[28-year old female patient with respiratory insufficiency, elevated liver enzymes, pancytopenia and fever]. / 28-jährige Patientin mit respiratorischer Insuffizienz, erhöhten Leberwerten, Fieber und Panzytopenie.

We report on a 28-year old female patient with fever and severe respiratory insufficiency requiring mechanical ventilation. Cytomegalovirus pneumonia was diagnosed by bronchoalveolar lavage, and antiviral therapy was initiated. However fever persisted and laboratory workup showed pancytopenia and elevated liver enzymes. Additional blood tests demonstrated a markedly elevated ferritin level and high concentrations of inflammatory cytokines. A diagnosis of hemophagocytic lymphohistiocytosis was made and immunosuppressive therapy was started. The patient's condition and laboratory values improved rapidly.

Standardized MRD quantification in European ALL trials: proceedings of the Second International Symposium on MRD assessment in Kiel, Germany, 18-20 September 2008.

Assessment of minimal residual disease (MRD) has acquired a prominent position in European treatment protocols for patients with acute lymphoblastic leukemia (ALL), on the basis of its high prognostic value for predicting outcome and the possibilities for implementation of MRD diagnostics in treatment stratification. Therefore, there is an increasing need for standardization of methodologies and harmonization of terminology. For this purpose, a panel of representatives of all major European study groups on childhood and adult ALL and of international experts on PCR- and flow cytometry-based MRD assessment was built in the context of the Second International Symposium on MRD assessment in Kiel, Germany, 18-20 September 2008. The panel summarized the current state of MRD diagnostics in ALL and developed recommendations on the minimal technical requirements that should be fulfilled before implementation of MRD diagnostics into clinical trials. Finally, a common terminology for a standard description of MRD response and monitoring was established defining the terms 'complete MRD response', 'MRD persistence' and 'MRD reappearance'. The proposed MRD terminology may allow a refined and standardized assessment of response to treatment in adult and childhood ALL, and provides a sound basis for the comparison of MRD results between different treatment protocols.

Cooperative study group for childhood acute lymphoblastic leukaemia (COALL): long-term results of trials 82,85,89,92 and 97.

In this study, the long-term outcome of 1818 patients treated in five consecutive clinical trials (the cooperative study group for childhood acute lymphoblastic leukaemia (COALL) 82, 85, 89, 92 and 97) from 24 cooperating centres in Germany is reported. The probability of event-free survival (pEFS) improved significantly from the first two trials conducted in the 1980s (COALL 82 and COALL 85) to the three trials conducted in the 1990s (COALL 89, 92 and 97) (P=0.001). Through all COALL studies, age > or =10 years and initial white blood cell count (WBC) > or =50 x 10(9)/l and pro-B immunophenotype were of significant prognostic relevance. A refinement of risk assessment has been achieved by in vitro drug sensitivity testing in COALL 92 and 97. In patients with very sensitive leukaemic cells, therapy could be reduced without loss of efficacy. In COALL 97, a further improvement in risk stratification was gained by the molecular assessment of minimal residual disease (MRD) under treatment, which proved to have a superior prognostic effect when compared with in vitro drug sensitivity testing. Importantly, the gradual reduction in central nervous system (CNS) irradiation led to a decreased incidence of brain tumours as a second malignancy. In general, the prevention of treatment-related late effects will be one of the major issues in future studies. It remains to be shown whether prolonged infusions of anthracyclines, which have been implemented into the COALL studies after equal efficacy compared with short-time infusions was confirmed, will be associated with fewer cardiac late effects. Another way to prevent late effects may be a more refined risk assessment allowing for a reduction in cumulative treatment burden. A great challenge in the future will be to improve the overall treatment results, which very likely can only be achieved by the identification of molecularly defined subgroups to which novel, rational therapeutic strategies can be applied.

Reduced expression and defective modulation of TNF receptor/ligand family molecules on proB-ALL blasts.

BACKGROUND: There is a subgroup of pediatric patients with an immature immunophenotype of proB-ALL that still poses a therapeutic challenge, even if the overall prognosis in B cell precursor acute lymphoblasic leukemia (BCP-ALL) is very good. Due to impaired treatment response these patients are prone to suffer relapse and are thus by definition stratified into the clinically defined high risk group receiving intensified chemotherapy. Besides response to chemotherapy long term prognosis is also influenced by immunological control mechanisms. Thus, high expression of the TNF receptor CD40 has been shown to prevent particularly late relapse in BCP-ALL suggesting a pivotal role of this regulatory molecule for maintenance of the remission status. PATIENTS AND METHODS: We therefore determined the baseline expression and CD40-mediated modulation of TNF receptor and costimulatory molecules in 5 patients with proB-ALL, 8 with preB-ALL and 22 with c-ALL performing FACS analysis. We particularly compared the TNF receptor status on proB-ALL blasts to the expression on more mature preB- and c-ALL blasts. RESULTS: Here, we demonstrate for the first time a significantly lower baseline expression and CD40-induced modulation capacity of TNF receptor and costimulatory molecules in pediatric proB-ALL compared to more mature precursor B-ALL blasts. CONCLUSION: The lower expression and defective capacity of proB-ALL blasts to respond to CD40 ligand stimulation might resemble the immature feature of these blasts and besides increased chemoresistance contribute to the impaired prognosis of these patients due to escape from apoptosis and immunological control mechanisms.

Daunorubicin-induced cell kill with 1-hour versus 24-hour infusions: a randomized comparison in children with newly diagnosed acute lymphoblastic leukemia.

BACKGROUND: Daunorubicin (DNR) is one of the most important drugs in treatment of acute lymphoblastic leukemia (ALL). Prolonged infusions of anthracyclines are less cardiotoxic but it has not been investigated whether the in vivo leukemic cell kill is equivalent to short-term infusions. PROCEDURE: In the cooperative treatment study COALL-92 for childhood ALL 178 patients were randomized to receive in a therapeutic window a single dose of 36 mg/m (2) DNR either as a 1-h (85 patients) or 24-h infusion (93 patients). Daily measurements of white blood cell count (WBC) and peripheral blood smears for seven days could be evaluated centrally in 101 patients (1-h: 43 patients, 24-h: 58 patients). RESULTS: The proportional decline of blasts at day 7 after DNR infusion showed no statistically significant difference between the two treatment arms. At day 3 the median percentage of blasts was less than 10%, at day 7 less than 2% for either the 1-h or 24-h infusion. Twelve patients (1-h: 5 patients, 24-h: 7 patients) had an absolute number of more than 1000 blasts per mul peripheral blood (PB) at day 7 after DNR infusion (DNR poor responders). Kaplan-Meier analysis showed an equal probability of EFS for the short- and long-term infusion group (24-h: 83%+/-5; 1-h: 81+/-6) after a median observation time of 12.3 years. CONCLUSIONS: We conclude that in children with ALL a 24-h infusion of DNR has the same in vivo cytotoxicity for leukemic cells as a 1-h infusion. This offers the possibility to use prolonged infusions with hopefully less cardiotoxicity without loss of efficacy.

Role of survivin splice variants in pediatric acute precursor B lymphoblastic leukemia.

BACKGROUND: Survivin, a member of the inhibitor of apoptosis protein (IAP) family is transiently expressed at low levels during normal hematopoesis but profoundly overexpressed in adult leukemia potentially contributing to leukemogenesis due to deregulated apoptosis and defective cell cycle control. Alternative splicing results in four different mRNA variants survivin, survivin2B, survivin-DeltaExon3 and survivin-3B, with distinct cellular localization patterns and anti-apoptotic potential. Due to co-localization of survivin and survivin-2B in the cytoplasm survivin-2B may permit interactive fine-tuning of survivin actions and moreover play an attenuating role in its anti-apoptotic function. Lack of survivin-2B is associated with disease progression of malignomas suggesting a differential role of these isoforms in tumorigenesis. PATIENTS AND METHODS: We therefore determined the expression of the functional survivin splice variants performing RT- and real-time PCR in a purely pediatric cohort of 20 patients suffering from precursor B-ALL (BCP-ALL). RESULTS: Here, we demonstrate for the first time in pediatric patients with precursor B-ALL an association between lower survivin-2B expression and affiliation to the high risk group. CONCLUSION: The idea that survivin-2B may act as natural antagonist of survivin could potentially be used in novel approaches of anti-cancer treatment by influencing the proportional expression of the different splice variants.

Recent developments in iron chelation therapy.

Since 1962, desferrioxamine (deferoxamine, DFO) has been utilized for the treatment of secondary hemosiderosis. For about 30 years, DFO therapy has been performed as nightly continuous subcutaneous infusion. About 20 years ago, the first oral iron chelator (deferiprone, DFP) was presented. Concerns about potential side effects were responsible for the late acceptance and license of this drug which is limited to the use as second-line therapy for patients with thalassemia major. During recent years, chelation therapy and its evaluation started to progress rapidly. Clinical research and drug development as well as the introduction of new methods for the assessment of iron overload contributed to these advances. By using cardiac T2 (*) MRI it was possible to examine the specific effect of a chelator on myocardial siderosis. Clinical studies using this method indicated superiority of DFP compared to DFO with respect to the treatment of myocardial siderosis. Several retrospective and first prospective clinical trials seem to confirm this observation. In parallel, treatment strategies based on the combination of DFO and DFP have been developed. Using both drugs simultaneously or sequentially, additive and synergistic effects contribute to the fast elimination of iron from different organs at risk for siderotic damage. Deferasirox (DSX) is a recently developed oral chelator which shows good efficacy and tolerability in patients with transfusional hemosiderosis due to various underlying disorders. Long-term studies will define the future importance of DSX for iron chelation treatment. For the first time, there is a choice between three commercially available chelating agents for patients with transfusional iron overload. This will allow a highly effective, individually tailored treatment hopefully leading to a fundamental improvement of patients' life expectancy and quality.

Differential expression of p73 isoforms in relation to drug resistance in childhood T-lineage acute lymphoblastic leukaemia.

The T-lineage phenotype of childhood acute lymphoblastic leukaemia (ALL) is associated with an increased relapse-risk and in vitro resistance to drugs as compared to a precursor B phenotype. Antiapoptotic isoforms of p73 that lack part of the transactivation (TA) domain (DeltaTA-p73, i.e. p73Deltaex2, p73Deltaex3, p73Deltaex2/3 and DeltaN-p73) may cause resistance to anticancer agents through inhibition of p53 and/or proapoptotic p73 family members (TA-p73). We demonstrate in our study that the expression of total p73 mRNA was higher in childhood T-ALL compared to controls (P=0.004). In T-ALL, the relative contribution of antiapoptotic DeltaTA-p73 (88%) was larger than of proapoptotic TA-p73 (12%). Leukaemic cells of T-ALL patients expressing higher levels of antiapoptotic p73 were more resistant to the DNA-damaging drug daunorubicin compared to cells of patients with low or negative expression or these isoforms (P(trend)=0.045). Interestingly, p73Deltaex2 was the most abundantly expressed antiapoptotic isoform in daunorubicin-resistant patient cells (44% of total p73). No association was found between high expression of proapoptotic TA-p73 or antiapoptotic DeltaTA-p73 and relapse-risk. Our results suggest that childhood T-ALL is associated with a high expression of DeltaTA-p73. These isoforms may play a role in cellular resistance to DNA-damaging drugs in children at initial diagnosis of T-ALL.

Incidence of additional genetic changes in the TEL and AML1 genes in DCOG and COALL-treated t(12;21)-positive pediatric ALL, and their relation with drug sensitivity and clinical outcome.

Clinical heterogeneity within t(12;21) or TEL/AML1-positive ALL (25% of childhood common/preB ALL) indicates that additional genetic changes might contribute to outcome. We studied the relation between additional genetic changes in TEL(ETV6) and AML1(RUNX1) (FISH), drug sensitivity (MTT assay) and clinical outcome in 143 DCOG and COALL-treated t(12;21)-positive ALL patients. Additional genetic changes in TEL and AML1 were present in 83% of the patients, and consisted of (partial) deletion of the second TEL gene (70%), an extra AML1 gene (23%) or an extra der(21)t(12;21) (10%). More than one additional change was observed in 20%. Disease-free survival (pDFS) of DCOG patients without additional genetic changes (4 years pDFS +/- s.e. 53 +/- 17%) and of those with an extra der(21)t(12;21) (60 +/- 22%) is poorer than that of compared to patients with other additional genetic changes in TEL or AML1 (79 +/- 6%; P-trend = 0.02). This was mainly due to the occurrence of early relapses within 2.5 years after the first diagnosis. Similar observations were found in the COALL cohort, albeit not significant owing to limited follow-up. Multivariate analysis including age, WBC and genetic abnormalities in TEL and/or AML1 showed that especially, in vitro resistance to prednisolone (hazard ratio 5.78, 95% CI 1.45-23.0; P=0.01) is an independent prognostic factor in DCOG- and COALL-treated t(12;21)-positive ALL.

Serum asparaginase activities and asparagine concentrations in the cerebrospinal fluid after a single infusion of 2,500 IU/m(2) PEG asparaginase in children with ALL treated according to protocol COALL-06-97.

BACKGROUND AND PROCEDURE: Pharmacological surrogate parameters are considered a useful tool in estimating the treatment intensity of asparaginase (ASNase) preparations. When a pegylated ASNase (single infusion of 2,500 IU/m(2) polyethylene glycol (PEG)-ASNase, Oncaspar) was introduced into the treatment protocols of the German Cooperative Acute Lymphoblastic Leukaemia (COALL) study group, this was accompanied by a drug monitoring programme measuring serum ASNase activity and asparagine (ASN) concentrations in the cerebrospinal fluid (CSF) in 70 children. RESULTS: Four hundred fifty-nine serum samples from 67 evaluable patients showed medians of ASNase activity of 1,189.5, 824.5, 310.5, 41 and 4 U/l on day 7 +/- 1, 14 +/- 1, 21 +/- 1, 28 +/- 1 and 35 +/- 1 respectively. One hundred eighty-four samples from 59 patients were evaluable for ASN concentrations in the CSF. The medians of ASN concentration were <0.2, 0.2, 0.9 and 3.2 microM on day 14 +/- 1, 21 +/- 1, 28 +/- 1 and 35 +/- 1 respectively. When relating CSF ASN levels to the serum ASNase activity measured on the same day, a median of 1.2 microM CSF ASN was associated with values of serum ASNase activity between > or =2.5 and <100 U/l. Serum ASNase activity values > or =100 U/l were associated with a median CSF ASN of <0.2 microM, with 13/27 samples being incompletely depleted. CONCLUSIONS: The treatment intensity achieved with PEG ASNase in the present study appears to be acceptable based on the surrogate of serum ASNase activity. However, the pharmacological objective of ASNase treatment, that is, complete CSF ASN depletion with an ASNase activity >100 U/l, was not ensured. Nevertheless, one must also be aware that the minimum ASN concentration required for leukaemic cell growth is yet to be established.

Risk factors for diabetes insipidus in langerhans cell histiocytosis.

BACKGROUND: Diabetes insipidus (DI) is the most frequent central nervous system (CNS)-related permanent consequence in Langerhans cell histiocytosis (LCH), which mostly requires life-long hormone replacement therapy. In an attempt to define the population at risk for DI, 1,741 patients with LCH registered on the trials DALHX 83 and DALHX 90, LCH I and LCH II were studied. RESULTS: Overall 212 of 1,741 patients (12%) was reported to have DI. In 102 of 1,741 patients (6%) DI was present at diagnosis of LCH. One thousand one hundred eighty three of 1,539 patients without DI at diagnosis had follow up information. One hundred ten of these (9%) later developed DI. The risk of developing DI was 20% at 15 years after diagnosis. Multisystem disease patients at diagnosis carried a 4.6-fold risk for DI compared to single system patients. Craniofacial lesions, in particular in the "ear," "eye," and oral region were associated with a significantly increased risk for DI (relative hazard rate, RHR 1.7), independent of the extent of disease. No influence of the duration of therapy could be determined, but the duration of initial disease activity (RHR 1.5) and the occurrence of reactivations (RHR 3.5) significantly increased the risk for DI. CONCLUSIONS: Patients with multisystem disease and craniofacial involvement at diagnosis, in particular of the "ear," "eye," and the oral region carry a significantly increased risk to develop DI during their course. This risk is augmented when the disease remains active for a longer period or reactivates.

Silencing of the tumor suppressor gene FHIT is highly characteristic for MLL gene rearranged infant acute lymphoblastic leukemia.

MLL rearranged acute lymphoblastic leukemia (MLL) is an aggressive type of acute lymphoblastic leukemia (ALL), diagnosed predominantly in infants (<1 years of age). Since current chemotherapy fails in >50% of patients with MLL, new therapeutic strategies are desperately needed. For this, understanding the biological features characterizing MLL is necessary. Analysis of gene expression profiles revealed that the expression of the tumor suppressor gene FHIT is reduced in children with MLL rearranged ALL as compared to ALL patients carrying germ line MLL. This finding was confirmed by quantitative real-time PCR. In 100% of the infant MLL cases tested, methylation of the FHIT 5'CpG region was observed, resulting in strongly reduced mRNA and protein expression. In contrast, FHIT methylation in infant and non-infant ALL patients carrying germ line MLL was found in only approximately 60% (P< or =0.004). FHIT expression was restored upon exposing leukemic cells to the demethylating agent decitabine, which induced apoptosis. Likewise and more specifically, leukemic cell death was induced by transfecting MLL rearranged leukemic cells with expression vectors encoding wild-type FHIT, confirming tumor suppressor activity of this gene. These observations imply that suppression of FHIT may be required for the development of MLL, and provide new insights into leukemogenesis and therapeutic possibilities for MLL.

Asparagine concentration in plasma after 2,500 IU/m(2) PEG-asparaginase i.v. in children with acute lymphoblastic leukemia.

UNLABELLED: Polyethylene glycol conjugated asparaginase (PEG-ASNase) can be substituted in cases of hypersensitivity to native Escherichia coli asparaginase. We measured asparagine (asn) levels in plasma after a single dose of 2,500 IU/m(2) i.v. PEG-ASNase (Oncaspar) in consolidation treatment of ALL and compared those with data from the previous protocol COALL-05-92. This protocol was similar to COALL-06-97, except that children had been given 45,000 IU/m(2) C-ASNase instead of PEG-ASNase. PATIENTS AND METHODS: Between May 2000 and December 2001 seventy-one children (38 boys, 33 girls) with newly diagnosed ALL treated according to the multicenter protocol COALL-06-97 were investigated in this study. Four hundred and seventy-four plasma samples (71 patients) were analysed by ion exchange chromatography after column derivatization with o-phthaldialdehyde. For comparison data (350 plasma samples) from 51 patients treated according to the protocol COALL-05-92 were available. The same method for detection of asn in plasma was used. RESULTS: The median asparagine level in plasma after 2,500 IU/m(2) PEG-ASNase i.v. was below the limit of detection for at least 5 weeks in 81 % of the patients. When divided into high risk (HR) and low risk (LR) group, HR patients who had previously received one dose more of C-ASNase showed a markedly shorter depletion than the LR patients compatible with a higher risk of antibody formation and consequent silent inactivation after a higher number of exposures to ASNase. In the previous protocol COALL-05-92 median asn levels in plasma after 45,000 IU/m(2) native C-ASNase i.v. were below the limit of detection for at least 5 weeks in 65 % of the patients. CONCLUSIONS: 2,500 IU/m(2) PEG-ASNase led to an equally long depletion of asn in plasma as did 45,000 IU/m(2) native C-ASNase i.v. used in COALL-05-92.

Relation between genetic variants of the ataxia telangiectasia-mutated (ATM) gene, drug resistance, clinical outcome and predisposition to childhood T-lineage acute lymphoblastic leukaemia.

The T-lineage phenotype in children with acute lymphoblastic leukaemia (ALL) is associated with in vitro drug resistance and a higher relapse-risk compared to a precursor B phenotype. Our study was aimed to investigate whether mutations in the ATM gene occur in childhood T-lineage acute lymphoblastic leukaemia (T-ALL) that are linked to drug resistance and clinical outcome. In all, 20 different single nucleotide substitutions were found in 16 exons of ATM in 62/103 (60%) T-ALL children and 51/99 (52%, P = 0.21) controls. Besides the well-known polymorphism D1853N, five other alterations (S707P, F858L, P1054R, L1472W, Y1475C) in the coding part of ATM were found. These five coding alterations seem to occur more frequently in T-ALL (13%) than controls (5%, P = 0.06), but did not associate with altered expression levels of ATM or in vitro resistance to daunorubicin. However, T-ALL patients carrying these five coding alterations presented with a higher white blood cell count at diagnosis (P = 0.05) and show an increased relapse-risk (5-year probability of disease-free survival (pDFS) = 48%) compared to patients with other alterations or wild-type ATM (5-year pDFS = 76%, P = 0.05). The association between five coding ATM alterations in T-ALL, their germline presence, white blood cell count and unfavourable outcome may point to a role for ATM in the development of T-ALL in these children.

The seventh international childhood acute lymphoblastic leukemia workshop report: Palermo, Italy, January 29--30, 2005.

Between 1995 and 2004, six International Childhood Acute Lymphoblastic Leukemia (ALL) Workshop have been held, and the completion of several collaborative projects has established the clinical relevance and treatment options for several specific genetic subtypes of ALL. This meeting report summarizes the data presented in the seventh meeting and the discussion.

Langerhans cell histiocytosis in neonates.

BACKGROUND: To study the incidence, clinical patterns, course, and outcome of neonatal Langerhans cell histiocytosis (LCH). PROCEDURE: Retrospective analysis of the data of the Austrian/German/Swiss/Netherlands LCH Study Group. The incidence of neonatal LCH was estimated with the data from the population-based German Childhood Cancer Registry. RESULTS: The estimated incidence of neonatal LCH (LCH diagnosed within 28 days after birth) in the population-based registry was 1-2/1,000,000. In 61/1,069 trial patients (6%), the first disease manifestations were observed in the neonatal period. However, in only 20 of them, the diagnosis was established within this period. There was a preponderance of multisystem (MS)-LCH 36/61 (59%). Cutaneous changes were the most common initial manifestation in both, single-system (SS)-LCH (92%), and MS-LCH (86%). In 72% of the MS-LCH patients, risk organs (ROs) were involved at diagnosis as well. The probability of survival at 5 years was 94% in SS-LCH and 57% in MS-LCH, which is significantly lower than in older age groups. CONCLUSIONS: In contrast to the available literature, neonatal LCH is characterized by a clear predominance of MS-LCH. Cutaneous changes are the most common initial manifestation in neonates with both SS-LCH and MS-LCH. Prompt evaluation of disease extent upon diagnosis is mandatory for risk-adapted treatment. The disease course is unpredictable upon diagnosis. Close monitoring for disease progression is mandatory if isolated cutaneous LCH is managed by the "wait and see" approach. Neonates with MS-LCH, especially those with RO involvement at diagnosis, have less favorable prognosis compared to infants and older children, and need systemic therapy.

Secondary cytogenetic aberrations in childhood Philadelphia chromosome positive acute lymphoblastic leukemia are nonrandom and may be associated with outcome.

Additional chromosomal aberrations occur frequently in Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL) of childhood. The treatment outcome of these patients is heterogeneous. This study assessed whether such clinical heterogeneity could be partially explained by the presence and characteristics of additional chromosomal abnormalities. Cytogenetic descriptions were available for 249 of 326 children with Ph+ ALL, diagnosed and treated by 10 different study groups/large single institutions from 1986 to 1996. Secondary aberrations were present in 61% of the cases. Chromosomes 9, 22, 7, 14, and 8 were most frequently abnormal. Most (93%) karyotypes were unbalanced. Three main cytogenetic subgroups were identified: no secondary aberrations, gain of a second Ph and/or >50 chromosomes, or loss of chromosome 7, 7p, and/or 9p, while other secondary aberrations were grouped as combinations of gain and loss or others. Of the three main cytogenetic subgroups, the loss group had the worst event-free survival (P=0.124) and disease-free survival (P=0.013). However, statistical significance was not maintained when adjusted for other prognostic factors and treatment. Karyotypic analysis is valuable in subsets of patients identified by molecular screening, to assess the role of additional chromosomal abnormalities and their correlation with clinical heterogeneity, with possible therapeutic implications.

In vitro drug-resistance profile in infant acute lymphoblastic leukemia in relation to age, MLL rearrangements and immunophenotype.

Acute lymphoblastic leukemia (ALL) in infants under 1 year is strongly associated with translocations involving 11q23 (MLL gene), CD10-negative B-lineage (proB) immunophenotype, and poor outcome. The present study analyses the relationship between age, MLL rearrangements, proB-lineage, and in vitro drug resistance determined using the MTT assay. Compared to 425 children aged over 1 year with common/preB (c/preB) ALL, the 44 infants were highly resistant to steroids (for prednisolone (PRED) more than 580-fold, P=0.001) and L-asparaginase (L-ASP) (12-fold, P=0.001), but more sensitive to cytarabine (AraC) (1.9-fold, P=0.001) and 2-chlorodeoxyadenosine (2-CdA) (1.7-fold, P<0.001). No differences were found for vincristine, anthracyclines, thiopurines, epipodophyllotoxines, or 4-hydroperoxy (HOO)-ifosfamide. ProB ALL of all ages had a profile similar to infant ALL when compared with the group of c/preB ALL: relatively more resistant to L-ASP and PRED (and in addition thiopurines), and more sensitive to AraC and 2-CdA. Age was not related to cellular drug resistance within the proB ALL group (<1 year, n=32, vs >/=1 year, n=19), nor within the MLL-rearranged ALL (<1 year, n=34, vs >/=1 year, n=8). The translocation t(4;11)(q21;q23)-positive ALL cases were more resistant to PRED (>7.4-fold, P=0.033) and 4-HOO-ifosfamide (4.4-fold, P=0.006) than those with other 11q23 abnormalities. The expression of P-glycoprotein, multidrug-resistance protein, and lung-resistance protein (LRP) was not higher in infants compared to older c/preB ALL patients, but LRP was higher in proB ALL and MLL-rearranged ALL of all ages. In conclusion, infants with ALL appear to have a distinct in vitro resistance profile with the proB immunophenotype being of importance. The role of MLL cannot be excluded, with the t(4;11) being of special significance, while age appears to play a smaller role.

Multidrug resistance genes in infant acute lymphoblastic leukemia: Ara-C is not a substrate for the breast cancer resistance protein.

Infants with acute lymphoblastic leukemia (ALL) are more resistant to chemotherapeutic drugs than older children with ALL, except for Ara-C. Drug resistance mechanisms in infant ALL, however, remain unknown. Possibly, multidrug resistance (MDR) proteins like P-glycoprotein, MDR-associated protein (MRP1), lung resistance-related protein (LRP/MVP) and the breast cancer resistance protein (BCRP) play a role. Accordingly, we measured the mRNA levels of these proteins in infants (n=13) and non-infants (n=13) with ALL, using quantitative RT-PCR. Infants expressed 2.4-fold less BCRP mRNA (P=0.009) than non-infants with ALL. MDR1, MRP1 and LRP/MVP expression did not differ between both groups. MDR gene expression levels did not correlate to prednisolone, vincristine, daunorubicin or Ara-C cytotoxicity, except for BCRP expression, which correlated with resistance to Ara-C (Rs=0.53, P=0.012), suggesting that Ara-C might be a BCRP substrate. However, culturing patients ALL cells in the presence of the BCRP inhibitor Ko143 had no effect on Ara-C sensitivity. Inhibiting Bcrp1 in the Mdr1a-, Mdr1b- and Mrp1-deficient and Bcrp1-overexpressing mouse cell line Mef3.8/T6400, also did not modulate Ara-C cytotoxicity. Therefore, we conclude that Ara-C is not a substrate for BCRP and that MDR proteins do not play a significant role in drug resistance in infant ALL.

Patient stratification based on prednisolone-vincristine-asparaginase resistance profiles in children with acute lymphoblastic leukemia.

PURPOSE: To confirm the prognostic value of a drug resistance profile combining prednisolone, vincristine, and l-asparaginase (PVA) cytotoxicity in an independent group of children with acute lymphoblastic leukemia (ALL) treated with a different protocol and analyzed at longer follow-up compared with our previous study of patients treated according to the Dutch Childhood Leukemia Study Group (DCLSG) ALL VII/VIII protocol. PATIENTS AND METHODS: Drug resistance profiles were determined in 202 children (aged 1 to 18 years) with newly diagnosed ALL who were treated according to the German Cooperative Study Group for Childhood Acute Lymphoblastic Leukemia (COALL)-92 protocol. RESULTS: At a median follow-up of 6.2 years (range, 4.1 to 9.3 years), the 5-year disease-free survival probability (pDFS) rate +/- SE was 69% +/- 7.0%, 83% +/- 4.4%, and 84% +/- 6.8% for patients with resistant (PVA score 7 to 9), intermediate-sensitive (PVA score 5 to 6), and sensitive (SPVA score 3 to 4) profiles, respectively (sensitive and intermediate-sensitive v resistant, P