We report incidence and deep molecular characteristics of lineage switch in 182 pediatric patients affected by B-cell precursor acute lymphoblastic leukemia (BCP-ALL), who were treated with ...blinatumomab. We documented six cases of lineage switch that occurred after or during blinatumomab exposure. Therefore, lineage conversion was found in 17.4% of all resistance cases (4/27) and 3.2% of relapses (2/63). Half of patients switched completely from BCP-ALL to CD19-negative acute myeloid leukemia, others retained CD19-positive B-blasts and acquired an additional CD19-negative blast population: myeloid or unclassifiable. Five patients had
gene rearrangements; one had
translocation. The presented cases showed consistency of gene rearrangements and fusion transcripts across initially diagnosed leukemia and lineage switch. In two of six patients, the clonal architecture assessed by
gene rearrangements was stable, while in others, loss of clones or gain of new clones was noted.
-r patients demonstrated very few additional mutations, while in the
case, lineage switch was accompanied by a large set of additional mutations. The immunophenotype of an existing leukemia sometimes changes via different mechanisms and with different additional molecular changes. Careful investigation of all BM compartments together with all molecular -minimal residual disease studies can lead to reliable identification of lineage switch.
Background
Detection of bone marrow (BM) involvement in patients with neuroblastoma is crucial for staging and defining prognosis. Furthermore, the persistence of residual tumor cells in the BM is ...associated with an unfavorable outcome.
Methods
Expression of PHOX2B, TH, ELAVL4, and B4GALNT1 (GD2‐synthase) was analyzed by quantitative polymerase chain reaction in neuroblastoma cell lines, control BM samples, and in BM samples from patients. The threshold level of expression for each gene was established through receiver operator characteristic analysis and used to determine the diagnostic test performance. The prognostic significance of BM involvement was assessed by survival rates calculations. The median of follow‐up time was 36.1 months.
Results
Neither PHOX2B nor TH expression was detected in control BM, while expression of ELAVL4 was found in 20 (76.9%) and GD2‐synthase in 15 (57.7%) of 26 samples. The overall correct predictive value for TH, ELAVL4, and GD2‐synthase, based on thresholds levels, was 0.952, 0.828, and 0.767, respectively, whereas the overall correct predictive value for PHOX2B was 0.994. The PHOX2B/TH expression in diagnostic BM of patients with neuroblastoma corresponded with a decreased survival rate (P < 0.001) in the total cohort and in different risk groups. Predominance of normalized expression of PHOX2B over TH > 1.68 in the diagnostic BM samples demonstrated an adverse prognostic effect (P = 0.006). Persistence of PHOX2B/TH expression in the BM during and after induction chemotherapy resulted in dismal outcome (P = 0.022 and P = 0.012).
Conclusion
PHOX2B and TH are the most optimal markers for detection of BM involvement, allowing identification of high‐risk patients. Predominance of PHOX2B expression over TH has a strong adverse prognostic impact.
This report presents the results of the assessment of MRD response by multicolor flow cytometry (MFC) with regard to the randomized use of pegylated asparaginase (PEG). In this study, PEG was ...randomly administered at a dose of 1000 U/m
on day 3 of induction therapy in children with B-lineage ALL.
Conventional induction therapy consisted of dexamethasone, vincristine, and daunorubicin. MRD data was available in 502 patients who were randomized at the start of induction therapy, standard-risk (SR) patients into three (conventional induction without PEG, induction with additional PEG and with PEG but without daunorubicin) and intermediate-risk (ImR) patients into two groups (with additional PEG and without PEG).
The single administration of PEG resulted in a significantly higher proportion of rapid responders, in SR patients even when no anthracyclines were used for induction. In the SR group, the event-free survival of the MFC-MRD fast responders was similar in the PEG- and PEG+ arms (92.0 ± 3.1% vs. 96.2 ± 1.5%, respectively), and the same unfavorable trend was observed for MFC-MRD slow responders (57.5 ± 12.3% vs. 66.7 ± 15.7%, respectively). Results were similar in ImR patients: (94.3 ± 3.2% vs. 95.1 ± 2.4%, for fast responders and 63.3 ± 7.6% vs. 78.1 ± 7.9%, for slow responders in PEG- and PEG+ arms, respectively). However, there is a large difference between the proportion of MFC-MRD slow responders in the PEG- and PEG+ groups (18.3% vs. 5.2% for the SR group and 44.2% vs. 25.0% for the ImR group).
Therefore, early use of PEG-ASP not only leads to an accelerated reduction of blasts, but also to an excellent outcome in a significantly larger proportion of patients in both risk groups.
Background
Quantitative measurement of minimal residual disease (MRD) is the “gold standard” for estimating the response to therapy in childhood B‐cell precursor acute lymphoblastic leukemia ...(BCP‐ALL). Nevertheless, the speed of the MRD response differs for different cytogenetic subgroups. Here we present results of MRD measurement in children with BCP‐ALL, in terms of genetic subgroups with relation to clinically defined risk groups.
Methods
A total of 485 children with non‐high‐risk BCP‐ALL with available cytogenetic data and MRD studied at the end‐of‐induction (EOI) by multicolor flow cytometry (MFC) were included. All patients were treated with standard‐risk (SR) of intermediate‐risk (ImR) regimens of “ALL‐MB 2008” reduced‐intensity protocol.
Results and Discussion
Among all study group patients, 203 were found to have low‐risk cytogenetics (ETV6::RUNX1 or high hyperdiploidy), while remaining 282 children were classified in intermediate cytogenetic risk group. For the patients with favorable and intermediate risk cytogenetics, the most significant thresholds for MFC‐MRD values were different: 0.03% and 0.04% respectively. Nevertheless, the most meaningful thresholds were different for clinically defined SR and ImR groups. For the SR group, irrespective to presence/absence of favorable genetic lesions, MFC‐MRD threshold of 0.1% was the most clinically valuable, although for ImR group the most informative thresholds were different in patients from low‐(0.03%) and intermediate (0.01%) cytogenetic risk groups.
Conclusion
Our data show that combining clinical risk factors with MFC‐MRD measurement is the most useful tool for risk group stratification of children with BCP‐ALL in the reduced‐intensity protocols. However, this algorithm can be supplemented with cytogenetic data for part of the ImR group.
Approximately 5-20% of chronic myeloid leukemia (CML) patients demonstrate primary resistance or intolerance to imatinib. None of the existing predictive scores gives a good prognosis of TKI ...efficacy. Gene polymorphisms, expression and microRNAs are known to be involved in the pathogenesis of TKI resistance in CML. The aim of our study is to find new molecular markers of TKI therapy efficacy in CML patients.
Newly diagnosed patients with Ph+ CML in chronic phase were included in this study. Optimal and non-optimal responses to TKI were estimated according to ELN 2013 recommendation. We performed genotyping of selected polymorphisms in 62 blood samples of CML patients, expression profiling of 33 RNA samples extracted from blood and miRNA profiling of 800 miRNA in 12 blood samples of CML patients.
The frequencies of genotypes at the studied loci did not differ between groups of patients with an optimal and non-optimal response to TKI therapy. Analysis of the expression of 34,681 genes revealed 26 differently expressed genes (p < 0.05) in groups of patients with different TKI responses, but differences were very small and were not confirmed by qPCR. Finally, we did not find difference in miRNA expression between the groups.
Using modern high-throughput methods such as whole-exome sequencing, transcriptome and miRNA analysis, we could not find reliable molecular markers for early prediction of TKI efficiency in Ph+ CML patients.
Chromosomal rearrangements of the human KMT2A/MLL gene are associated with acute leukemias, especially in infants. KMT2A is rearranged with a big variety of partner genes and in multiple breakpoint ...locations. Detection of all types of KMT2A rearrangements is an essential part of acute leukemia initial diagnostics and follow-up, as it has a strong impact on the patients’ outcome. Due to their high heterogeneity, KMT2A rearrangements are most effectively uncovered by next-generation sequencing (NGS), which, however, requires a thorough prescreening by cytogenetics. Here, we aimed to characterize uncommon KMT2A rearrangements in childhood acute leukemia by conventional karyotyping, FISH, and targeted NGS on both DNA and RNA level with subsequent validation. As a result of this comprehensive approach, three novel KMT2A rearrangements were discovered: ins(X;11)(q26;q13q25)/KMT2A-BTK, t(10;11)(q22;q23.3)/KMT2A-NUTM2A, and inv(11)(q12.2q23.3)/KMT2A-PRPF19. These novel KMT2A-chimeric genes expand our knowledge of the mechanisms of KMT2A-associated leukemogenesis and allow tracing the dynamics of minimal residual disease in the given patients.
IKZF1 deletion (ΔIKZF1) is an important predictor of relapse in both childhood and adult B-cell precursor acute lymphoblastic leukemia (B-ALL). Previously, we revealed that COBL is a hotspot for ...breakpoints in leukemia and could promote IKZF1 deletions. Through an international collaboration, we provide a detailed genetic and clinical picture of B-ALL with COBL rearrangements (COBL-r). Patients with B-ALL and IKZF1 deletion (n = 133) were included. IKZF1 ∆1-8 were associated with large alterations within chromosome 7: monosomy 7 (18%), isochromosome 7q (10%), 7p loss (19%), and interstitial deletions (53%). The latter included COBL-r, which were found in 12% of the IKZF1 ∆1-8 cohort. Patients with COBL-r are mostly classified as intermediate cytogenetic risk and frequently harbor ETV6, PAX5, CDKN2A/B deletions. Overall, 56% of breakpoints were located within COBL intron 5. Cryptic recombination signal sequence motifs were broadly distributed within the sequence of COBL, and no enrichment for the breakpoint cluster region was found. In summary, a diverse spectrum of alterations characterizes ΔIKZF1 and they also include deletion breakpoints within COBL. We confirmed that COBL is a hotspot associated with ΔIKZF1, but these rearrangements are not driven by RAG-mediated recombination.
Background: Vincristine polyneuropathy is a major neurotoxic complication of treatment for acute lymphoblastic leukemia in children. A close relationship between genetic variants in candidate genes ...associated with the vincristine neurotoxicity in various ethnic groups has been proposed. Therefore, identification of the genetic risk factors underlying the predisposition to vincristine polyneuropathy could allow the development of effective tools for preventive diagnostics aimed at identifying a high-risk group among patients treated with vincristine for a personalized approach to their chemotherapy.
Aim: To study an association between the rs924607 polymorphism of the CEP72 gene and vincristine polyneuropathy in children with acute lymphoblastic leukemia.
Materials and methods: This single center cohort study enrolled 199 children aged 3 to 17 years with newly diagnosed acute lymphoblastic leukemia, who received ALL-MB 2015 chemotherapy regimen. All patients were genotyped for the single nucleotide variant rs924607 in the CEP72 gene by real-time polymerase chain reaction and subsequent allelic discrimination. A comparative analysis of the incidence and clinical signs of vincristine polyneuropathy depending on the carrier of the genetic polymorphism was performed.
Results: The incidence of vincristine polyneuropathy in the study pediatric group was 81.0% (n = 161); mostly these were patients with NCI-STCAE grade 2 severity. The rs924607 single nucleotide variant in the CEP72 gene was significantly associated with the neurotoxic complication, with 19.1% (n = 38) of the patients were homozygous for the minor allele (rs924607 genotype TT) and 46.2% (n = 92) had the ST genotype. Among the carriers of at least one rs924607 risk allele (T), the odds ratio for vincristine polyneuropathy was 2.91 (95% confidence interval 1.415.99, p = 0.004). No significant association between the genetic variant assessed and clinical signs of vincristine-induced polyneuropathy was found.
Conclusion: The single nucleotide rs924607 polymorphism of the CEP72 gen can be a putative pharmacogenetic marker for vincristine polyneuropathy.
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