Total body irradiation is a crucial risk factor for developing secondary carcinomas after allogeneic hematopoietic stem cell transplantation in childhood.

Allogeneic hematopoietic stem cell transplantation (HSCT) has become a standard part of therapy for a variety of malignant and non-malignant disorders. With improved outcomes after HSCT, increasing attention has been drawn to late complications in long-term survivors. The development of secondary malignancies is recognized as one of the most serious complications. We have evaluated data from 426 patients (272 males, 154 females) who underwent allogeneic transplantation at a median age of 7.9 years from 1989 till 2017 and were alive more than one year after transplantation for the occurrence of secondary solid tumors. We have documented the occurrence of secondary solid tumors in 20 patients (4.7%). The median duration of the development of secondary solid cancer from HSCT was 11.7 (range, 5.4-21.5 years). 18 out of 20 patients (90%) had total body irradiation (TBI) 12-14.4 Gy as a part of a conditioning regimen. All but two had transplantation for malignant disease. All patients underwent surgery and/or chemo-radiotherapy. Eighteen are alive, and two died due to the progression of their secondary malignancy. The most frequent solid cancer was thyroid carcinoma (n=9). Cumulative incidence of secondary solid cancer in all groups was 15.2±3.9%, in a group using TBI based regimen 34.7±8.9%, in non-TBI (only chemo) group was 1.5±1.1%. Overall, the cumulative incidence is statistically significantly different between the TBI based and non-TBI (chemo only) group. The incidence and number of complications following allogeneic HSCT in childhood are increasing in time. The early diagnosis of secondary malignancies is one of the key tasks of long-life multidisciplinary post-transplant care.

Blastic plasmacytoid dendritic cell neoplasm: First retrospective study in the Czech Republic.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with aggressive behavior and poor prognosis. We present the first retrospective analysis mapping its incidence and therapeutic outcomes in patients diagnosed and treated from 2000 to 2017 in the Czech Republic. The cohort comprised 14 patients (10 males, 4 females) with a median age at diagnosis of 39 years (range, 5-68 years). Initially, skin involvement was noted in 10 (71%) patients and bone marrow infiltration was present in 9 (64%). The first complete remission was achieved in 6/14 (43%) patients after acute lymphoblastic leukemia/lymphoma induction therapy and in 3/14 (21%) patients after acute myeloid leukemia regimen. Nine patients underwent allogeneic hematopoietic cell transplantation, with two patients achieving the first complete remission only after allogeneic transplantation. Patients undergoing allogeneic hematopoietic cell transplantation had longer overall survival than those treated without transplantation (the median survival over the period 16.4 vs. 8.1 months). Relapse of the disease was a significant predictor of mortality (p=0.05). Over the study period, patients' survival ranged from 3.3 to 44.2 months, with a median overall survival of 13 months. Our results revealed an effectivity of allogeneic hematopoietic cell transplantation on complete remission achievement in refractory/relapsed disease. The study aimed to present the actual data from the Czech Republic and thus contribute to a global understanding of BPDCN.

Trends in incidence of childhood cancers in the Czech Republic: population- based analysis of national registries (1994-2014).

The purpose of this study is to summarize incidence and trends in the pediatric cancer burden in the Czech Republic over the period 1994-2014. The recently established Childhood Cancer Registry was combined with retrospective data from the Czech National Cancer Registry to analyze the annual patterns of incidence and long-term trends of pediatric cancer patients aged 0-14 years diagnosed between 1994 and 2014. Malignancies were classified according to the International Classification of Childhood Cancer. The distribution of incidence was stratified according to gender, age at diagnosis, type of cancer and geographic area. Annual age-standardized rates were adjusted using the world standard population. Changes over time were quantified as the average annual percentage change. This analysis comprised records of 5,605 children diagnosed with cancer within the period 1994-2014, annually 267 records on average; the overall age-standardized average annual incidence rate was 169 cases per million. Boys were affected more frequently than girls: the M/F crude incidence ratio was 1.2:1. The highest incidence rates were observed for ICCC groups I (27.8%), III (21.8%), II (12.4%) and IV (7.8%); other groups formed 30.2%. There are significant differences in the geographic distribution of incidence between regions. A borderline statistically significant increase (0.6%) in the overall average annual percentage change was detected between 1994 and 2014 (95% CI: 0.01 to 1.12; p = 0.05). This study provides reliable recent information on trends in the incidence of childhood cancers in the Czech Republic.

Improved outcome for children and adolescent with acute lymphoblastic leukemia in the first decade of the 21st century: A report from the Slovak Republic.

Our aim was to analyze event-free (EFS) and overall survival (OS) among children and adolescents with acute lymphoblastic leukemia (ALL) treated with International BFM Intercontinental trial (ALL IC 2002) therapy in the Slovak Republic. In total, 280 children and adolescent age 1 to 18 years were treated with ALL IC BFM 2002 based therapy from 2002 to 2012, which was divided into two periods. During 2002-2007, when patients were actively enrolled in the ALL IC-BFM 2002 trial, and during 2008-2012 when the trial was closed and patients were treated with the same therapy without randomization. Five-year EFS and OS rates were 79% (+/- 2.6%) and 86% (+/- 2.1%), respectively, similar to results obtained in the ALL-BFM 95 trial, which was the basis for ALL IC BFM 2002 therapy. The EFS (p<0.012) and OS (p<0.003) were significantly better than the prior Slovak experience in 1997-2001. Survival is improved in standard and intermediate risk groups, including those age 1 to 6 years, and older; with B-cell or T-cell immunophenotype, and is also excellent for those with good early response. The rate of death in induction, cumulative incidence of death in complete remission and of relapse decreased. However, outcome was suboptimal for patients in the high risk group. Current EFS and OS rates for children and adolescents with ALL in the Slovak Republic resembled those obtained in Western Europe as a result of clinical trial participation, and clinical experience acquired with intensive BFM type treatment.

[Nephroblastoma -  30-years period of its treatment in the University Hospital Motol, Prague]. / Nefroblastom -  30 let lécby ve Fakultní nemocnici v Motole.

INTRODUCTION: Nephroblastoma (Wilms tumor - WT) is the most common solid tumor of kidney in children. We present treatment development of WT at the Department of Pediatric Hematology and Oncology, Charles University in Prague, 2nd Faculty of Medicine and University Hospital Motol (KDHO) in the Czech Republic over 30 years. Patients that were treated prior to access to the International Society of Pediatric Oncology (SIOP) protocols are considered to be the historical group, then we have patients treated according to SIOP 9, SIOP 93-01 and SIOP 2001 protocols as full participants of SIOP studies. PATIENTS AND METHODS: Between January 1980 and April 2009, we treated 330 patients with WT at KDHO: 91 patients in historical group (1980-1988), 94 pts in SIOP 9 (1988-1993), 80 pts in SIOP 93-01 (1994-2001) and 65 pts in SIOP 2001 (2002-2009). Overall survival (OS) and event-free survival (EFS) were analyzed by Kaplan-Meier test. RESULTS: The overall ten-year EFS was 81.2% and OS 87.6%. Fifty-eight patients from the 330 (17.6%) had metastases at diagnosis, EFS without metastatic process was 84.6% compared to 65.4% with metastasis presented at diagnosis (p = 0.0003), OS was 70.7% compared to 91.2% (p < 0.0001). One hundred and seventy patients (51.5%) were treated with preoperative chemotherapy and/or radiotherapy, whereas 158 patients (47.5%) underwent primary nephrectomy; EFS and OS did not differ: neoadjuvant vs primary nephrectomy EFS was 81.2% vs 80.9% (p = 0.85), OS 89.4% vs 85.4% (p = 0.38). Sixty (18%) patients experienced disease recurrence; OS after relapse was 33%. In the historical group, EFS and OS were 85.7% and 91.2%. In patients treated according to the SIOP 9 protocol, EFS and OS were 68.1% and 74.5%, resp. In patients treated according to SIOP 93-01, it was 83.6% and 93.7%, resp. and in patients treated according to 87 SIOP 2001, it was 7% and 95.4% (p = 0.001 and p = 0.0008), resp. CONCLUSION: WT is a well treatable disease. The aim for the future is to maintain the current very good survival while minimizing the treatment intensity.

Minimal residual disease and outcome characteristics in infant KMT2A-germline acute lymphoblastic leukaemia treated on the Interfant-06 protocol.

BACKGROUND: The outcome of infants with KMT2A-germline acute lymphoblastic leukaemia (ALL) is superior to that of infants with KMT2A-rearranged ALL but has been inferior to non-infant ALL patients. Here, we describe the outcome and prognostic factors for 167 infants with KMT2A-germline ALL enrolled in the Interfant-06 study. METHODS: Univariate analysis on prognostic factors (age, white blood cell count at diagnosis, prednisolone response and CD10 expression) was performed on KMT2A-germline infants in complete remission at the end of induction (EOI; n = 163). Bone marrow minimal residual disease (MRD) was measured in 73 patients by real-time quantitative polymerase chain reaction at various time points (EOI, n = 68; end of consolidation, n = 56; and before OCTADAD, n = 57). MRD results were classified as negative, intermediate (<5∗10-4), and high (≥5∗10-4). RESULTS: The 6-year event-free and overall survival was 73.9% (standard error [SE] = 3.6) and 87.2% (SE = 2.7). Relapses occurred early, within 36 months from diagnosis in 28 of 31 (90%) infants. Treatment-related mortality was 3.6%. Age <6 months was a favourable prognostic factor with a 6-year disease-free survival (DFS) of 91% (SE = 9.0) compared with 71.7% (SE = 4.2) in infants >6 months of age (P = 0.04). Patients with high EOI MRD ≥5 × 10-4 had a worse outcome (6-year DFS 61.4% [SE = 12.4], n = 16), compared with patients with undetectable EOI MRD (6-year DFS 87.9% [SE = 6.6], n = 28) or intermediate EOI MRD <5 × 10-4 (6-year DFS 76.4% [SE = 11.3], n = 24; P = 0.02). CONCLUSION: We conclude that young age at diagnosis and low EOI MRD seem favourable prognostic factors in infants with KMT2A-germline ALL and should be considered for risk stratification in future clinical trials.

[Clinical relevance of chromosomal aberrations in bone and soft tissue tumors in children and young adults]. / Klinický význam chromozomálních zmen u nádoru kostí a mekkých tkání detí a mladistvých.

BACKGROUND: We present the results of a cytogenetic and molecular cytogenetic analysis of a series of patients with bone and soft tissue tumors. PATIENTS ANDMETHODS: We analyzed a cohort of 26 patients with Ewing sarcoma/PNET, 15 patients with rhabdomyosarcoma, 5 with synovial sarcoma and one patient with an undifferentiated sarcoma using the cytogenetic and molecular cytogenetic techniques M-FISH and arrayCGH. RESULTS: We found nonrandom chromosomal structural and numerical changes with diagnostic and prognostic relevance in most patients. Eight patients with ES/PNET had only a t(11;22)(q24;q12), eight patients had secondary aberrations as well and six had only secondary aberrations. In the RMS patients we detected the t(1;13)(p36;q14) once and the t(2;13)(q35;q14) four times, both of them characteristic for the alveolar subtype with poor prognosis and numerical aberrations, characteristic for the embryonal subtype, in five patients. Four patients with synovial sarcoma had the diagnostic t(X;18)(p11.2;q11.2), one of them had a complex karyotype with a complex t(X;18;21) (p11.2;q11.2;q11.2) together with t(2;5)(q24-32;p13-14) and t(12;20)(p11;q13). We correlated the karyotype of cancer cells with histopathologic morphologic analysis, clinical outcome and foreign published results. CONCLUSION: Cytogenetic and molecular cytogenetic analysis is a valuable diagnostic tool in bone and soft tissue tumors, especially in less differentiated subtypes, and as such it should be an integral part of curative care.

[Radical surgery and intensive chemotherapy are necessary for successful treatment of osteosarcoma]. / Radikální operacní výkon a intenzivní chemoterapie jsou podmínkou úspesné lécby osteosarkomu.

BACKGROUND: We evaluated the therapeutic results in 44 patients (17 girls and 27 boys) with osteosarcoma from 1997 to 2006.Their average age was 12.8 years (2.5-20.2). 41 patients had localised disease and 3 had primary metastases. PATIENTS AND METHODS: We treated our 44 patients using CCG 7921 POG 9351 INT 0133, the therapeutic protocol of the North American cooperative Children's Oncology Group.The median of the follow up was 5.5 years (2-11 years). RESULTS: 40 patients went into complete remission. 19 patients suffered relapses. Of these, 17 patients died - 15 progressed, 1 died due to treatment-related toxicity, 1 died due to secondary acute myeloid leukaemia. As a whole, the patients had a 5-year overall survival rate (OS) of 58.4% and a 5-year event free survival rate (EFS) of 46.7%. The patients with localised extremity osteosarcoma (n = 40) had a 5-year EFS rate of 51%. The patients with good histological response (n = 22) had a 5-year EFS rate of 63.6%, while patients with poor histological response (n = 18) achieved a 5-year EFS rate of 30.5% (p = 0.009). CONCLUSION: The results of treatment of patients with localised extremity osteosarcoma and patients with good histological response to preoperative treatment were very good. The prognosis of patients with axial localisation and metastatic involvement was poor.

Epidemiological Trends for Childhood and Adolescent Cancers in the Period 1994-2016 in the Czech Republic.

BACKGROUND: Our study aimed to evaluate incidence and mortality trends for childhood and adolescent cancers in the period 1994-2016 in the Czech Republic. MATERIAL AND METHODS: Data on childhood cancers, which are recorded in the Czech National Cancer Registry, were validated using a clinical database of childhood cancer patients and combined with data from the National Register of Hospitalised Patients and with data from death certificates. These validated data were used to establish cancer incidence. Data from death certificates were used to evaluate long-term trends in mortality. Incidence and mortality trends were assessed by the average annual percentage change. RESULTS: The age-standardised incidence trend for childhood cancers (i.e. those diagnosed in patients aged 0-19 years) showed a statistically significant slight long-term increase in the number of new cases, +0.5% annually on average (p < 0.01), more specifically an increase of +0.6% in girls and a statistically insignificant decrease of 0.1% in boys. In children aged 0-14 years, other malignant epithelial neoplasms and malignant melanomas showed the largest statistically significant average annual increase in incidence (+4.9%; p < 0.01), followed by central nervous system neoplasms (+1.3%; p < 0.05). Lymphomas, by contrast, showed a statistically significant average annual decrease in incidence in children aged 0-14 years (2.1%; p < 0.01). In adolescents aged 15-19 years, other malignant epithelial neoplasms and malignant melanomas also showed a statistically significant average annual increase in incidence (+5.2%; p < 0.01), followed by central nervous system neoplasms (+1.5%; p < 0.05). Mortality trends showed a statistically significant long-term decrease: on average, 5.1% annually in children aged 0-14 years (p < 0.01), and 3.7% annually in adolescents aged 15-19 years (p < 0.01). CONCLUSION: Available data make it possible to analyse long-term trends in childhood cancer incidence and mortality.

B-cell reconstitution after allogeneic SCT impairs minimal residual disease monitoring in children with ALL.

Minimal residual disease (MRD) detection using quantification of clone-specific Ig or TCR rearrangements before and after transplantation in children with high-risk ALL is an important predictor of outcome. The method and guidelines for its interpretation are very precise to avoid both false-negative and -positive results. In a group of 21 patients following transplantation, we observed detectable MRD positivities in Ig/TCR-based real-time quantitative PCR (RQ-PCR) leading to no further progression of the disease (11 of 100 (11%) total samples). We hypothesized that these positivities were mostly the result of nonspecific amplification despite the application of strict internationally agreed-upon measures. We applied two non-self-specific Ig heavy chain assays and received a similar number of positivities (20 and 15%). Nonspecific products amplified in these RQ-PCR systems differed from specific products in length and sequence. Statistical analysis proved that there was an excellent correlation of this phenomenon with B-cell regeneration in BM as measured by flow cytometry and Ig light chain-kappa excision circle quantification. We conclude that although Ig/TCR quantification is a reliable method for post transplant MRD detection, isolated positivities in Ig-based RQ-PCR systems at the time of intense B-cell regeneration must be viewed with caution to avoid the wrong indication of treatment.

Haematopoietic stem cell transplantation in children in eastern European countries 1985-2004: development, recent activity and role of the EBMT/ESH Outreach Programme.

The paediatric population of 19 eastern European countries amounts to approximately 80 million children. Between 1985 and 2004, the number of centres performing haematopoietic stem cell transplantation (HSCT) in children increased from 1 in 1985 to 24 in 2004 and the yearly number of paediatric HSCTs rose from 1 in 1985 to 291 in 2004. Altogether, 2342 transplants were reported to the EBMT Registry during this time (Poland 953, Czech Republic 501, Hungary 269, Russia 217, Croatia 129, Slovakia 71, Bulgaria 45, Serbia and Montenegro 36, Slovenia 35, Belarus 33, Estonia 26, Lithuania 19 and Romania 8). Out of the 2342 transplants, 1487 (63.5%) transplants were performed in paediatric centres, 453 (19.3%) in centres for adults and 402 (17.2%) in combined centres. The number of children who underwent autologous HSCT (auto-HSCT) was 1053 (45%), whereas 1289 (55%) underwent allogeneic HSCT (allo-HSCT). Peripheral blood (PB) was the source of HSC in 751 (71.3%) out of 1053 auto-transplants, BM in 246 (23.4%) and PB+BM in 52 (4.9%) (missing data in 4, that is, 0.4%). Among the 1289 allo-transplants, BM was the source of HSC in 827 (64.3%), PB in 416 (32.3%), CB in 23 (1.8%) and BM+PB in 14 (1.1%) (missing data in 9, that is, 0.7%). Among them, 728 (57.4%) obtained HSC from MSD, 322 (25.4%) from UD, 195 (15.4%) from MMFD, 14 (1.1%) from CB family donor and 9 (0.7%) from CB unrelated donor (missing data in 21, that is, 1.6%). The number of children who underwent allo-HSCT for malignant diseases was 945 (73.4%), including ALL 376 (29.2%), AML 234 (18.2%), CML 177 (13.8%), MDS 97 (7.5%), NHL 35 (2.7%) and other malignancy 31 (2.4%), while 339 (26.9%) for non-malignant disorders, including SAA 202 (15.7%), immunodeficiencies 61 (4.7%), inborn errors of metabolism 40 (3.1%), Fanconi anaemia 19 (1.5%) and others 17 (1.3%). Out of 1053 recipients of auto-HSCT, 168 (16%) were transplanted for neuroblastoma, 129 (12.2%) for NHL, 124 (11.7%) for AML, 114 (10.8%) for ALL, 109 (10.4%) for Hodgkin's disease, 62 (5.9%) for Ewing's sarcoma, 16 (1.5%) for CNS tumour, 15 (1.4%) for Wilms tumour and 316 (30%) for other tumours. In 2001, the EBMT in collaboration with the European School of Haematology (ESH) developed the Outreach Programme, that is a programme supporting emerging HSCT projects and transplant centres in countries with limited resources and/or experience.

Childhood secondary ALL after ALL treatment.

Data on secondary acute lymphoblastic leukaemia (sALL) following ALL treatment are very rare. However, the incidence might be underestimated as sALLs without a significant lineage shift might automatically be diagnosed as relapses. Examination of immunoglobulin and T-cell receptor gene rearrangements brought a new tool that can help in discrimination between relapse and sALL. We focused on the recurrences of childhood ALL to discover the real frequency of the sALL after ALL treatment. We compared clonal markers in matched presentation and recurrence samples of 366 patients treated according to the Berlin-Frankfurt-Munster (BFM)-based protocols. We found two cases of sALL and another three, where the recurrence is suspicious of being sALL rather than relapse. Our proposal for the 'secondary ALL after ALL' diagnostic criteria is as follows: (A) No clonal relationship between diagnosis and recurrence; (B) significant immunophenotypic shift--significant cytogenetic shift--gain/loss of a fusion gene. For the sALL (A) plus at least one (B) criterion should be fulfilled. With these criteria, the estimated frequency of the sALL after ALL is according to our data 0.5-1.5% of ALL recurrences on BFM-based protocols. Finally, we propose a treatment strategy for the patients with secondary disease.

Prognosis of pediatric patients transplanted for Ph+ chronic myeloid leukemia in the period from 1989 to 2006 in the Czech Republic.

Chronic myeloid leukemia (CML) is a myeloproliferative disorder caused by clonal proliferation of primitive hematopoietic stem cell. The median age at diagnosis is 55 to 60 years with less than 10% of patients younger 20 years. Incidence of CML in children in the Czech Republic is 0.106 cases/100 thousands per year. Here we report outcome of 38 pediatric patients (median age 12.5 years; range 1.8 - 17.3) with Ph-positive CML diagnosed between years 1989 to 2006. Primarily chronic phase of the disease was diagnosed in 32 (84%) patients. 32 (84.2%) patients underwent hematopoietic stem cell transplantation (HSCT) with the median age at transplantation of 14.9 years (range 6.9 - 20.5 years). Out of transplanted patients 16 (50%) obtained graft from unrelated donor, 13 (41%) from matched sibling donor, 2 from haploidentical family donor and autologous transplantation has been performed in one case. 6 patients were not transplanted, 4 of them died (median 1.2 years from diagnosis), 2 are alive 0.6 and 17.8 years from the diagnosis. Overall survival (OS) in 25 patients after HSCT at our department during the whole period is 66.7% with 15/16 being in stable continuous molecular-genetic remission (94%). During the period of time results of transplantations have been significantly improved (p=0.0071). OS after HSCT until year 1997 is 25% while from year 1998 until now is 87.5%. All centers OS of patients after HSCT is 71%. Results of HSCT in children with CML obtained from the year 1998 at our center are fully comparable with results achieved in large and experienced centers. HSCT remains the only proven and effective method for the treatment of CML. Clinical studies assessing the role of tyrosine kinase inhibitors in children instead of early HSCT should be planned carefully in order to avoid sub-optimal outcomes.

[Therapy of acute promyelocytic leukemia in Czechia: results and analysis of prognostic factors]. / Lécba akutní promyelorytárni leukemie v Cesku: výsledky a analýza prognostických faktoru.

We have retrospectively evaluated a cohort of 144 patients (including 17 pediatric ones) with de novo acute promyelocytic leukemia registered in databases of institutions cooperating within the CELL group (The Czech Leukemia Study Group for Life). The patients were diagnosed according to WHO criteria from 1989 until 2006. The aim was to check how well fared the patients, the majority of whom was not included into clinical trials, in real life. Of 140 evaluable patients, 97 (69.3%) attained complete remission (CR). The projected overall survival (OS) 4 years after diagnosis was 58.9%, and 55.3% at 6 years. In 8 patients (6.0%), no antileukemic therapy at all was given (either they died shortly after admission to the ward or therapy was not feasible due to their clinical status). Of 125 patients with documented commencement of some kind of therapy, 96 (76.8%) achieved CR. Of 102 patients with induction treatment with a combination of anthracycline and tretinoin (ATRA), 84 individuals (82.4%) attained CR (typically, this cohort might have been subjected to clinical trials). This result was better than that of patients treated by chemotherapy only (n = 15; CR 46.7%; P = 0.003) or by ATRA monotherapy (n = 13; CR 62.5%; P = 0.17). Another parameter with a significant impact on attaining CR was the leukocyte (WBC) count at diagnosis: its median values in patients achieving and not achieving CR were 2.1 and 24.0 x 10(9)/l, respectively (P < 0.0001). The WBC counts affected OS as well (P = 0.0001). However, when only patients after attaining CR were evaluated, the initial WBC counts no longer affected OS (P = 0.18). Achieving CR was also influenced by the performance status (PS) 0-1 (P = 0.005), which was in turn closely correlated to WBC counts (P = 0.0006). Additional factors (most likely connected with leukocytosis) influenced attaining CR with borderline statistical significance: e.g. FAB M3v morphology, LDH serum level, fibrinogen level, presence of internal tandem duplication (ITD) of the FLT3 gene (which was strongly associated with leukocytosis and also with the short PML/RARalpha transcript resulting from the bcr3 break in the PML gene). It may be speculated that FLT3-ITD is just one of the possible factors that lead to leukocytosis. The platelet counts at diagnosis had no impact on entering CR. Thus, we have not validated the current PETHEMA risk stratification in distinguishing intertermediate and low risk patients. Our study points to a significant difference of the results obtained in real life and of the results that could be achieved in patients who were fit to enter clinical trials. Among the prognostic factors, the most important one was the WBC count, the PS (which is highly affected by the WBC count), and feasibility of administration of the most potent induction therapy with anthracyclines and ATRA.

Imatinib mesylate is effective in children with chronic myelogenous leukemia in late chronic and advanced phase and in relapse after stem cell transplantation.

A multicentric phase 2 study was conducted to determine the efficiency and the tolerance of imatinib mesylate in children with chronic myelogenous leukemia (CML) in advanced phase of the disease, in relapse after stem cell transplantation, or in case of failure to an interferon alpha-based regimen. In all, 30 children from eight European countries were enrolled. In 18 children assessable for hematologic response, imatinib mesylate induced complete hematologic response in eight (80%) of the 10 patients included in chronic phase and in six (75%) of eight enrolled in advanced phase of the disease with acceptable toxicity. In 27 patients assessable for cytogenetic response, imatinib mesylate induced disappearance of Philadelphia chromosome-positive bone marrow cells in 12 (60%) of 20 children included in chronic phase and in two (29%) of seven included in advanced phase. A reduction of the bcr-abl/abl ratio to less than 10(-4) was achieved in 11 (50%) of the children included in chronic phase. Estimated 12-month overall survival rate was 95% (95% CI, 87-100%) for the patients included in chronic phase and 75% (95%CI, 45-100%) for those enrolled in advanced phase. Imatinib mesylate is well tolerated and molecular remission can be achieved in children with CML.

Wilms' tumor gene 1 (WT1) expression in childhood acute lymphoblastic leukemia: a wide range of WT1 expression levels, its impact on prognosis and minimal residual disease monitoring.

Wilms' tumor gene 1 (WT1) is overexpressed in the majority (70-90%) of acute leukemias and has been identified as an independent adverse prognostic factor, a convenient minimal residual disease (MRD) marker and potential therapeutic target in acute leukemia. We examined WT1 expression patterns in childhood acute lymphoblastic leukemia (ALL), where its clinical implication remains unclear. Using a real-time quantitative PCR designed according to Europe Against Cancer Program recommendations, we evaluated WT1 expression in 125 consecutively enrolled patients with childhood ALL (106 BCP-ALL, 19 T-ALL) and compared it with physiologic WT1 expression in normal and regenerating bone marrow (BM). In childhood B-cell precursor (BCP)-ALL, we detected a wide range of WT1 levels (5 logs) with a median WT1 expression close to that of normal BM. WT1 expression in childhood T-ALL was significantly higher than in BCP-ALL (P<0.001). Patients with MLL-AF4 translocation showed high WT1 overexpression (P<0.01) compared to patients with other or no chromosomal aberrations. Older children (> or =10 years) expressed higher WT1 levels than children under 10 years of age (P<0.001), while there was no difference in WT1 expression in patients with peripheral blood leukocyte count (WBC) > or =50 x 10(9)/l and lower. Analysis of relapsed cases (14/125) indicated that an abnormal increase or decrease in WT1 expression was associated with a significantly increased risk of relapse (P=0.0006), and this prognostic impact of WT1 was independent of other main risk factors (P=0.0012). In summary, our study suggests that WT1 expression in childhood ALL is very variable and much lower than in AML or adult ALL. WT1, thus, will not be a useful marker for MRD detection in childhood ALL, however, it does represent a potential independent risk factor in childhood ALL. Interestingly, a proportion of childhood ALL patients express WT1 at levels below the normal physiological BM WT1 expression, and this reduced WT1 expression appears to be associated with a higher risk of relapse.

Next-generation sequencing indicates false-positive MRD results and better predicts prognosis after SCT in patients with childhood ALL.

Minimal residual disease (MRD) monitoring via quantitative PCR (qPCR) detection of Ag receptor gene rearrangements has been the most sensitive method for predicting prognosis and making post-transplant treatment decisions for patients with ALL. Despite the broad clinical usefulness and standardization of this method, we and others have repeatedly reported the possibility of false-positive MRD results caused by massive B-lymphocyte regeneration after stem cell transplantation (SCT). Next-generation sequencing (NGS) enables precise and sensitive detection of multiple Ag receptor rearrangements, thus providing a more specific readout compared to qPCR. We investigated two cohorts of children with ALL who underwent SCT (30 patients and 228 samples). The first cohort consisted of 17 patients who remained in long-term CR after SCT despite having low MRD positivity (<0.01%) at least once during post-SCT monitoring using qPCR. Only one of 27 qPCR-positive samples was confirmed to be positive by NGS. Conversely, 10 of 15 samples with low qPCR-detected MRD positivity from 13 patients who subsequently relapsed were also confirmed to be positive by NGS (P=0.002). These data show that NGS has a better specificity in post-SCT ALL management and indicate that treatment interventions aimed at reverting impending relapse should not be based on qPCR only.

Outcome of relapsed infant acute lymphoblastic leukemia treated on the interfant-99 protocol.

This corrects the article DOI: 10.1038/leu.2015.246.

Low mortality of children undergoing hematopoietic stem cell transplantation from 7 to 8/10 human leukocyte antigen allele-matched unrelated donors with the use of antithymocyte globulin.

Human leukocyte antigen (HLA)-matched sibling donor hematopoietic stem cell transplantation (HSCT) is available for only approximately 30% patients needing HSCT. Use of alternative donors is associated with a high incidence and severity of graft-versus-host disease (GVHD). Here we report our experience with GVHD prophylaxis using pre-transplant rabbit antithymocyte globulin (rATG), in addition to post transplant cyclosporin A and methotrexate. Seventy-five children received unmanipulated grafts from 7 to 10/10 HLA allele-matched unrelated donors. Median follow-up was 25 months (range, 6-65 months). Only 2/75 patients (2.5%) developed acute GVHD grades III-IV, and 17/75 (25%) developed extensive chronic GVHD. Overall survival was 79%. It was similar in patients receiving grafts from 7 or 8/10 to 9 or 10/10 allele-matched donors, and similar in patients receiving peripheral blood stem cells and marrow. Six (11%) patients died owing to relapse, and 10 (13%) due to transplant-related complications. The addition of rATG appears to result in a low incidence of severe GVHD and overall mortality.