Allelic Forms Of PRDM9 Associated With High Hyperdiploid Childhood Acute Lymphoblastic Leukaemia

Abstract Whilst a great deal is known about acquired somatic aberrations associated with the diagnosis and prognosis of acute leukaemias, relatively little is known about the effects of germline variation. A recent study reported a link between germline variations in the zinc finger (ZnF) binding domain array of the PR domain-containing 9 (PRDM9) gene, regulator of meiotic recombination, with the development of acute lymphoblastic leukaemia (ALL) in children. An excess of rare PRDM9 alleles that affect meiotic recombination events were seen in parents of children affected with B-cell precursor ALL (pre-B-ALL), and in an independent cohort of children with pre-B-ALL; in particular in aneuploid and infant ALL. In the present study, we carried out Sanger sequencing to investigate variation of PRDM9 alleles in a cohort of parents (n=59) with children diagnosed with high hyperdiploid ALL (HeH; 51-67 chromosomes) (n=31) and a control cohort of individuals (n=66) from the south of Sweden. Whereas similar numbers of rare PRDM9 alleles were observed in both groups, a larger number of rare alleles that affect recombination events were observed in the parents from the family cohort with children diagnosed with HeH ALL compared to individuals of the population control cohort (15.3% vs. 4.5%, P=0.0414). Two-thirds of the parents transmitted the rare allele to their affected children. A previously unreported ZnF repeat was also detected in two individuals of the control cohort but it was not detected in the family cohort. A statistically significant difference in frequency of rare alleles affecting recombination events between the two groups indicates a true association between PRDM9 allelic forms and HeH ALL in an independent cohort. Thus, our results confirm the previous findings that PRDM9 may play a role in the development of childhood ALL. Disclosures: No relevant conflicts of interest to declare.

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Investigating the Expression of the MRD Marker CD58 on Leukaemia Initiating Cells in Childhood Acute Lymphoblastic Leukaemia

Blood ◽

10.1182/blood.v118.21.1887.1887 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1887-1887 ◽

Cited By ~ 1

Author(s):

Charlotte Victoria Cox ◽

Paraskevi Diamanti ◽

Allison Blair

Keyword(s):

Acute Lymphoblastic Leukaemia ◽

Lymphoblastic Leukaemia ◽

Conflicts Of Interest ◽

Residual Disease ◽

Model Systems ◽

Childhood All ◽

Therapy Assessment ◽

Childhood Acute Lymphoblastic Leukaemia

Abstract Abstract 1887 Further improvements in outcome for childhood acute lymphoblastic leukaemia (ALL) will require a better understanding of the underlying biology of this disease and the fundamental mechanisms of drug resistance. The discoveries that a few populations can initiate leukemia in mouse models and that new populations of leukaemia initiating cells (LIC) can be detected following an initial round of transplantation in these models raises important questions about the biology of the leukaemias. If several cell populations have LIC properties, what are the relationships of these populations to each other and which populations are most important to target with therapy? It will also be important to determine whether there is any correlation in the biological properties of LIC identified in the model systems with the response of the patients to therapy. Assessment of minimal residual disease (MRD) levels provides a sensitive measurement of early treatment response and permits detection of the in vivo selected drug resistant population. CD58 (leucocyte function-associated antigen 3; LFA-3) is a useful marker in MRD tracking of B cell precursor (BCP) ALL. CD58 is over expressed in these cases permitting discrimination of leukaemia blasts from normal B cells. In this study we investigated whether CD58 is expressed on LIC populations in childhood ALL. Expression of CD58 and CD34 was assessed in a cohort of 12 diagnostic samples with mixed prognoses and compared to levels detected in 11 normal bone marrow (NBM) samples. Levels of CD58 were significantly higher in the ALL cases (57.4±37.7%) than on NBM cells (21.1±12.2%; p=0.007). Likewise, the CD34+/CD58+ population was larger in ALL cases than in normal cells (22.2±34.7% and 0.25±0.25%, respectively; p=0.05). Cells from eight of the 12 patients, were sorted on the basis of expression or lack of expression of these markers and the functional ability of the sorted subpopulations was assessed in vitro and in vivo. On sorting, the majority of cells were CD34−/CD58− (43.7±39.2%), 20.7±30.7% were CD34−/CD58+, 19±14.3% were CD34+/CD58+ and the CD34+/CD58− population accounted for 16.6±35.3%. Unsorted cells and all 4 sorted populations were set up in long-term culture to assess proliferative capability and the in vivo propagating potential was assessed in NSG mice. All 4 sorted subpopulations proliferated over the 6 week period but the highest levels of expansion were observed in the cultures of CD34+/CD58+ (6–420 fold) and CD34+/CD58− (3–24 fold) cells. Cytogenetic analyses confirmed that leukaemia cells were maintained in the culture system. Results from the in vivo analyses on 5 cases to date indicate that all 4 subpopulations contain LIC. In these cases, higher levels of engraftment were observed with CD34+/CD58+ (up to 20%) and with CD34−/CD58− subpopulations (6.1-98%). Serial transplantation studies will determine whether there are differences in the repopulating and self-renewal abilities of these LIC. These findings suggest that using CD58 alone or in combination with CD34 would be insufficient to track disease progression in ALL. Incorporating additional markers that are commonly used in MRD panels will provide valuable information on LIC populations and facilitate development of improved disease monitoring. Disclosures: No relevant conflicts of interest to declare.

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Investigating the Effect of Hsp90 Inhibitors on Initiating Cells in Childhood Acute Lymphoblastic Leukaemia

Blood ◽

10.1182/blood.v118.21.2952.2952 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2952-2952

Author(s):

Paraskevi Diamanti ◽

Charlotte Victoria Cox ◽

Allison Blair

Keyword(s):

Acute Lymphoblastic Leukaemia ◽

Cell Survival ◽

Lymphoblastic Leukaemia ◽

Conflicts Of Interest ◽

Hsp90 Inhibitor ◽

Childhood Leukaemia ◽

Hsp90 Inhibitors ◽

Childhood All ◽

Childhood Acute Lymphoblastic Leukaemia ◽

Haemopoietic Cells

Abstract Abstract 2952 Enhanced risk stratification protocols and intensified therapies have improved outcomes and reduced the risk of relapse in childhood acute lymphoblastic leukaemia (ALL). Nevertheless, 20% of patients relapse, due to failure to eradicate the disease. Current chemotherapeutic regimens are designed around the properties of the bulk leukaemia cells, which might differ from those of the leukaemia initiating cell populations (LIC). Therefore, if drugs have no effect on LIC, these cells may expand and eventually cause relapse. Since several populations in childhood ALL have been shown to have LIC properties, developing therapies that are effective against all LIC populations may prevent relapse. We have previously shown that the NF-κB inhibitor parthenolide (PTL) could prevent proliferation and engraftment of unsorted cells and all LIC populations in NSG mice, in most cases examined. Heat shock protein (Hsp) 90 inhibitors are promising targets in cancer therapy. Targeting this protein has a combined impact on many oncogenic pathways involved in malignant progression. In order to investigate whether the ablation of LIC that we observed using PTL could be improved, we examined the effects of two Hsp90 inhibitors on childhood ALL cells in this study. 17-DMAG is used in preclinical and clinical phase I and II testing in breast cancers. It targets the binding site of ATP in Hsp90 and has low toxicity and high oral bioavailability. Celastrol is a novel Hsp90 inhibitor, which has recently been shown to eradicate LIC in AML by inhibiting NF-κB survival signals and inducing oxidative stress. Dose-response effects using 0.01–100nM of each Hsp90 inhibitor were assessed in primary T- and B-ALL cases and on normal haemopoietic cells at 24, 48 and 72h. Cells were stained with Annexin V and PI then viability and apoptosis were assessed by flow cytometry. An IC50 was observed in leukaemia samples using 1nM of both 17-DMAG and Celastrol after 72h. Increasing the dose of 17-DMAG to 100nM and reducing the incubation time to 48 hours for each drug further reduced ALL cell survival, without impacting normal cells. At these doses, 17-DMAG reduced the viability of T-ALL cells to 36±30% and B-ALL cells to 32±13%. In T-ALL cases, 43±15% survived treatment with Celastrol and similar results were observed with B-ALL cells (43±16%). Normal haemopoietic cells were relatively unaffected at these doses (17-DMAG: 81±2% and Celastrol: 86±36%). Subsequently, T-ALL cells were sorted for expression of CD34 and CD7 and B-ALL cells were sorted for CD34 and CD19. The subpopulations were treated with 1nM of each inhibitor and the results compared to those observed using untreated controls. However, at these concentrations the drugs had limited effects on the ALL subpopulations; 31–100% and 28–89% T-ALL subpopulations survived treatment with 17-DMAG and Celastrol respectively. Similar results were observed with B-ALL subpopulations, 9–86% survived treatment with 17-DMAG and 62–100% survived following Celastrol treatment. A number of studies have shown that a regulatory loop may exist between Hsp90 and NF-κB in that downregulation of NF-κB could lead to reduction in Hsp90 protein levels. Therefore, we investigated whether using the Hsp90 inhibitors in combination with a NF-κB inhibitor would be more effective. Samples were treated with 100nM 17-DMAG or 1nM Celastrol for 48h and 7.5mM PTL was added for the last 24 hours. In 3 T-ALL cases, PTL reduced the viability to 28±13%, 17-DMAG to 25±12% and Celastrol to 35±15%. When PTL was used in combination, cell survival was further reduced to only 18±9% (PTL + 17-DMAG) and to 19±10% (PTL + Celastrol). In 3 B-ALL cases, PTL treatment reduced viability to 57±9%, similar results were seen with 17-DMAG (59±6%), while Celastrol appeared to be the most effective of the 3 drugs (38±4%, P=0.02). When PTL was combined with the Hsp90 inhibitors the cell killing was increased by 2 fold compared to PTL or 17-DMAG alone (PTL + 17-DMAG: 31±6%, P=0.04 and PTL + Celastrol: 28±3% P=0.01). Results to date indicate a promising role for the use of Hsp90 inhibitors with PTL and data on the functional ability of treated LIC populations will provide further information on the potential of these drug combinations. In conclusion, these Hsp90 inhibitors were as effective as PTL against childhood leukaemia cells and when used in combination with PTL, cell survival was further reduced by up to 20%. Disclosures: No relevant conflicts of interest to declare.

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Importance of genotyping of Thiopurine S-methyltransferase in children with acute lymphoblastic leukaemia during maintenance therapy

Srpski arhiv za celokupno lekarstvo ◽

10.2298/sarh0812609d ◽

2008 ◽

Vol 136 (11-12) ◽

pp. 609-616 ◽

Cited By ~ 3

Author(s):

Lidija Dokmanovic ◽

Dragana Janic ◽

Nada Krstovski ◽

Branka Zukic ◽

Natasa Tosic ◽

...

Keyword(s):

Acute Lymphoblastic Leukaemia ◽

Lymphoblastic Leukaemia ◽

Tandem Repeats ◽

Gene Mutations ◽

Maintenance Phase ◽

Variable Number ◽

Childhood All ◽

Dose Therapy ◽

Significant Difference ◽

Tpmt Gene

INTRODUCTION Thiopurine S-methyltransferase (TPMT) is an enzyme that catalyses the inactivation of mercaptopurine (MP) which is widely used in the treatment of acute lymphoblastic leukaemia (ALL) of childhood. Potentially fatal myelotoxicity may develop after standard doses of MP in TPMT deficient patients. OBJECTIVES To establish if individually tailored doses of MP can reduce myelotoxicity in ALL patients carrying mutations in the TPMT gene. To establish if variable number of tandem repeats (VNTR) genotype influences the treatment effects of MP. METHOD Fifty randomly selected patients treated according to ALL IC-BFM 2002 protocol were tested for most frequent TPMT gene mutations using PCR based methods. VNTR genotype was determined in 20 children by PCR methods. During the maintenance phase, we recorded the number of weeks when therapy was applied in either full doses, reduced doses or when patients were without any therapy. RESULTS Fifty children were examined, 29 boys (58%) and 21 girls (42%); age ranged from 1.8-17.3 years (median 6.2 years). Four patients (8%) were heterozygous for TPMT mutations, all of them carrying the TPMT*3A variant. After 12, 14, 16 and 19 weeks of therapy with reduced doses of MP, the patients switched to full doses due to good tolerance. There was no therapy omission. Cumulative dose of MP was reduced for 7.8%, 7.4%, 11.2% and 16.6%, respectively, in patients with TPMT mutations. No significant difference was found between children with no mutations and TPMT heterozygotes regarding full dose therapy (53.6 vs. 55.7 weeks, respectively) and reduced dose therapy (19.9 vs. 15.2 weeks respectively). The number of detected VNTRs ranged from four to seven. The majority of patients had different number of VNTRs on homologous chromosomes. Most frequently detected polymorphism was VNTR*5. No correlation was found between TPMT and VNTR genotype inheritance. CONCLUSION Obeying pharmacogenetic principles in the treatment of childhood ALL may improve the tolerance of therapy with MP.

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Sub-Clonal Genetic Heterogeneity in BCR-ABL1 Positive Acute Lymphoblastic Leukaemia

Blood ◽

10.1182/blood.v118.21.1348.1348 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1348-1348

Author(s):

Maria-Jose Carnicer ◽

Frederik W van Delft ◽

Lyndal Kearney ◽

Mel Greaves

Keyword(s):

Acute Lymphoblastic Leukaemia ◽

Lymphoblastic Leukaemia ◽

Poor Prognosis ◽

Genomic Sequence ◽

Conflicts Of Interest ◽

Fusion Gene ◽

Snp Array ◽

Childhood All ◽

Cdkn2a Deletion ◽

Blast Cells

Abstract Abstract 1348 Philadelphia-positive (Ph+) acute lymphoblastic leukaemia (ALL), characterised by the BCR-ABL1 fusion gene, occurs in approximately 30% of adult and 5% of childhood ALL and is associated with a poor prognosis. It is considered a single clinical entity with identifiable and recurrent copy number alterations (CNA); notably deletions of the lymphoid transcriptional regulator IKAROS (encoded by IKZF1), PAX5, and CDKN2A/B that are presumed to cooperate with BCR–ABL 1 in lymphoid leukaemogenesis. In particular, IKZF1 deletions are present in 80% of BCR-ABL1 positive ALL cases, and have been implicated as an independent indicator of poor prognosis in childhood ALL. Our previous studies of twin pairs either concordant or discordant for BCR-ABL1+ ALL indicate that the fusion gene is a first hit that occurs prenatally. However, the order and sequence of acquisition of CNA is unknown. We recently reported a complex sub-clonal genetic architecture for leukaemic blasts and leukaemia-propagating (‘stem’) cells in childhood ETV6-RUNX1-positive ALL (Anderson et al., Nature 469: 356–361, 2011). In the present study, we aimed to determine whether similar sub-clonal genetic diversity occurs in BCR-ABL1+ ALL. We carried out five colour FISH to diagnostic blast cells from eight BCR-ABL1 positive cases with differentially-labelled probes for BCR, ABL1, IKZF1, CDKN2A and PAX5. In a subset of cases we also performed Affymetrix single nucleotide polymorphism (SNP 6.0) arrays to determine the specific boundaries of deletions. Four out of the eight cases screened had concurrent IKZF1, PAX5 and CDKN2A deletions. In one case the order of acquisition of these deletions was uninformative, with 97% of cells exhibiting a single FISH pattern (BCR-ABL1+ with monoallelic deletions of all three genes). In the second case, a linear clonal progression was observed with IKZF1 deleted first, PAX5 second and CDKN2A third. In the two remaining cases a branching sub-clonal pattern was observed. In one of these monoallelic IKZF1, CDKN2A and PAX5 deletions all arose independently in different sub-clones; i.e. IKZF1 was deleted first in one subclone, CDKN2A first in another and PAX5 first in a third sub-clone. In the final case we also studied matched diagnosis and relapse samples. Here, SNP array analysis revealed different deletions in all three genes at diagnosis and relapse. Genomic fusion breakpoint analysis revealed an identical BCR-ABL1 genomic sequence at diagnosis and relapse, confirming the same clonal origin of leukaemia. The different deletion boundaries in IKZF1, PAX5 and CDKN2A permitted us to design specific FISH probes to distinguish between ‘diagnostic’ and ‘relapse’ deletions and to track their evolution. The predominant clone at relapse was not a direct evolutionary product of any of the major clones found at diagnosis. The dominant sub-clone at diagnosis was BCR-ABL1+, with a large 9p deletion (encompassing PAX5 and CDKN2A) and a focal CDKN2A deletion, all sub-clonal to a focal IKZF1 deletion. At relapse, the dominant sub-clone had acquired a different IKZF1 deletion, which was sub-clonal to two different (focal, biallelic) deletions of CDKN2A and a different monoallelic PAX5 deletion. The large 9p deletion was not present at relapse. These results indicate the existence of a pre-leukaemic BCR-ABL1 fusion gene positive clone that has given rise to at least two sub-clones, each with different IKZF1, PAX5 and CDKN2A deletions, that have evolved independently. These data indicate that the sub-clonal architecture in this poor prognosis subtype of ALL is genetically diverse, and that key ‘driver’ CNA can arise independently and in no preferential order. Disclosures: No relevant conflicts of interest to declare.

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The Genomic Landscape of Relapsed B-Cell Acute Lymphoblastic Leukaemia (B-ALL) in Adolescents and Adults

Blood ◽

10.1182/blood.v124.21.3769.3769 ◽

2014 ◽

Vol 124 (21) ◽

pp. 3769-3769

Author(s):

Vikki Rand ◽

Stephen Johnstone ◽

Rachel E Crossland ◽

Sarah Wilkinson ◽

Andrew G Hall

Keyword(s):

Acute Lymphoblastic Leukaemia ◽

B Cell ◽

Disease Progression ◽

Lymphoblastic Leukaemia ◽

De Novo ◽

Chromosomal Abnormalities ◽

Conflicts Of Interest ◽

Childhood All ◽

Genomic Landscape ◽

Backtracking Analysis

Abstract Despite significant advancements in the treatment of paediatric B-cell acute lymphoblastic leukaemia (B-ALL), ALL remains one of the most challenging adult malignancies. Outcome of adult B-ALL is poor with only 40% 5-year event-free survival compared to >80% in children. B-ALL is characterised by the acquisition of chromosomal abnormalities and many are strong predictors of outcome. The difference in the prevalence of cytogenetic subtypes and specific genomic abnormalities observed between adult and childhood ALL suggests a difference in tumour biology that may contribute to the differences in patient outcome. Detailed analysis of the paediatric B-ALL genome have revealed a plethora of abnormalities targeting key pathways. Although specific alterations have been investigated in adult and adolescent B-ALL, studies of the genomic landscape remain scarce. In this study we set-out to define the genomic landscape of adolescent and adult relapsed B-ALL. Genomic backtracking analysis of sequential diagnostic and relapse samples revealed known and novel abnormalities that may play a role in chemoresistance and disease progression in these tumours. DNA was isolated from the diagnostic and relapse samples from 12 adolescents/adult patients (5 female and 7 male) diagnosed with B-ALL. Eight of the 12 patients had remission samples available. Known cytogenetic abnormalities were detected in 7 patients: high hyperdiploid, t(1;19), t(8;14) and t(4;11) rearrangements. Two cases were positive for the BCR-ABLfusion gene. The mean age at diagnosis was 36.8 years (range 16-59 years) of which 10 relapsed early, within 2 years of initial diagnosis. DNA for the 12 diagnostic, 12 relapse and 8 remission sample were hybridised to the Affymetrix SNP6.0 array to determine copy number abnormalities (CNAs). The mutational landscape was captured for 4 cases using the Agilent SureSelect Human All Exon V4+UTR kit and sequenced to depths of 200X. The incidences of the most prevalent abnormalities in paediatric B-ALL were determined in each adult/adolescent sample: CDKN2A/B 88% (21/24), IKZF1 20% (5/24), PAX5 8% (2/24), ETV6 0% (0/24), RB1 8% (2/24), BTG1 8% (2/24) and EBF1 17% (4/24). Deletions of CDKN2A/B were detected in all but one patient. In 9 cases the abnormality was seen at both diagnosis and relapse and one case had a de novo deletion at relapse. A further case had a sub-clone harbouring CDKN2A/B deletion at diagnosis that emerged as the dominant clone at relapse. Deletion of CDKN2A/Bhas been associated with poor overall survival and has been reported at high incidence in relapsed adult BCR-ABL1-ALL, but the association with prognosis and relapse in other subtypes has not been confirmed. Genomic backtracking analysis of the matched diagnostic and relapse samples identified, on average, 36 somatic mutations at relapse that were either not detected or were only detectable in a sub-clone at diagnosis. An average of 0.05 mutations per Mb were computationally predicted to be damaging to the function of the protein. Novel de novo mutations seen at relapse were identified in cancer-related genes: FAT4, CDCA7 and PVRL4. Sequencing at depth of >200X demonstrates the ability to detect mutations in the resistant clone which could be involved in disease progression. Mutations in the ATP-binding cassette transporter gene, ABCC9, were identified in a sub-clone at diagnosis at a variant frequency of 5% (13/268 reads) and at 43% (113/260) in the relapse sample. ABCC9is involved in drug resistance suggesting a potential role in chremoresistance in this patient. In conclusion, in-depth genomic analysis and whole-exome sequencing of matched diagnostic and relapse samples in adult/adolescent B-ALL has identified known and novel genomic abnormalities. Deletion of CDKN2A/B was prevalent in 11 of the 12 cases confirming the importance of this region in relapsed B-ALL. We have identified novel mutations in genes associated with chemoresistance and tumorigenesis: ABCC9, FAT4, CDCA7 and PVRL4. Our study provides the most comprehensive genetic portrait of adult relapsed B-ALL to date and is a significant step to defining the genetic causes of disease progression and chemoresistance. Disclosures No relevant conflicts of interest to declare.

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Combining BCL-2 Inhibitors with Parthenolide to Treat Childhood Acute Lymphoblastic Leukaemia

Blood ◽

10.1182/blood.v126.23.2531.2531 ◽

2015 ◽

Vol 126 (23) ◽

pp. 2531-2531

Author(s):

Paraskevi Diamanti ◽

William J Barendt ◽

Benjamin C Ede ◽

Charlotte V. Cox ◽

Allison Blair

Keyword(s):

Clinical Trials ◽

Drug Treatment ◽

Acute Lymphoblastic Leukaemia ◽

Lymphoblastic Leukaemia ◽

Conflicts Of Interest ◽

Minimal Risk ◽

Childhood All ◽

Childhood Acute Lymphoblastic Leukaemia

Abstract Current therapies for the treatment of childhood acute lymphoblastic leukaemia (ALL) have resulted in vastly improved survival rates of around 90% in recent years. Despite these successes, around 15% of patients die of relapse. It is possible that ALL may be maintained by subpopulations of cells, known as leukaemia stem cells (LSC), that are resistant to therapy and subsequent relapses may arise from these cells. Parthenolide (PTL), a naturally occurring sesquiterpene lactone, is an NF-κB inhibitor that kills leukaemia cells by apoptosis and/or increase of reactive oxygen species. PTL has been shown to be remarkably effective against several LSC subpopulations in vivo, with complete ablation of leukaemia. In a minority of cases, leukaemia burden was reduced following PTL treatment but not eliminated. Therefore, it may be necessary to combine PTL with other agents to improve killing of all LSC subpopulations. Another pathway of increasing interest in the treatment of leukaemias is the BCL-2 family. BCL-2 has been shown to be overexpressed in over 66% of B-ALL cases and is associated with tumourigenesis in several cancers. ABT-263 is an inhibitor of BCL-2, BCL-xL and BCL-w, it has been shown to selectively target AML LSC and is in early clinical trials in lymphoid malignancies. ABT-199 is another promising inhibitor that is currently in clinical trials for CLL. ABT-199 is specific for BCL-2 and has minimal risk for thrombocytopenia. In the present study the effects of both ABT-263 and ABT-199 alone or in combination with PTL were assessed in childhood ALL samples to determine whether toxicity to leukaemia cells could be improved in vitro and in vivo. The viability of bulk cells from 11 B cell precursor (BCP) ALL cases and 11 cord blood (CB) samples following drug treatment for 24 hours were assessed using flow cytometry by staining with Annexin V and propidium iodide. Initially, PTL was used at a range of 1 to 10μM, ABT-263 from 0.025 to 1μM and ABT-199 from 0.1 to 10μM. Only PTL and ABT-263 significantly reduced the viability of ALL cells compared to CB with IC50 values of 1.2μM and 0.125μM (P≤0.01 and P≤0.0015), respectively. In vitro drug combination studies demonstrated synergism when combining PTL with ABT-263 in a 9.5:1 ratio using the Chou Talalay model. The viability of ALL cells following combination therapy (1.2μM PTL with 0.125μM ABT-263) was reduced to 38.3±32.5%, while CB viability was unaffected (96.9±29%, P<0.0001). Using this combined dose, toxicity to ALL cells was increased by a further 35% compared to PTL alone and by 25% compared to ABT-263 alone. Even at the highest combined doses tested (9.6μM PTL: 1μM ABT-263) normal CB remained relatively unaffected with 73.3±25% surviving. The effects of these drugs alone and in combination were also assessed in LSC subpopulations in 3 of these cases. Unsorted ALL cells, CD34+/CD19+ and CD34-/CD19+ subpopulations were the most responsive with viabilities ranging from 17.6±4% to 23.9±11% using 1.2μM PTL and 0.125μM ABT-263. The CD34+/CD19- and CD34-/CD19- cells were more resistant with 70.3±40% and 73.3±15% surviving, respectively. However, since we have previously shown that the effects of in vitro drug treatment do not always accurately reflect the response in vivo, it was important to evaluate the effects of these drugs in mice with established leukaemia. NOD/LtSz-scid IL-2Rγc null (NSG) mice were inoculated with 1-1.15x106 unsorted BCP-ALL cells. Once the levels of leukaemia engraftment in murine peripheral blood reached ≥ 0.1%, mice were treated with 100mg/kg ABT-263 or ABT-199 and vehicle by oral gavage for 21 consecutive days and the levels of leukaemia burden were monitored weekly. Results to date demonstrate that leukaemia levels continued to rise in placebo-treated mice, reaching 49.2±7% by day 21, while the levels in ABT-263 and ABT-199 treated mice were significantly lower at 8.6±10% and 23.7±12%, respectively (P<0.0001). The use of ABT-263 and ABT-199 significantly improved the survival of NSG compared to untreated controls (P=0.0001). These data indicate that combining PTL with ABT-263 shows promising results in the killing of bulk and LSC populations in BCP-ALL. Ongoing in vivo studies will assess the potential of using BCL-2 inhibitors in combination with PTL compared to standard chemotherapeutics. Disclosures No relevant conflicts of interest to declare.

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Single Centre Audit of Testicular Examination Practice in Children with Acute Lymphoblastic Leukaemia

Blood ◽

10.1182/blood.v128.22.5159.5159 ◽

2016 ◽

Vol 128 (22) ◽

pp. 5159-5159

Author(s):

Isobelle Wardach ◽

Aisha Aslam ◽

Russell D Keenan

Keyword(s):

Acute Lymphoblastic Leukaemia ◽

Lymphoblastic Leukaemia ◽

Maintenance Treatment ◽

Conflicts Of Interest ◽

Residual Disease ◽

Clinic Visit ◽

Significant Difference ◽

Chi Squared ◽

Extramedullary Relapse ◽

Self Examination

Abstract Introduction The second commonest site of extramedullary relapse in boys with acute lymphoblastic leukaemia (ALL) is the testes. As therapy stratifications based on minimal residual disease (MRD) reduce marrow relapses, testicular relapses are becoming relatively more frequent. Currently the only strategy to detect testicular relapse is regular clinical and self examination. Based on previous UK protocols timing of testicular relapses, our centre policy is to perform testicular examinations monthly whilst on maintenance treatment and at each clinic visit until 2 years off treatment. After this time we encourage monthly self/parent examination. Parents, boys, medical and nursing staff are on occasions reluctant for this examination. We performed an audit to evaluate our practice and assess areas to improve testicular relapse detection. Methods We retrospectively audited 46 patient records which included 322 consultations over a 6 month period (December 2015 to May 2016) in male patients with ALL. 30 patients (232 consultations) were on maintenance treatment and 16 patients (90 consultations) were within 2 years off treatment. To assess factors and potential barriers to examination, data was collected on age of patient (age 11 and under/age 12 and over), gender of examiner and profession of examiner (Doctor/Advanced Nurse Practitioner (ANP)) in patients on maintenance or off treatment. Differences in testicular examination rates were analysed by chi-squared testing. Results Only 4 of the 46 patients had monthly testicular examinations. 24 were not examined at all over a 6 month period. Of the 322 consultations, 42 had documented testicular examinations (13%). Patients off treatment (26 of 90 consultations) were significantly more likely to be examined than patients on maintenance treatment (16 of 232 consultations), (p < 0.0001). There was no significant difference between doctors (10 of 126 consultations) and ANPs (6 of 106 consultations) in patients on maintenance treatment, (p=0.50). More ANPs documented testicular examination (23 of 55 consultations) in patients off treatment than doctors (3 of 35 consultations), (p = 0.0007). Male examiners (11 of 74 consultations) were significantly more likely to document testicular examination in patients on maintenance treatment than female examiners (5 of 158 consultations), (p = 0.001). In patients off treatment, there was no significant difference between male examiners (3 of 15 consultations) and female examiners (23 of 75 consultations), (p=0.41). There was no significant difference between incidence of examinations in children aged 11 and under (13 of 181 consultations) and children aged 12 and over (3 of 51 consultations) on maintenance treatment, (p=0.75). In patients off treatment, children aged 11 and under (23 of 62 consultations) were significantly more likely to be examined than children aged 12 and over (3 of 26 consultations), (p=0.02). Conclusions Currently our testicular examination rates are very poor and practice is not adhering to hospital guidance. Male examiners were more likely to perform testicular examinations than female examiners on children on maintenance treatment, however all rates were poor. ANPs were more likely to perform testicular examination than doctors on children off treatment. This may be affected by trainee doctors, not consultants in these clinics. Improved incidence of testicular examination in patients off treatment is maybe due to the clinic pro-forma specifying to document testicular examination, or a difference in clinic focus. In patients off treatment children aged 11 and under were more likely to be examined than those aged 12 and over, highlighting increasing age as a possible barrier. Testicular examination is an area where staff are often hesitant due to the sensitive and intimate nature of the examination. Barriers may include concerns over patient embarrassment, staff embarrassment and time pressures in clinic. Recommendations Training update for examiners regarding importance of performing testicular examination monthlyPro-forma modification to specify documentation of testicular examination on maintenance treatmentPatient/parent teaching of the rationale and importance of testicular examination to improve understanding and normalise the expectation of this examinationRe-audit following implementation of afore mentioned recommendations Disclosures No relevant conflicts of interest to declare.

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DNA Methylation Profiling of Childhood Acute Lymphoblastic Leukaemia Using Illumina Infinium DNA Methylation27 Bead Arrays Identifies a Distinct DNA Methylation Signature Associated with Leukaemogenesis

Blood ◽

10.1182/blood.v116.21.4650.4650 ◽

2010 ◽

Vol 116 (21) ◽

pp. 4650-4650

Author(s):

Nicholas C. Wong ◽

Zac Chatterton ◽

Katrina Bell ◽

Adam Kowalcyk ◽

Justin Bedo ◽

...

Keyword(s):

Dna Methylation ◽

Acute Lymphoblastic Leukaemia ◽

Lymphoblastic Leukaemia ◽

Significant Proportion ◽

Chromosome Translocation ◽

Support Vector ◽

Childhood Leukaemia ◽

Gene Promoters ◽

Childhood All ◽

Network Analyses

Abstract Abstract 4650 Acute Lymphoblastic Leukaemia (ALL) is the most common form of cancer in children. Although up to 80% of cases can be characterised by either abnormal chromosome number (hyper- or hypo-diploidy) or a specific chromosome translocation, a significant proportion of cases do no exhibit any major chromosome abnormality. Indeed, no common gene mutation has been found to be associated with childhood leukaemia. This suggests that epigenetic modifications, in particular DNA methylation, may also play a significant role in ALL pathogenesis. Understanding the specific epigenetic changes associated with this disease is therefore of paramount importance for predicting onset and disease outcome and understanding disease aetiology. From our cohort of over 450 cases of childhood leukaemia we analysed 12 cases of childhood ALL that carried the TEL/AML1 (RUNX1/ETV6) chromosome translocation using Illumina Infinium Human Methylation27K bead chip arrays. These interrogate 27,578 CpG methylation sites across the human genome covering 14,495 RefSeq gene promoters. We analysed matching leukaemia and remission bone marrow with the aim of identifying DNA methylation signatures associated with this leukaemia subtype. We used a number of computational methods to determine the DNA methylation signatures associated with childhood ALL including LIMMA, Centroid Analysis and Support Vector Machine Modelling. This identified 16 probes sufficient to define a leukaemia sample from a remission sample based on methylation level. We are currently validating our results using high throughput SEQUENOM and performing gene pathway and network analyses to look for commonly affected genes associated with leukaemia. These methylation changes we have identified may help refine the diagnosis of childhood ALL and identify cellular pathways subject to epigenetic disruption in ALL. Disclosures: No relevant conflicts of interest to declare.

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What Role for Angiogenesis in Childhood Acute Lymphoblastic Leukaemia?

Advances in Hematology ◽

10.1155/2011/274628 ◽

2011 ◽

Vol 2011 ◽

pp. 1-8 ◽

Cited By ~ 7

Author(s):

P. Schneider ◽

I. Dubus ◽

F. Gouel ◽

E. Legrand ◽

J. P. Vannier ◽

...

Keyword(s):

Bone Marrow ◽

Growth Factor ◽

Acute Lymphoblastic Leukaemia ◽

Lymphoblastic Leukaemia ◽

Leukemia Cell ◽

Myelogenous Leukemia ◽

Leukemia Cell Line ◽

Prognostic Impact ◽

Childhood All ◽

Acute Myelogenous

The role of angiogenesis in acute leukaemia has been discussed since the cloning of the gene ofvascular endothelial growth factor(VEGF) from the acute myelogenous leukemia cell line (HL60) and, thereafter, when the first studies reported increased bone marrow vascularity and elevation of angiogenic cytokines in acute lymphoblastic leukaemia (ALL). VEGF andbasic fibroblast growth factor(bFGF) are the major proangiogenic cytokines that have been studied, and evaluation of their prognostic impact in childhood ALL has been reported in several studies, though with controversial results. The antiangiogenic response, contributing to the angiogenic balance, has scarcely been reported. The origin of the factors, their prognostic value, and their relevance as good markers of what really happens in the bone marrow are discussed in this paper. The place of antiangiogenic drugs in ALL has to be defined in the global treatment strategy.

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The Genetic Variants of IKZF1 Gene Linked with the Growing Risk of Childhood Acute Lymphoblastic Leukaemia

Current Molecular Medicine ◽

10.2174/1566524019666190219123900 ◽

2019 ◽

Vol 19 (1) ◽

pp. 32-39

Author(s):

Safaa I. Tayel ◽

Sally M. El-Hefnway ◽

Wafaa Moustafa M. Abo El-fotoh ◽

Rania S. El-Zayat

Keyword(s):

Acute Lymphoblastic Leukaemia ◽

Lymphoblastic Leukaemia ◽

Genetic Variants ◽

Transferrin Saturation ◽

Significant Risk ◽

Control Group ◽

Childhood Acute Lymphoblastic Leukaemia ◽

Group I ◽

Egyptian Children ◽

Significant Difference

Background: The zinc finger protein IKAROS (IKZF1) is an essential transcription factor in haematopoiesis that is involved primarily in lymphoid tissue differentiation. Many studies have indicated that IKZF1 alterations may be associated with acute lymphoblastic leukaemia, but the results remain controversial. Objective: We aimed to investigate the association of the rs4132601 T/G and rs10272724 T/C IKZF1 gene polymorphisms with the risk of childhood acute lymphoblastic leukaemia and to determine whether these genetic variants affect the clinical parameters and the iron profiles of these children cohort. Methods: This case control study was conducted on 170 Egyptian children comprising of two groups: group (I) included 90 children diagnosed with acute lymphoblastic leukaemia and group (II) comprised of 80 ages and sex-matched healthy control children. The studied polymorphisms were genotyped using PCR restriction fragment length polymorphism (PCR-RFLP). Results: A higher frequency of the mutant GG genotype and G allele of rs4132601 was found in the patient group than in the control group. The results also showed a significant difference among the rs10272724 genotypes, with a higher frequency of the mutant CC genotype and C allele in the patients than in controls. The mutant GG genotype of rs4132601 and the mutant CC genotype of rs10272724 were associated with a higher serum ferritin level and transferrin saturation and an older age at diagnosis of acute lymphoblastic leukaemia than the other genotypes. Conclusion: IKZF1 rs4132601 and rs10272724 could be considered significant risk contributors to childhood acute lymphoblastic leukaemia and may impact the iron profiles in these children.

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