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Chromothripsis is a mitotic catastrophe that arises from multiple double strand breaks and incorrect re-joining of one or a few chromosomes. We report on incidence, distribution, and features of chromothriptic events in T-cell acute lymphoblastic leukemias (T-ALL). SNP array was performed in 103 T-ALL (39 ETP/near ETP, 59 non-ETP, and 5 with unknown stage of differentiation), including 38 children and 65 adults. Chromothripsis was detected in 11.6% of all T-ALL and occurred only in adult cases with an immature phenotype (12/39 cases; 30%). It affected 1 to 4 chromosomes, and recurrently involved chromosomes 1, 6, 7, and 17. Abnormalities of genes typically associated with T-ALL were found at breakpoints of chromothripsis. In addition, it gave rise to new/rare alterations, such as, the SFPQ::ZFP36L2 fusion, reported in pediatric T-ALL, deletions of putative suppressors, such as IKZF2 and CSMD1, and amplification of the BCL2 gene. Compared to negative cases, chromothripsis positive T-ALL had a significantly higher level of MYCN expression, and a significant downregulation of RGCC, which is typically induced by TP53 in response to DNA damage. Furthermore we identified mutations and/or deletions of DNA repair/genome stability genes in all cases, and an association with NUP214 rearrangements in 33% of cases.

Minimal/measurable residual disease (MRD) evaluation has resulted in a fundamental instrument to guide patient management in acute lymphoblastic leukemia (ALL). From a methodological standpoint, MRD is defined as any approach aimed at detecting and possibly quantifying residual neoplastic cells beyond the sensitivity level of cytomorphology. The molecular methods to study MRD in ALL are polymerase chain reaction (PCR) amplification-based approaches and are the most standardized techniques. However, there are some limitations, and emerging technologies, such as digital droplet PCR (ddPCR) and next-generation sequencing (NGS), seem to have advantages that could improve MRD analysis in ALL patients. Furthermore, other blood components, namely cell-free DNA (cfDNA), appear promising and are also being investigated for their potential role in monitoring tumor burden and response to treatment in hematologic malignancies. Based on the review of the literature and on our own data, we hereby discuss how emerging molecular technologies are helping to refine the molecular monitoring of MRD in ALL and may help to overcome some of the limitations of standard approaches, providing a benefit for the care of patients.

To shed light onto the molecular basis of Philadelphia chromosome-positive acute lymphoblastic leukemia and to investigate the prognostic role of additional genomic lesions, we analyzed copy number aberrations using the Cytoscan HD Array in 116 newly diagnosed adult patients with Philadelphia chromosome-positive acute lymphoblastic leukemia enrolled in four different GIMEMA protocols, all based on a chemotherapy-free induction strategy. This analysis showed that patients with Philadelphia chromosome-positive acute lymphoblastic leukemia carry an average of 7.8 lesions/case, with deletions outnumbering gains (88% versus 12%). The most common deletions were those targeting IKZF1, PAX5 and CDKN2A/B, which were detected in 84%, 36% and 32% of cases, respectively. Patients carrying simultaneous deletions of IKZF1 plus CDKN2A/B and/or PAX5 had a significantly lower disease-free survival rate (24.9% versus 43.3%; P=0.026). The only IKZF1 isoform affecting prognosis was the dominant negative one (P=0.003). Analysis of copy number aberrations showed that 18% of patients harbored MEF2C deletions, which were of two types, differing in size: the longer deletions were associated with the achievement of a complete molecular remission (P=0.05) and had a favorable impact on disease-free survival (64.3% versus 32.1% at 36 months; P=0.031). These findings retained statistical significance also in multivariate analysis (P=0.057). KRAS deletions, detected in 6% of cases, were associated with the achievement of a complete molecular remission (P=0.009). These results indicate that in adults with Philadelphia chromosome-positive acute lymphoblastic leukemia a detailed evaluation of additional deletions - including CDKN2A/B, PAX5, IKZF1, MEF2C and KRAS - has prognostic implications and should be incorporated in the design of more personalized treatment strategies.

The GIMEMA LAL1509 protocol, designed for adult (≥18-60 years) de novo Ph+ acute lymphoblastic leukemia patients, was based on a dasatinib plus steroids induction - with central nervous system prophylaxis - followed by dasatinib alone in patients in complete molecular response or chemotherapy and/or allogeneic transplantation in patients not reaching a complete molecular response. Sixty patients (median age 41.9 years) were enrolled: 33 were p190+, 18 p210+ and 9 p190/p210+. At the end of induction (day +85), 58 patients (97%) achieved a complete hematologic remission. No deaths in induction were recorded. Eleven patients (18.3%) obtained a complete molecular response. Among non-complete molecular responders (n=47), 22 underwent an allogeneic transplant. Seventeen hematologic relapses occurred (median 7 months, range 3-40.1), 13 during consolidation and 4 post-transplant. ABL1 mutations (5 T315I, 3 V299L, 1 E281K and 1 G254E) were found in 10/13 relapsed cases. With a median follow-up of 57.4 months (range: 4.2-75.6), overall survival and disease-free survival are 56.3% and 47.2%. A better diseasefree survival was observed in patients who obtained a molecular response at day +85 compared to cases who did not. The presence of additional copy number aberrations - IKZF1 plus CDKN2A/B and/or PAX5 deletions - was the most important unfavorable prognostic factor on overall and disease-free survival (p=0.005 and p=0.0008). This study shows that in adult Ph+ ALL long-term survivals can be achieved with a total-therapy strategy based on a chemo-free induction and, in complete molecular responders, also without further systemic chemotherapy. Finally, the screening of additional copy number aberrations should be included in the diagnostic work-up. EudraCT 2010-019119-39

In Ph+ acute lymphoblastic leukaemia (Ph+ ALL), minimal residual disease (MRD) is the most relevant prognostic factor. Currently, its evaluation is based on quantitative real-time polymerase chain reaction (Q-RT-PCR). Digital droplet PCR (ddPCR) was successfully applied to several haematological malignancies. We analyzed 98 samples from 40 Ph+ ALL cases, the majority enrolled in the GIMEMA LAL2116 trial: 10 diagnostic samples and 88 follow-up samples, mostly focusing on positive non-quantifiable (PNQ) or negative samples by Q-RT-PCR to investigate the value of ddPCR for MRD monitoring. DdPCR BCR/ABL1 assay showed good sensitivity and accuracy to detect low levels of transcripts, with a high rate of reproducibility. The analysis of PNQ or negative cases by Q-RT-PCR revealed that ddPCR increased the proportion of quantifiable samples (p

We investigated MYB rearrangements (MYB-R) and the levels of MYB expression, in 331 pediatric and adult patients with T-cell acute lymphoblastic leukemia (T-ALL). MYB-R were detected in 17 cases and consisted of MYB tandem duplication (tdup) (= 14) or T cell receptor beta locus (TRB)-MYB (= 3). As previously reported, TRB-MYB was found only in children (1.6%) while MYB tdup occurred in both age groups, although it was slightly more frequent in children (5.2% vs 2.8%). Shared features of MYB-R T-ALL were a non-early T-cell precursor (ETP) phenotype, a high incidence of NOTCH1/FBXW7 mutations (81%) and CDKN2AB deletions (70.5%). Moreover, they mainly belonged to HOXA (=8), NKX2-1/2-2/TLX1 (=4), and TLX3 (=3) homeobox-related subgroups. Overall, MYB-R cases had significantly higher levels of MYB expression than MYB wild type (MYB-wt) cases, although high levels of MYB were detected in similar to 30% of MYB-wt T-ALL. Consistent with the transcriptional regulatory networks, cases with high MYB expression were significantly enriched within the TAL/LMO subgroup (P = .017). Interestingly, analysis of paired diagnosis/remission samples demonstrated that a high MYB expression was restricted to the leukemic clone. Our study has indicated that different mechanisms underlie MYB deregulation in 30%-40% of T-ALL and highlighted that, MYB has potential as predictive/prognostic marker and/or target for tailored therapy.

Adolescents and young adults (AYA) with acute lymphoblastic leukemia (ALL) represent a unique patient population with specific characteristics and needs. Growing evidences suggest that pediatric-inspired approaches improve the outcome in AYA. These results prompted the design of a pediatric AIEOP-BFM ALL 2000-based regimen - the GIMEMA LAL-1308 protocol - for newly diagnosed AYA (range 18-35 years) with Philadelphia negative (Ph-) ALL. The protocol included minimal residual disease (MRD) analysis at two different time-points (TP), that is, at the end of induction IA and consolidation IB, and a modulation in post-consolidation intensity according to MRD. Seventy-six patients were eligible between September 2010 and October 2014. The regimen was well tolerated, with 2.7% induction deaths and no deaths in the post-consolidation phase. The complete response (CR) rate was 92%; the 48-month overall survival (OS) and disease-free survival (DFS) were 60.3% and 60.4%. Both OS and DFS were significantly better in T-ALL than B-ALL. A molecular MRD

Background Outcomes in patients with Philadelphia chromosome (Ph)–positive acute lymphoblastic leukemia (ALL) have improved with the use of tyrosine kinase inhibitors. Molecular remission ...

Early recognition of Philadelphia-like (Ph-like) acute lymphoblastic leukemia (ALL) cases could impact on the management and outcome of this subset of B-lineage ALL. In order to assess the prognostic value of the Ph-like status in a pediatric-inspired, minimal residual disease (MRD)- driven trial, we screened 88 B-lineage ALL cases negative for major fusion genes (BCR-ABL1, ETV6-RUNX1, TCF3-PBX1 and KTM2Ar) enrolled in the GIMEMA LAL1913 front-line protocol for adult BCR/ABL1-negative ALL. The screening - performed using the “BCR/ABL1-like predictor” - identified 28 Ph-like cases (31.8%), characterized by CRLF2 overexpression (35.7%), JAK/STAT pathway mutations (33.3%), IKZF1 (63.6%), BTG1 (50%) and EBF1 (27.3%) deletions, and rearrangements targeting tyrosine kinases or CRLF2 (40%). The correlation with outcome highlighted that: i) the complete remission rate was significantly lower in Ph-like compared to non-Phlike cases (74.1% vs. 91.5%, P=0.044); ii) at time point 2, decisional for transplant allocation, 52.9% of Ph-like cases versus 20% of non-Ph-like were MRD-positive (P=0.025); iii) the Ph-like profile was the only parameter associated with a higher risk of being MRD-positive at time point 2 (P=0.014); iv) at 24 months, Ph-like patients had a significantly inferior event-free and disease-free survival compared to non-Ph-like patients (33.5% vs. 66.2%, P=0.005 and 45.5% vs. 72.3%, P=0.062, respectively). This study documents that Ph-like patients have a lower complete remission rate, event-free survival and disease-free survival, as well as a greater MRD persistence also in a pediatric-oriented and MRD-driven adult ALL protocol, thus reinforcing that the early recognition of Ph-like ALL patients at diagnosis is crucial to refine risk-stratification and to optimize therapeutic strategies. Clinicaltrials gov. Identifier: 02067143.

During the past three decades, allogeneic stem cell transplant (allo-SCT) has been considered the standard of care for adult patients with high-risk acute lymphoblastic leukemia (ALL) and, given th...

Background and aims. B-lineage acute lymphoblastic leukemia (B-ALL) carrying t(4;11)(q21;q23)/KMT2A-AFF1 accounts for roughly 10% of adult B-ALL, it is associated to pro-B immunophenotype and aggressive clinical features. However, the role of KMT2A-AFF1 in pediatric-like, minimal residual disease (MRD)-driven clinical trials and the impact of transplant in this poor prognostic subgroup are still debated. To address these issues we investigated the incidence, clinical features and outcome of KMT2A-AFF1-positive ALL treated in 6 consecutive GIMEMA (Gruppo Italiano Malattie EMatologiche dell'Adulto) clinical trials. Materials and methods. Between November 1996 and September 2016, 926 BCR-ABL1-negative B-ALL patients were enrolled in the GIMEMA clinical trials LAL0496, LAL2000, LAL0904, LAL1104, LAL1308, LAL1913. The median follow-up is 25.4 months (range: 0.1-146.9). Starting from LAL2000, KMT2A-AFF1-positive patients were classified as high-risk and managed more intensively. LAL1308 and LAL1913 adopted a similar pediatric-like backbone, at variance from LAL0496, LAL2000 and LAL0904. Overall, median age was 34.3 (range, 14.1 - 81.9), there were 502 males (54.2%) and 424 females (45.8%) and the median WBC count was 8.80 x 109/L (range, 0.4- 872.3). Incidence, clinical features and outcome of KMT2A-AFF1-positive were analyzed in comparison with KMT2A-AFF1-negative B-ALL. MRD evaluation after induction treatment was available in 197 patients enrolled in the more recent protocols. Results. Overall, 97/926 (10.5%) samples harbored KMT2A-AFF1 fusion gene. The comparison between KMT2A-AFF1-positive and the 829 KMT2A-AFF1-negative B-ALL patients revealed that KMT2A-AFF1-positive patients had a higher median age (42 vs 32.5 years old, p Conclusions. The present study examined a cohort of 926 BCR-ABL1-negative B-ALL treated in Italian multicenter clinical trials. Overall, though not differing in the achievement of CR and MRD negativity, the analysis of survival curves confirms that KMT2A-AFF1-positive patients have a significantly shorter survival than KMT2A-AFF1-negative patients. This result holds true also when censoring for transplant, thus suggesting that allograft does not confer a survival advantage to KMT2A-AFF1-positive patients. Moreover, KMT2A-AFF1-positive patients perform poorly also in more intensive regimen, as emerged from the analysis of the GIMEMA LAL1913 clinical trial. These findings encourage the adoption of alternative strategies: among the available targeted therapies, preclinical models of KMT2A-leukemia show sensitivity to BCL2-inhibitors, thus providing the rationale for testing this approach in upcoming clinical trials for KMT2A-AFF1-positive patients. Figure Disclosures Chiaretti: Amgen: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Shire: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Krampera:Novartis: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. Di Raimondo:Amgen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy. Bassan:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Shire: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Vignetti:Pfizer: Membership on an entity's Board of Directors or advisory committees, Other: Educational Training; Incyte: Membership on an entity's Board of Directors or advisory committees, Other: Educational Training.

Background. The management of adult patients with Ph+ acute lymphoblastic leukemia (Ph+ ALL), including the elderly, has changed since the introduction of tyrosine kinase inhibitors (TKI). A significantly better survival is observed in patients who become minimal residual disease (MRD)-negative. Aims. To increase the rate of MRD-negative patients, we designed a front-line chemo-free induction-consolidation trial (D-ALBA, GIMEMA LAL2116) based on the combination of the second-generation TKI dasatinib with the bispecific monoclonal antibody blinatumomab. The primary endpoint of the study was the rate of patients who achieved a complete molecular remission (CMR) or a positive non-quantifiable (PNQ) disease after at least two cycles of blinatumomab. Secondary endpoints included disease-free survival (DFS), overall survival (OS), cumulative incidence of relapse (CIR) and safety. We also sought to evaluate the prognostic impact of additional genomic lesions - performed on diagnostic samples - and the potential changes in the immunologic compartment, in terms of T cells and T-regulatory cells (Tregs), evaluated by flow cytometry (CD3+/CD4+, CD3+/CD8+ and CD3+/CD4+/CD25+/FOXp3+, respectively). Methods. This multicenter phase II study enrolled Ph+ ALL patients aged 18 years or older, with no upper age limit. Prior to dasatinib, patients received a 7-day steroids pre-phase: steroids were continued for further 24 days and stopped at day 31. Dasatinib (140 mg/day) was administered as induction for 85 days. Thereafter, patients who obtained a complete hematologic response (CHR) received a post-induction consolidation treatment with blinatumomab at a flat dose of 28 μg/day. A minimum of 2 cycles was mandatory, while the administration of up to 3 additional cycles was allowed based on the response to blinatumomab and medical decision. Dasatinib was continued during treatment with blinatumomab. CNS prophylaxis was carried out during the whole treatment. Post-consolidation treatment was open. Results. Between May 2017 and January 2019, 63 patients have been enrolled. Median age was 54.5 years (range: 24.1-81.7), 54% were female, the median white blood cell count (WBC) was 42 x109/l (range: 0.63-63.5) and 65.1% carried the p190 fusion. Copy number aberration analysis showed that the most frequent lesion was, as expected, IKZF1 deletion (54%): 23.9% of patients were thus classified as IKZF1plus (i.e. IKZF1 and/or PAX5 and/or CDKN2A/B deletions). The median follow-up is 10 months (range: 0.9-21.5). So far, 61 patients have completed induction, 55 the 1st cycle of blinatumomab, 47 the 2nd cycle, 33 the 3rd, 26 the 4th and 17 the 5th. Two patients have gone off protocol for medical decision and toxicity, and 1 died during induction. At the end of the induction with dasatonib, 17/58 pts (29.3%) had a molecular response (6 CMR and 11 PNQ). At the primary endpoint (end of the 2nd cycle of blinatumomab), 27/47 (56.3%) had a molecular response (17 CMR and 10 PNQ). The rates of molecular responses further increased after subsequent cycles of blinatumomab: 65.7% after the 3rd cycle and 80% after the 4th cycle. ABL1 mutational analysis was carried out in 15 patients with evidence of a MRD increase: 8 cases were WT, while mutations were detected in 7 (6 T315I, and 1 E255K). All mutations but 1 occurred prior to the start of blinatumomab and all were "cleared" by blinatumomab. The analysis of the immunologic compartment carried out in 12 patients who completed all 5 cycles of blinatumomab showed a significant increase in the rate of CD8+ T cells (19.8% before the start of blinatumomab and 29% after the 5th cycle, p=0.04) and a significant reduction in the rate of Tregs (11% before blinatumomab and 3.7% after the 5th cycle, p=0.02). Overall, 5 relapses have been recorded (2 hematologic, 2 isolated CNS and 1 nodal). The 12-month OS and DFS are 94.2% and 87.8%. A significantly inferior DFS (61.4%, p=0.01) was observed in IKZF1plus cases: these patients were prone to develop deleterious mutations. So far, 12 patients have been allografted and no transplant-related mortality has been recorded. Conclusions. In the first chemo-free induction-consolidation protocol for adult Ph+ ALL patients of all ages based on a combination of a targeted and immunotherapeutic strategy, the rates of molecular responses and survival are highly promising; patients harboring IKZF1 plus represent, also in this setting, a clinical challenge. Disclosures Chiaretti: Pfizer: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Shire: Membership on an entity's Board of Directors or advisory committees. Bassan:Amgen Inc.: Honoraria; Incyte: Honoraria; Pfizer: Honoraria; Shire: Honoraria. Bonifacio:BMS: Honoraria; Novartis: Honoraria; Amgen: Honoraria; Pfizer: Honoraria; Incyte: Honoraria. Vignetti:Pfizer: Membership on an entity's Board of Directors or advisory committees, Other: Educational Training; Incyte: Membership on an entity's Board of Directors or advisory committees, Other: Educational Training. Rambaldi:Omeros: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Speakers Bureau; Italfarmaco: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding, Speakers Bureau; Jazz: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau, travel support. Foà:Celltrion: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Consultancy, Speakers Bureau; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celltrion: Membership on an entity's Board of Directors or advisory committees; Shire: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Speakers Bureau; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Shire: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Consultancy, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Speakers Bureau.

Background. Hematologic and, to a lesser extent, molecular relapsed/refractory in adult acute lymphoblastic leukemia (R/R ALL) is associated with a poor outcome, with low rates of subsequent complete remission (CR) and short survival. Blinatumomab has shown to be effective in both settings. Aims and methods. In this retrospective, single center study we aimed at: 1) evaluating the efficacy of blinatumomab in both hematologic and molecular R/R patients enrolled in clinical trials and in a real life setting; 2) identifying predictive factors impacting on overall and disease free-survival (OS and DFS), and 3) establishing the feasibility and the role of a subsequent allogenic stem cell transplantation (HSCT). Thirty-six adult patients (≥18 years) in hematologic or molecular R/R ALL were treated with blinatumomab between January 2012 and March 2017. Blinatumomab was administered either in the context of a clinical trial (Blast, MT103-211, Tower, Alcantara), in a compassionate use program or according to AIFA (Agenzia Italiana del Farmaco) guidelines. Blinatumomab was administered as continuous infusion for 4 weeks, followed by a 2-week wash out. A stepwise dose of 9 µg/day during the first week of cycle 1 followed by 28 µg/day thereafter, was administered for hematologic R/R cases and a flat dose of 15 µg /m2/day for molecular R/R patients. Patients who witnessed a response received up to 4 additional cycles or underwent a HSCT; patients showing after 1 cycle an increase in the blast count or of minimal residual disease levels, discontinued treatment. Results. Thirty-six patients were analyzed: 21 (58.4%) were in hematologic R/R and 15 (41.6%) in molecular R/R. Four patients had high-risk genetic features (2 BCR/ABL1 and 2 MLL/AF4). Thirteen patient were treated in the context of a clinical trial. All patients received at least one cycle of blinatumomab. At the end of the first cycle, among the 21 hematologic R/R pts, 14 (67%) achieved a CR and 10/14 (71%) also a CMR, while in the molecular R/R group 12/15 (80%) achieved a CMR. As expected, the rate of CMR was significantly higher in the molecular R/R cases as opposed to hematologic R/R (80% vs 52%, p=0.05). Notably, all 4 patients treated for a primary refractory disease, achieved a CR and CMR after the first cycle as opposed to hematologic relapsed cases (p=0.08). With a median follow-up of 33.9 months (range 1-89), the overall OS and DFS at 3 years are 34% and 42.5%, respectively. OS was significantly better for molecular R/R cases than for hematologic R/R cases (54.2% vs 26.1%, p=0.05), while no significant differences were observed in DFS. OS and DFS are 100%, respectively, for refractory cases. Median OS is 6.75 months for hematological R/R, while it is not reached for molecular R/R. Median DFS is 26 months for both groups. Predictive factors for non-response were the status of disease prior to blinatumomab (hematologic vs molecular R/R) and primary refractoriness. A better, though not significant, outcome was observed for patients treated in first rather than in subsequent relapse, and in cases without molecular aberrations (p=0.07, p=0.09). Overall, 14 patients - 9 with molecular and 5 with hematologic R/R at enrollment - underwent a HSCT: 8 are in continuous CR (median follow-up: 17 months, range 5-73). Among the 22 patients who did not receive a HSCT, including 16 molecular and 6 hematologic R/R at enrollment), 7 are in continuous CR (median follow-up: 51 months, range 10-89). Due to the small sample size, we cannot define the role of transplant; transplant-related mortality (TRM) was observed in 3/14 (21.4%). Treatment was well tolerated: the most common adverse events were pyrexia (55%), infectious events (33.3%) and neurotoxicity (19.4%); hematologic toxicity was rare and more frequent in hematologic R/R. Conclusions. Treatment with blinatumomab was safe and effective. As expected, patients treated in molecular R/R had better survival rates than hematologic R/R patients. Despite the small number, all primary refractory patients responded to blinatumomab, suggesting that in these cases immunotherapeutic strategies can be extremely effective, irrespective of a chemo-insensitive disease. HSCT did not impact on OS and DFS, possibly due to the small number of the cohort. Finally, no differences in terms of adverse events, DFS or OS were observed between patients treated in the context of a clinical trial or in a real-life setting. Disclosures Chiaretti: Incyte: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Shire: Membership on an entity's Board of Directors or advisory committees. Foà:Abbvie: Consultancy, Speakers Bureau; Roche: Consultancy, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Shire: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Speakers Bureau; Roche: Consultancy, Speakers Bureau; Shire: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celltrion: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celltrion: Membership on an entity's Board of Directors or advisory committees.

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.

We describe the case of a patient with a Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) treated with dasatinib plus steroids as the first-line therapy who achieved a molecular complete remission and then underwent a matched, unrelated donor allogeneic transplant. Five months after the transplant, he experienced a disease relapse with an T315I mutation, which was resistant to salvage chemotherapy. Once the details of the T315I mutation were acquired, we initiated ponatinib treatment at a standard dosage and observed a rapid decrease of minimal residual disease (MRD) at molecular assessment. The bone marrow evaluation after 2, 3, 6, 10 and 13 months was negative for MRD. After starting ponatinib, the patient experienced a skin graft-versus-host disease (GVHD), whereas no occurrence of GVHD was observed after transplant, suggesting that the efficacy of ponatinib could be related not only to the direct antileukemic effect, but also to its ability to promote an indirect graft-versus-leukemia effect. Ponatinib was well tolerated but a thyroid dysfunction mimicking a cardiovascular toxicity was observed and solved with hormonal substitutive treatment.

Despite therapeutic improvements, a sizable number of patients with T-cell acute lymphoblastic leukemia still have a poor outcome. To unravel the genomic background associated with refractoriness, we evaluated the transcriptome of 19 cases of refractory/early relapsed T-cell acute lymphoblastic leukemia (discovery cohort) by performing RNA-sequencing on diagnostic material. The incidence and prognostic impact of the most frequently mutated pathways were validated by Sanger sequencing on genomic DNA from diagnostic samples of an independent cohort of 49 cases (validation cohort), including refractory, relapsed and responsive cases. Combined gene expression and fusion transcript analyses in the discovery cohort revealed the presence of known oncogenes and identified novel rearrangements inducing overexpression, as well as inactivation of tumor suppressor genes. Mutation analysis identified JAK/STAT and RAS/PTEN as the most commonly disrupted pathways in patients with chemorefractory disease or early relapse, frequently in association with NOTCH1/FBXW7 mutations. The analysis on the validation cohort documented a significantly higher risk of relapse, inferior overall survival, disease-free survival and event-free survival in patients with JAK/STAT or RAS/PTEN alterations. Conversely, a significantly better survival was observed in patients harboring only NOTCH1/FBXW7 mutations: this favorable prognostic effect was abrogated by the presence of concomitant mutations. Preliminary in vitro assays on primary cells demonstrated sensitivity to specific inhibitors. These data document the negative prognostic impact of JAK/STAT and RAS/PTEN mutations in T-cell acute lymphoblastic leukemia and suggest the potential clinical application of JAK and PI3K/mTOR inhibitors in patients harboring mutations in these pathways.

In the GIMEMA LAL 0904 protocol, adult Philadelphia positive acute lymphoblastic leukemia patients were treated with chemotherapy for induction and consolidation, followed by maintenance with imatinib. The protocol was subsequently amended and imatinib was incorporated in the induction and post-remission phase together with chemotherapy. Due to the toxicity of this combined approach, the protocol was further amended to a sequential scheme based on imatinib plus steroids as induction, followed by consolidation with chemotherapy plus imatinib and, when applicable, by a hematopoietic stem cell transplant. Fifty-one patients (median age 45.9 years) were enrolled in the final sequential protocol. At the end of induction (day +50), 96% of evaluable patients (n=49) achieved a complete hematologic remission; after consolidation, all were in complete hematologic remission. No deaths in induction were recorded. Overall survival and disease-free survival at 60 months are 48.8% and 45.8%, respectively. At day +50 (end of imatinib induction), a more than 1.3 log-reduction of BCR-ABL1 levels was associated with a significantly longer disease-free survival (55.6%, 95%CI: 39.0-79.3 vs. 20%, 95%CI: 5.8-69.1; P=0.03), overall survival (59.1%, 95%CI: 42.3-82.6 vs. 20%, 95%CI: 5.8-69.1; P=0.02) and lower incidence of relapse (20.5%, 95%CI: 7.2-38.6 vs. 60.0%, 95%CI: 21.6-84.3; P=0.01). Mean BCR-ABL1 levels remained significantly higher in patients who subsequently relapsed. Finally, BCR-ABL1p190 patients showed a significantly faster molecular response than BCR-ABL1p210 patients (P=0.023). Though the study was not powered to evaluate the role of allogeneic stem cell transplant, allografting positively impacted on both overall and disease-free survival. In conclusion, a sequential approach with imatinib alone in induction, consolidated by chemotherapy plus imatinib followed by a stem cell transplant is a feasible, well-tolerated and effective strategy for adult Philadelphia positive acute lymphoblastic leukemia, leading to the best long-term survival rates so far reported. (clinicaltrials.gov identifier: 00458848).

Background A deregulated CRLF2 (d- CRLF2 ) expression was described in B-cell acute lymphoblastic leukemia without recurrent fusion genes (B-NEG ALL). While the role of d- CRLF2 in children has been extensively described, little is known about its role and impact in adult ALL. Methods Expression levels of CRLF2 were evaluated by quantitative real-time PCR in 102 newly-diagnosed adult B-NEG ALL and correlated with the clinico-biological characteristics and outcome. Incidence and clinical impact of the P2RY8/CRLF2 transcript was also assessed. Results High CRLF2 levels, as continuous variable, were significantly associated with hyperleucocytosis ( p = 0.0002) and thrombocytopenia ( p = 0.005); when a cut-point at ΔCt ≤ 8 was applied, 35 cases (34.3%), mostly males (80%), proved positive for CRLF2 expression. High CRLF2 levels, as continuous or categorical variable, were associated with a worse disease-free ( p = 0.003 and p = 0.015) and overall survival ( p = 0.017 and 0.0038). Furthermore, when CRLF2 was analyzed as a categorical variable, a high statistical association was found with IKZF1 deletion and mutations in the JAK/STAT pathway ( p = 0.001 and p P2RY8/CRLF2 transcript, identified in 8/102 patients (7.8%), was associated with a poor outcome. Conclusions In adult B-NEG ALL, high CRLF2 expression is associated with distinct clinico-biological features and an unfavourable prognosis in both univariate and multivariate analysis; similarly, P2RY8/CRLF2 positivity correlates with a poor outcome. The quantification of CRLF2 is an important prognostic marker in adult B-lineage ALL without known genetic lesions.

In an adult case of B-cell acute lymphoblastic leukemia (B-ALL) with a complex karyotype, both chromosomes 14 were involved in unbalanced rearrangements, specifically, der(14)t(13;14)(q21;q21) and dup(14)(q11q32). Fluorescence in situ hybridization (FISH) detected two CEBPE-IGH rearrangements at the dup(14). One was found at the duplication breakpoint and the other derived from insertion of CEBPE into an apparently normal IGH locus. Hypotheses to account for these unusual chromosomal rearrangements are discussed. This case provides the first evidence that chromosome duplication and cryptic insertion produce the CEBPE-IGH fusion and that more than one CEBPE-IGH recombination can occur in a leukemic cell. Our findings confirm that deregulated CEBPE plays a crucial role in the pathogenesis of CEBPE-IGH positive B-ALL.

Monoclonal antibody (MoAb)-based therapies have opened innovative treatment avenues that have impacted on the management of patients with both neoplastic and non-neoplastic hematological diseases. The aim of our study was to evaluate in a large series of cases of acute lymphoblastic leukemia (ALL) the expression of specific antigens, CD19, CD20, CD22, and CD33, for which MoAbs are available for clinical use. For each antigen, evaluation was based on the percentage of positive leukemic cells and the degree of antigen expression by mean fluorescence intensity (MFI) and antibody binding capacity (ABC) that were correlated with age, immunophenotype, and presence/absence of particular molecular markers. We can document that some of the analyzed antigens showed a degree of expression related to the B-cell maturation profile, and that the antigen expression intensity appeared to vary according to the presence of specific genetic markers. These findings suggest that the possible clinical use of a given MoAb in patients with ALL should take into account both the maturation profile of the leukemic cells and the presence of a given molecular transcript. Only clinical studies will conclusively demonstrate whether the differences in antigenic expression truly correlate with the different therapeutic efficacies of the various clinical grade MoAbs.