ETV6/RUNX1-Postitive Childhood Acute Lymphoblastic Leukemia (ALL): Do Additional Aberrations Influence Treatment Response and Outcome?

Abstract ETV6/RUNX1 rearrangement, being the most common genetic abnormality in childhood ALL, is combined with controversial prognostic behavior and frequent late relapses, indicating the need for identification of additional prognostic markers. In our study, we examined the relation between ETV6/RUNX1 and presenting clinical/biological features, co-existing subclones/secondary aberrations, early response to treatment (MRD) and their impact on outcome in a pediatric cohort of 133 ALL pts , treated in one Center over a 12-year period. Data from 133 newly diagnosed ALL pts(83 males) with a median age of 5.1 yrs(range 1.2-16.7), have been retrospectively recorded and analyzed. Pts were consecutively diagnosed and homogeneously treated on BFM based protocols during the years 2000-2011. FISH evaluation using commercial probe sets was performed for the detection of ETV6-RUNX1, E2A-PBX1, BCR-ABL fusion genes, MLL gene rearrangements as well as ETV6, RUNX1, CDKN2A/2B and other gene duplications, deletions or amplifications. Twenty seven pts (27/133, 20.3%) were tested positive for the t(12;21)(p13;q22) translocation(16 males), with a median age of 3.9 yrs(range 2.0-16.7). Immunophenotype revealed 22/27 common (81.5%) and 5/32 pre-B cases (18.5%). All pts were characterized as GPR and treated in the IR Arm. 8/27 (29.6%) were positive for the ETV6/RUNX1 fusion gene only with no secondary aberrations. 19/27 ETV6/RUNX1-positive pts (70.4%) harbored additional structural or numerical genetic abnormalities while 8 of those pts showed presence of subclones with multiple patterns of additional ETV6 and RUNX1 aberrations. The most common abnormalities were del12p13(37%), 3-6x21q22(22.2%), del9p21(18.5%), +21(14.8%), and 2-3xETV6/RUNX1(18.5%). On day 15, 13/27 ETV6/RUNX1+ pts (48.1%) presented with FCM-MRD(d15) values≥10-3 while the corresponding percent among IR ETV6/RUNX1- pts was 46.9%. Out the 8 pts with sole t(12;21)(p13;q22) translocation, only 25%(2/8 pts) presented with MRD(d15)>10-3 while among the 19 pts with additional aberrations, the corresponding percent was 52.6% (10/19). Interestingly, referring only to ETV6/RUXN1+ pts with subclones, the percent reflecting MRD(d15)>0.1% rises to 87.5% (7/8 pts). Among the 14 pts with no MRD(d15) detection only 1/14 appeared with clonal heterogeneity. 3/27 pts (11.1%) relapsed, in a median time of 30.3 months (median follow-up time 64 months). Common features of all relapses were sub-clonal diversity at diagnosis, del(9p21) and MRD(d15) positivity. 5-year RFS for the ETV6/RUNX1+ subgroup was 86.4%±7.4 vs 87.7%±3.5 for ETV6/RUNX1- pts. The presence of the ETV6/RUNX1 fusion gene as a favorable genetic marker did not seem to have a statistically significant impact on the probability of relapse (p=0.906). The 5-year RFS for those with MRD≥0.1% was limited to 67.3% ±16.0, while the corresponding rate for MRD- pts reached 100%. ETV6/RUNX1+ childhood ALL is characterized by extreme heterogeneity and the prognostic value of the fusion itself varies, depending on coexisting clinical and biological features. In our series, the presence of additional genetic aberrations/subclones (such as del9p21 or ETV6/RUNX1 duplication) and impaired FCM-MRD clearance, influences patient outcome. Longer follow-up is needed in order to further validate these initial results. FISH and FCM data may help establish new prognostic markers to predict relapse and refine risk stratification. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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Early T Acute Lymphoblastic Leukemia in Childhood: Prevalence and Clinical Characteristics

Blood ◽

10.1182/blood.v124.21.3656.3656 ◽

2014 ◽

Vol 124 (21) ◽

pp. 3656-3656

Author(s):

Jorge Gabriel Rossi ◽

Carolina Carrara ◽

Patricia L. Rubio ◽

Cristina N. Alonso ◽

Andrea Bernasconi ◽

...

Keyword(s):

Chromosomal Abnormalities ◽

Conflicts Of Interest ◽

Lymphoblastic Leukemia ◽

Poor Response ◽

Early Response ◽

Response To Treatment ◽

Differentiation Potential ◽

Lineage Switch ◽

Conventional Cytogenetics

Abstract Background: Early T precursor ALL has been defined as a poor prognosis subtype, characterized phenotypically by absence of CD1a and CD8, CD5 weak expression and presence of at least one myeloid and progenitor cell marker. Objectives: Our aims were to identify Early T-ALL among our T ALL cases, based on the characteristic phenotype and thus evaluate the prevalence, biological characteristics and outcome of this particular subset of T-ALL Methods: From April ’94 to December ’13, 197 T-ALL cases were diagnosed and 20 of them showed the typical Early T marker profile by flow cytometry (FC). Conventional cytogenetics, FISH and RT-PCR studies were performed according to standard techniques. Clonality assessment for TRG, TRB, TRD, IGH and IGK was performed by PCR (Biomed-2), heteroduplex and sequencing. Results: Sex distribution was: 16 males and 4 females; median of age: 7.9 (range: 0.3-16.6) years; median WBC: 14.9 (range: 0.6-254.0) x109/L. All but one case expressed CD34, 70% HLA-DR, 61% CD117 and 50% TdT. The most frequently expressed myeloid markers were: CD33 (85%) and CD13 (55%). Three cases expressed g/d TCR. Chromosomal abnormalities were detected in 14 of 16 evaluated cases, in 5 of them compromising 12p13 region. TCR/IgH rearrangements were detected in 63% (10/16). FLT3-ITD mutations were found in 14 % (2/14). Patients were treated with BFM-based ALL schedules and were stratified as Intermediate Risk ALL (n: 7) and High Risk ALL (n: 13) according to protocol criteria. Early response to treatment was poor in 16 cases: 6 presented poor response to prednisone (day 8), 3 MRD >10%, 5 presented bone marrow M2-M3 and 2 non response. Seventeen cases (85%) achieved CR on day 33 and 2 achieved CR later. Five patients underwent HSCT in first CR. Three patients relapsed at 5, 6 and 65 months from diagnosis and one showed lineage switch to M5-AML at 12 months from CR. Three pts died in CR (2 after HSCT and 1 patient with primary immunodeficiency due to pneumonia) and one is in palliative care. Twelve patients remain in CR with a median follow-up of 54 (r: 8-144) months. Conclusions: The prevalence of Early T precursor phenotype within T ALL was 10.5% in our setting. The most frequent progenitor marker was CD34 and CD33 among myeloid markers. Of note, translocations involving 12p13 region were found in 5 patients. Sixty percent of patients remain disease free, although longer follow-up is needed in order to define prognosis of this group in our cohort of patients. The lineage switch case supports the notion of the myeloid differentiation potential of these blasts. Disclosures No relevant conflicts of interest to declare.

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Results of the Treatment for Relapsed Acute Lymphoblastic Leukemia (ALL) in Childhood

Blood ◽

10.1182/blood.v116.21.4339.4339 ◽

2010 ◽

Vol 116 (21) ◽

pp. 4339-4339

Author(s):

Myriam Ruth Guitter ◽

Elizabeth M Alfaro ◽

Jorge Rossi ◽

Marta Gallego ◽

Cristina Alonso ◽

...

Keyword(s):

Bone Marrow ◽

Conflicts Of Interest ◽

Lymphoblastic Leukemia ◽

Childhood All ◽

New Therapeutic Approaches ◽

High Doses ◽

Null Response ◽

The Moment ◽

Se 33

Abstract Abstract 4339 INTRODUCTION: Relapses occur in 25–30% of childhood ALL. We evaluated the outcome of this group of patients (pts) according to the duration of the 1st CR, immunophenotype and site of relapse in our Institution. PATIENTS AND METHODS: From Sept’94 to Aug’09, 245 ALL relapses were diagnosed: 73 cases were not evaluable due to: different treatments received (n: 36), palliative care (n: 26) and insufficient data (n: 11); 172 pts were evaluable (54 F/118 M), with a mean age at the moment of the relapse of 9.8 (range 1.8–20.8) years. Induction therapy combined a pre-phase with 10 days of prednisone and 1 block of high doses of chemotherapy, followed by 5 blocks of similar intensity, CNS or testicular (preventive/therapeutic) radiotherapy, and weekly rotational maintenance, until completing two years from the moment of diagnosis. High-risk relapsed pts who had an available identical donor received HSCT. RESULTS: Immunophenotype was B-cell precursor (Bcp) in 89% of the pts and T-cell in 11 %. The duration of the 1st CR was <18 mo in 41 (24%), 18–36 mo in 79 (46%), >36 mo in 52 (30%) pts. The sites of relapse were bone marrow (BM) in 106 pts (61%), combined bone marrow (cBM) in 27 pts (17%) and isolated extramedullar in 39 pts (22%). The response to induction was: CR 134 pts (78%), death during induction 20 pts (12%) and partial/null response 18 pts (10%). Among the 134 pts who achieved CR, 69 (52%) presented a second relapse at 18,8 (r 0.7–88.8) mo from the 2nd CR, 10 (7%) died in CR and 1 developed a 2nd neoplasm. With a mean follow-up of 49 (r 2–155) mo, 54 pts remain in CR, 37 of them out of therapy. Of the 26 pts who received HSCT, 12 relapsed and 3 died in CR. The EFSp (SE) for the total group of pts was 25 (3)% and LFS probability (SE) 33 (4)%; for Bcp relapses it was 28%, and for T relapses 6% (P=0.0025); for BM+cBM cases it was 21%, and 40% for extramedullar (P=0.0061). However, testicular relapses achieved EFSp of 80%, and 12% for the remaining extramedullar cases (P=0.0004). The EFSp for relapses at <18mo of 1st CR was 5%, between 18–36 mo 25% and >36 m 41% (P=0.0001). CONCLUSIONS: The immunophenotype, the duration of the 1st CR and site of relapse significantly influenced the EFSp. Isolated testicular relapses achieved the best EFSp. HSCT is an eligible option for a small group of pts. New therapeutic approaches must be developed to improve outcome of most of relapsed ALL patients. Disclosures: No relevant conflicts of interest to declare.

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Results of PETHEMA LAL-BR-01 Protocol for Low-Risk (LR) Acute Lymphoblastic Leukemia (ALL) In Children

Blood ◽

10.1182/blood.v116.21.4334.4334 ◽

2010 ◽

Vol 116 (21) ◽

pp. 4334-4334

Author(s):

Josep-Maria Ribera ◽

Albert Oriol ◽

Mireia Morgades ◽

Pilar Bastida ◽

Olga Garcia ◽

...

Keyword(s):

Conflicts Of Interest ◽

Residual Disease ◽

Lymphoblastic Leukemia ◽

Normal Karyotype ◽

Complete Response ◽

Low Risk ◽

Response To Treatment ◽

Intrathecal Therapy ◽

Childhood All ◽

Additional Tool

Abstract Abstract 4334 Background and objectives. Children with ALL and low-risk (LR) features have a survival over 80%. The study of minimal residual disease (MRD) is an additional tool for best risk definition and for optimal selection of post-remission treatment. The results of PETHEMA LAL-BR-01 for low-risk childhood ALL (LR-ALL) including sequential MRD evaluation are presented. Patients and Method. Baseline LR-ALL criteria included age 1–9 yr., B-precursor ALL, WBC count <50×109/L, no CNS involvement and absence of hypodiploidy, t(9;22) (BCR-ABL) or 11q23 (MLL) rearrangements. Induction therapy included VCR, DNR, PDN, ASP and CPM (4 weeks), followed by reinduction-consolidation (R-C), consolidation with intensification (C-I) (both including HD-MTX and HD-ARAC among other drugs), maintenance (MP and MTX) with reinductions (with VCR, PDN and ASP)(M-R) during the first yr., and maintenance (M) without reinductions during the second year. CNS prophylaxis consisted of triple intrathecal therapy (MTX, ARA-C and hydrocortisone). Patients with slow cytologic response (>1× 109 peripheral blood blasts/L on day 8 or >20% bone marrow blasts on day 14), or MRD>0.1% after induction, or MRD >0.01% after R-C or at the 1st or 1.5 yr of therapy were moved to a high-risk (HR) protocol. Results. By April 2010, 176 pts (mean (SD) age 4 (2) yr., 96 males) were evaluable. Baseline ALL characteristics: WBC 8 (SD 6) ×109/L, common ALL 144 (35%), pre-B 30 (17%), hyperdiploidy >50 chromosomes 32 (19%), TEL/AML1 40/140 (29%), normal karyotype 41(24%). Treatment response (172 pts): induction death 2 (infection in both), abandon 2, and complete response (CR) 168 (98%). Five patients were moved to a HR protocol because of slow cytologic response (n=4) or MRD >0.1% at the end of induction (n=1). During consolidation and maintenance 4 pts relapsed and 4 were moved to HR protocol because of MRD>0.01%. Out of 104 pts who completed therapy, 4 relapsed. Seven out of 9 patients moved to the HR protocol (including the 5 pts transferred due to high MRD level) are in first CR and the remaining 2 relapsed. With a median follow-up of 3 (0.1-8.3) yr, 6-yr probabilities of CR duration, overall survival and event-free survival were 92±5%, 97±3% y 87±5%, respectively. The most frequent toxicity was due to infections, and was observed in all phases of the protocol, especially in induction. Dose modifications were documented in 6% of induction cycles, 15% of R-C, and 18% of C-I, in 27% of the patients during M-R and in 25% of the patients during M phase. Conclusions. 1. Most LR-ALL pts achieved a durable CR. 2. Most patients shifted to a HR protocol on the basis of slow response to treatment or MRD positivity maintained CR with HR protocol. 3. Toxicity was acceptable, although frequent dose reductions were required. Supported in part by grants P-EF09 from FJC and RD06/0020/1056 from RTICC. Disclosures: No relevant conflicts of interest to declare.

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The Role of SMAD7 Downstream of TEL-AML1 Signalling in t(12;21) Acute Lymphoblastic Leukemia

Blood ◽

10.1182/blood.v126.23.4823.4823 ◽

2015 ◽

Vol 126 (23) ◽

pp. 4823-4823 ◽

Cited By ~ 1

Author(s):

Aishwarya Sundaresh ◽

Maurizio Mangolini ◽

Jasper de Boer ◽

Mike Hubank ◽

Nicholas Goulden ◽

...

Keyword(s):

Gene Expression ◽

Cell Lines ◽

Conflicts Of Interest ◽

Fusion Gene ◽

Lymphoblastic Leukemia ◽

Xenograft Model ◽

Direct Role ◽

Hematopoietic Stem ◽

Childhood All

Abstract The single most frequent chromosomal translocation associated with childhood ALL is the t(12;21) rearrangement that creates a fusion gene between TEL (ETV6) and AML1 (RUNX1). Although TEL-AML1+ patients have very good prognoses, relapses occur in up to 20% of patients and many patients face long-term side effects of chemotherapy. Recent data has shown that TEL-AML1 has a direct role in inducing signal transducer and activator of transcription 3 (STAT3) activation in human t(12;21) leukemia. This activation has been shown to transcriptionally induce MYC and is critical for survival of TEL-AML+ leukemia cells. Here, we demonstrate that STAT3 also regulates SMAD7 gene expression. SMAD7 is an antagonist of TGF-β signaling, functioning through a negative feedback mechanism, but is also known to function in other biological pathways. Interestingly, SMAD7 has also been shown to play a role in promoting self-renewal of hematopoietic stem cells. We show that both pharmacological and mechanistic inhibition of STAT3 results in down regulation of SMAD7 gene expression in TEL-AML1+ cell lines. This result was specific to TEL-AML1+ cells and not found in cells of other ALL subtypes. To understand the role played by SMAD7 in TEL-AML1+ cells, we used lentiviral vectors expressing shRNA targeting SMAD7. Interestingly, SMAD7 silencing was found to inhibit proliferation of TEL-AML1+ cell lines, eventually leading to growth arrest and apoptosis. Furthermore, we have established that this effect is not mediated through TGF-β signalling. This poster highlights the results of RNA-seq performed on TEL-AML1+ cells with SMAD7 knockdown and in vivo xenograft model of SMAD7 shRNA in TEL-AML+ ALL. Disclosures No relevant conflicts of interest to declare.

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Clonal Origins of 'late' Relapses in ETV6-RUNX1 Acute Lymphoblastic Leukemia..

Blood ◽

10.1182/blood.v114.22.1583.1583 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1583-1583

Author(s):

Frederik W van Delft ◽

Sharon W Horsley ◽

Kristina Anderson ◽

Caroline M Bateman ◽

Susan Colman ◽

...

Keyword(s):

Acute Lymphoblastic Leukemia ◽

B Cell ◽

Copy Number ◽

Conflicts Of Interest ◽

Fusion Gene ◽

Lymphoblastic Leukemia ◽

Leukemic Cells ◽

Childhood All ◽

Remission Duration ◽

Clonal Origin

Abstract Abstract 1583 Poster Board I-609 Approximately a quarter of B cell precursor childhood acute lymphoblastic leukemia (ALL) is characterized by an ETV6-RUNX1 (TEL-AML1) fusion gene and has an overall good prognosis. The majority of these children will be treated on the standard risk arm of the United Kingdom ALL treatment protocols. Relapse usually occurs after cessation of treatment but remarkably can present many years later. The incidence of ETV6-RUNX1 at relapse has been reported to be less than or similar to de novo ALL. Molecular studies on neonatal bloodspots and on twins with concordant ALL have demonstrated the prenatal origin of major subtypes of childhood ALL, including most ETV6-RUNX1 fusion gene positive cases. In addition these investigations have suggested the existence of a preleukaemic stem cell requiring additional mutations or ‘hits’ in order to develop frank leukemia. To understand the genetic basis and clonal origin of late relapses we have compared the profiles of genome-wide copy number alterations (CNA) at relapse versus presentation in samples matched with remission DNA from 24 patients. The selected samples had tumor cell purity >75% before DNA extraction. DNA copy number alteration data was generated using the Affymetrix 500K SNP arrays. LOH analysis was performed using CNAG 3.0 and dCHIP 2008. Overall we identified 168 CNA at presentation and 252 at relapse (excluding deletions at IgH and TCR loci), equating to 6.96 and 10.3 CNA at presentation and relapse respectively. Although the number of CNA increased at relapse, no single gene or pathway was uniquely targeted in relapse. The most frequent alterations involved loss of 12p3.2 (ETV6), 9p21.3 (CDKN2A/B), 6q16.2-3 and gain of 21q22.1-22.12. A novel observation was gain of part or whole of chromosome 16 (2 patients at presentation, 5 at relapse) and deletion of the oncogene Plasmocytoma Variant Translocation 1 (PVT1) in 3 patients. Pathway analysis demonstrated frequent involvement at presentation and relapse of genes implicated in both B cell development (44 versus 46%) and cell cycle control (46 versus 71%). In order to study the clonal origin of relapse, we devised a classification describing the change in CNA between presentation and relapse in each individual patient. The clonal relationship between the presentation and relapse clone was established by the persistence of both the ETV6-RUNX1 fusion and at least 1 Ig and/or TCR rearrangement. We used a classification focussed on ‘driver’ CNA, defined as CNA that target genes functionally involved in leukemogenesis or CNA that are recurrently targeted as described in the literature. The four categories of relapse were type 1 (the dominant clone at presentation presented unchanged at relapse), type 2 (the relapse clone was derived from the major subclone at presentation with additional CNA), type 3 (the relapse clone was derived from a minor clone at presentation with gains and losses of CNA) and type 4 (the relapse clone is derived from an ancestral or preleukemic clone at initial presentation with all CNA gained). Twenty-one of the 24 patients were classifiable in this way (Figure 1). Although comparative relapse / presentation CNA profiles cannot identify precise clonal origins of relapse, the data indicate that irrespective of time to relapse (<2 to 9.9 years), the relapse clone appeared to be derived from either a major or minor clone at diagnosis with none (0/6) of the very late relapses (>5 years) derived from pre-leukemic cells lacking CNA. This data indicate diverse clonal origins of relapse and extended periods of dormancy, possibly via quiescence, for stem cells in ETV6-RUNX1+ ALL. Relapse type Remission duration (years) < 2 2 - 5 > 5 1 • • 2 • ••••••• •• 3 •• •• ••• 4 •• Figure 1. Each patient is represented by a black dot. Each patient is classified on the basis of the relapse type and remission duration. Disclosures No relevant conflicts of interest to declare.

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Amplification of AML1 Does Not Impact Early Outcome of Children with Acute Lymphoblastic Leukemia (ALL) Treated with Risk-Directed Chemotherapy: A Report From the Children's Oncology Group (COG).

Blood ◽

10.1182/blood.v114.22.2598.2598 ◽

2009 ◽

Vol 114 (22) ◽

pp. 2598-2598

Author(s):

Nyla A. Heerema ◽

Andrew J. Carroll ◽

Michael J. Borowitz ◽

Meenakshi Devidas ◽

Eric C. Larson ◽

...

Keyword(s):

Conflicts Of Interest ◽

Risk Group ◽

Lymphoblastic Leukemia ◽

Early Response ◽

Response To Therapy ◽

Chromosome 21 ◽

Single Chromosome ◽

Early Outcome ◽

Early Results

Abstract Abstract 2598 Poster Board II-574 Amplification of a region of chromosome 21 (which includes the AML1 (RUNX1) locus (amp(AML1)) has been reported as a recurring abnormality in pediatric ALL that is associated with increased age (median 9 years), a low white blood cell (WBC) count, and a poor outcome. (Moorman et al Blood 109:2327, 2007; Attarbaschi et al JCO 26:3046, 2008). Early results in these studies indicated approximately a 75% event-free survival (EFS) at 2 years. Amp(AML1) can be reliably detected only by fluorescence in situ hybridization (FISH), and can be recognized when blasts are tested by FISH for the presence of the TEL(ETV6)/RUNX1 translocation. We reviewed the clinical features and outcome of children with ALL and amp(AML1) treated on current generation COG trials from 2003–2009 (median follow up 1.2 years, range: 0.03–3.83 yrs). Diagnosis of amp(AML1) required at least 5 copies of AML1, with 4 copies on a single chromosome. Children with B-precursor ALL received a 3- or 4-drug induction based on NCI risk group, with post-induction therapy based on further risk stratification variables measured during the first month of induction. Patients with a poor early response to therapy (day 15 bone marrow (BM) with >5% blasts or day 29 BM minimal residual disease (MRD) >0.1%) were non-randomly assigned to receive augmented chemotherapy. Treatment was not altered for patients with amp(AML1). Since June 1, 2007, ETV6/RUNX1 FISH was required on all children enrolled on this study. From Dec 29, 2003 to June 1, 2007, FISH was not required on all patients so ascertainment of amp(AML1) may not be complete. There were 89/5470 (1.6%) children with B-precursor ALL in whom amp(AML1) was detected. Similar to previous reports (see Table), their median age was 9.1 years, median WBC was 4.5×109/l; and 55.1% were female, a higher proportion than previously reported (43%–48%). While the distribution of day 29 MRD by flow cytometry was different, NCI risk group distribution, 2-year EFS and overall survival (OS) were similar between patients with and without amp(AML1). Of the 10 events that occurred in patients with amp(AML1), there were 3 induction failures, 3 induction deaths, and 4 relapses. Thus, early response to risk-adapted therapy is similar in children with and without amp(AML1). We conclude that, using risk-adapted therapy, children with ALL and amp(AML1) have an early outcome similar to those lacking this feature; however, longer follow up is needed to determine the full impact of amp(AML1) on eventual outcome. Disclosures: No relevant conflicts of interest to declare.

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Long-Term Sequelae and Late Effects In Childhood Acute Lymphoblastic Leukemia (ALL) Survivors: A Single AIEOP Center Experience

Blood ◽

10.1182/blood.v122.21.1720.1720 ◽

2013 ◽

Vol 122 (21) ◽

pp. 1720-1720 ◽

Cited By ~ 1

Author(s):

Rosanna Parasole ◽

Fara Petruzziello ◽

Antonia De Matteo ◽

Argia Mangione ◽

Gaia Sepe ◽

...

Keyword(s):

Acute Lymphoblastic Leukemia ◽

Late Effects ◽

Conflicts Of Interest ◽

Lymphoblastic Leukemia ◽

Childhood Acute Lymphoblastic Leukemia ◽

Late Effect ◽

Cranial Radiotherapy ◽

Childhood All

Abstract The advent of more intensive chemotherapy and the improvement of supportive cares have dramatically changed the natural history of childhood acute lymphoblastic leukemia (ALL), with current estimated 5-year overall survival of about 80%. The increased survival rate and the establishment of follow-up survey for long term survivors (LTS) have allowed the identification of late chemo-radiotherapy adverse effects on psychological and general health. We retrospectively evaluate the incidence and type of sequelae and / or late effects in a cohort of 301 childhood ALL LTS, followed in a single pediatric AIEOP center. From June 1986 to June 2013, 301 LTS (154 male and 147 female), aged <18 years at ALL diagnosis, were followed-up by a multidisciplinary team. The surveillance protocol is summarized in Figure 1. The timing of follow-up (FU) was modified, case by case, in relation to the appearance of adverse events or organ diseases. Survivors' results were compared with chronic medical and psychological conditions of siblings (n=89). Mean FU time (time from the stop therapy to the last control) was 6 years (range 1.8-26.8 years). The majority of LTS were teenager or young adults : 35% ranged between 15 and 20 years; 19.7% was more than 21 years old and the 45.3% was less than 14 years old. During FU, 16 late recurrences (5.3%) were identified and 3 secondary malignancies (0.99%) such as one mesenteric paraganglioma and two Acute Myeloid Leukemia in second complete remission ALL LTS. 40 patients (13.3%) received cranial radiotherapy during treatment. 39 LTS (13%) reported at least one sequelae. The most frequent sequelae were neurological and orthopedic (6% and 3% respectively) as summarized in Figure 2 151 LTS (50.17%) presented at least one late effect as showed in Figure 3. In our experience at least one late effect occurred in 50.17% of LTS; these late complications affect negatively the quality of life of survivors. Endocrine-metabolic events are the most frequent late effect (34,5%). 13% of LTS have at least one sequelae mainly neurological and orthopedic. Prevention and/or early identification of complications during follow-up survey of LTS are crucial in order to decrease the long-term health risks associated with curative treatment for childhood ALL. Disclosures: No relevant conflicts of interest to declare.

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The Molecular Landscape of KMT2A-Rearranged Leukemia from Infancy to Adulthood Reveals Age and Leukemia-Specific Mutational Patterns

Blood ◽

10.1182/blood-2021-152082 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 3479-3479

Author(s):

Mattias Pilheden ◽

Ton Falqués ◽

Louise Ahlgren ◽

Helena Sturesson ◽

Michael P Walsh ◽

...

Keyword(s):

Rna Sequencing ◽

Conflicts Of Interest ◽

Fusion Gene ◽

Lymphoblastic Leukemia ◽

Chromatin Condensation ◽

Mouse Bone Marrow ◽

Whole Genome ◽

Childhood All ◽

Pediatric Aml ◽

Molecular Patterns

Abstract Genetic rearrangements involving the KMT2A gene (KMT2A-R) are seen in around 10% of acute leukemia overall. KMT2A-R occurs in all ages and usually correlates with high-risk clinical features, in particular in infants aged 0-12 months of age with acute lymphoblastic leukemia (ALL). To uncover age- and leukemia-subtype specific molecular patterns in KMT2A-R ALL and acute myeloid leukemia (AML), we performed whole genome (WGS), whole exome (WES), and RNA-sequencing on a well-annotated Nordic KMT2A-R cohort of 104 patients, including infant ALL (n=33), childhood ALL (n=18), adult ALL (n=15), and pediatric AML (n=38) patients. For 77 patients, we performed WGS (40x) at diagnosis and remission as well as WES (140x) on the diagnostic sample, and remaining patients underwent WES only (n=27). RNA-sequencing was performed on 58 cases with available RNA. Twenty-two genes were recurrently altered and remarkably, NRAS, KRAS, FLT3, PAX5, TP53, CDKN2A/B and IKZF1 accounted for 70% of mutations. The landscape of mutations suggested the presence of leukemia and age-specific associations with MYST4, PTPN11, and SETD2 uniquely altered in AML and PIK3CD, DNAH11, NOTCH1, CSMD3 and CDKN2A/B in ALL. Some genes were mutated in both KMT2A-R ALL and AML, but were more common in one disease, such as FLT3 and KRAS in AML and PAX5, TP53 and IKZF1 in ALL. Moreover, age-associated patterns were seen in ALL with NRAS more frequently mutated than KRAS in infant ALL (26% vs 15%), and KRAS more frequently mutated than NRAS in childhood ALL (24% vs 18%), with adult ALL having fewer such mutations (NRAS 13%; KRAS 7%). Alterations of CDKN2A/B and TP53 were absent in infant ALL, detected in childhood and adult ALL only. PAX5 alterations were primarily detected in childhood ALL (22%, 9% infant ALL, 7% adult ALL), with all three PAX5-altered infant cases having the KMT2A-MLLT3 fusion gene. Finally, KMT2A-R pediatric AML had the highest fraction of FLT3 mutations (24%, 9% infant ALL, 11% childhood ALL, 0% adult ALL) and all but one mutation occurred in KMT2A-MLLT3 rearranged cases and most were kinase domain point mutations. We next expanded our analysis to include non-recurrent alterations. PI3K/RAS pathway alterations were detected across ages and subtypes with the highest fraction in pediatric AML (63%) and the lowest in adult ALL (27%, 43% infant ALL, 41% childhood ALL). Further, cell cycle related genes were primarily mutated in childhood (39%) and adult ALL cases (33%) and rarer in infant ALL (12%) and pediatric AML (16%) and genes within the B-cell pathway were more commonly altered in childhood ALL (29%) than in infant ALL (9%). Finally, in line with our previous study (Andersson et al, Nat Genet 2015) epigenetic mutations were absent in infant ALL, but present in 20-35% of the other patients. RNA-sequencing identified the KMT2A-fusion in 56/58 cases, with low exonic coverage preventing detection of the fusion in two cases. The reciprocal KMT2A fusion was only expressed in 13/39 cases where it was predicted to be expressed based on karyotype or whole genome sequencing data with 11/13 cases having the KMT2A-AFF1 fusion gene. In addition, RNA-sequencing identified 6 in-frame and 12 out-of-frame fusion genes that had formed either as part of the KMT2A-R itself or that were independent genetic events. Further, a novel in-frame KMT2A-ACIN1 fusion was identified in a child aged 1 year with B-precursor ALL. ACIN1 encodes Apoptotic Chromatin Condensation Inducer 1 and the fusion was formed through an insertion of 14q11 into 11q23. ACIN1 is also rearranged as part of the ACIN1-NUTM1 that we identified in an infant with ins(15;14)(q22;q11.2q32.1) (Andersson et al Nat Genet 2015). To study the ability of KMT2A-ACIN1 to induce leukemia in mice, we injected retrovirally transduced mouse bone marrow cells containing the fusion into syngeneic mice and KMT2A-MLLT3 was used as control. All mice succumbed to disease at an average of 112 days for KMT2A-ACIN1 (n=12) and 63 days for KMT2A-MLLT3 (n=5) and mice displayed splenomegaly and leukocytosis with an immunophenotype indicative of AML. Primary leukemia cells isolated from moribund mice gave rise to leukemia in sublethally irradiated recipients with reduced disease latency. In conclusion, these results highlight the differential molecular patterns in KMT2A-R leukemia across infancy to adulthood thereby providing novel pathogenetic insight. Disclosures No relevant conflicts of interest to declare.

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