Characteristics and treatment results of refractory and relapsed acute myeloid leukaemia in paediatric patients treated in Polish Paediatric Leukaemia/Lymphoma Study Group institutions according to the Protocol Acute Myeloid Leukaemia Berlin-Frankfurt-Munster 2012 and a review of novel treatment possibilities in paediatric acute myeloid leukaemia.

Introduction: This study aimed to present the clinical features and results of treatment of patients diagnosed with refractory or relapsed acute myeloid leukaemia (AML) in Polish Paediatric Leukaemia/Lymphoma Study Group (PPL/LSG) institutions, treated in accordance with the Protocol Acute Myeloid Leukaemia Berlin-Frankfurt-Munster 2012, as their first-line therapy. Material and methods: The outcome data of 10 patients with refractory AML (median age 9.5 years) and 30 with relapsed AML (median age 12 years) were analysed retrospectively. Re-induction was usually based on idarubicin, fludarabine, and cytarabine along with allogeneic haematopoietic stem cell transplant (allo-HSCT) in 5 patients with refractory AML and 7 relapsed AML children. Results: 37.5% (3/8) of refractory AML patients achieved second complete remission second complete remission (CRII). One of ten patients (1/10; 10%) was alive and stayed in complete remission for 34 months after the allo-HSCT. The probability of 3-year event-free survival (pEFS) in this group was 0.125 ±0.11. In the group of relapsed AML patients, the CRII was achieved in 9 patients (34%), and the probability of survival was: pEFS = 0.24 ±0.08; probability overall survival (pOS) = 0.34 ±0.09, with significantly better results achieved in patients who underwent allo-HSCT (pOS = 0.54 ±0.14 vs. 0.08 ±0.08, p < 0.0001). Conclusions: The prognosis of refractory AML and the first AML recurrence in children who were first-line treated in PPL/LSG centres according to Protocol Acute Myeloid Leukaemia Berlin-Frankfurt-Munster 2012 is poor. Failures of re-induction treatment particularly result from difficulties in achieving remission. Allogeneic HSCT improves prognosis in children with refractory and first recurrent AML, under the condition it is performed in complete remission. Novel therapeutic approaches are needed to increase the remission rate and improve the outcomes.

High Frequency of Fusion Gene Transcript Resulting From t(10;11)(p12;q23) Translocation in Pediatric Acute Myeloid Leukemia in Poland.

11q23/MLL rearrangements are frequently detected in pediatric acute myeloid leukemia. The analysis of their clinical significance is difficult because of the multitude of translocation fusion partners and their low frequency. The presence of t(10;11)(p12;q23) translocation was previously identified in pediatric acute myelogenous leukemia (AML). It is considered as the second most common translocation detected in pediatric 11q23/MLL-rearranged (present KMT2A) AML, after t(9;11)(p22;q23). The presence of the above translocation was previously identified as an unfavorable prognostic factor. Since June 2015, the Polish Pediatric Leukemia/Lymphoma Study Group has applied the therapeutic protocol requiring extensive diagnostics of genetic changes in pediatric AML. Until November 2019, molecular genetic studies were performed in 195 children with diagnosed AML to identify carriers of fusion gene transcripts for 28 most common chromosomal translocations in acute leukemia. The fusion gene transcript for translocation t(10;11)(p12;q23) involving MLL gene was detected with unexpectedly high frequency (8.9%) in our research. It was the highest frequency of all detected MLL rearrangements, as well as other detected fusion gene transcripts from chromosomal aberrations characteristic for AML. It seems that chromosomal aberration between chromosomes 10 and 11 can be relatively frequent in some populations. Paying attention to this fact and ensuring proper genetic diagnosis seem to be important for appropriate allocation of patients to risk groups of pediatric AML treatment protocols.

Treatment Outcome and the Genetic Characteristics of Acute Promyelocytic Leukemia in Children in Poland From 2005 to 2018.

Background: The aim of the study was to analyze the treatment outcome and genetic characteristics of acute promyelocytic leukemia (APL) in children in Poland from 2005 to 2018. Methods: All 41 patients diagnosed with APL in Poland during the analysis period were eligible for the study. In period I (2005-2015), 33 patients were treated with chemotherapy and all-trans retinoic acid (ATRA), and in period II (2015-2018), 3 patients (high risk) received induction chemotherapy with ATRA and arsenic trioxide (ATO), and 5 patients (standard risk) received ATRA and ATO without chemotherapy. Results: Probability of 5-years overall survival (OS), event-free survival (EFS), and relapse-free survival (RFS) was 0.819 ± 0.069, 0.831 ± 0.063, and 0.961 ± 0.037, respectively, in the whole cohort. Four (11%) early deaths were observed. One patient died of severe infection in the course of disease progression. Relapse occurred in one patient, who died finally because of disease progression. All events occurred in the patients from period I. Variant APL was identified in one patient (successfully treated with chemotherapy with ATRA) and complex translocation in one patient (the only patient with relapse). Additional chromosomal aberrations were found in 26% of patients and FLT3-ITD mutation was detected in 44% of patients; none of those changes influenced clinical outcome. Conclusion: Treatment outcome in the analyzed group is similar to the results reported by other study groups. The main cause of death was coagulation disorders in the early stage of disease. Early, accurate diagnosis followed by specific treatment enables the reduction in the number of early deaths.

Imatinib in the treatment of chronic myeloid leukemia in children and adolescents is effective and well tolerated: Report of the Polish Pediatric Study Group for the Treatment of Leukemias and Lymphomas.

BACKGROUND: Chronic myeloid leukemia (CML) constitutes only 2-3% of all leukemias in pediatric patients. Philapelphia chromosome and BCR-ABL fusion are genetic hallmarks of CML, and their presence is crucial for targeted molecular therapy with tyrosine kinase inhibitors (TKIs), which replaced hematopoietic stem cell transplantation (HSCT) as a standard first-line therapy. The disease in pediatric population is rare, and despite molecular and clinical similarities to CML in adults, different approach is needed, due to the long lifetime expectancy and distinct developmental characteristics of affected children. OBJECTIVES: The objective of this study is to evaluate treatment with imatinib in Polish pediatric patients with CML. MATERIAL AND METHODS: We analyzed the results of treatment with imatinib in 57 pediatric patients (June 2006 - January 2016) from 14 Polish pediatric hematology and oncology centers. RESULTS: In the study group, 40 patients continued imatinib (median follow-up: 23.4 months), while in 17 the treatment was terminated (median follow-up: 15.1 months) due to therapy failure. In the latter group, 13 patients underwent HSCT, while 4 switched to second-generation TKIs. The 5-year overall survival rate (OS) in the study group was 96%, and the 5-year event-free survival (EFS) was 81%. CONCLUSIONS: Our results confirm that the introduction of TKI therapy has revolutionized the treatment of CML in the pediatric population by replacing the previous method of treatment with HSCT and allowing a high percentage of OS and EFS.

Outcome of refractory and relapsed acute myeloid leukemia in children treated during 2005-2011 - experience of the Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG).

AIM OF THE STUDY: Recent studies showed relatively better outcome for children with refractory (refAML) and relapsed acute myeloid leukemia (relAML). Treatment of these patients has not been unified within Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG) so far. The goal of this study is to analyze the results of this therapy performed between 2005-2011. MATERIAL AND METHODS: The outcome data of 16 patients with refAML and 62 with relAML were analyzed retrospectively. Reinduction was usually based on idarubicine, fludarabine and cytarabine with allogenic hematopoietic stem cell transplant (alloHSCT) in 5 refAML and 30 relAML children. RESULTS: Seventy seven percent relAML patients entered second complete remission (CR2). Five-year OS and disease-free survival (DFS) were estimated at 16% and 30%. The outcome for patients after alloHSCT in CR2 (63%) was better than that of those not transplanted (36%) with 5-year OS of 34% vs. 2-year of 7% and 5-year DFS of 40% vs. 12.5%. Second complete remission achievement and alloHSCT were the most significant predictors of better prognosis (p = 0.000 and p = 0.024). The outcome of refAML children was significantly worse than relAML with first remission (CR1) rate of 33%, OS and DFS of 25% at 3 years and 53% at 2 years, respectively. All survivors of refAML were treated with alloHSCT after CR1. CONCLUSIONS: The uniform reinduction regimen of the documented efficacy and subsequent alloHSCT in remission is needed to improve the outcome for ref/relAML children treated within PPLLSG. The focus should be on the future risk-directed both front and second line AML therapy.

Clinical factors in relapses of Wilms' tumor--results for the Polish Pediatric Solid Tumors Study Group.

BACKGROUND: The risk factors responsible for recurrences of Wilms' tumor (nephroblastoma) are still under discussion. The aim of the study was to analyze the relationship between relapses of Wilms' tumor and the patients' clinical history. MATERIAL AND METHODS: Clinical data from children registered in the Polish Pediatric Solid Tumors Study Group were analyzed. The clinical stages (CS), pathology variants (high risk: HR, intermediate risk: INT, and low risk: LOW) and chemotherapy regimens were correlated with the outcomes. RESULTS: Recurrences developed in 34 out of 288 (11.8%) patients with Wilms' tumor treated in accordance with International Society for Pediatric Oncology 2001 (SIOP 2001) protocols. Of these 34 patients, 11 initially had CS I, seven were at CS II, four were at CS III, 11 were at CS IV and one had CS V. There were eight patients with second recurrences; of these, seven were in the INT risk group and one in the high histological risk group. There was no correlation between age (p=0.256) or gender (p=0.538) and the risk of tumor recurrence. In the study group, seven out of 10 patients with local recurrences are alive; as are 13 out of 22 patients with distant recurrences (p=0.703). Those who died due to disease progression comprised six out of 26 patients with a first recurrence (four HR, two INT), and seven out of eight with a second recurrence (one HR, six INT). CONCLUSIONS: The prognosis after relapse in initially metastatic patients did not differ from that in patients who had primarily localized disease. The pathology variants probably had more significance.

Development of treatment and clinical results in childhood acute myeloid leukemia in Poland.

BACKGROUND: Since 1983 four consecutive unified regimens: acute myeloid leukemia-Polish pediatric leukemia/lymphoma study group (AML-PPLLSG) 83, AML-PPLLSG 94, AML-PPLLSG 98 and AML-BFM 2004 Interim, for AML have been conducted by the Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG). In this paper, we review four successive studies on the basis of acute myeloid leukemia-Berlin-Frankfurt-Munster (AML-BFM) protocol, in which a stepwise improvement of treatment outcome was observed. Treatment results of the last protocol AML-BFM 2004 Interim are presented in detail. METHODS: Three hundred and three patients with de novo AML were treated according to the AML-BFM 2004 Interim at 15 Polish centers from January 1, 2005 to June 30, 2011. A confrontation with previous treatment periods was based upon historical, already published data. RESULTS: In four consecutive periods, 723 children were eligible for evaluation (208, 83, 195, and 237, respectively). Complete remission rates in consecutive periods were: 71, 68, 81 and 87 %, respectively. The 5-year overall survival rates, event-free survival rates, and relapse-free survival rates were 33, 32, and 45%, respectively for AML-PPLLSG 83 regimen; 38, 36, and 53 % respectively for AML-PPLLSG 94 regimen; 53, 46, and 65 % respectively for AML-PPLLSG 98 regimen, and 63, 52, and 64 % for AML-BFM Interim 2004, respectively. Incidence of early deaths and that due to complications (mainly infections) in the first remission decreased over time from 22 to 4.6 % and from 10 to 5.9 %, respectively. CONCLUSIONS: Despite continuous improvement in the treatment outcome, the number of failures still remains too high. Further progress seemed to be possible due to continued cooperation of oncology centers within large international study groups.

[Treatment failure in children with acute myelocytic leukemia: over 25-year experience of Polish Pediatric Leukemia/Lymphoma Study Group with four consecutive unified treatment protocols for childhood acute myelocytic leukemia]. / Niepowodzenia leczenia w ostrej bialaczce szpikowej u dzieci: ponad 25-letnie doswiadczenia Polskiej Pediatrycznej Grupy ds. Leczenia Bialaczek i Chloniaków.

Four consecutive intensive unified regimens (BFM-AML-83, PGP-AML 94, PGP-AML 98 AML-BFM 2004 Interim) for acute myelocytic leukemia (AML) have been conducted by the Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG) since 1983. The last one, introduced four years ago is still active, and only preliminary result may be presented. There were 726 children with AML diagnosed (226, 102, 247 and 151 in the I, II , III and IV periods, respectively), and 603 of them were eligible for evaluation (208, 83, 195 and 117, respectively). Complete remission rates were: 71.4%, 67.5%, 81.4% and 87% in consecutive periods, respectively. Five-year overall survival (OS) and event-free survival (EFS) rates were: 33% and 32% for PGP-AML 83 regimen, 38% and 36% for PGP-AML 94 regimen, and 53% and 46% for PGP-AML 98 regimen, respectively. For AML-BFM Interim 2004 the 3-year OS and EFS were 57% and 57%, respectively. Despite continuous improvement of the treatment results, the number of failures have remained too high, but the pattern have changed in the following way: Early deaths (from diagnosis to 15 day of treatment) decreased only in the fourth period to 3%. "Aplasia deaths" (between day 15 and 42) decreased gradually from 16% in the first period to 1.5% and 2.2% in the third and in the fourth period, respectively. Deaths in remission decreased from 10% in first and second period to 3.5% at present. Number of non responders increased between first and second period from 6% to 18%, later decreased to 8.2% at present. These trends e.g. decrease of early death and treatment related mortality reflect both the better efficacy of antileukemic treatment and the improvement of supportive care.