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.

Infectious complications in children treated for hodgkin and non-hodgkin lymphomas in polish pediatric leukemia/lymphoma study group: incidence, epidemiology and etiology.

The objective of this nation-wide study was to evaluate the epidemiology and profile of bacterial (BI), viral (VI), and invasive fungal disease (IFD) in patients treated for non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL) between the years 2013-2015. In the analyzed period of time, within the studied group of 328 children diagnosed and treated for lymphomas, at least one infectious complication (IC) was diagnosed i.e. 39.3% children. In these patients there were 350 episodes of IC, therein 80.6% episodes of BI, 11.1% episodes of VI, and 8.3% episodes of IFD. In both groups, NHL and HL patients, a stable level of bacterial infections, with an increase in resistance rates, and increased levels of viral and fungal infections were observed. Profile of BI does not depend on lymphoma type, with predominance of Gram-negative bacteria and higher prevalence of MDR pathogens. The overall survival of lymphoma patients with IC was comparable for different types of infections.

Correction to: Health status of Polish children and adolescents after cancer treatment.

The first and family names of the authors were interchanged. The correct author names are now correctly presented in this article.

Health status of Polish children and adolescents after cancer treatment.

In the last 40 years, considerable progress was made in the treatment of childhood cancer. Nearly 80% of children achieve long-term clinical remission or are permanently cured. This improvement is however not without sacrifice. This is the first Polish study analyzing the general health status and epidemiology of organ late effects in the cohort of Polish childhood and adolescent cancer survivors monitored by doctors and registered in the on-line national database for late effects (N = 1761). This tool collects information on previous therapy and current health status (medical history, physical examination, laboratory tests) of cancer survivors. The survivors are invited to take part in the follow-up examination 5 years after the end of treatment. In the study group, 207 survivors (11.75%) had no complaints; whereas in 1554 cases (88.25%), one or more symptoms/complaints suggesting organ dysfunction were reported. In the whole group, the circulatory problems were most common (31.7%); more than 20% of survivors presented complaints or abnormal function of the urinary tract and had skin, dental, skeletal/muscular problems, or difficulty with chewing. Obesity or short stature alone (21.4%) and a variety of endocrine problems (short stature, obesity, thyroid dysfunction, and gonads toxicity) were present in 323 patients (118 females 15.0% and 205 males 21.0%). Gonadal dysfunction, as the only problem, occurred in 75 girls (9.6%) and 131 boys (13.4%). In our cohort, severe or life-threatening health conditions (3 and 4 grade according to toxicity criteria) were present in low percentage, i.e., 0.2% in the circulatory system, 0.3% in the respiratory tract and, 0.7% in kidney insufficiency. CONCLUSION: Our findings indicate that many childhood cancer survivors demonstrate numerous complaints, even a short time after treatment, suggesting the importance of regular follow-up examinations in subsequent years. What is Known: • Contemporary studies indicate that a significant number of childhood cancer survivors present different long-term side effects which influence their quality of life. What is New: • This is the first nationwide study performed in the largest cohort of Polish childhood cancer survivors concerning general health status and frequency of organ dysfunction.

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.

Structural incorporation of As5+ into hematite.

Hematite (α-Fe2O3) is one of the most common iron oxides and a sink for the toxic metalloid arsenic. Arsenic can be immobilized by adsorption to the hematite surface; however, the incorporation of As in hematite was never seriously considered. In our study we present evidence that, besides adsorption, the incorporation of As into the hematite crystals can be of great relevance for As immobilization. With the coupling of nanoresolution techniques and X-ray absorption spectroscopy the presence of As (up to 1.9 wt %) within the hematite crystals could be demonstrated. The incorporated As(5+) displays a short-range order similar to angelellite-like clusters, epitaxially intergrown with hematite. Angelellite (Fe4As2O11), a triclinic iron arsenate with structural relations to hematite, can epitaxially intergrow along the (210) plane with the (0001) plane of hematite. This structural composite of hematite and angelellite-like clusters represents a new immobilization mechanism and potentially long-lasting storage facility for As(5+) by iron oxides.

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.

Individualized tumor response testing profile has a prognostic value in childhood acute leukemias: multicenter non-interventional long-term follow-up study.

A total number of 817 children with acute lymphoblastic leukemia (ALL) and 181 with acute myeloblastic leukemia (AML) were assessed for individualized tumor response testing (ITRT) profile as a prognostic factor in long-term follow-up. For each patient, ITRT, initial response to therapy and long-term outcome were assessed. In initial ALL, an impact on long-term response was shown in ITRT for 13 drugs, while in initial AML only for cytarabine. For patients with ALL, a combined five-drug ITRT profile for prednisolone, l-asparaginase, vincristine, cytarabine and daunorubicin or doxorubicin had predictive value for probability of disease-free survival (pDFS) in univariate analysis, whereas in multivariate analysis, bone marrow response by day 33 was the only prognostic factor. For patients with AML, no factor had prognostic value for pDFS in univariate analysis, while ITRT to cytarabine almost reached significance. In conclusion, ITRT can possibly be regarded as a risk factor in childhood acute leukemias.

[Characteristics of extracranial malignant germ cell tumours in two age groups of children (0-10 and 10-18 years). Multicentre experiences]. / Charakterystyka pozaczaszkowych zltosliwych guzów germinalnych u dzieci w dwóch grupach wiekowych 0-10 lat i 11-18 lat. Badania wieloosrodkowe.

UNLABELLED: In order to assess if any differences exist in children germ cell tumours depending on age, we compared some features of germ cell tumours in two age groups:younger than 10 and between 11 and 18 years. MATERIAL AND METHODS: Data of 146 patients with germ cell tumours treated in 15 Polish paediatric oncology departments between 1995 and 2005 were evaluated. They were divided into two groups: 76 children 0-10 years old (group I) and 70 patients 11-18 years old (group II). Tumour morphology, sex of patients, primary tumour and metastases localization, disease stage, biochemical markers, treatment response, disease relapse and long survival were analyzed. Every patient was treated according to the TGM 95 protocol. RESULTS: In group 1, 67 tumours were assessed histologically. 64%t tumours had homogenous structure with yolk sac tumour in predominance and 36% were mixed. Yolk sac tumour (YST) or teratoma as components of mixed tumours were the most commonly found. In older group 64 tumours were examined, 41% were homogenous, and seminoma/dysgerminoma predominated. In 59% mixed tumours the most common components were YST embryonal carcinoma and teratoma. The most common primary site in group I was the sacrococcygeal region while in group II - the gonads. Disseminated disease was recognized mostly in older children. Among two evaluated serum markers, AFP was increased mostly in younger patients (76% vs 44%), and 3HCG in older group (40% vs 9%). Treatment response was comparable in both groups. Two relapses were observed in each group. Poor outcome was noted in 17/140 analyzed patients: 9 (12%) in group I and 8 (11%) in group II. In 12 of patients with poor outcome the cause of death was progression and in 5 of them - treatment complications. CONCLUSIONS: 1. Germ cell tumours in younger and older children differ in histology, primary localization and serum level of biochemical markers. 2. In older patients germ cell tumours are recognized more frequently in advanced clinical stages. 3. Treatment response was comparable in both groups. 4. There is a need to analyze the intensity of chemotherapy to precise the adequate risk groups according to primary treatment response.

Ba2Gd2(Si4O13): a silicate with finite Si4O13 chains.

The title compound, dibarium digadolinium(III) tetrasilicate, crystallized from a molybdate-based flux. It represents a new structure type and contains finite zigzag-shaped C(2)-symmetric Si(4)O(13) chains and Gd(2)O(12) dimers built of edge-sharing GdO(7) polyhedra. The [9+1]-coordinated Ba atoms are located in voids in the atomic arrangement. All atoms are in general positions except for one O atom, which lies on a twofold axis. The structure is compared with those of the few other known tetrasilicates.

[Genotyping and minimal residual disease study in children with acute myeloid leukemia: preliminary results]. / Genotypowanie i oznaczania choroby resztkowej u dzieci z ostra bialaczka mieloblastycznq: wstepne wyniki.

The aim of the paper is to present the initial results of molecular examination which was started in 2006 for children with acute myeloid leukemia. Better knowledge of biology of this disease, can result in establishing of new risk factors what allows more precise patient stratification to different therapeutic groups. Study was obtained patients until to 18 years of age treated according to AML-BFM 2004 INTERIM protocol in 14 centers of the Polish Pediatric Leukemia/Lymphoma Study Group. Mononuclear cells were collected from bone marrow on time points established according to the AML-BFM 2004 INTERIM protocol. Collected cells were isolated on Ficoll gradient, and RNA and DNA were isolated using TRIZOL reagent. To synthesize cDNA an amount of 1 mg of total RNA was used. To perform quantitative RT-PCR and RQ-PCR reactions 4 fusion gene transcripts (AML1-ETO, CBFb-MYH11, PML-RARA /subtype bcrl and bcr3/) were used according to the protocol established by Europe Against Cancer Program. An expression of WT1 gene was tested additionally. An analysis of ABL control gene was used to normalize of achieved results. Determination of duplication of FLT3 gene in DNA sample was performed with starters complementary to JM region. Genotyping was performed in 75 patients with acute myeloid leukemia so far. AML1-ETO fusion gene transcript was found in 14 patients (19%). PML-RARA (subtype bcr3) and CBFB-MYH11 gene transcripts were detected in 3 (4%) and 3 (4%) patients, respectively. Duplication of FLT3 gene was found in 4 (5.3%) cases. Between 67 tested children over expression of WT1 was present in 51 patients (76%). Analysis of MRD level in subsequent time points showed systematic decrease of number of fusion gene transcript copies and gene WT1 expression. To establish the rate of molecular marker presence in AML in children and the influence of the presence of MRD on the treatment results as well, the study has to be conducted on a larger group of patients with longer follow-up.

[Can children with Hodgkin's disease be treated with chemotherapy only?]. / Czy dzieci z choroba Hodgkina moga byc leczone wylacznie chemioterapia?

Currently over 90% of children and adolescents with Hodgkin's disease (HD) can be cured thanks to use of multidrug chemotherapy (CT) combined with involved-field radiotherapy (IF-RT). However, the intensive treatment may increase the risk of late complications which may impair the patients' quality of life. In order to decrease the incidence of late complications the protocol with limited use of IF-RT was introduced in centers of Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG). This study presents the treatment results of patients treated with CT only in comparison with the therapy results of children treated with CT and IF-RT. From 1997 to 2006, 634 children (age: 2-22,5 years) with HD were treated in 14 oncological centers of PPLLSG. Majority of patients received CT (3-8 cycles of MVPP/B-DOPA) combined with IF-RT. In 45 patients with IA-IIA stages presenting favorable risk factors (small mediastinal tumor, peripheral nodular mass of a maximum diameter < 6 cm, involvement of less than three nodular regions, ESR < 50 mm after 1 h, histologic type other than lymphocyte depletion and very good treatment response assessed after 3 CT cycles) IF-RT was omitted. Among 634 children first complete remission (RC) was not achieved in 2.4% of patients. Relapses occurred in 24 children (3.9%). The rates of 5-year overall survival (OS), relapse-free survival (RFS) and event-free survival (EFS) were 97%, 96% i 92%, respectively. All patients treated with CT only remain in first CR. All serious late complications (including 7 second neoplasms) occurred in patients treated with CT combined with RT. Seven children died because of severe complications, among them two in first CR (aplastic anemia, sepsis). Our results show that the use of CT only in precisely selected group of patients with HD do not impair the treatment results and may decrease the risk of late life threatening complications. Treatment response assessment with the use of PET may in future increase the number of patients treated without RT and limit the need of the use of invasive diagnostic methods in patients with residual mass.

[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.

[Treatment results of children with neuroblastoma: report of Polish Pediatric Solid Tumor Group]. / Wyniki leczenia dzieci ze zwojakiem zarodkowym wspólczulnym: wstepny raport Polskiej Pediatrycznej Grupy Guzów Litych.

Approximately 60 children aged 0-18 years are diagnosed of NBL each year in Poland. About 60% of all patients suffering from NBL have a chance for durable cure. Unfortunately the prognosis for patients within the high-risk group accounting for more than 50% of all NBL patients remains poor despite the introduction of more intensive chemotherapy regimens with radical surgery procedures and megachemotherapy with subsequent stem cell transplantation. Only one third of patients in this group can be cured. To improve the treatment results of the high-risk patient group and to decrease the rate of therapy related side effects current European treatment protocols have been introduced systematically in Poland. In February 2009 information about 389 patients (age 0.1-16.5 years) diagnosed between 2001 and 2008 were obtained. Results of therapy of 319 patients who started treatment from 2001 to 2007 were analyzed. Between 104 infants and 215 children over 1 year of age, stage 4 of disease was found in 25% and 54.5%, respectively. In this period additionally to European treatment protocols, two another protocols were used. Satisfactory treatment results were obtained in 104 infants (5-year event free survival /EFS/=82.6%), irrespective of the type of treatment protocol. Over 5-year EFS for children over 1 year of age in 1, 2 and 3 stage of disease was: 100%, 86.3% and 64.5%, respectively. On the contrary, 107 patients with 4 stage of disease achieved the 5-year EFS of 27% only. Treatment results obtained in patients treated according to the European HR-NBL-1/ESIOP protocol were better than for patients treated according to other treatment protocols (5-year EFS: 31.1% and 16.4%, respectively), but difference between these groups was not significant. Between 2001 and 2007 data reporting increased to 81% from 19% noted earlier. Unfortunately, results of treatment for children over 1 year of age remain still unsatisfactory. That is why there is a need of improvement of modern, unified treatment realization as well as better data reporting. For realization of these aims adequate financial support is essential.

[Hemophagocytic syndrome in children with different underlying conditions]. / Zespól hemofagocytarny u dzieci w róznych jednostkach chorobowych.

Hemophagocytic syndrome (HS) is a life-threatening condition of hyperinflammation. Main symptoms are: prolonged fever, cytopenia, hepatosplenomegaly, hemophagocytosis, hyperferritinemia, hypertriglyceridemia and hypofibrinogenemia. Primary genetic form and secondary HS associated with infections, malignancies or autoimmune disorders can be distinguished. Untreated HS in most cases leads to death. We analyzed retrospectively 7 cases of HS in children (3 girls, 4 boys; aged 10 days -14 years) treated in 3 different pediatric centers from 2004 to 2009. In 3 cases HS was associated with infections (EBV, CMV, Bacillus Calmette Guerin - BCG), in 1 child with non-Hodgkin anaplastic large cell lymphoma (ALCL), in 1 patients probably with side effect of antiepileptic drug. In 2 cases cause of HS remained unknown. Fever, hepatomegaly, pan- or bicytopenia and hyperferritinemia were present in all children. In addition, splenomegaly was noted in 6 cases, hemophagocytosis in 6 children, impaired function or decreased number of NK cells in 4 cases, hypofibrino-genemia in 5 and hypotriglyceridemia in 4 patients. Among other symptoms and signs we observed: lymphadenopathy, hepatic failure, oedema, rash, neurological symptoms, increased level of LDH and inflammatory markers. In one child acute pancreatitis occurred. Among others, antibiotics, antiviral and immunosuppressive drugs were used in therapy. HLH-2004 protocol was applied in 4 cases. Patient with ALCL was treated with chemotherapy and allogeneic stem cell transplantation. Four patients are alive, 2 died because of HS, child with ALCL died because of generalized infection in peritrans-plantation period. In case of prolonged fever, splenomegaly and cytopenia diagnosis of HS should be considered. Following tests are recommended: complete blood count, ferritin, triglycerides, fibrinogen, bone marrow aspiration and NK cell assessment. Patients should be also screened for infections and malignancies. Early diagnosis of HS and underlying condition is crucial to start lifesaving therapy.

Comparison of clofarabine activity in childhood and adult acute leukemia: individual tumor response study.

BACKGROUND: Clofarabine is a second-generation nucleoside analogue. The aim of the study was the analysis of ex vivo activity of clofarabine and 14 other anticancer drugs in pediatric and adult acute lymphoblastic (ALL) and myeloid (AML) leukemia. PATIENTS AND METHODS: The ex vivo drug resistance profile was analyzed in 282 patients, including 201 children with ALL de novo, 24 children with relapsed ALL, 25 children with AML de novo and 32 adults with AML. Cellular ex vivo drug resistance was tested by means of the MTT assay. RESULTS: Clofarabine had comparable ex vivo activity against lymphoblasts and myeloblasts, both on initial diagnosis and at relapse, both in children and in adults. Its activity in acute myeloid leukemia was independent of patient age. No significant differences in drug resistance to clofarabine between pediatric age-based subgroups of ALL were detected, while it was observed for most of other drugs. An activity of clofarabine in relapsed pediatric ALL patients was as good as in newly-diagnosed ones. CONCLUSION: In comparison to childhood acute lymphoblastic leukemia, lack of differences in ex vivo activity gives rationale for use of clofarabine in refractory and relapsed pediatric and adult patients with acute myeloid leukemia.

Prognostic impact of combined fludarabine, treosulfan and mitoxantrone resistance profile in childhood acute myeloid leukemia.

BACKGROUND: The role of cellular drug resistance in childhood acute myeloid leukemia (AML) has not yet been established. The aim of the study was the analysis of the clinical value of ex vivo drug resistance in pediatric AML. PATIENTS AND METHODS: A cohort of 90 children with de novo AML were assayed for drug resistance profile by the 3-4,5-dimethylthiazol-2-yl-2,5-difenyl tetrazolium bromide (MTT) assay and prognostic model of in vitro drug sensitivity was analyzed. RESULTS: Children who relapsed during follow-up showed higher in vitro resistance of leukemic blasts to most of the drugs tested, except for cytarabine, cladribine, vincristine, mercaptopurine and thioguanine. A combined in vitro drug resistance profile to fludarabine, treosulfan and mitoxantrone (FTM score) was defined and it had an independent prognostic significance for disease free survival in pediatric AML. CONCLUSION: The combined fludarabine, treosulfan and mitoxantrone resistance profile to possibly may be used for better stratification of children with AML or indicate the necessity for additional therapy.

Predictive value of multidrug resistance proteins and cellular drug resistance in childhood relapsed acute lymphoblastic leukemia.

PURPOSE: Cellular resistance in childhood acute leukemias might be related to profile and function of multidrug resistance proteins and apoptosis regulating proteins. The aims of the study were: (1) analysis of expression of MRP1, PGP1, LRP, BCL-2 and p53 proteins; (2) correlation with ex vivo drug resistance, and (3) analysis of their prognostic impact on clinical outcome in childhood acute lymphoblastic (ALL) and acute myeloid (AML) leukemia. METHODS: Total number of 787 children diagnosed for initial ALL (n = 527), relapsed ALL (n = 104), initial AML (n = 133) and relapsed AML (n = 23) were included into the study. Mean follow-up period was 3.5 years. Drug resistance for up to 30 anticancer agents was performed by the MTT assay. Expression of all proteins was tested by flow cytometry. RESULTS: Both initial AML and relapsed ALL samples showed higher drug resistance than initial ALL samples. No significant differences were found in drug resistance between initial and relapsed AML samples. The presence of multidrug resistance and apoptosis proteins had no impact on pDFS in iALL and iAML, however strong trend towards adverse prognostic impact of MRP1, PGP and LRP on pDFS in rALL was observed. The same trend was observed for each of analyzed co-expressions of tested multidrug resistance proteins. CONCLUSIONS: The phenomenon of cellular drug resistance in childhood acute leukemias is multifactorial and plays an important role in response to therapy. Expression of MRP1, PGP and LRP proteins, as well as their co-expression play possible role in childhood relapsed ALL.

CD40L and IL-4 stimulation of acute lymphoblastic leukemia cells results in upregulation of mRNA level of FLICE--an important component of apoptosis.

The use of cancer vaccines based on dendritic cells (DC) presenting tumor antigens can be a promising tool in the treatment of leukemia. The functional characteristics of leukemia derived DC is still to be elucidated. CD40 promotes survival, proliferation and differentiation of normal B cells. CD40 triggering was used to enhance the poor antigen-presenting capacity of leukemic B-cells. Since it is still unclear whether CD40 ligation drives neoplastic B-cells to apoptosis or not, we assessed the mRNA expression of FLICE, FAS, FADD and TRADD - important components of apoptosis machinery, using real-time PCR in acute lymphoblastic leukemia cells before and after CD40 and IL-4 stimulation. ALL cells stimulated with CD40L/IL-4 expressed dendritic cell phenotype at mRNA and protein levels (upregulation of main costimulatory and adhesion molecules noted in real-time RT PCR and flow cytometry); they also expressed higher amounts of mRNA for FLICE, TRADD and FADD after CD40L/IL-4 stimulation. However differences statistically significant comparing cells cultured with CD40L/IL-4 and medium alone regarded only FLICE. Concluding, we showed upregulation of important elements of apoptosis at mRNA level in ALL cells after CD40 ligation.