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Diagnostic criteria for juvenile myelomonocytic leukemia (JMML) are currently well defined, however in some patients diagnosis still remains a challenge. Flow cytometry is a well established tool for diagnosis and follow-up of hematological malignancies, nevertheless it is not routinely used for JMML diagnosis. Herewith, we characterized the CD34+ hematopoietic precursor cells collected from 31 children with JMML using a combination of standardized EuroFlow antibody panels to assess the ability to discriminate JMML cells from normal/reactive bone marrow cell as controls (n=29) or from cells of children with other hematological diseases mimicking JMML (n=9). CD34+ precursors in JMML showed markedly reduced B-cell and erythroid-committed precursors compared to controls, whereas monocytic and CD7+ lymphoid precursors were significantly expanded. Moreover, aberrant immunophenotypes were consistently present in CD34+ precursors in JMML, while they were virtually absent in controls. Multivariate logistic regression analysis showed that combined assessment of the number of CD34+CD7+ lymphoid precursors and CD34+ aberrant precursors or erythroid precursors had a great potential in discriminating JMMLs versus controls. Importantly our scoring model allowed highly efficient discrimination of truly JMML versus patients with JMML-like diseases. In conclusion, we show for the first time that CD34+ precursors from JMML patients display a unique immunophenotypic profile which might contribute to a fast and accurate diagnosis of JMML worldwide by applying an easy to standardize single eight-color antibody combination.

ABL-class fusions other than BCR-ABL1 characterize around 2-3% of precursor B-cell acute lymphoblastic leukemia. Case series indicated that patients suffering from these subtypes have a dismal outcome and may benefit from the introduction of tyrosine kinase inhibitors. We analyzed clinical characteristics and outcome of 46 ABL-class fusion positive cases other than BCR-ABL1 treated according to AIEOP-BFM (Associazione Italiana di Ematologia-Oncologia Pediatrica-Berlin-Frankfurt-Münster) ALL 2000 and 2009 protocols; 13 of them received a tyrosine kinase inhibitor (TKI) during different phases of treatment. ABL-class fusion positive cases had a poor early treatment response: minimal residual disease levels of ≥5×10 -4 were observed in 71.4% of patients after induction treatment and in 51.2% after consolidation phase. For the entire cohort of 46 cases, the 5-year probability of event-free survival was 49.1+8.9% and that of overall survival 69.6+7.8%; the cumulative incidence of relapse was 25.6+8.2% and treatment-related mortality (TRM) 20.8+6.8%. One out of 13 cases with TKI added to chemotherapy relapsed while eight of 33 cases without TKI treatment suffered from relapse, including six in 17 patients who had not received hematopoietic stem cell transplantation. Stem cell transplantation seems to be effective in preventing relapses (only three relapses in 25 patients), but was associated with a very high TRM (6 patients). These data indicate a major need for an early identification of ABL-class fusion positive acute lymphoblastic leukemia cases and to establish a properly designed, controlled study aimed at investigating the use of TKI, the appropriate chemotherapy backbone and the role of hematopoietic stem cell transplantation. (Registered at: clinicaltrials.gov identifier: NTC00430118, NCT00613457, NCT01117441) ., (Copyright© 2020 Ferrata Storti Foundation.)

B-cell precursor-acute lymphoblastic leukemia modulates the bone marrow (BM) niche to become leukemia-supporting and chemo-protective by reprogramming the stromal microenvironment. New therapies targeting the interplay between leukemia and stroma can help improve disease outcome. We identified ActivinA, a TGF-β family member with a well-described role in promoting several solid malignancies, as a factor favoring leukemia that could represent a new potential target for therapy. ActivinA resulted over-expressed in the leukemic BM and its production was strongly induced in mesenchymal stromal cells after culture with leukemic cells. Moreover, MSCs isolated from BM of leukemic patients showed an intrinsic ability to secrete higher amounts of ActivinA compared to their normal counterparts. The pro-inflammatory leukemic BM microenvironment synergized with leukemic cells to induce stromal-derived ActivinA. Gene expression analysis of ActivinA-treated leukemic cells showed that this protein was able to significantly influence motility-associated pathways. Interestingly, ActivinA promoted random motility and CXCL12-driven migration of leukemic cells, even at suboptimal chemokine concentrations, characterizing the leukemic niche. Conversely, ActivinA severely impaired CXCL12-induced migration of healthy CD34 + cells. This opposite effect can be explained by the ability of ActivinA to increase intracellular calcium only in leukemic cells, boosting cytoskeleton dynamics through a higher rate of actin polymerization. Moreover, by stimulating the invasiveness of the leukemic cells, ActivinA was found to be a leukemia-promoting factor. Importantly, the ability of ActivinA to enhance BM engraftment and the metastatic potential of leukemic cells was confirmed in a xenograft mouse model of the disease. Overall, ActivinA was seen to be a key factor in conferring a migratory advantage to leukemic cells over healthy hematopoiesis within the leukemic niche., (Copyright© 2019 Ferrata Storti Foundation.)

The prognostic value of minimal residual disease (MRD) in Philadelphia-chromosome-positive (Ph+) childhood acute lymphoblastic leukemia (ALL) treated with tyrosine kinase inhibitors is not fully established. We detected MRD by real-time quantitative polymerase chain reaction (RQ-PCR) of rearranged immunoglobulin/T-cell receptor genes (IG/TR) and/or BCR/ABL1 fusion transcript to investigate its predictive value in patients receiving Berlin-Frankfurt-Münster (BFM) high-risk (HR) therapy and post-induction intermittent imatinib (the European intergroup study of post-induction treatment of Philadelphia-chromosome-positive acute lymphoblastic leukemia (EsPhALL) study). MRD was monitored after induction (time point (TP)1), consolidation Phase IB (TP2), HR Blocks, reinductions, and at the end of therapy. MRD negativity progressively increased over time, both by IG/TR and BCR/ABL1. Of 90 patients with IG/TR MRD at TP1, nine were negative and none relapsed, while 11 with MRD<5×10 -4 and 70 with MRD≥5×10 -4 had a comparable 5-year cumulative incidence of relapse of 36.4 (15.4) and 35.2 (5.9), respectively. Patients who achieved MRD negativity at TP2 had a low relapse risk (5-yr cumulative incidence of relapse (CIR)=14.3[9.8]), whereas those who attained MRD negativity at a later date showed higher CIR, comparable to patients with positive MRD at any level. BCR/ABL1 MRD negative patients at TP1 had a relapse risk similar to those who were IG/TR MRD negative (1/8 relapses). The overall concordance between the two methods is 69%, with significantly higher positivity by BCR/ABL1. In conclusion, MRD monitoring by both methods may be functional not only for measuring response but also for guiding biological studies aimed at investigating causes for discrepancies, although from our data IG/TR MRD monitoring appears to be more reliable. Early MRD negativity is highly predictive of favorable outcome. The earlier MRD negativity is achieved, the better the prognosis., (Copyright© 2018 Ferrata Storti Foundation.)

The outcome of children and adults with acute lymphoblastic leukemia is markedly different. Since there is limited information on the distribution of clinico-biological variables in different age cohorts, we analyzed 5202 patients with acute lymphoblastic leukemia enrolled in the Italian multicenter AIEOP and GIMEMA protocols and stratified them in nine age cohorts. The highest prevalence of acute lymphoblastic leukemia was observed in children, although a second peak was recorded from the 4(th) decade onwards. Interestingly, the lowest incidence was found in females between 14-40 years. Immunophenotypic characterization showed a B-lineage in 85.8% of patients: a pro-B stage, associated with MLL/AF4 positivity, was more frequent in patients between 10-50 years. T-lineage leukemia (14.2%) was rare among small children and increased in patients aged 10-40 years. The prevalence of the BCR/ABL1 rearrangement increased progressively with age starting from the cohort of patients 10-14 years old and was present in 52.7% of cases in the 6th decade. Similarly, the MLL/AF4 rearrangement constantly increased up to the 5(th) decade, while the ETV6/RUNX1 rearrangement disappeared from the age of 30 onwards. This study shows that acute lymphoblastic leukemia in adolescents and young adults is characterized by a male prevalence, higher percentage of T-lineage cases, an increase of poor prognostic molecular markers with aging compared to cases in children, and conclusively quantified the progressive increase of BCR/ABL(+) cases with age, which are potentially manageable by targeted therapies.

New prognostic markers are needed for upfront identification of patients with acute lymphocytic leukemia with a high risk of relapse or who are not likely to respond to the most aggressive chemotherapy. We focused our analysis on Ikaros (IKZF1) gene deletions in a homogeneous cohort of 410 pediatric patients with Philadelphia chromosome-negative, B-cell precursor acute lymphoblastic leukemia enrolled in Italy into the AIEOP-BFM ALL2000 study. We confirm their reported poor prognostic value, although the associated event-free survival was relatively high (approximately 70%). The difference in the cumulative incidence of relapse between patients positive or not for IKZF1 deletions was not marked: 24.2% (5.9) versus 13.1% (1.8) overall and 23.9% (6.6) versus 16.5% (2.5) in the intermediate-risk subgroup. In line with this, IKZF1 deletions were not an independent prognostic factor for the hazard of relapse. Most IKZF1-deleted cases stratified in the high-risk group relapsed, suggesting that once identified, patients with these deletions require an alternative treatment. In conclusion, the need of and benefit from introducing IKZF1 deletions as an additional stratification marker for patients with Philadelphia-negative B-cell precursor acute lymphoblastic leukemia remain questionable.

Acute lymphoblastic leukemia in infants represents an aggressive malignancy associated with a high incidence (approx. 80%) of translocations involving the Mixed Lineage Leukemia (MLL) gene. Attempts to mimic Mixed Lineage Leukemia fusion driven leukemogenesis in mice raised the question whether these fusion proteins require secondary hits. RAS mutations are suggested as candidates. Earlier results on the incidence of RAS mutations in Mixed Lineage Leukemia-rearranged acute lymphoblastic leukemia are inconclusive. Therefore, we studied frequencies and relation with clinical parameters of RAS mutations in a large cohort of infant acute lymphoblastic leukemia patients. Using conventional sequencing analysis, we screened neuroblastoma RAS viral (v-ras) oncogene homolog gene (NRAS), v-Ki-ras Kirsten rat sarcoma viral oncogene homolog gene (KRAS), and v-raf murine sarcoma viral oncogene homolog B1 gene (BRAF) for mutations in a large cohort (n=109) of infant acute lymphoblastic leukemia patients and studied the mutations in relation to several clinical parameters, and in relation to Homeobox gene A9 expression and the presence of ALL1 fused gene 4-Mixed Lineage Leukemia (AF4-MLL). Mutations were detected in approximately 14% of all cases, with a higher frequency of approximately 24% in t(4;11)-positive patients (P=0.04). Furthermore, we identified RAS mutations as an independent predictor (P=0.019) for poor outcome in Mixed Lineage Leukemia-rearranged infant acute lymphoblastic leukemia, with a hazard ratio of 3.194 (95% confidence interval (CI):1.211-8.429). Also, RAS-mutated infants have higher white blood cell counts at diagnosis (P=0.013), and are more resistant to glucocorticoids in vitro (P<0.05). Finally, we demonstrate that RAS mutations, and not the lack of Homeobox gene A9 expression nor the expression of AF4-MLL are associated with poor outcome in t(4;11)-rearranged infants. We conclude that the presence of RAS mutations in Mixed Lineage Leukemia-rearranged infant acute lymphoblastic leukemia is an independent predictor for a poor outcome. Therefore, future risk-stratification based on abnormal RAS-pathway activation and RAS-pathway inhibition could be beneficial in RAS-mutated infant acute lymphoblastic leukemia patients.

Background: Flow cytometric analysis of leukemia-associated immunophenotypes and polymerase chain reaction-based amplification of antigen-receptor genes rearrangements are reliable methods for monitoring minimal residual disease. The aim of this study was to compare the performances of these two methodologies in the detection of minimal residual disease in childhood acute lymphoblastic leukemia., Design and Methods: Polymerase chain reaction and flow cytometry were simultaneously applied for prospective minimal residual disease measurements at days 15, 33 and 78 of induction therapy on 3565 samples from 1547 children with acute lymphoblastic leukemia enrolled into the AIEOP-BFM ALL 2000 trial., Results: The overall concordance was 80%, but different results were observed according to the time point. Most discordances were found at day 33 (concordance rate 70%) in samples that had significantly lower minimal residual disease. However, the discordance was not due to different starting materials (total versus mononucleated cells), but rather to cell input number. At day 33, cases with minimal residual disease below or above the 0.01% cut-off by both methods showed a very good outcome (5-year event-free survival, 91.6%) or a poor one (5-year event-free survival, 50.9%), respectively, whereas discordant cases showed similar event-free survival rates (around 80%)., Conclusions: Within the current BFM-based protocols, flow cytometry and polymerase chain reaction cannot simply substitute each other at single time points, and the concordance rates between their results depend largely on the time at which they are used. Our findings suggest a potential complementary role of the two technologies in optimizing risk stratification in future clinical trials.

Background: The aim of this study was to describe the patterns of marriage and parenthood in a cohort of childhood cancer survivors included in the Off-Therapy Registry maintained by the Italian Association of Pediatric Hematology and Oncology., Design and Methods: We analyzed a cohort of 6,044 patients diagnosed with cancer between 1960 and 1998, while aged 0 to 14 years and who were 18 years old or older by December 2003. They were followed up through the regional vital statistics registers until death or the end of follow up (October 30, 2006), whichever occurred first, and their marital status and date of birth of their children were recorded. The cumulative probabilities of being married and having a first child were computed by gender and compared by tumor type within the cohort. Marriage and fertility rates (the latter defined as the number of live births per woman-year) were compared with those of the Italian population of the same age, gender, area of residence and calendar period by means of the observed to expected (O/E) ratios., Results: During the follow-up period, 4,633 (77%) subjects had not married. The marriage O/E ratios were 0.56 (95% CI: 0.51-0.61) and 0.70 (95% CI: 0.65-0.76) among men and women, respectively. Overall, 263 men had 367 liveborn children, and 473 women had 697 liveborn children. The female fertility O/E ratio was 0.57 (95% CI: 0.53-0.62) overall, and 1.08 (95% CI: 0.99-1.17) when analyses were restricted to married/cohabiting women, Conclusions: Childhood cancer survivors are less likely to marry and to have children than the general population, confirming the life-long impact of their previous disease on their social behavior and choices. The inclusion of counseling in the strategies of management and long-term surveillance of childhood cancer patients could be beneficial to survivors as they approach adulthood.

The advantage of allogeneic transplant from compatible related donors versus chemotherapy in children with very-high-risk acute lymphoblastic leukemia in first complete remission was previously demonstrated in an international prospective trial. This study quantified the impact of time elapsed in first remission in the same cohort. Of 357 pediatric patients with very-high-risk acute lymphoblastic leukemia, 259 received chemotherapy, 55 transplantation from compatible related and 43 from unrelated donors. The 5-year disease-free survival was 44.2% overall and 42.5% for chemotherapy only patients. The chemotherapy conditional 5-year disease-free survival increased to 44.4%, 47.6%, 51.7%, and 60.4% in patients who maintained their first remission for at least 3, 6, 9, and 12 months respectively. The overall outcome was superior to that obtained with chemotherapy-only at any time-point. The relative advantage of transplant from compatible related donors in very-high-risk childhood acute lymphoblastic leukemia was consistent for any time elapsed in first remission.

Fifty-two infants with acute lymphoblastic leukemia (ALL) enrolled in the AIEOP ALL-91 and ALL-95 studies were treated with the intermediate or high risk protocols according to their presenting features and early response to treatment. The 5-year event-free survival was 33.3% (95% CI 12.1-54.5), 53.5% (95% CI 35.7-71.3) and 45.0% (95% CI 31.3-58.7) in the ALL-91 and ALL-95 studies and in the overall cohort, respectively. In the ALL-95 high-risk group (BFM therapy intensified by three blocks and double protocol II) nine of 17 patients treated with chemotherapy only and three of four transplanted patients were alive and in complete remission. The corresponding figures for patients treated in the ALL-91 high-risk protocol (reduced induction and nine blocks) were one of seven patients treated with chemotherapy only and none of two who were transplanted.

Background and Objectives: Treatment of childhood standard-risk (SR) acute lymphoblastic leukemia (ALL) is generally successful. However, intensive chemotherapy regimens may be associated with severe treatment sequelae. Efforts are therefore being made to identify those patients in whom less intensive treatment would be equally successful but cause fewer long-term sequelae. The aim of this study was to evaluate the efficacy of treatment reduction in a subset of children with ALL at minimal risk of failure., Design and Methods: The population of patients with SR ALL included children aged between 1 and 6 years with less than 20,000 WBC/mm3, non-T immunophenotype, DNA index between 1.16 and 1.6, absence of t(9;22) and t(4;11) clonal translocations, no extramedullary leukemia, good response to prednisone and complete remission (CR) at the end of induction therapy. A reduced-intensity, BFM-type treatment schedule (AIEOP-ALL 9501 protocol) was used. Induction therapy was based on vincristine, prednisone, L-asparaginase and intrathecal methotrexate only; high-dose-methotrexate (2 g/m2) was given x4. The BFM Protocol II was given as reinduction therapy; thus the total dose of anthracyclines was 120 mg/m2 and no epipodophyllotoxins or cranial irradiation were employed., Results: Between May 1995 and December 1999, 123 patients were identified as having SR-ALL (7.8% of the ALL-95 population), of whom 102 received the SR protocol. After a median follow-up of 5.9 years, 11 patients in the SR protocol had relapsed, 1 had died in remission, and 1 had developed a second malignant neoplasm. The probabilities (standard errors) of survival and event-free survival (EFS) were, respectively, 97.0% (1.7) and 86.7% (3.5) at 5 years, and 95.3% (2.4) and 86.7% (3.5) at 7 years., Interpretation and Conclusions: Although most of the relapsed patients were rescued, the long-term EFS probability in this small, highly selected group of patients remains inferior to expectation. Thus, alternative selection criteria, such as treatment response measured by minimal residual disease, should be considered to address the issue of treatment reduction.

Background and Objectives: Few data are available on the long-term outcome of children who present with a very late relapse of acute lymphoblastic leukemia, so treatment of these patients remains controversial. The present study was aimed at investigating clinical features and treatment outcome of children with very late relapse, diagnosed and treated in Italy in the last 20 years., Design and Methods: All children diagnosed in Italian centers with a first relapse of acute lymphoblastic leukemia occurring >or= 60 months after attainment of first complete remission were included in this study. These relapses were diagnosed between 1982 and 1997., Results: Ninety-three patients (58 males, 62.4%) had a first very late relapse occurring at a median time of 6.1 years (range 5.8 - 13.7 years) after the initial diagnosis. At a median follow-up time of 9.1 years after relapse, the overall 5-year survival (SE) and event-free-survival (SE) were 55.6% (5.2) and 39.5% (5.1), respectively. In multivariate analysis the site of relapse was the only significant predictor of duration of the second complete remission. Patients with isolated bone marrow relapse fared worse than those with combined or isolated extramedullary relapse [5-year event-free survival (SE) 24.5% (5.9), 51.3% (11.1) and 68.4% (10.7), respectively; (p=0.004)]. All 7 patients who underwent an allogeneic bone marrow transplantation from a matched related donor are alive in second complete remission., Interpretation and Conclusions: In this evaluation patients with a very late relapse isolated to the bone marrow had a poor outcome while re-treatment of extramedullary or combined relapse was associated with better cure rate. Our data suggest that patients with very late isolated bone marrow relapse should be treated intensively; bone marrow transplantation from a matched related donor may be indicated.