to 26 years). Initial TKI was imatinib in 21 patients, and imatinib was switched to second generation (2G)-TKI in 2 patients because of intolerance or poor response. One patient was treated only with 2G-TKI. Median treatment duration of TKI before discontinuation was 100 months (range, 42 to 178 months), and median duration of MR4.0 was 53.5 months (range, 25 to 148 months). TFR at 12 months was 50.0% (90% CI=31.7-65.8%). Eleven patients experienced molecular relapse and restarted TKI at median of 102 days (range, 67 to166 days) after discontinuation of TKI (Figure. 1). No progression was observed during study, and all 11 patients reachieved MR4.0 at median of 64 days (range, 25 to 196 days) after restart of TKI. All the patients who lost MR4.0 within 3 months after stopping TKI failed to maintain MMR thereafter and restarted TKI. On the other hand, a single patient who lost MR4.0 after 32 months of stopping TKI reachieved MR4.0 without TKI. Plasma trough concentration level of imatinib was determined just before stopping imatinib in 18 patients. In univariate analysis, plasma concentration level of imatinib was associated with TFR after stopping TKI (p=0·005). Higher plasma concentration of imatinib was associated with higher risk of relapse. In contrast, treatment duration of TKI, duration of MR4.0, Sokal, Hasford, or EUTOS scores had no impact on TFR. Of 3 patients who underwent HSCT, 2 patients succeeded in maintenance of MR4.0 without TKI. In terms of adverse effects, grade 1 musculoskeletal or joint pain observed in 3 patients, and grade 1 to 3 elevation of creatine phosphokinase observed in 6 patients regressed after discontinuation of TKI. No withdrawal syndrome as reported in adults was observed in this study. In 3 males who discontinued TKI before puberty (5, 9, and 13 years of age with testicular size 〈 3mL), slight recovery in growth associated with increase in both serum bone type alkaline phosphatase and urine N-Telopeptides of Type I collagen was observed soon after discontinuation of TKI. However, these 3 patients relapsed and restarted TKI within 4 months after discontinuation of TKI. Conclusion: These data indicate that as in adults, TKI may be safely discontinued also in children younger than 15 years of age at diagnosis, treated with TKI for ≥ 3 years, and sustained MR4.0 for ≥ 2 years, including patients who relapsed after HSCT. We suggest that plasma trough concentration level of imatinib may predict TFR for children with CML and sustained MR4.0 with imatinib. Further study of TKI discontinuation in children with CML is expected. Disclosures Kada: Bayer Yakuhin: Other: personal fees for a member of independent data monitoring committee of clinical trials, outside of the submitted work.. Imai:Juno Therapeutics: Patents & Royalties.

Beschreibung: Background: Secondary or subsequent malignant neoplasms (SMNs) are one of the most serious late complications in children and adolescents after treatment for acute lymphoblastic leukemia (ALL). Several studies have reported that excess dosing of 6-mercaptopurine (6-MP) therapy and polymorphisms of 6-MP metabolizing enzyme coding gene might influence the risk of SMNs. Recently, nucleoside diphosphate-linked moiety X-type motif 15 (NUDT15) variants have been identified as a cause of high sensitivity to 6-MP, which reflects a high sensitivity to 6MP in East Asians. Therefore, we investigated an association between NUDT15 genotype and incidence of SMNs in pediatric ALL. Methods: Germline samples including bone marrow samples, peripheral blood samples and buccal swab samples during remission were obtained from 13 cases who suffered from SMN after childhood ALL. The prevalence of major NUDT15 non-functional alleles (*2 and *3), which is categorized intermediate or poor metabolizer of 6-MP in Clinical Pharmacogenetics Implementation Consortium Guideline (Relling M et al. Clin Pharmacol Ther 2019), was evaluated by using Sanger sequencing and/or whole exome sequencing. The NUDT15 variants prevalence in SMN patients with primary ALL was compared to those without SMN, who were registered in the TCCSG L04-16 study, which was conducted by the Tokyo Children's Cancer Study Group (TCCSG). Results: Patients' profiles and NUDT15 genotypes were summarized in table 1. Median ages at diagnoses of ALL and SMNs were 4 (1-15) and 13 (5-44) years, respectively. Median duration between ALL and SMNs was 8 (1-30) years. SMNs included acute myeloblastic leukemia (AML) / myelodysplastic syndrome (MDS) (n = 8), brain tumor (n = 1), basal cell carcinoma (n = 1), bladder cancer (n = 1), Ewing sarcoma (n = 1) and osteosarcoma (n = 1). Among the 13 SMN cases, six patients (46.2%) possessed NUDT15 non-functional alleles. The SMNs of these cases included AML / MDS (n = 4), bladder cancer (n = 1) and osteosarcoma (n = 1). Among them, 3 patients, whose SMNs were AML, bladder cancer and osteosarcoma, were treated with radiation therapy against primary ALL. All NUDT15 genotypes were heterozygous variants (3 were *1/*2 and 3 were *1/*3) and seemed to be intermediate metabolizers. In patients without known SMNs in TCCSG ALL L04-16 cohort study, 73 of 437 (16.7%) possessed NUDT15 non-functional alleles. Three of them had bi-allelic variants (2 cases were *3/*3, 1 case was *2/*3), and the others were all heterozygous. The prevalence of NUDT15 non-functional alleles was significantly higher in SMNs compared to that of non-SMN cases (P = 0.012). Conclusion: Our study indicated the NUDT15 hypomorphic variant alleles could be a risk of SMNs after ALL treatment with 6-MP. NUDT15 heterozygotic variants carriers are generally tolerable of 6-MP, and are usually treated with normal or slightly low-dose of 6-MP. However, our results suggested that standard adjustment of 6-MP in maintenance therapy might cause potential overdose of 6-MP for cases with NUDT15 variants, leading to increased risk of SMNs. To certify it, a higher number of study samples and somatic samples analysis of 6-MP induced SMNs are required. To obtain the best long-term event-free survival probability, it might be necessary to reduce the risk of SMNs development without compromising therapeutic effect by further optimal adjustment of 6-MP dose (or alternative agents). Disclosures No relevant conflicts of interest to declare.