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BACKGROUND: Many efforts have been made in the attempt to address the conundrum question of fitness definition ad prognosis prediction in elderly acute myeloid leukemia (AML) patients. Parametric definitions are expected to give an advantage in patient stratification; however, clinical examination remain de facto pivotal to formulate therapy decisions and frequently the comorbidities are empirically evaluated. METHODS: We conducted a multicenter study collecting baseline comorbidity, laboratory data, CTCAE 4.0.3 adverse events (AE), and outcome of elderly patients (>65 years old) with new onset AML who received hypomethylating agents as 1st line therapy. We tested the impact on prognosis of baseline clinical and biological risk factors. Furthermore, we evaluated a score - acute myeloid leukemia-composite model, AML-CM (Mukherjee et al, 2017) - developed in chemotherapy-eligible patients, that accounts for baseline comorbidities, laboratory parameters, age and cytogenetic-molecular risk. The study was approved by local Ethical Authority (316/2019/Oss/AOUBo). RESULTS: We collected data from 131 consecutive elderly patients who received 1 st line HMAs between January 2008 and January 2021. Patients had a median age of 76 years (IQR 72 -79). Seventy-seven out of 131 patients (58.8%) had de novo AML, 32/131 (32.8%) had secondary AML, and 11/131 (8.4%) had therapy-related AML. Out of 123 evaluable patients, 43 (34.9%) had complex karyotype, 1 (0.8%) inv(16), 59 (48.4) normal karyotype, 18 (14.7%) other alterations; 8/108 patients harbored FLT3 ITD mutation (7.4%, 23 not tested), 12/101 NPM1 mutation (11.9%, 30 not tested). Based on these data, 111 patients were evaluable for ELN2010 risk stratification; 9 over 111 patients (8.1%) were stratified in the low risk, 42/111 (37.8%) in intermediate-1 risk, 17/111(15.3%) in intermediate-2 risk, and 43/111 (38.7%) in high-risk class. As expected, most of the patients had at least one comorbidity. Particularly, baseline arrhythmia was present in 29/130 (22.1%, 1 no data), cardiovascular comorbidity in 20/130 (15.4%, 1 no data), diabetes in 20/131 (15.3%), cerebrovascular comorbidity in 11/131 (8.4%), kidney disease in 15/130 (11.5%, 1 no data), lung chronic disease 19/130 (14.6% 1 no data), hypoalbuminemia in 25/111 patients (22.5%, 20 no data). With a median follow up of 28.2 months, median overall survival (OS) of the entire cohort was 15.8 months (95% C.I. 11.2-19.4). We confirmed that patient who obtained a response (complete remission, partial response, hematological improvement) after 2 months of therapy had the best OS (figure A, median OS of 21 months for responders vs 7.4 months for non-responders, p To test the impact of comorbidities combined with cytogenetic and molecular risk, AML-CM was used. Our results indicate that AML-CM score was able to stratify prognosis in elderly patients receiving frontline HMAs (figure B, median OS in score group 1: 29.7 months, score group 2: 16.5 months, score group 3: 11.2 months, score group 4: 6.6 months, p=.038). The worse prognosis of patients with higher AML-CM score, which includes patients with increased baseline comorbidities, may be explained with a higher incidence of AEs (84.55, 116.01, 131.45, 229.3 events for 100 patients per year for score group 1,2,3, and 4, respectively) and infections (53.80, 55.10, 85.95, 140.13 events for 100 patients per year for score group 1,2,3, and 4, respectively), in patients with higher baseline comorbidities. CONCLUSION: In this study we found that baseline comorbidities, captured by AML-CM score, may define prognosis of elderly patients receiving 1st line HMAs; parametric comorbidity scores may improve our ability to predict outcome and tailor interventions. The impact of comorbidity on OS may be increased with novel and more aggressive therapy. For this reason, specific studies on functional fitness tests and geriatric assessments are highly warranted in patients receiving HMAs plus venetoclax. This work was supported by Bologna AIL. CP and AC shared last authorship. Figure 1 Figure 1. Disclosures Martinelli: Daichii Sankyo: Consultancy; Pfizer: Consultancy, Speakers Bureau; Astellas: Consultancy, Speakers Bureau; Roche: Consultancy; Abbvie: Consultancy; Stemline Therapeutics: Consultancy; Celgene /BMS: Consultancy, Speakers Bureau; Incyte: Consultancy; Jazz Pharmaceuticals: Consultancy. Cavo: Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Accommodations, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Speakers Bureau; Adaptive Biotechnologies: Consultancy, Honoraria; GlaxoSmithKline: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol-Myers Squib: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Papayannidis: Pfizer, Amgen, Novartis: Honoraria. Curti: Abbvie: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Membership on an entity's Board of Directors or advisory committees.

Introduction In the setting of clinical trials Venetoclax (VEN) combined with hypomethylating agents (HMAs) has shown fair activity in Relapsed/Refractory (R/R) AML and impressive results in newly diagnosed (ND) elderly AML patients. However, no clear guidelines are available on real-life management, especially in the outpatient setting. This study involving AML patients treated with VEN combined with HMAs aims to amelioratate physicians' knowledge about the administration of these regimens. Methods This is a single-center retrospective study involving AML patients treated with Venetoclax combined with HMAs. Data were collected in accordance with GCP and Helsinky declaration. Adverse events (AEs) were graded according to CTCAE v4.03. Survival is estimated with Kaplan-Meyer method. Results A total of 59 AML patients, 43 R/R and 16 ND, have been treated with VEN plus HMAs from March 2018 to June 2021 and completed at least 1 therapy course (range 1-9, median 2, IQR 1.0 - 4.0). The median age was 70 (range 22-88) years and 15.3 % had a documented ECOG score greater than 1. VEN was combined with azacitidine in 35/59 (59.3 %) patients and with decitabine in 22/59 (37.3 %) patients (Table 1: patient and disease characteristics). The majority of patients (40/59, 67.8 %) (28/43 R/R, 12/16 ND) received the first cycle as out-patients, 19 out of 59 (32.2 %) patients were hospitalized and used as control. No significant differences with regards to disease and patients' characteristics were observed between in- and out-patients. During the ramp-up phase only 2 cases of tumor lysis syndrome (TLS) and 5 AEs were documented. During the first course, a total of 54 AEs were recorded and experienced by 16 over 19 hospitalized patients (84.2 %) and 20 over 40 outpatients (50 %). The 30-day and 60-day mortality were 2.5% (1/40) and 20 % (8/40), respectively, among patients receiving first course as out-patents, comparable to those documented in hospitalized patients. Overall, we reported 118 AEs, of which 74 were grade III-IV and the most common were hematological 23/74 (31.1 %) or infective 41/74 (55.4 %). Regarding infections, at least one bacterial infection was experienced in 10/40 (25%) and 12/19 (63.1%) patients of the outpatient and hospitalized cohorts, respectively (p = 0.009, IC 1.37 - 19.74, OR 4.98). Pneumonia and sepsis (13 and 18 cases) were the most frequent infections. Sepsis incidence was higher among hospitalized patients (13/19, 68.4 %, vs 5/40, 12.5 %, p = 0.000029). No significant difference in infective risk was documented between R/R and ND patients (65.1 vs 50 %). Thirty-two out of 59 (54.2 %) patients experienced at least one VEN withdrawal due to treatment toxicity. Twenty out of 43 AEs requiring VEN suspensions occurred during the first cycle. Patients treated in-patient showed the tendency for a higher probability to suspend therapy due to treatment toxicity (10/19 IN vs 10/40 OUT, p = 0.04). While twenty-three out of 59 (38.9 %) patients were hospitalized for treatment complications at least once, the average number of days spent in hospital was significantly different between patients receiving the first course as outpatients as compared to those who were hospitalized (5.9 vs 39.7, respectively, p < 0.0001). With a median follow-up of 117 days (IQR 92 - 173.75) in ND patients the Overall Response Rate (ORR), defined as CR + CRi + HI, was 62.5 % (10/16), with a CR/CRi rate of 50 % (8/16) and a median OS of 247 days (95% C.I. 177.71- 316.58)(Fig 1a). In the R/R setting the ORR rate was 41.8 % (18/43), with a CR/CRi rate of 25.6 % (11/43) and a median OS of 219 days (95% C.I. 91.8 - 346.2) (Fig 2a). No differences in OS were documented between patients who underwent VEN plus HMAs outpatient and patients who underwent the first cycle hospitalized (p = 0,38) (Fig. 1b-2b). Conclusions With the limitations of a single-center retrospective study, our real-life data indicate that VEN plus HMAs is feasible in an outpatient management, with minimal TLS rate and no limiting toxicities. Of note, infections rate was acceptable, bacterial infections and sepsis risk were lower in outpatients than in hospitalized patients. There was no significant impact of the outpatient management on treatment effectiveness, with data in line with published AML cohorts. Further studies evaluating the clinical, social and economic impact of outpatient VEN-based treatments are highly warranted. Figure 1 Figure 1. Disclosures Papayannidis: Pfizer, Amgen, Novartis: Honoraria. Cavo: Adaptive Biotechnologies: Consultancy, Honoraria; GlaxoSmithKline: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Accommodations, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Speakers Bureau; Novartis: Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol-Myers Squib: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Curti: Jazz Pharma: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees.

Background and Rationale. miRNAs are small non-coding RNAs that regulate gene expression by acting on the epigenetic machinery and are themselves controlled by epigenetic mechanisms. The expression of miRNAs is linked to cancer development and miRNA profiles are studied as new prognostic factors or therapeutic new perspectives (Jiang X et al. Nat Commun 2016). High-risk MDS are now treated with hypomethylating agents, like Azacitidine (AZA), alone or in combination with other drugs, such as Lenalidomide (LEN). Recent data showed that the concurrent acquisition of specific point mutations on PI3KCD, PLCG2 and AKT3 genes is associated with loss of response to AZA+LEN therapy (Follo MY et al. Leukemia 2019). Inositide signalling regulated by Phospholipase C (PLC) and PI3K/AKT is indeed involved in epigenetic processes and in MDS progression to AML, through the regulation of proliferation, differentiation and apoptosis. Patients and Methods. This study included 26 high-risk MDS patients treated with AZA (75 mg/m2/day, days 1-5, sc) and LEN (10 mg/day, days 1-21 or 8-21, orally) every 4 weeks. Patients showing complete remission (CR), partial remission (PR), any hematologic improvement (HI) or marrow CR+HI following IWG response criteria were considered as responders, while patients showing stable disease or disease progression were considered as non-responders. miRNAs expression was assessed using an Affymetrix miRNA 4.0 array on patients' cells extracted at baseline and during the therapy, at the 4th (T4) and 8th (T8) cycle of therapy. Results were then validated by Real-Time PCR and miRNA targets were studied by dual Luciferase assay. Real-Time PCR was also used to examine the expression of PLC genes. Results. All patients included in this study were considered evaluable for response. According to the revised IWG criteria (14), the overall response rate (ORR) was 76.9% (20/26 cases): CR (5/26, 19.2%), PR (1/26, 3.8%), marrow CR (mCR, 2/26, 7.7%), HI (6/26, 23.1%), mCR+HI (6/26, 23.1%), whereas 6/26 patients (23.1%) had a stable disease. For our analyses, we considered 10 patients as responders (R, showing response within T4 and maintaining it at T8), 10 losing response (LR, showing response within T4 and losing it at T8) and 6 non-responders (NR, never showing a response). Paired analysis between R and NR patients showed a statistically significant up-regulation of miR-192-5p and miR-21-5p between T0 and T4, as well as a down-regulation of miR-224-5p between T4 and T8, hinting at a relevant role for these miRNAs during AZA+LEN response. Real-Time PCR analyses confirmed the modulation of miR-192-5p and an altered expression of PLC genes during AZA+LEN therapy in all patients' subgroups, as well as an involvement of BCL-2 (possible target of miR-192-5p) that was also proven in vitro by dual Luciferase assays. Furthermore, as miR-192-5p expression seemed to be correlated with response, we performed Kaplan-Meier analyses and found out an association between high levels of miR-192-5p at T4 and OS (p=0.08) or LFS (p=0.04) in our MDS cases. More interestingly, this correlation was stronger (p=0.03) in R, as compared with LR and NR. Conclusions. This study shows that AZA+LEN therapy in MDS affects the expression of miR-192-5p, whose high level at T4 is associated with higher OS and LFS in responder patients. Moreover, we showed that miR-192-5p specifically targets and inhibits BCL-2, hinting at a regulation of MDS proliferation and apoptosis. Additional studies, to be performed in a larger cohort of MDS patients, are needed to confirm these data, as well as better understand the molecular mechanisms and the prognostic relevance of miR-192-5p in AZA+LEN therapy. Disclosures Cavo: AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Honoraria; Novartis: Honoraria; GlaxoSmithKline: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Accommodations, Speakers Bureau; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol-Myers Squib: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Finelli: Celgene BMS: Consultancy, Research Funding, Speakers Bureau; Takeda: Consultancy; Novartis: Consultancy, Speakers Bureau.

Introduction A large body of evidence has increasingly demonstrated that the immune tumor microenvironment (TME) critically contributes to acute myeloid leukemia (AML) development. However, current AML prognostic classifications only rely on leukemia cell-intrinsic alterations and do not incorporate immunological markers referring to TME. Indoleamine 2,3-dioxygenase 1 (IDO1), which is negatively regulated by the BIN1 proto-oncogene, is a central mediator of immune tolerance in the AML TME. This study aimed to identify IDO1-interacting genes in the AML TME and to develop a prognostic immune gene signature. Methods Biological and clinical data of 732 patients with de novo AML treated with curative intent were retrieved from public TCGA and HOVON datasets. Patients >= 65 years were excluded from survival analyses. Co-expression analysis was performed through cBioPortal on TCGA data aiming at discovering new IDO1-interacting genes. Cox regression analysis was used to identify most survival-predicting genes in order to generate a prognostic score. Differential expression (DE) analysis was performed using the nSolver software package (NanoString Technologies, Seattle, WA). Results BIN1 and IDO1 expression were negatively correlated in HOVON cases (P Conclusions Our data identify PLXNC1 as a novel IDO1-correlated gene. A three-gene immune signature that includes PLXCN1, IDO1 and BIN1 strongly predicted clinical outcome in large AML cohorts. Moreover, IDO1 and PLXNC1 expression-based DE analysis generated an immunological signature highly predictive of prognosis. In light of the emerging role of immunotherapies for AML, our findings support the incorporation of TME-associated immune biomarkers into current AML classification and prognostication algorithms. Figure Disclosures Cavo: Jannsen, BMS, Celgene, Sanofi, GlaxoSmithKline, Takeda, Amgen, Oncopeptides, AbbVie, Karyopharm, Adaptive: Consultancy, Honoraria. Rutella:NanoString Technologies, Inc.: Research Funding; MacroGenics, Inc.: Research Funding; Kura Oncology: Research Funding.

Background and Rationale. Inositide signalling regulated by Phospholipase C (PLC) and AKT is involved in epigenetic processes and in MDS progression to AML. miRNAs are small non-coding RNAs that regulate gene expression by acting on the epigenetic machinery and are themselves controlled by epigenetic mechanisms. The expression of miRNAs has been definitively linked to cancer development and miRNA profiles are studied as new prognostic factors or therapeutic new perspectives (Jiang X et al. Nat Commun 2016). Azacitidine (AZA) is a standard first-line therapy in high-risk MDS. Its combination with Lenalidomide (LEN) has been tested, but its molecular effect is still under investigation, although the concurrent acquisition of specific point mutations on PI3KCD, PLCG2 and AKT3 genes has recently been associated with loss of response to this combination therapy (Follo MY et al. Leukemia 2019). Here we further analyzed the effect of AZA+LEN therapy on epigenetic processes and inositide regulation, focusing on miRNA expression in MDS patients. Patients and Methods. This study included 12 high-risk MDS patients treated with AZA (75 mg/m2/day, days 1-5, sc) and LEN (10 mg/day, days 1-21, orally) every 4 weeks. Patients showing complete remission (CR), partial remission (PR) or any hematologic improvement were considered as responders, while patients showing stable disease or disease progression were considered as non responders. miRNAs expression was assessed using an Affymetrix miRNA 4.0 array on patients' cells extracted at baseline and during the therapy, at the 4th (T4) and 8th (T8) cycle of therapy. Results. All patients included in this study were considered evaluable for response. 2 patients never responded, while 10 patients showed a positive response within T4: 9 of them maintained it at T8, whereas the remaining patient lost response at T8. These clinical results do not mirror the expected clinical outcomes, but this is due to our small population. However, our analyses could be relevant to test the molecular effect of the therapy in a time course, as well as comparing different phases (baseline vs T4; baseline vs T8; T4 vs T8). Paired analysis within the same patients during treatment course showed 61 miRNAs up- or down-regulated (p Conclusions. This preliminary study shows that AZA+LEN therapy affects the expression of specific clusters of miRNAs that target the PI3K signalling and, more specifically, three inositide genes that are mutated and associated with loss of response to this combination therapy, i.e. PI3KCD, AKT3 and PLCG2. Additional studies are warranted to confirm these data and to further analyze the role of these clusters, especially to test their pathogenetic or therapeutic relevance in MDS. Disclosures Cavo: AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; GlaxoSmithKline: Honoraria, Speakers Bureau; Karyopharm: Honoraria. Finelli:Janssen: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

JN and CP equally contributed Introduction In the setting of clinical trials Venetoclax (VEN) combined with hypomethylating agents (HMAs) has shown fair activity in R/R AML and impressive results in treatment-naïve elderly AML patients. However, no clear guidelines are available on real-life management, especially in the outpatient setting. This study involving R/R AML patients treated with VEN combined with HMAs aims to amelioratate physicians' knowledge about the administration of these regimens. Methods This is a single-center retrospective study involving AML patients treated with Venetoclax combined with HMAs. Data were collected in accordance with GCP and Helsinky declaration. Adverse events (AEs) were graded according to CTCAE v4.03. Survival is estimated with Kaplan-Meyer method. Results Thirty-one R/R AML patients have been treated with VEN plus HMAs from March 2018 to March 2020 and completed at least 1 therapy course (range 1-9, median 2, IQR 1.0 - 5.0) (Table 1: patients' characteristics). Seventeen out of 31 (54,8 %) had received intensive chemotherapy as induction therapy. Twenty-two patients (71 %) had already received HMAs therapy, of which 14/31 (45,2 %) as first and only previous line of therapy. VEN was combined with azacitidine in 13/31 (41,9%) and with decitabine in 18/31 patients (58.1 %). The majority of patients (22/31, 70,9%) received the first cycle as out-patients, special focus of our analysis. For clinical reasons, only 9 out of 31 (29,1 %) patients were hospitalized and were used as control. In the outpatients setting, VEN dose escalation was managed with at least a weekly laboratory and clinical monitoring and the drug was often increased more slowly to carefully prevent tumor lysis syndrome or other complications. Specifically, there has been a trend toward a ramp-up schedule different from that indicated in clinical trials in the outpatient setting in comparison with hospitalized patients (77,2 % vs 33,3 %). In term of safety, no cases of tumor lysis syndrome (TLS) and only 2 AEs were documented during ramp-up phase, both experienced by hospitalized patients. Seventeen AEs were documented during cycle 1, affecting more frequently hospitalized patients (77,9% vs 31,8 %). In the outpatient setting, the early 30-days and 60-days mortalities were 4,5 % (1/22) and 13,6 % (3/22), respectively, comparable to percentages documented in hospitalized subgroup (0% and 11,1%). Overall, with a median follow-up of 138 days (IQR 69 - 285), we reported 48 AEs, of which 28 were grade III-IV and the most common were hematological (13/28, 48,1 %) or infective (14/28, 51,8 %). Twenty out of 31 (64,5 %) patients reduced VEN dosage during treatment, of which 12/20 (60 %) due to occurring AEs, and remaining patients for azole coadministration. Eleven out of 31 (35,5 %) patients required hospitalization, specifically 3 out of 9 hospitalized patients (33,3 %) during the subsequent outpatient phase of treatment, and 8/22 (36,3 %) patients who underwent VEN therapy outpatient, of which only 2 during the first 28 days of treatment. Twenty-four and 5 AEs were followed by a VEN temporary (median duration 14 days, range 5-120) and permanent withdrawn, respectively. As for the rate of response, the Overall Response Rate (ORR) by VEN plus HMAs therapy in our R/R study population, defined as CR + CRi + HI, was 41,9 % (13/31), with a CR/CRi rate of 22,6 % (7/31). The median time to first response was 67.0 days (IQR 37.0 - 133.5) and the median duration of response was 131.0 days (IQR 89.0 - 151.0). Four out of 31 (12,9 %) patients received subsequent HSCT. The median OS was 285 days (95% C.I. 178 - 392), with no difference in OS between patients who underwent VEN plus HMAs outpatient and patients who underwent the first cycle hospitalized (p = 0,38). Conclusions With the limitations of a single-center retrospective study, our real-life data indicate that VEN plus HMAs is feasible in an outpatient management, without TLS or other limiting toxicities and with comparable early-mortality and toxicity profiles, even in the ramp-up phase and first therapeutic cycle. There was no significant impact of the outpatient management on treatment effectiveness, with data in line with published R/R AML cohorts. Further studies evaluating the clinical, social and economic impact of outpatient VEN-based treatments are highly warranted. Disclosures Papayannidis: Abbvie, Janssen, Novartis, Amgen, Pfizer:Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.Cavo:Jannsen, BMS, Celgene, Sanofi, GlaxoSmithKline, Takeda, Amgen, Oncopeptides, AbbVie, Karyopharm, Adaptive:Consultancy, Honoraria. OffLabel Disclosure: In R/R AML, available data regarding the combination of VEN plus HMAs come only from retrospective studies where VEN is administered as an off-label prescription due to its widespread approval for chronic lymphocytic leukemia due to promising results obtained in treatment-naive elderly AML patients

Introduction. The association of Azacitidine (AZA) and Lenalidomide (LEN), either administered concurrently or sequentially, has proven effective in Myelodysplastic Syndromes (MDS), however the optimum dose and schedule remains unknown. The aim of this study was to evaluate the efficacy and safety of the combination vs the sequential use of AZA and LEN in higher-risk MDS pts. Primary endpoint: ORR, defined as the Rate of Complete Remission (CR), Partial Remission (PR), Marrow Complete Remission (mCR), and Hematological Improvement (HI), following the IWG criteria (Cheson, 2006). Moreover, the aim of this analysisis is to enucleate the clinical and biological features of pts who showed long-lasting (≥ 20 cycles) responses. Methods. This is a randomized, phase II, multicenter, open label study, including pts with MDS with IPSS risk High or Intermediate-2, without previous treatment with AZA or LEN. ARM 1 (combined treatment): AZA: 75 mg/m2/day (days 1-5) I.C. + LEN: 10 mg/day (days 1-21), orally, every 4 weeks. ARM 2 (sequential treatment): AZA: 75 mg/m2/day (days 1-5) I.C. + LEN: 10 mg/day (days 6-21), orally, every 4 weeks. The induction treatment was planned for 8 cycles. For responder pts the same treatment was continued until disease progression or unacceptable toxicity. Results. From March 2013, 44 pts (27 males), median age: 72 (48-83 yrs) were enrolled, from 13 hematologic Centers. 21 pts were randomly assigned to ARM 1, and 23 pts to ARM 2. Treatment was given for a median of 8.5 (1-68) cycles; in ARM 1: 9 (1-68) cycles; in ARM 2: 8 (1-63) cycles, respectively. Median follow-up: 15 (2-77) months. 10/44 pts (22.7%) did not complete at least 6 cycles of treatment for causes other than disease progression, and were not considered evaluable for response. Among the 34/44 pts (77.3%) evaluable for response, 26/34 pts (ORR: 76.5 %) showed a favourable response to treatment. Intention-to-treat (ITT) analysis: ORR: 59.1%. First response was observed after a median of 2 (1-8) cycles. The Best Response achieved was: CR: 8 pts (23.5%) (ITT: 18.1%), PR: 1 pt (2.9%) (ITT: 2.2%), mCR: 3 pts (8.8%) (ITT: 6.8%), HI: 8 pts (23.5%) (ITT: 18.1%), mCR+HI: 6 pts (17.6%) (ITT: 13.6%). Median duration of hematologic response: 10.5 months. 37 pts (84.1%) died , and 20 pts (45.4%) showed progression to AML. Grade >2 non haematological toxicity: 54.5%. Median OS: 15 months. OS was significantly longer in responder pts as compared to the other pts (28 vs 7 months, p2 non haematological toxicity (ARM 1: 66.7%; ARM 2: 43.5%), AML incidence (ARM 1: 33.3%; ARM 2: 56.5%; p=0.2150) and OS (ARM 1: 14 months; ARM 2: 16 months). However, among responder pts, sequential treatment showed a longer clinical benefit, as compared to combined treatment. Responder pts of ARM 2 showed a significantly longer median duration of response (18 vs 6 months, p=0.0481), a longer median duration of therapy (28 vs 10 months, p=0.0870; 20 vs 10 cycles, p=0.1181), more long-lasting (≥ 20 cycles) responses (34.8% vs 9.5%, p=0.1017) and a longer OS (35 vs 26 months, p=0.3868), as compared to responder pts of ARM 1. Overall, 10/44 long-responder pts (22.7%) received ≥ 20 cycles; 5/10 pts (50%) achieved CR. IPSS risk: Intermediate-2 (8 pts); High (2 pts); IPSS-R risk: Intermediate (2 pts); High (6 pts); Very High (2 pts); IPSS cytogenetic risk: Good (5 pts); Intermediate (3 pts); Poor (2 pts); IPSS-R cytogenetic risk: Good (5 pts); Intermediate (4 pts); Very Poor (1 pt); 4/6 patients with altered karyotype achieved cytogenetic remission; it is noteworthy that the only 3 pts of the entire series who showed no gene mutations at baseline are included in this subset of long-responders pts, while 5/10 pts showed at baseline ≥ 1 prognostically unfavorable gene mutations (none with TP53 mutations), with variable VAFs during treatment. Moreover all long-responder pts showed a common gene mutation on SOD2 gene, and mutations on PLCG2 gene. Conclusions. Our results confirm the efficacy of both AZA+LEN treatment regimens in higher-risk MDS pts, in terms of ORR and OS, although sequential treatment was associated with a longer clinical benefit among responder pts. A subset of pts (22,7 %) with less unfavorable cytogenetic and molecular characteristics showed a long-lasting response to treatment. Disclosures Finelli: Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees. Crugnola:BMS: Honoraria; Janssen: Honoraria; Celgene: Honoraria; Novartis: Honoraria. Rigolin:Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Cavo:Jannsen, BMS, Celgene, Sanofi, GlaxoSmithKline, Takeda, Amgen, Oncopeptides, AbbVie, Karyopharm, Adaptive: Consultancy, Honoraria.

Background The oral anti-apoptotic B-cell lymphoma 2 protein inhibitor venetoclax has shown strong activity in R/R AML in controlled clinical trials, and recently impressive results in treatment-naïve AML elderly patients with acute myeloid leukemia. However, limited data are available in the real-life setting. Methods This is a multi-center (n=4), retrospective study involving patients with treatment-naïve or Relapsed/Refractory (R/R) AML treated with Venetoclax in combination with HMAs. Data were collected after anonymous aggregation, in accordance with GCP and Helsinky declaration. Adverse events (AEs) were graded according CTCAE v4.03. Survival is estimated with Kaplan-Meyer method. Results Forty-four patients have been prescribed Venetoclax from March 2018 to June 2019 and completed at least 1 course of venetoclax (range 1-8, median 2, IQR 2.0 - 4.0), being evaluable in this analysis. Patients's characteristics are summarized in Table 1. Five/44 (11.4%) patients had a low risk AML, 21/44 (47.7%) had an intermediate risk AML and 14/44 (31.8%) patients had a high risk AML, according to ELN 2017 risk stratification (4 patients had no available ELN risk at baseline). Six out of 44 (13.6%) patients received Venetoclax in combination with HMAs as first line of therapy, whereas 14/44 (31%) as first line rescue for resistant AML, 15/44 (34.1%) at first relapse, 9/44 (20.5%) for second or further R/R AML. Among R/R patients who received Venetoclax, 17/38 (44.7%) and 21/38 (55.2 %) had received chemotherapy or HMAs as induction therapy, respectively. Overall, Venetoclax was combined with azacitidine in 19/44 patients (43.2%), with decitabine in 19/44 patients (43.2%), with Low-dose of Cytarabine in 5/44 (11.4%), and was performed in monotherapy in 1/44 (2.3%) patient. Three out of 44 patients (6.8%) received a maximum dosage of 100 mg daily, 2/44 (4.5%) received 200 mg, 37/44 (84.1%) received 400mg and 2/44 (4.5%) received 600 mg. Fifteen out of 44 (34.1%) patients reduced the dosage of venetoclax for concomitant Azole administration. The median follow-up is 75.5 (IQR 45.2 - 178.5) days for patients who received upfront venetoclax therapy, while 143 (IQR 49.2 - 235.7) days for R/R patients. In the first-line setting, no patients reduced venetoclax dosage for concomitant adverse events; two neutropenia grade IV and two thrombocytopenia grade III have been documented. In the R/R setting, 14/38 (36.6%) patients reduced venetoclax dosage for concomitant adverse events. Specifically, we reported 22 adverse events, of which 10 were grade III-IV (5 neutropenia grade IV, 2 pancytopenia grade IV, 1 neutropenia grade III and 2 febrile neutropenia grade III). The overall CR rate is 16.7 % in newly-onset AML patients and 28.9 % in R/R patients, respectively. Two out of 6 treatment-naive patients had an evaluable response at 2 months after the beginning of Venetoclax treatment, and 2/6 had an evaluable 4-months response: 1 stable disease (SD) and 1 disease progression (PD) at 2 months,1 SD e 1 complete remission (CR )at 4 months. Thirty-one out of 38 R/R patients had an evaluable response at 2 months and 21/38 had an evaluable 4-month response: 10 CR, 1 complete response with incomplete hematologic recovery (CRi), 14 SD and 6 PD at 2 months; 6 CR, 10 SD and 3 PD at 4 months have been documented. After a short follow-up period (75.5 days), no patients who received Venetoclax as upfront therapy underwent an allogeneic hematopoietic stem cell transplantation (HSCT). On the other hand, after a longer follow-up period (143 days), 5 out of 38 patients (13.2%) received a HSCT after Venetoclax therapy among R/R patients. Median Overall Survival was not reached in the newly-onset cohort. In R/R setting, median OS was 253 days (95% C.I. 157-349). Interpretation These data extend to the real-life setting some previous evidence obtained from trials. In particular, our data confirm that venetoclax plus HMAs or LDAC has an acceptable toxicity profile and is safe and manageable. However, especially in the R/R setting, hematological toxicity represents the most frequent adverse event, arising some concerns about the optimal drugs management. Although our data suggest a similar clinical activity of venetoclax combinations to that reported in clinical trials, further studies from the real-life setting are highly warranted to confirm venetoclax efficacy under normal clinical practice. GG and JN equally contributed CP and AC equally contributed Disclosures Boccadoro: Janssen: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; AbbVie: Honoraria; Mundipharma: Research Funding; Sanofi: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Amgen: Honoraria, Research Funding. Cavo:celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; bms: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; novartis: Honoraria; takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Papayannidis:Shire: Honoraria; Pfizer: Honoraria; Incyte: Honoraria; Novartis: Honoraria; Amgen: Honoraria; Teva: Honoraria. OffLabel Disclosure: Venetoclax is not approved to treat Acute Myeloid Leukemia in Italy

Background Although much efforts have been made to precisely define fitness of AML patients, in patients who are not candidate to chemotherapy, there is no prognostic model and the respective weight of AML biology and patient fitness are not well established. Here we test AML-CM score (Sorror, JAMA 2018), that is validated in fit population, in a set of old AML patients who received HMAs. Methods We retrospectively collected data of consecutive patients who received HMAs in our institution from 1st Jan 2008 with an age > 65 years at AML diagnosis. AML-CM score was applied to all the patients. Patients were divided in 4 groups (score 1-4: group 1, score 5-6: group 2; score 7-9: group 3, score > 9: group 4) and in 2 macro-groups (score 1-6: group A and score > 6 group B) for the analyses. Descriptive data are presented as median with interquartile ranges (IQR). Adverse events are graded according to CTCAE v4.03. Survival analysis was conducted with Kaplan-Meyer and are presented as 95% confidence intervals (C.I.) and differences in overall survival (OS) were tested with 2-side log rank test. Fisher exact test and Person's chi squared test were used whenever appropriate. Results At data cut-off, 1st Jan 2019, 60 consecutive patients received decitabine or azacytidine as 1st line therapy for AML. Median age of the population was 75.94 years (IQR 72.53-80.38). Most of the patients (37/62, 59.7%) had de novo AML, 19/62 (30.6%) had AML secondary to previous myeloid disorders and 6/62 (9.7%) had AML secondary to chemotherapy or radiotherapy. Most of the patients were smokers (19/33, 57.57%, 29 no data), and few were usual drinkers (4/16, 25.00%, 46 no data). In our set, out of 62 patients, 2 patients (3.2%) had inv(3), 1 (1.6%) a translocation involving 11q23, 1 (1.6%) del(5q), 4 (6.4%) mon(7) or del (7q), 1 (1.6%) del(17p), 15 (24.2%) complex karyotype, 27 (43.5%) normal karyotype, 4 (6.5%) other alterations and 5 were not evaluable; 3/17 (17.65%, 45 no data) harbored IDH2 mutation, 1/16 (6.25%) IDH2 mutation, 2/33 FLT3 mutation (6.06%, 29 no data), 1/24 (4.17%, 38 no data), 2/15 (13.33%, 47 no data) TP53 mutation. According to ELN 2017, 3/62 patients (4.83%) had low risk, 34/62 (54.84%) intermediate risk and 23/62 (37.10%) high risk AML. According to AML-CM score, 13/62 patients (20.97%) were in group A, 20/62 (32.36%) in group B, 21/62 (33.87%) in group C, 6/62 (9.68%) in group D, 2/62 (3.23%) were not allocated for incomplete AML-CM score. There was no difference in term of age, ELN risk, secondary AML prevalence, HMA administered, or response to HMA according to ELN criteria between group 1, 2, 3, 4 or between macro-group A and B. Cardiovascular comorbidity, diabetes mellitus, obesity, previous tumor, hypoalbuminemia, elevated LDH were prevalent in higher risk AML-CM groups (3-4) and in macro-group B. Median OS was 658 days (95% C.I. 316-1000) in group 1, 556 days (95% C.I. 463-649 in group 2, 243 days (95% C.I. 153-353) in group 3, 107 days (95% C.I. 47-167) in group 4 (p=.021, figure 1A). Furthermore, we observed a median OS of 589 days (95% C.I. 328-850) in macro-group A and 219 days (95% C.I. 96-342) in macro-group B (p=.003, figure 1B). Reduced survival was correlated with a non-statistical trend toward augmented incidence of infections and adverse events in higher risk AML-CM groups (3-4). Conclusions AML-CM is a useful indicator of prognosis in old patients that receive HMAs. Prognosis in our set is influenced by comorbidity (measured with AML-CM, a quantitative score) more than by disease biology. We identified a group of patients (macro-group A) that has median OS after HMAs outlying OS reported in literature. This brilliant result can be due to lower comorbidity. AML-CM could help in defining candidate patients for therapy intensification and care utilization or for team comorbidity management. GM and RDN equally contributed Figure 1 Disclosures Martinelli: Roche: Consultancy; Novartis: Consultancy; ARIAD: Consultancy; BMS: Consultancy; Pfizer: Consultancy. Baccarani:Novartis: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Takeda: Consultancy. Papayannidis:Pfizer: Honoraria; Teva: Honoraria; Shire: Honoraria; Novartis: Honoraria; Amgen: Honoraria; Incyte: Honoraria. Cavo:janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; bms: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; novartis: Honoraria; takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Introduction: ELN intermediate-risk AML poses considerable challenges to clinicians both in terms of accurate prognostication and optimal treatment. Indoleamine 2,3-dioxygenase 1 (IDO1) plays a central role as a mediator of immune tolerance in AML through the increase of Treg cells. IDO1 activity is negatively regulated by the BIN1 proto-oncogene. Herein, we analyzed the correlation between BIN1 and IDO1 expression in AML, also focusing on IDO1-interacting genes, with the aim to identify a predictive gene signature for OS. Methods: Biological and clinical data of 732 patients with de novo AML were retrieved from public TCGA and HOVON datasets. Since details on chemotherapy regimens were not available in the HOVON dataset, we decided to exclude patients >= 65 years from survival analyses. IDO1-interacting genes were selected through a co-expression analysis performed on TCGA RNA-sequencing data accessed through cBioPortal. The best genes combination predicting overall survival was plotted in a gene expression score. Patients were split in three different groups using score quartiles as cut-off. Results: In the HOVON dataset, IDO1 and BIN1 mRNA expression were negatively correlated (r = -0.40, P Conclusions: Our study shows a negative correlation between IDO1 and BIN1 in AML, suggesting IDO1 inhibition by BIN1, and identifies for the first time PLXNC1, a receptor for semaphorines, as an IDO1-interacting gene potentially implicated in immune response regulation. This finding corroborates the role of IDO1 and its interacting genes in the promotion of a tolerogenic microenvironment in AML. Lastly, our gene expression score predicted OS in intermediate-risk AML patients not undergoing HSCT, a finding which has clinical implications for accurate patient stratification and for clinical decision making, i.e., bridging these patients to transplant. Figure Disclosures Papayannidis: Pfizer: Honoraria; Amgen: Honoraria; Incyte: Honoraria; Novartis: Honoraria; Shire: Honoraria; Teva: Honoraria. Cavo:celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; bms: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; novartis: Honoraria; takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Rutella:MacroGenics, Inc.: Research Funding; NanoString Technologies, Inc.: Research Funding; Kura Oncology: Research Funding.

Rationale: Inotuzumab ozagomicin (IO) has been linked to an increased incidence of veno-occlusive disease (VOD) and liver alterations. Most VOD events occurred during hematopoietic stem cell (HSCT) transplantation after IO therapy. We have previously described that the measurement of liver stiffness can anticipate the diagnosis of VOD in the context of HSCT. The mechanisms underlying the increased risk of VOD and liver damage in patients receiving IO are not well understood; in the pathogenesis endothelial damage, ozagomicin release and on-target off-tumor effects may be involved. Here, we aimed to assess the effects of IO on the changes of liver, vascular and biochemistry parameters. Methods: Intensive monitoring of the liver was incorporated into the standard of care of patients who received IO for relapsed or refractory (R / R) acute lymphoblastic leukemia (ALL). Upper abdomen ultrasound with Doppler was performed at baseline and at the end of therapy; liver stiffness measurement (LSM) by Fibroscan® (Echosens, Paris, France) at every IO course or at every IO infusion. With the exception of ursodeoxycholic acid, the patients did not receive prophylaxis for VOD. Data was collected after anonymous aggregation, in accordance with GCP and Helsinki declaration. Results are reported as median with interquartile ranges (IQR). Results: At data cut-off, 1st Apr 2019, 16 patient received baseline assessment and at least a post-IO assessment in our monitoring program. In our patent set, median age was 44.5 (IQR 30.7 - 64.0); 12/16 (75 %) patients relapsed after the last treatment and 4/16 (25 %) patients were refractory to the last treatment; patients received a median of 3 (IQR 2 - 3.7) lines before IO; 6/16 (37.5 %) patients undergone HSCT before IO, of which a patient had 1st and 2nd HSCT before IO; 5/16 (31.25 %) undergone HSCT after IO therapy (no patients had second HSCT after IO). Patients received a median of 2 (IQR 2.0 - 3.7) IO administration according to the schedule of the phase 3 trial. The median duration of the therapy was 61.5 days (IQR 43.2 - 114.0) and median progression-free survival in our population was 278.0 days (95% C.I. 264.0 - 292.0). In our patient set, we performed 113 biochemistry determination, 30 liver ultrasounds with Doppler and 116 LSM examination. One patient received a liver biopsy. Among the biochemical exams (AST, ALT, GGT and alkaline phosphatase) only the AST values significantly increased after 1st course of IO (from the median value of 21 U/L to 53 U/L after course 3). Liver ultrasound with Doppler revealed portal hypertension signs in half of the patients during IO monitoring program. Among these patients 7/16 (44%), 3/16 (17%), 5/16 (33.3%) and 3/16 (17%) showed splenomegaly, recanalization of the paraumbilical vein, dilatation of portal vein and ascites, respectively. Median LSM significantly increased from a baseline value of 6 kPa to 7.8 kPa after last post-IO assessment (p-value 7.1 kPa). With a median follow up of 387.5 days (IQR 182.8-524.5) we observed one VOD event (7%); the VOD was graded severe and occurred after HSCT post-IO. Conclusions: Our clinical experience represents the first step to better understand the IO-related liver alterations, as we described the frequency and relevance of quantitative markers. Most of the patients in our set developed ultrasound and/or elastography alteration during IO therapy. Furthermore, these alterations do not seem to correlate with biochemistry. Even if most of the patients had sub-clinical vascular and parenchymal alterations of the liver portal-hypertension related, VOD incidence in our set is comparable with literature. Long-term follow-up results are expected to test whether alterations return or evolve over time. Stratifying the tailored risk liver complications with prospective non-invasive and marker-driven strategies in term of IO dosing and HSCT timing could be a great benefit for patients. * FR and GM contributed to this manuscript equally # AC and CP contributed to this manuscript equally Figure Disclosures Martinelli: Roche: Consultancy; BMS: Consultancy; Novartis: Consultancy; Pfizer: Consultancy; ARIAD: Consultancy. Cavo:janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; bms: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; novartis: Honoraria; takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau. Papayannidis:Amgen: Honoraria; Novartis: Honoraria; Teva: Honoraria; Pfizer: Honoraria; Incyte: Honoraria; Shire: Honoraria.

Introduction Indoleamine 2,3-dioxygenase (IDO) is an intracellular heme-containing enzyme that catalyzes the initial rate-limiting step in tryptophan degradation along the kynurenine pathway. IDO is physiologically expressed by a wide variety of human cells in response to several stimuli and it is known to have a crucial role in the induction of immune tolerance during pregnancy, infections, transplantation, autoimmunity and tumors. IDO-mediated tryptophan degradation results in inhibition of T-cell proliferation, increase of T-cell apoptosis and T-reg induction. Several studies demonstrated that IDO production can induce the increase of Regulatory T-cells (Tregs) directly through the conversion of CD25- into CD25+ T cells, even in acute myeloid leukemia (AML) patients. IDO expression can be considered a novel mechanism of leukemia escape from immune control and its inhibition may represent an antileukemia therapeutic strategy. Aim of our work is to analyze IDO mRNA expression in a cohort of AML patients and to investigate the presence of any significant correlation between IDO expression and standard prognostic factors or clinical outcome. Methods We analyzed a cohort of 68 adult patients aged 18 years or older, who were diagnosed with de novo or secondary AML. IDO mRNA expression was evaluated by Real-Time (RT)-PCR in blood bone marrow and peripheral blood samples at diagnosis. Patients were then retrospectively stratified according to standard risk factors at diagnosis and to IDO mRNA expression levels. Results Median age of analyzed patients was 57 years (range 21-76). Fifty-nine out of 68 patients (87%) had de novo AML, whereas 9 out of 68 patients (13%) had secondary AML. A comprehensive risk assessment was available for 61 patients. Among these 61 patients who were evaluable for risk stratification, 13 patients (21%) resulted to have a favorable risk AML, 30 (49%) had an intermediate risk AML and 17 patients (30%) were stratified as high-risk AML. Sixty out of 68 patients received intensive, standard, induction chemotherapy regimens. The remaining 8 patients were not candidate to receive intensive chemotherapy mainly because of comorbidities. Twenty-three out of 68 patients (34%) were considered eligible for allogeneic stem cells transplantation (alloSCT) as consolidation therapy, after obtaining complete remission with standard chemotherapy. IDO expression in peripheral blood (PB) samples was between 0.07 and 4272.26 (median 5.60). Conversely, IDO expression in bone marrow (BM) samples was between 0.17 and 243.16 (median 1.21). Our data did not establish any significant correlation between IDO expression and leukemia risk factors at diagnosis, in particular cytogenetics, de novo or secondary AML, leukocytosis. Among the 60 patients who received induction chemotherapy, 35 achieved morphological complete remission (CR), 24 did not respond and 1 patient was not evaluable for response. Response to induction chemotherapy was not influenced by IDO mRNA expression levels. Interestingly, among patients undergoing alloSCT, high levels of IDO mRNA expression in PB samples negatively correlated with patients' overall survival. In particular, high IDO expression of more than 10 was associated with worse overall survival after alloSCT even when adjusted by patients' age and disease status at transplant (log rank P=0.02) (Fig.1). With the limitations of the low number of patients, these results from the group of transplanted patients were not likely due to differences in the incidence and severity of graft-versus-host-disease, whereas high IDO mRNA expression level was predictive of increased incidence of relapse. Conclusions This work suggests that IDO mRNA expression levels can be considered as predictive of AML outcome, independently from other risk factors at diagnosis. In our set, higher level of IDO mRNA expression at diagnosis was correlated with worse clinical outcome in patients undergoing alloSCT. Larger studies are warranted in order to establish the real predictive role of IDO mRNA expression in influencing AML outcome. Disclosures Cavo: Adaptive Biotechnologies: 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; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

Introduction Monosomy 7 (-7) and interstitial deletions of chromosome 7 (7q-) are among the most recurrent chromosomal aberrations found in myeloid neoplasms. Patients carrying these cytogenetical alterations present a poor overall survival (OS), mainly due to a low sensitivity to standard chemotherapy and a high incidence of relapse. In our study, we aimed to disentangle the biology of patients with -7/7q- and find new candidate therapeutic targets for a disease with such a dismal prognosis, by integrating wide genomic approaches. Methods We collected bone marrow samples from 487 adult patients at diagnosis, treated in 3 institutions: Institute L. & A. Seragnoli (Italy, n = 213), CEMM (Austria, n = 160), University of Michigan (US, n = 114, GSE23452). Three hundred ninety-five samples were analyzed by SNP arrays (Affymetrix™), 51 samples by mass spectrometry (Metabolon™) and 57 samples by GEP (Affymetrix™) approaches. Chi-squared, fisher's exact test and ANOVA were used to test differences in proportion and distributions. False discovery rate, Bonferroni correction, and Welch's correction were calculated whenever appropriate. Results Among the 474 patients with evaluable karyotype, 65 (13.7%) had -7/7q-; 47 (9.9%) had -7, while 18 (3.8%) had 7q-. In our sets, the median age at AML diagnosis was 64 years (21-86) and most of the subjects had a de novo AML (65.1%). WBC count at diagnosis was significantly lower in -7/7q- patients (10.4 vs 35.2 k/mm3 p Within patients tested for FLT3, NPM1 and TP53 mutation at diagnosis, 1/50 among -7/7q- patients vs 59/300 controls harbored FLT3 ITD mutation (350 patients tested, 2% vs 19.7%, p In terms of outcome, -7/7q- AML had a median of overall survival of 10.3 months (95% C.I 5.8-14.8), which accounted for 49.5 months (95% C.I. 40.5-58.4) in other AML cases. GEP data of a cohort of 57 patients (8 with -7/7q- and 49 controls) revealed that 24 genes were under-expressed in -7/7q- AML (with e-4 significance threshold, Figure 1A). Twenty-three out of 24 genes mapped on chromosome 7; one gene, COX17, mapped on chromosome 3 (Figure 1A). COX17 plays a role in the recruitment of copper to mitochondria. By metabolomic analyses, we considered quantitative data of 300 different metabolites in 32 patients (4 with -7/7q- vs 28 controls, 19 patients were excluded because samples at diagnosis were not available). In -7/7q- AML, fatty acids (sphingomyelin, 1-linoleoylglycerol), β-cytrilglutamate and the UDP were overrepresented if compared with other AML cases; on the other hand, galactiol and 1-(1-enyl-palmitoyl)-2-linoleoyl-GPC were underrepresented in -7/7q- patients. Furthermore, -7/7q- AML cells seem to accumulate 3-hydroxy-3-methylglutarate and to have lower levels of 2-Hydroxyglutarate (Figure 1C). With SNP arrays, we considered copy number alterations in 395 patients (52 -7/7q- patients vs 343 controls, Figure 1B). 5q was the most recurrent concurrent deletion, with a minimal common deleted region (MCDR) in q31.3-q33.3. Additionally, 17p (MCDR p11.2 - p13.1), 12p (MCDR p12.3-p13.1), 16q (MCDRs q11.2-q12.1, q21-q22.1 and q24.2-q24.3), 16p (MCDR p11.2) and chromosome 4 (MCDRs q34.1 and q35.2) deletions also co-occurred in -7/7q-, listed per frequencies (Figure 1B). These regions are enriched for genes controlling cell signaling, DNA transcription, post-transcriptional modifications (such as SUMOylation), mRNA splicing and cellular senescence. Conclusions SNP, GEP and metabolomic approaches gave new insights on -7/7q- AML biology, identifying 24 new genes differentially expressed in -7/7q-, and 6 MCDR associated with -7/7q- AML. Deletion of chromosome 16q and 4 were never reported in literature associated to AML. Furthermore, for the first time, we described metabolites associated with -7/7q- AML. These data may represent a useful backbone to search for candidate targets in the setting of one of the most aggressive AML subtypes. Supported by:EHA Non-Clinical Junior Research Fellowship,HARMONY,Fondazione del Monte,FP7-NGS-PTL,AIRC. *MCF and MO equally contributed &CP and GS shared the last authorship Disclosures Haferlach: MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Kralovics:MyeloPro Diagnostics and Research GmbH: Equity Ownership. Soverini:Incyte Biosciences: Consultancy; Bristol Myers Squibb: Consultancy; Novartis: Consultancy. Martinelli:Ariad/Incyte: Consultancy; Celgene: Consultancy, Speakers Bureau; Novartis: Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Amgen: Consultancy; Janssen: Consultancy; Abbvie: Consultancy; Roche: Consultancy; Jazz Pharmaceuticals: Consultancy. Cavo:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: 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; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

Background and Rationale. Azacitidine (AZA) is a standard first-line therapy in high-risk MDS. Also its combination with Lenalidomide (LEN) has been tested, but its molecular effect is still under investigation. Here we analyzed the effect of AZA+LEN therapy on gene mutations and microRNA expression in MDS patients. Patients and Methods. This study included 44 high-risk MDS patients treated with AZA (75 mg/m2/day, days 1-5, sc) and LEN (10 mg/day, days 1-21, orally) every 4 weeks. Patients showing complete remission (CR), partial remission (PR) or any hematologic improvement were considered as responders, while patients showing stable disease or disease progression were considered as non responders. Molecular analyses were performed at baseline and during the therapy. Gene mutations were studied by an Illumina Cancer Myeloid Panel and an Ion Torrent specific panel, whereas microRNAs expression was assessed using an Affymetrix miRNA 4.0 array. Results. 34/44 patients were considered evaluable for response, with an overall response rate of 76.25% (26/34 cases). 13 patients showed a positive response within the 4th cycle (T4) and maintained it at T8; 9 patients showed a positive response within T4 and lost response at T8; 4 patients responded after T4 and maintained the response at T8; 8 patients never responded. Molecular analyses were performed on serial samples (baseline, T4 and T8) available for 30 patients. Results from the Illumina analysis on cancer myeloid genes showed that 3/30 cases had no mutations at all, all other cases showed mutations both at baseline and during the therapy. The most frequently mutated genes were ASXL1 (14 cases = 47%), TET2 (11 cases = 37%), RUNX1 (8 cases = 27%) and SRSF2 (5 cases = 17%). All samples with a decreasing variant allele frequency (VAF) had a favourable response at T8 (CR, marrow CR or PR), while none of the non responders showed a decreasing VAF. Ion Torrent analysis of 24 inositide-specific genes showed that all patients had mutations both at baseline and during the therapy. Interestingly, all patients responding at T4 and losing response at T8, as well as cases that did not respond, acquired the same 3 point mutations at T8, affecting respectively PIK3CD (D133E), AKT3 (D280G) and PLCG2 (Q548R) genes. Patients responding at T4 and losing response at T8 showed these mutations even at T4. Kaplan-Meier analyses revealed that the presence of these mutations was significantly associated with a decreased duration of therapy (39.5 vs 8.5 months; p As for microRNA profiling, paired analysis between responders and non responders showed specific clusters of up- or down-regulated microRNAs. Interestingly, unpaired analysis on patients responding at T4 and losing response at T8 showed 18 up- and 11 down-regulated microRNAs, like miR-3613-3p and miR-6757-5p, whose predicted targets are our 3 genes among the others. Also in patients never responding to the therapy there was a specific cluster of 3 up- and 12 down-regulated microRNAs and, interestingly, 7 of these microRNAs, like miR-4786-5p or miR-6853-3p, targeting our 3-gene cluster among the others, were altered also in patients losing response. Conclusions. Our results show that the presence of a common cluster of point mutations affecting 3 inositide-specific genes (PI3KCD, AKT3, PLCG2, all regulating cell proliferation), is significantly associated with loss of response to AZA+LEN therapy. Moreover, also a cluster of 7 microRNAs, targeting our 3 genes among the others, is associated with unfavourable outcome. Further studies are warranted to confirm these data, to further analyze the role of this 3-gene cluster and to identify the specific targets for the dysregulated microRNAs identified. Disclosures Gobbi: Janssen: Consultancy; Amgen: Consultancy; Ariad: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; Celgene: Membership on an entity's Board of Directors or advisory committees; Pfister: Membership on an entity's Board of Directors or advisory committees. Cavo:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees. Finelli:Janssen: Consultancy, Speakers Bureau; Celgene: Research Funding, Speakers Bureau; Novartis: Consultancy, Speakers Bureau.

Introduction. The association of Azacitidine (AZA) and Lenalidomide (LEN), either administered concurrently (Sekeres, 2010; 2012; 2017), or sequentially (Platzbecker, 2013; Di Nardo 2015; Mittelman 2016; Narayan 2016) has proven effective in Myelodysplastic Syndromes (MDS), however the optimum dose and schedule remains unknown. The aim of this study was to evaluate the efficacy and safety of the combination vs the sequential use of AZA and LEN in higher-risk MDS pts. Primary endpoint: ORR, defined as the Rate of Complete Remission (CR), Partial Remission (PR), Marrow Complete Remission (mCR), and Hematological Improvement (HI), following the IWG criteria (Cheson, 2006). Secondary endpoints: a) rate of CR; b) duration of responses; c) overall survival (OS). Methods. This is a randomized, phase II, multicenter, open label study, including pts with MDS with IPSS risk High or Intermediate-2, without previous treatment with AZA or LEN. ARM 1 (combined treatment): AZA: 75 mg/m2/day (days 1-5) I.C. + LEN: 10 mg/day (days 1-21), orally, every 4 weeks. ARM 2 (sequential treatment): AZA: 75 mg/m2/day (days 1-5) I.C. + LEN: 10 mg/day (days 6-21), orally, every 4 weeks. The induction treatment was planned for 8 cycles. For responder patients the same treatment was continued until disease progression or unacceptable toxicity. Results. From March 2013, 44 pts (27 males), median age: 72 (48-83 yrs) were enrolled, from 13 hematologic Centers. At baseline, IPSS risk was: Intermediate-2: 31 pts; High: 9 pts; not determined (N.D.) (because of lack of cytogenetic data): 2 pts. (all with RAEB-2). In 2 pts IPSS risk was Intermediate-1, but they were enrolled because of severe thrombocytopenia and neutropenia, respectively. IPSS-R risk was: intermediate: 8 pts; High: 16 pts; Very-High: 18 pts; N.D.: 2 pts. In 5 pts (11.4%) del(5q) was present (additional cytogenetic alterations: 1 in 1 pt, and > 1 in 4 pts , respectively). 21 pts were randomly assigned to ARM 1, and 23 pts to ARM 2. Treatment was given for a median of 8.5 (1-52) cycles; in ARM 1: 9 (1-51) cycles; in ARM 2: 8 (1-52) cycles, respectively. Median follow-up: 15 (2-54) months; 47 (37-54) months for survivors. 10/44 pts (22.7%) did not complete at least 6 cycles of treatment for causes other than disease progression (6 pts for adverse events, 2 pts for consent withdrawal and 2 pts for medical decision), and were not considered evaluable for response. Among the 34/44 pts (77.3%) evaluable for response, 26/34 pts (ORR: 76.5 %) showed a favourable response to treatment. Intention-to-treat (ITT) analysis: ORR: 59.1%. First response was observed after a median of 2 (1-8) cycles. The Best Response achieved was: CR: 8 pts (23.5%) (ITT: 18.1%), PR: 1 pt (2.9%) (ITT: 2.2%), mCR: 3 pts (8.8%) (ITT: 6.8%), HI: 8 pts (23.5%) (ITT: 18.1%), mCR+HI: 6 pts (17.6%) (ITT: 13.6%). The remaining 8 pts showed either Stable Disease (SD) (6 pts, 17.6%) or Disease Progression (DP) (2 pts, 5.9%). Among the 27 pts (21 evaluable for response) with an abnormal karyotype at baseline, ORR was 66.7% (ITT: 51.8%) and 4 pts achieved complete cytogenetic response. Median duration of hematologic response: 10.5 months. 34 pts (77,3%) died , and 17 pts (38.6%) showed progression to AML. Grade >2 non haematological toxicity: 54.5%. Median OS: 15 months. No significant differences between the 2 arms were observed, in terms of ORR (ARM 1: 76.5%, ITT: 61.9%; ARM 2: 76.5%, ITT: 56.5%), CR rate (ARM 1: 17.6%, ITT: 14.3%; ARM 2: 29.4%, ITT: 21.7%), grade >2 non haematological toxicity (ARM 1: 66.7%; ARM 2: 43.5%), AML incidence (ARM 1: 28.6%; ARM 2: 47.8%) and OS (ARM 1: 14 months; ARM 2: 16 months), but the median response duration was significantly longer in ARM 2 (18 months) as compared to ARM 1 (6 months) (p=0.0459). At the time of last analysis, 5/44 (11.4%) patients, 1/21 (4.8%) in ARM 1, and 4/23 (17.4%) in ARM 2, were still maintaining the haematological response, and were still in treatment, after 54, 54, 52, 51 and 37 months, and after 52, 51, 33, 48 and 35 cycles of therapy, respectively. The changes observed during treatment in mutational status of inositide-specific genes and microRNA expression profiling were related to clinical outcome, predicting a negative response to therapy. Conclusions. Our results confirm the efficacy of both AZA+LEN treatment regimens in higher-risk MDS pts, in terms of ORR and OS, although pts treated with the sequential regimen showed a significantly longer duration of haematological response. Disclosures Finelli: Celgene: Other: speaker fees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: speaker fees; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: speaker fees. Candoni:Janssen: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Gilead: Honoraria, Speakers Bureau; Pfizer: Honoraria, Speakers Bureau; Merck SD: Honoraria, Speakers Bureau. Gobbi:Novartis: Consultancy; Janssen: Consultancy; Ariad: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy; Pfister: Membership on an entity's Board of Directors or advisory committees. Rigolin:Gilead: Research Funding. Cavo:GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: 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.

Introduction Relapsed/refractory (R/R) AML patients continue to be a formidable clinical challenge, mainly in consideration of associated very poor outcome, with a median overall survival (OS) of less than 12 months. SCT represents the only curative option for these patients. Although, there is no standard-of-care approach which may serve as a bridge to SCT. Our study aims to investigate the effectiveness of MEC regimen as a rescue therapy for R/R AML patients by specifically addressing the CR rate, including minimal residual disease (MRD) negativity, the number of patients who subsequently underwent SCT and the presence of predictive factors of response. Methods Fifty-five consecutive adult AML patients were treated with MEC regimen in our Institution. In patients under 66 years old, we administered mitoxantrone 6 mg/sqm/die from day 1 to day 6, etoposide 100 mg/sqm/die from day 1 to day 6 and cytarabine 1000mg/sqm/die from day 1 to day 6, whereas in patients over 66 years old, the treatment schedule was reduced to 4 consecutive days. Data were retrospectively collected by using RedCap in accordance with Helsinki declaration and GCP. We used Kaplan-Meyer to estimate survival, and log rank to test differences in survival. Chi-squared, fisher's exact test and linear-by-linear correlation were used to test differences in proportions and distributions. Response was defined in accordance with 2017 ELN recommendations. CTCAE 4.03 was used to grade adverse events. MRD was assessed with WT1 or specific fusion transcripts. Results Fifty-five patients received MEC from 2008 to 2018. Age at diagnosis ranged from 17 to 72 years, with a median age of 51 years. Our set was enriched for high-risk patients. Interestingly, twenty percent of patients harbored FLT3-ITD at diagnosis (table 1). Two main groups were included: resistant AML, 28/55 patients (50,9%), and relapsed AML, 27/55 patients (49,1%). At induction, almost half of patients received "3+7" (n=25, 45,5%), while fludarabine-based regimens were administered to 14 patients (25,5%). In our set, after MEC median duration of hospitalization was 30 days (14-78); PMN >500/mm3 was reached after 26 days (range 18-67). Fever and febrile neutropenia was the most recurrent adverse events (AE). AEs were low in grade; out of 80 graded AEs, 38 (47,5%) were grade 2, 27 (33,8%) were grade 3, 9 (11,3%) were grade 4 and only 3 events resulted in death (3,8%). E. coli was the most recurrent cause of infection (10 cases). Overall, 25/55 patients (45,5%) achieved a complete remission (CR) after one course of MEC chemotherapy. Twelve patients (21.9%) achieved MRD negativity and 13 patients (23,6%) obtained an MRD+ CR or had no MRD test. Six patients (10,9%) had a partial response (PR) and 1 patient (1,8%)had hematological improvement (HI). Four patients (7.3%) died during post-MEC aplastic phase. Disease risk at diagnosis and R/R status did not influence the chance to obtain CR (figure 1 A). In 12 patients, a second MEC was administered. Four out of 12 patient improved their response with the 2nd MEC (2 patients obtained MRD - from MRD+ CR, 1 patient obtained PR and 1 patients obtained CR from hematological improvement). MEC was an effective bridge to SCT, 32/55 patients (58,2%, figure 1 B), received SCT; 15/32 patients (46,9%) received SCT directly after the 1st course of MEC, 9/32 patients (28,1%) after the 2nd course of MEC and 2 patients (6,3%) after an additional course of post-remission chemotherapy. Of note, only 6 patients (18,8%), who were not responsive to MEC, underwent SCT after an alternative rescue therapy. Median overall survival (OS) from MEC was 455 days (95% C.I. 307-602 days.); 1-year OS, 3-year OS and 5-years OS were 57,9%, 33,2% and 23,1%, respectively (std. error ± 0,067). Patients who responded to MEC (CR MRD+ or CR MRD- after 1 or 2 courses) had better OS than non-responders (median OS 1389 vs 160 days, p=.003). Stepwise multiple logistic regression analysis with COX-HR model established that pre-MEC R/R status, diagnosis class risk, response to one or two courses of MEC, and SCT were independent predictors of survival in the optimal model. Conclusions Taken together, our data indicate that MEC is an effective salvage regimen with affordable toxicity, and gives a high chance to obtain CR. MEC is particularly useful as a bridge to SCT, and has to be considered as a rescue therapy whenever a clinical trial is not available. *GM and AT equally contributed Disclosures Martinelli: Ariad/incyte: Consultancy; Pfizer: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Janssen: Consultancy; Roche: Consultancy. Cavo:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: 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; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Phosphoinositide-specific phospholipase C (PI-PLC) gamma1 is involved in erythroid differentiation, via activation of the Akt/PI-PLCgamma1 pathway, and its increase has been associated with erythropoiesis in MDS cells. On the other hand, PI-PLCbeta1 is a nuclear inositide-dependent enzyme implicated in the regulation of hematopoietic differentiation. Interestingly, PI-PLCbeta1 increase plays an important predictive role in the response of MDS cells to epigenetic therapy. Indeed, PI-PLCbeta1 promoter is specifically hypomethylated by azacitidine, a demethylating agent that is clinically used in MDS to improve patients' overall survival and delay the AML evolution. Moreover, azacitidine is currently studied in combination with lenalidomide, to sustain both myeloid and erythroid lineages and balance MDS cell proliferation and differentiation. However, the molecular effects of this combination therapy on inositide signalling pathways and microRNA expression are still unclear. This study included 44 patients diagnosed with high-risk MDS who were given azacitidine and lenalidomide. Patients were considered clinically evaluable after at least 6 cycles of treatment. Molecular analyses were performed at baseline and during the therapy. At first, Real-Time PCR and immunocytochemical experiments were performed to determine PI-PLCbeta1 and PI-PLCgamma1 expression. Then, we also carried out cell cycle analyses and studied both PI-PLCbeta1 methylation status and the expression of erythroid-specific molecules, i.e. Globin genes. On the other hand, to further investigate the effect of the combination therapy on epigenetic mechanisms, we analyzed microRNA expression at baseline and during the treatment. In particular, we started by comparing the 4th cycle of the therapy to baseline, and in case of significant differences, for responder patients, we carried out microRNA profiling at the 8th cycle of the therapy or during the follow-up. Our study included 44 patients, but only 28 subjects were clinically evaluable, with an overall response rate of 78.6% (22/28 cases). At a molecular level, a significant increase of PI-PLCbeta1 expression was associated with a favourable clinical response to the combination therapy. Moreover, responder cases also showed an increased expression of Beta-Globin and PI-PLCgamma1, hinting at a specific contribution of lenalidomide on erythroid activation. On the other hand, the frequent demethylation of PI-PLCbeta1 promoter in responder cases could be specifically linked to azacitidine. Furthermore, MDS cells treated with azacitidine and lenalidomide not only showed an increased G0/G1 phase of cell cycle, but also microRNA expression was affected. In fact, responder and non responder cases showed a specific molecular pattern of microRNAs and, interestingly, some of these microRNAs can target or are strictly associated with inositide signalling pathways. Our results show that the combination of azacitidine and lenalidomide in high-risk MDS patients can be important to induce PI-PLCbeta1, and possibly PI-PLCgamma1. These enzymes can regulate cell cycle, myeloid and erythroid differentiation, thus improving peripheral cytopenia. On the other hand, a specific microRNA signature is important to make a molecular distinction between responder and non responder cases, so that their expression or interactions, possibly with PI-PLCs or other nuclear inositides, can be important to disclose new mechanisms in MDS pathogenesis and identify new predictive markers for the assessment of the response to azacitidine and lenalidomide therapy. Disclosures Gobbi: Novartis: Consultancy, Research Funding; Mundipharma: Consultancy, Research Funding; Roche: Honoraria; Janssen: Consultancy, Honoraria; Gilead: Honoraria; Celgene: Consultancy; Takeda: Consultancy. Finelli:Novartis: Other: Speaker fees; Celgene: Other: Speaker fees; Celgene: Research Funding.

Introduction. Azacitidine (AZA) is the standard of care of higher-risk myelodysplastic syndromes (MDS), but the duration of clinical response is limited, and outcome after AZA failure is dismal. Several studies have demonstrated the efficacy and safety of combining AZA with Lenalidomide (LEN), either administered concurrently or sequentially, however the optimum dose and schedule for this combination remains unknown. The aim of this study was to evaluate the efficacy and safety of the combination vs the sequential use of AZA and LEN in higher-risk MDS pts (IPSS score risk: High or INT-2), and to look for possible biomarkers able to predict response. Primary endpoint: ORR, defined as the Rate of Complete Remission (CR), Partial Remission (PR), Marrow Complete Remission (mCR), and Hematological Improvement (HI), following the International Working Group (IWG) criteria (Cheson, 2006). Methods. This is a randomized, phase II, multicenter, open label study, including pts with MDS (WHO 2008 classification) with International Prognostic Scoring System (IPSS) risk High or Intermediate-2, without previous treatment with AZA or LEN. ARM 1 (combined treatment): AZA: 75 mg/m2/day (days 1-5) I.C. + LEN: 10 mg/day (days 1-21), orally, every 4 weeks. ARM 2 (sequential treatment): AZA: 75 mg/m2/day (days 1-5) I.C. + LEN: 10 mg/day (days 6-21), orally, every 4 weeks. The induction treatment was planned for 8 cycles (32 weeks). For responder patients (CR, PR, mCR, or HI) the same treatment was continued until disease progression or unacceptable toxicity. A sample size of 44 pts was planned. Results. From March 2013, 44 pts (27 males), with a median age of 72 (48-83 yrs) were enrolled, from 13 hematologic italian Centers. At baseline, IPSS risk was: Intermediate-2: 31 pts; High: 9 pts; not determined (N.D.) (because of lack of cytogenetic data): 2 pts. (all with RAEB-2). In 2 pts IPSS risk was Intermediate-1, but they were enrolled because of severe thrombocytopenia and neutropenia, respectively. IPSS-R risk was: intermediate: 8 pts; High: 16 pts; Very-High: 18 pts; N.D.: 2 pts. In 5 pts (11.4%) del(5q) was present. 21 pts were randomly assigned to ARM 1, and 23 pts to ARM 2. 34/44 pts (77.3%) completed ≥ 6 cycles of treatment, and are evaluable for response. The remaining 10 pts (4 in ARM 1 and 6 in ARM 2) are not evaluable for response, as they discontinued treatment before completing the 6th cycle because of adverse events (6 pts, 13.6%), consent withdrawal (2 pts, 4.5%) or medical decision (2 pts, 4.5%), respectively. Treatment was given for a median of 8.5 (1-37) cycles; in ARM 1: 9 (1-32) cycles, in ARM 2: 8 (1-37) cycles, respectively. 6 pts (ARM 1: 2; ARM 2: 4) are still on treatment. Pts have been followed for a median of 15 (2-37) months for all subjects, for a median of 32 (18-37) months for survivors. Among the 34 pts evaluable for response, 26/34 pts (ORR: 76.5 %) showed a favourable response to treatment. The Best Response achieved was: CR: 8 pts (23.5%), PR: 1 pt (2.9%), mCR: 3 pts (8.8%), HI: 8 pts (23.5%), mCR+HI: 6 pts (17.6%). The remaining 8 pts showed either Stable Disease (SD) (6 pts, 17.6%) or Disease Progression (DP) (2 pts, 5.9%). First Response was detected after a median of 2 (1-8) cycles. The median duration of hematologic response was 10.5 months. A grade > 2 non hematologic toxicity was observed in 54.5 % of pts, and an emerging (from grade 0-2 to > 2) hematologic toxicity in 27.3% of pts. In 61.4% of pts LEN dose was reduced because of hematologic or non-hematologic toxicity. 32 pts (72.7%) died , and 17 pts (38.6%) showed progression to AML. Median overall survival (OS) was 15 months. No significant differences between the 2 arms were observed, in terms of ORR, CR rate, toxicity, AML incidence and OS, but there was a trend (although still not significant) towards a longer median duration of response in the sequential arm: ARM 1: 6 months; ARM 2: 18 months (p=0.0847). MDS cells showed alterations of the inositide-dependent signalling as well as an altered microRNA profile. In particular, responder cases showed a frequent downregulation of miR-3613 and mir-4668, that were upregulated in non responder cases. Further analyses are ongoing. Conclusions. Our results confirm the efficacy of both AZA+LEN treatment regimens in higher-risk MDS pts, in terms of ORR, although the sequential schedule seems to induce more durable responses. Moreover, possible relationships with signal transduction pathways and microRNA profile are under evaluation. Disclosures Finelli: Novartis: Other: Speaker fees; Celgene: Other: Speaker fees; Celgene: Research Funding. Gobbi:Janssen: Consultancy, Honoraria; Novartis: Consultancy, Research Funding; Roche: Honoraria; Takeda: Consultancy; Gilead: Honoraria; Celgene: Consultancy; Mundipharma: Consultancy, Research Funding. Cavo:Bristol-Myers Squibb: Consultancy, Honoraria; Millennium: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria.

Background Ponatinib, a potent third generation pan BCR-ABL inhibitor, has recently shown relevant activity against native and mutant forms of BCR-ABL, including the TKI resistant T315I mutant. The aim of this compassionate protocol was to confirm and evaluate the efficacy and the safety of the compound in patients with advanced Ph+ ALL and CML. Design and Methods Ponatinib was obtained through a compassionate use named patient program, approved by ARIAD Pharmaceuticals and by the Bologna Ethical Committee. After informed consent was signed, 17 patients (M/F: 8/9) have been treated with Ponatinib (45 mg orally, once daily) between February 2012 and July 2013, including 14 Ph+ ALL (10 p190, 4 p210) and 3 blast phases of CML (2 Myeloid and 1 Lymphoid, p210). The median age of the patients was 64 years (range 23 -77). The median time from diagnosis was 754 days (range 46-2264). All the patients were resistant or intolerant to previous TKIs (median number of previous TKIs: 2; range 1-3). Standard chemotherapy was previously performed in 7/17 patients (41%). Four patients (23%) had previously received allogeneic stem cell transplantation. At the time of enrolment, median Hb, PLTs and WBC values were 10,9 g/dl (range 8.6-13.9), 139000/mmc (range 14000-325000) and 4300/mmc (range 1700-17000), respectively. In 6 out of 17 patients, additional cytogenetic alterations were revealed. Mutational analysis showed the presence of T315I mutation (9 pts), G250E (1 pt), T315I and Y253H (1 pt), T315I and Y253A (1 pt), V299L (1 pt). No mutations were detected in 4 patients. Results The median treatment duration was 139 days (range 14-540+). Causes of treatment stop were: progression disease (5 patients), savage allogenic stem cell transplantation (6 patients), drug intolerance (1 patient), consisting in grade III headache. With a median follow up of 284 days (range 8-540+), a maHR was obtained in 13/17 patients (76%). After one month of treatment, a reduction of BCR-ABL fusion transcript level was observed in 9/15 patients (60%). For two patients the follow up is too short to be evaluable. The level became undetectable in 4 patients (3 presenting with T315I mutation). After treatment, T315I mutation disappeared in 6 out of the 9 patients who showed this molecular alteration at the beginning of therapy. At the time of this report, 6/17 patients are still on study (35%). Five patients died due to progression disease. As expected, the drug was well tolerated. Non-hematologic adverse events were described in 7/17 patients (grade >III skin rash in 3 patients; grade>II serum lipase increase in 2 patients; grade>II myalgia in 1 patient; grade III headache). Conclusion In our experience, the activity of Ponatinib in advanced Ph+ leukemias, mainly in T315I mutated patients, was confirmed. No treatment-related deaths occurred. The understanding of molecular mechanisms responsible for resistance or lack of response to the drug will be necessary in order to identify patients early on who could take advantage of this treatment. Acknowledgments Work supported by European LeukemiaNet, AIRC, PRIN 2010-2011, University of Bologna and BolognAIL. Disclosures: Soverini: Novartis: Consultancy; Bristol-Myers Squibb: Consultancy; ARIAD: Consultancy. Martinelli:NOVARTIS: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau; PFIZER: Consultancy; ARIAD: Consultancy.

Introduction. Autologous Bone Marrow Transplantation (Auto-BMT) is currently rarely used in the treatment of Acute Myeloid Leukemia (AML). However, it may represent a good therapeutic option in a specific subset of patients, mainly in consolidation of both low risk (LR) and MRD negative AML without an available HLA matched donor. Aims. To review our database of AML patients who received Auto-BMT from 2005 to 2014 and who were referred to Bologna Institution, in order to assess the efficacy of the procedure in terms of Overall Survival (OS) and Disease Free Survival (DFS). Patients and methods: From 2005 to 2014, 98 AML patients underwent Auto-BMT in several Italian Institutions. 89/98 patients are evaluable for survival and outcome data. The 89 patients considered (42 female, 47 male), had a median age of 49 years (range 15-70). Cytogenetics was performed in all patients by conventional karyotype (22 patients were also analyzed by Single Nucleotide Polymorphisms Array); molecular analysis (FLT3 TKD and ITD, and NPM1 mutational analysis) was available for 51/89 patients. Molecular monitoring by specific fusion transcripts (CBF-MYH11 and AML1-ETO) was performed in CBF positive leukemias (inv(16) and t(8;21)) at the time of diagnosis, after induction, consolidation courses, and every 3 months in the first 2 years of follow-up. Based on this data, and according to ELN guidelines, a risk stratification identified 41 patients with a LR AML (t(8:21), inv(16) or NPM1+/FLT3- with normal karyotype), 4 patients with a high risk (HR) AML (complex karyotype or FLT3 ITD mutated or inv(3) or t(6;9)) and 44 patients with a standard risk (SR) AML (normal karyotype, other alterations). Results. All the patients received an induction chemotherapy treatment, as follows: a "3+7-like" course in 48 cases, a Fludarabine-based regimen in 20 patients and a Gemtuzumab-ozogamicin (GO)-based regimen in 21. 83/89 (93.3%) patients received a median of 2 consolidation courses of chemotherapy (range 1-4) before proceeding to Auto-BMT, performed in 1st CR. 6/89 (6.7%) patients received Auto-BMT in first relapse. 41 patients relapsed after auto-BMT and were treated with a re-induction chemotherapy, or were enrolled in clinical trials. 24 patients reached a 2nd complete remission, and 12 patients underwent an allogeneic BMT in 2nd CR. With a median follow up of 6 years, the median Overall Survival (OS) of the entire population was 64.3 months (range 5.8-294.2 months); the 1 year OS and the 5 years OS were, 97.1%, and 67.9%, respectively. The median Disease Free Survival (DFS) of the 83 patients treated with Auto-BMT in 1st CR was 36 months (range 1.3-293 months). The 1-year DFS and the 5-years DFS were 85% and 56.7%, respectively. Transplant related mortality (TRM, death in 100 days after BMT) was 1.2% for auto-BMT and 6.5% for allogeneic BMT. First, to assess the role of the number of consolidation courses we compared patients who received none or 1 consolidation course with patients who received 2 or more cycles, who showed a better OS (p= 0.0061, Figure 1). There was no statistical difference in terms of OS between young and elderly patients (cut off=65 years). Second, we compared patients who achieved a negative minimal residual disease status before auto-BMT (n=37) with patients who did not (n=9). MRD negativity offered a significantly better outcome in terms of 5-years OS (83.4% and 50% respectively); the median OS of MRD neg was not yet reached; the median OS of MRD pos was 27 months (p= 0.0130) (Figure 2). Conclusions: Auto-BMT offers a chance to achieve long-term DFS and OS if used as a consolidation therapy both in patients with LR and SR AML. The major role could be played in MRD negative patients, offering the best chances to achieve a long-term OS. Auto-BMT can be also a good choice as consolidation therapy for elderly patients, in which allo-BMT could induce high morbidity and mortality rates. The small patients cohort and the retrospective analysis don't allow us to define the best induction therapy to be used before auto-BMT. However, based on our findings we suggest a therapy schedule including two or more consolidation courses in patients who obtain a first CR, and to proceed then to auto-BMT. Acknowledgments: work supported by ELN, AIL, AIRC, Progetto Regione-Università 2010-12 (L.Bolondi), Fondazione del Monte di Bologna e Ravenna, FP7 NGS-PTL project. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Soverini: Novartis, Briston-Myers Squibb, ARIAD: Consultancy. Rodeghiero:Celgene Corporation: Honoraria, Research Funding. Cavo:Janssen-Cilag, Celgene, Amgen, BMS: Honoraria. Martinelli:AMGEN: Consultancy; Novartis: Consultancy, Speakers Bureau; Ariad: Consultancy; BMS: Consultancy, Speakers Bureau; ROCHE: Consultancy; Pfizer: Consultancy; MSD: Consultancy.

Abstract 2497 Introduction: The gene TP53 encoding the tumour suppressor protein p53 is among the most commonly mutated genes in human cancer. TP53 tumour-associated alterations often cause dramatic defects in p53 function and correlate with increased malignancy, dismal survival and resistance to treatment. In contrast, only a small fraction, if any, of the >200 single nucleotide polymorphisms (SNPs) of TP53 in human populations are expected to cause measurable perturbation of p53 function. Aim: Since the pattern, frequency and significance of TP53 aberrations and SNPs in adult BCR-ABL1 positive ALL have still to be investigated, in this study we used a massively parallel pyrosequencing technique to address these issues. Patients and methods: Forty-three adults with BCR-ABL1 positive ALL were analyzed (median age 63 years, range 18–84). Twenty-four cases (56%) were analyzed only at the time of diagnosis, four cases (9%) only at the time of relapse and fifteen cases (35%) at both time points. Massively parallel pyrosequencing in picoliter-sized wells was used to allow highly-sensitive deep-sequencing detecting molecular aberrations at a low burden rate. As part of the IRON (Interlaboratory RObustness of Next generation sequencing) II study network, we applied preconfigured plates including primers for TP53 (exons 4 to 11) and allowing the simultaneous screening of 11 patients, each being recognized by a unique molecular identifier. For each plate, after generating 88 amplicons, 8 per each patient, PCR products were purified using Agencourt AMPure XP beads and Biomek 3000 Laboratory Automation Workstation (Beckam Coulter) and quantified using the Quant-iT PicoGreen kit (Invitrogen). All amplicons were pooled in an equimolar ratio to generate one single library. Subsequent emulsion PCR and amplicon sequencing was performed according to the manufacturer's recommendations on the Genome Sequencer Junior Instrument (Roche Applied Science). Data were analyzed using the GS Amplicon Variant Analyzer software version 2.7 (Roche Applied Science). For the detection of variances, filters were set to display sequence variances occurring in more than 5% of bidirectional reads per amplicon in at least one sample. Results: On average, we generated 63,068 sequencing beads (key pass wells) per plate (range, 50,798-79,486) with a median read length range between 284 and 365 base pairs. The median number of generated reads per case was 5,413 (range, 687-9,604). The median number of reads per amplicon was as follows: exon 4: 275 (range, 0–888), exon 5: 222 (range, 0–1,013); exon 6: 316 (range, 84–854); exon 7: 317 (range, 5–720); exon 8: 313 (range, 0–784); exon 9: 215 (range, 0–785); exon 10: 328 (range, 0–826), exon 11: 447 (range, 0–1,511). Forward and reverse reads were homogeneously distributed allowing a sensitive detection of variances. In total, 8 single nucleotide variations were identified. All variances, except for one nucleotide substitution occurring at position 7576743 (GRCh37/hg19), were found to represent SNPs according to the NCBI dbSNP Build 137. They included: rs1042522 C/G (41/43, 95%) and rs1800370 A/G (1/43, 2%) in exon 4, rs1800372 A/G (2/43, 5%) in exon 6, rs1625895 A/G (42/43, 98%) in intron 6–7, rs12947788 A/G (3/43, 7%) and rs12951053 A/C (4/43, 9%) in intron 7–8 and rs1800899 C/T (1/43, 2%) in intron 9–10. Interestingly, in 2 cases (12%) loss of heterozygosity occurred at the relapse at the C wild-type allele of rs1042522 in leukemia cells. The same mechanism has been identified for one case at the wild-type allele of rs1625895 with the expansion of the variant form at relapse. Both rs1042522 and rs1625895 have been described to alter p53 functionality and increase susceptibility to cancers (Whibley et al.,2009). Although the role of rs12947788 and rs12951053 has not yet deeply investigated, in our study they were found in 3 cases that all relapsed. Conclusion: Comprehensive next generation deep-sequencing of TP53 by a screening assay set up within the IRON II study has demonstrated its ability to efficiently detect TP53 variant. The inactivation of the wild-type allelic forms of rs1042522 and rs1625895, altering the p53 functionality, may serve as an important background for leukemia progression in BCR-ABL1-positive ALL. Disclosures: Kohlmann: MLL Munich Leukemia Laboratory: Employment. Luppi:CELGENE CORPORATION: Research Funding. Haferlach:MLL Munich Leukemia Laboratory: Equity Ownership. Baccarani:ARIAD, Novartis, Bristol Myers-Squibb, and Pfizer: Consultancy, Honoraria, Speakers Bureau. Martinelli:NOVARTIS: Consultancy, Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria, Speakers Bureau; PFIZER: Consultancy; ARIAD: Consultancy.

Abstract 4250 Background. Nelarabine (N) is approved for the treatment of T-ALL and T-LBL that have not responded to or has relapsed after treatment with at least 2 chemotherapy regimens. Aim. To evaluate safety profile and efficacy of N as savage therapy in 16 adult relapsed or refractory T-ALL or T-LBL. Methods. After obtaining an informed consent, 16 patients (median age 33 years, range 19–45, M/F= 13/3) affected by T-ALL (n=10) and T-LBL (n=6) received savage therapy with N (median cycle=1, range 1–3), administered at standard adult dosage (1500 mg/sqm on days 1, 3 and 5, every 21). Four patients were primary resistant to induction treatment, 7 patients were relapsed after two previous chemotherapy regimens (including allogeneic BMT in 4 cases and autologous SCT in 1 case); the remaining 6 patients had a molecular relapsed disease (MRD positive). Molecular characterization was performed, including NOTCH and WT-1 genes mutational status. GEP analysis, according to Ferrando A. stratification (Cancer Cell 2002), is still ongoing. Results. Currently, 12 out of 16 patients are evaluable, due to a too short follow up in the other 4 cases. Seven out of 12 patients obtained a complete remission (CR) (5 T-ALL 2 T-LBL);a partial remission (PR) was documented in 2 cases, with an overall response rate (ORR) of 75%. Median duration of CR was 10 weeks (range 2.8–54+). Among these, 2 out of 4 patients in molecular relapse reached a molecular CR and underwent an allogenic BMT (currently in CR after a median follow up of 12 months). Extra- hematological toxicity, not clearly related to the drug, occurred in 3 cases, determining, a complete and irreversible paraplegia, a condition of mental confusion, and a peripheral neuropathy, respectively. Conclusions. N showed a strong efficacy also in cases with low levels of residual disease, in addition to a good safety profile. Neurological toxicity needs to be strictly monitored. Acknowledgments. European LeukemiaNet, AIL, AIRC, Fondazione Del Monte di Bologna e Ravenna, FIRB 2006, PRIN 2008, PRIN 2009, Ateneo RFO grants, Project of integrated program (PIO), Programma di Ricerca Regione – Università 2007 – 2009. Disclosures: Baccarani: Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria. Martinelli:Pfizer: Consultancy; BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria.

Abstract 3580 Introduction: Although treatment with tyrosine kinase inhibitors (TKIs) has revolutionized the management of adult patients with BCR-ABL1 -positive acute lymphoblastic leukemia (ALL) and significantly improved response rates, relapse is still an expected and early event in the majority of them. It is usually attributed to the emergence of resistant clones with mutations in BCR-ABL1 kinase domain or to BCR-ABL1 -independent pathways but many questions remain unresolved about the genetic abnormalities responsible for relapse after TKI and chemotherapy-based regimens. Patients and methods: In an attempt to better understand the genetic mechanisms responsible for this phenomenon, we have analyzed matched diagnosis-relapse samples from 30 adult BCR-ABL1 -positive ALL patients using high resolution Affymetrix single nucleotide polymorphism (SNP) arrays (GeneChip® Human Mapping 250K NspI, n=15 pairs and Genome-Wide Human SNP 6.0, n= 15 pairs). Genetic differences were analyzed in terms of copy number changes and loss of heterozygosity (LOH) events. 20 patients were enrolled in clinical trials of GIMEMA AL Working Party and treated with imatinib alone or in combination with conventional chemotherapy (40%) or dasatinib as frontline therapy (60%). The median age at diagnosis was 54 years (range 23–74) and the median blast cell count was 97% (range 60–99). The median time to relapse was 27 months (range, 9–104). 10 patients were treated according to the GMALL trials, a high-dose chemotherapy based protocol in combination with imatinib. The median age at diagnosis was 65 years (range 19–79) and the median leucocyte count was 37300/μl (range 5000 – 220000/μl). The median time to relapse was 9.8 months (range, 3 – 25). Results: First, we compared diagnosis and relapse samples for the presence of macroscopic (> 1.5 MB) copy number alterations (CNA). Novel acquired macroscopic CNAs were detected in 7/20 (35%) TKI relapse cases and included losses of 3p12-p14, 5q34, 9q34, 10q24 and 12p13-p12 and gains of 1q, 9q34-q33 and 22q and in 4/10 (40%) chemotherapy-relapse cases and included losses of 9p21 and 12q21–22 and gains of all chromosome 8 or part of it in 2 patients. Since no common patterns of acquired alterations were observed, it is likely that relapse may be due to a more generalized genetic instability rather than to specific mechanisms. Moreover, chemotherapy did not select resistant clones with higher number of alterations. 8/20 (40%) TKI resistant cases and 4/10 chemotherapy resistant patients harbored the same CNAs present in the matched diagnosis sample (losses of 9p21 in 7 cases, 7p and 22q11 in single cases and gains of chromosomes 1q, 4, 8q, 17q and 21), indicating a common clonal origin. In contrast, in 5/20 (25%) TKI resistant cases and 4/10 (40%) chemotherapy resistant patients macroscopic CNAs present at diagnosis were lost at relapse (losses of chromosomes 7, 11q, 14q, 15q, 16q and 19p and gains of 5q, 8q, 9q34 and 22q11). Thereafter, we compared diagnosis and relapse samples for microscopic CNAs (< 1.5 MB). The alteration most frequently acquired at relapse was loss of the tumor suppressor CDKN2A (53% vs 33 % of diagnosis). Other common acquired CNAs at relapse included gains of ABC transporter genes, such as ABCC1, ABCC6 (1q41) and BCL8 (15q11); losses affected EBF1 (5q33) and IGLL3 (22q11) genes involved in B-cell development, BTG1 (12q21) involved in cell cycle regulation and CHEK2 (22q12) involved in DNA repair. Interestingly, for all relapse cases analysis of IKZF1 deletions, identified in 80% of patients, demonstrated a clonal relationship between diagnostic and relapse samples, suggesting that this alteration is not acquired with relapse but it is maintained with fidelity from diagnosis working as a marker of disease. The majority (92%) of relapse samples harbored at least some of the CNAs present in the matched diagnosis sample, indicating a common clonal origin. Conclusions: Genomic copy number changes evolving from diagnosis to relapse have been identified demonstrating that a diversity of alterations contributes to relapse and with the most common alterations targeting key regulators of tumor suppression, cell cycle control, and lymphoid/B cell development. Supported by European LeukemiaNet, AIL, AIRC, Fondazione Del Monte di Bologna e Ravenna, FIRB 2006, PRIN 2009, Ateneo RFO grants, PIO program, Programma di Ricerca Regione – Università 2007 – 2009. Disclosures: Soverini: Novartis: Consultancy; ARIAD: Consultancy; Bristol-Myers Squibb: Consultancy. Baccarani:Pfizer Oncology: Consultancy; Novartis: Consultancy; BMS: Consultancy; Ariad: Consultancy; Novartis: Research Funding; Pfizer Oncology: Honoraria; Novartis: Honoraria; BMS: Honoraria; Ariad: Honoraria; Novartis: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Ariad: Membership on an entity's Board of Directors or advisory committees. Ottmann:Novartis Corporation: Consultancy, Honoraria, Research Funding, Speakers Bureau. Martinelli:Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Pfizer: Consultancy.

Abstract 1677 The BCR-ABL1 positive ALL is the most frequent and prognostically most unfavorable subtype of ALL in adults. Treatment strategies based on tyrosine kinase inhibitors of first and second generation have improved overall treatment results, with a rapid and complete remission (CR) rate ranging 90%. Nevertheless most patients experienced hematological relapse in a short time, also after hematopoietic stem cell transplantation. Therefore, the detection of residual leukemic cells by measuring BCR-ABL1 transcript level is absolutely required to monitor minimal residual disease and to detect early relapse. Different assays based on quantitative polymerase chain reaction (qPCR) are available and they vary in respect to the type of instrument used, the primer and probe location, the real-time chemistry and the control gene used. Differences among methods can lead to a variation in the sensitivity and measurement reliability. In order, to investigate the efficacy of a high sensitive method based on nanofluidic platform (Fluidigm Corporation, South San Francisco, CA) to detect and quantify residual and rare BCR-ABL1 copies, we compared the molecular results obtained by conventional qPCR with those obtained by nanofluidic Fluidigm approach. At the time of writing, 60 BCR-ABL1-positive ALL samples (42 positive for the p190 BCR-ABL1 isoform and 18 for the p210) were analyzed. First, we performed a TaqMan absolute quantitative PCR (Applied Biosystems 7900HT Fast Real-Time PCR System); RNA integrity was evaluated using the control gene ABL1. Both BCR-ABL1 or ABL1 copy number copies were derived by the interpolation of cycle threshold (Ct) values to the appropriate standard curve obtained using different plasmid dilutions (Ipsogen), each containing known BCR-ABL1 or ABL1 gene copies. Samples resulted in complete (38.3%) or major (61.7%) molecular response (BCR-ABL1/ABL1 ratio ≤ 0.001 or < 0.1, respectively and according to the International Scale). Subsequently, we quantified again the samples using the 12.765 Digital array (Fluidigm). This is a nanofluidic biochip that consists in twelve panels, each containing 765 individual reaction chambers of 6 nL volume. Samples are portioned prior to qPCR into the single chambers of the panel; as fluorescent signal is produced only in chambers containing copies of the target sequence, digital array provides an absolute quantification by counting the number of positive reactions. Following amplification, digital raw data are processed by the BioMark Digital PCR Analysis software (Fluidigm), that estimates the true number of molecules per chamber using the Poisson probabilistic distribution. First, we assessed the sensitivity and reproducibility of the assay using six serial dilutions of plasmids (Ipsogen) expressing known copy number of BCR-ABL1 p190 transcript (10000; 1000; 100; 50; 10; 1 copies). A 2 μl volume of input leukemia cDNA was loaded and two panels for each dilution were used. Analysis parameters chosen for digital raw data processing were automated set threshold and target Ct range 20–40. Results showed a detection rate until a copy of target sequence (Fig. 1) and a pairing significantly effective between replicates. We then analyzed duplicates of BCR-ABL1 positive ALL samples with a positive control for each chip: digital array resulted positive in 22 major molecular response samples (59.46%; 3.25 median number of copies detected, range 0.5–33.5), and in 1 complete molecular response sample (4.34%). Moreover, the comparison between TaqMan and Fluidigm methods resulted in the detection of the same BCR-ABL1 copies in 53.34% (group I); in 35.0% the quantity detected by Fluidigm was lower than that detected by TaqMan (group II); finally, in 11.66% the Fluidigm approach resulted more sensitive than TaqMan (group III). In conclusion, we demonstrated that the Fluidigm nanofluidic platform provides a high sensitive assay, able to detect until a single copy of BCR-ABL1 transcript, as demonstrated with plasmid serial dilution detection rate and with samples in molecular remission and it could provide an accurate monitoring method for BCR-ABL1-positive ALL CR patients. Supported by: European LeukemiaNet, AIL, AIRC, Fondazione Del Monte di Bologna e Ravenna, FIRB 2006, PRIN 2008, Ateneo RFO grants, Project of integreted program (PIO), Programma di Ricerca Regione – Università 2007 – 2009. Disclosures: Baccarani: NOVARTIS: Honoraria; BRISTOL MYERS SQUIBB: Honoraria. Martinelli:Novartis: Consultancy, Honoraria; BMS: Honoraria; Pfizer: Consultancy.

Abstract 4359 We conducted a phase I-II study aiming to assess efficacy and toxicity of tipifarnib-bortezomib treatment in elderly AML patients. RASGRP1/APTX genetic ratio, which is associated with treatment response in patients treated with tipifarnib alone, was tested. Eighty patients were enrolled with secondary-AML: 14 had high risk cytogenetics; 42 were previously untreated. Seventy-five patients were treated. Nine patients achieved complete remission (CR), 1 patient obtained a partial response (PR) and in 2 cases an hematological improvement (HI) was documented for an overall response rate (ORR) of 19%. Median time to response was 112 days, corresponding to 4 cycles (range 2–14). Marrow response (CR+PR) was significantly associated with overall survival (OS) (p8 (p8 and We conclude that the clinical efficacy of the combination of tipifarnib and bortezomib was evident. We confirmed that the RASGPR1/APTX BM or PB level is an effective predictor of response and survival and our now studying the response of such patients to tipifarnib, alone. Supported by: European LeukemiaNet, AIL, AIRC, Fondazione Del Monte di Bologna e Ravenna, FIRB 2006, PRIN 2008, Ateneo RFO grants, Project of integrated program (PIO), Programma di Ricerca Regione – Università 2007 – 2009. Disclosures: Martinelli: Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Pfizer: Consultancy. Baccarani:Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria.

Abstract 4338 Background. Acute lymphoblastic leukemia (ALL) presents with different outcome in children and adults, with event-free-survival (EFS) rates of 70–80% and 30–40% at 5 years, respectively. This reflects both a different disease biology and different therapeutic approaches. Recently, results apparently improved in young adults/adolescents aged 15–21 years, with de novo ALL, when treated with pediatric intensive regimens rather than with typical adult regimens. Similarly, clinical studies are ongoing in older patients, toxicity related-therapy seeming the limiting issue. Aims. We report a single centre experience on adult ALL patients treated with an intensive pediatric-inspired schedule, designed to assess its tolerability and efficacy. Methods. From November 2007 to June 2010 seventeen ALL patients (M/F=12/5) were treated at our Center according to a modified AIEOP LAL2000 regimen. Treatment consisted of 7 days steroid pre-treatment, and four drugs 78-days induction (phase IA and phase IB) after which high risk (HR) patients were treated with three polychemotherapy blocks, while intermediate (IR) and standard risk (SR) patients went on 8-weeks consolidation and subsequent delayed intensification. Allo-SCT was planned for all patients with HLA-matched donor, as alternative to 2-years maintenance therapy. Median age was 31 years (range, 17–47). According to cytogenetic, response to steroid and minimal residual disease patients were classified into HR (n=7), IR (n=6) and SR (n=4). Results. 15/17 patients completed the induction phase IA, two being out for toxicity (grade IV infection and intestinal occlusion). Twelve (71%) obtained a complete remission (CR); three were refractory. However, one of them subsequently achieved CR after polychemotherapy blocks, for an overall response rate of 76% (13/17). Eleven patients then completed the 28-days induction IB. One patient is ongoing. Median induction duration was 92 days (range 82–136). Delays were mostly due to extra-hematological toxicity, the commonest being gastrointestinal (n=12), infective (n=7) and thrombotic (n=3). Delays were accumulated in both induction phases without significant difference between phase IA (median 18.5 days, range 4–37) and phase IB (median 17 days, range 9–66), despite an absolute number of moderate-severe AE superior in phase-IA versus phase-IB (12 vs 5). After induction, 4/12 patients already received consolidation therapy; 2/4 then received allo-SCT. The median duration of consolidation was 51 days (range 22–94). Conversely, 6/12 patients received polychemotherapy-blocks, one patient went directly on alloSCT and the remaining is ongoing. After polychemotherapy-blocks, five out six patients received allo-SCT. The median CR duration was 13 months (range 1+-42+); two patients relapsed, both after allo-SCT. With a median follow-up of 11 months (range 2–43) 11/17 (65%) patients are alive, 9 in CR (5 undergone allo-SCT). Six patients dead, three in CR for infectious complications, 3 for relapsed/refractory disease. Conclusions. Though in a small series, pediatric-like intensive chemotherapy seemed to be feasible in adult ALL. Extra-hematological toxicity, however, caused significant treatment delays during induction. Finally, the overall outcome appeared promising, though longer follow-up and larger populations are needed to draw definitive conclusions. Acknowledgments. BolognAIL, European LeukemiaNet, AIRC, Fondazione Del Monte di Bologna e Ravenna, FIRB 2006, PRIN 2008, Ateneo RFO, Project of Integrated Program (PIO), Programma di Ricerca Regione – Università 2007–2009. Disclosures: No relevant conflicts of interest to declare.

Abstract 3136 Deletions of the 9p21 chromosomal region are frequent events for the development of a variety of cancers, including solid tumors and hematological malignancies, such as childhood ALL. This region contains the 40-kb region encoding the p16INK4a/CDKN2A (cyclin-dependent kinase inhibitor 2a) tumor suppressor gene and two other related genes, p14/ARF and p15INK4b/CDKN2B, all of which encode critical factors for the regulation of cell cycle and/or apoptosis. In order to explore the frequency and size of deletions affecting the 9p21 locus in adult BCR-ABL1-positive ALL, to determine the main mechanism of inactivation and to investigate the influence on the prognosis, 112 patients were analyzed: 82 (73%) de novo cases, 11 (10%) unpaired relapse cases, 19 (17%) diagnosis-relapse matched samples. The median age was 53 years (range: 18–76) and the median blast percentage was 90% (range, 18–99). Affymetrix single nucleotide polymorphism (SNP) arrays (GeneChip® Human Mapping 250K NspI and Genome-Wide Human SNP 6.0) were used to identify at a high resolution copy number changes on 9p21. PCR amplification and mutation screening of each exon by cloning and subsequent sequencing were also performed. Moreover, gene-expression profiling was performed (Affymetrix Human Exon 1ST Array) to draw a specific signature associated with deletions. At diagnosis, CDKN2A/ARF and CDKN2B genomic alterations were identified in 29% and 24% of patients, respectively. Deletions were monoallelic in the majority of cases (72%) with a median of 1,012 kb in size (range, 2.8–31,319 kb). In some of them, 43%, the minimal overlapping region of the lost area spanned only the CDKN2A/ARF/CDKN2B gene locus, but more often (57%) the loss was considerable larger and extended sometimes over the entire short arm eliminating a large number of genes. In contrast, cases with bi-allelic inactivation were 28% with the majority of deletions (75%) limited to CDKN2A/ARF/CDKN2B genes. FISH analysis was performed using three different BAC clones, but since they overlooked microdeletions we only appreciated a mild fluorescent signal reduction. In order to assess whether 9p21 loss is responsible for progression, the genomic status of this locus was assessed at the time of relapse and an almost significant increase in the detection rate of CDKN2A/ARF loss (47%) compared to diagnosis (p = 0.06) was found. Functionally, deletions led to a strong down-regulation at the transcript level of CDKN2A/ARF (p= 0.0005), as demonstrated by Fluidigm Dynamic Array real-time qPCR assay (Fluidigm Corporation, South San Francisco, CA) which enables to perform TaqMan nano-reactions at high sensitivity. Finally, the mutation screening performed on each exon of ARF, CDKN2A and CDKN2B genes showed that the 9p21 locus is rarely affected by point mutations with only the identification of the missense D146N in the CDKN2A exon 2. Furthermore, 2 mutations were found in the 5′UTR of CDKN2A [UTR A 21965011 (33%), UTR G/A 21965011 (47%), UTR C/T 21964875 (3%)] and a variation, known as SNP was found in the exon 2 (rs3731249). Finally, 2 SNPs were found in the 3′ UTR region of CDKN2A/ARF (rs11515 and rs3088440). The role of the mutations identified in the UTR is not yet defined, but the comparison with the germline material from saliva samples showed that these mutations were inherited. Since the prognostic relevance of CDKN2A/ARF deletions is still controversial in literature, we addressed this issue in our study cohort, finding out that deletions in this locus are significantly associated with poor outcome both in terms of disease free-survival (p=0.003) and cumulative incidence of relapse (p= 0.004). In conclusion, the inactivation of the tumor suppressor genes CDKN2A/ARF is a frequent event in Ph+ ALL. The main mechanism of inactivation is represented by genomic deletions, whereas missense mutations are rare. Deletions are frequently acquired at the leukemia progression and work as a poor prognostic marker, impairing disease free-survival and cumulative incidence of relapse. Novel treatment strategies targeting the ARF-MDM2-p53 pathway may be effective in this subset of patients and in vitro studies are ongoing to confirm this hypothesis. Supported by: European LeukemiaNet, AIL, AIRC, Fondazione Del Monte di Bologna e Ravenna, FIRB 2006, Ateneo RFO grants, Project of integreted program (PIO), Programma di Ricerca Regione – Università 2007 – 2009. Disclosures: Baccarani: Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria. Martinelli:Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Pfizer: Consultancy.

Abstract 4831 Patient with CML harbor the chromosomal translocation t(9;22) which corresponds to fusion of the BCR and ABL genes at the DNA level. Traditionally, CML disease status has been monitored by detecting the t(9;22) translocation by cytogenetics, fluorescence in situ hybridization or southern blot. To date, reverse transcriptase-polymerase chain reaction (RQ-PCR) is considered the most sensitive method available for detecting low copy numbers of the BCR-ABL gene fusion. Current RQ-PCR Taqman assay used to detect the BCR-ABL transcript are relatively time consuming because they require RNA purification and reaction setup steps. The GeneXpert BCR-ABL Monitor Assay (Cepheid, Sunnyvale, Calif) simplifies the testing procedure by using a single use cartridge, which automates the step involved and therefore significantly reduces the technical time required to run the assay. The closed system used in this assay also reduces the chance of contamination. The aim of this study was to compare the two methods of BCR-ABL quantification: the manual TaqMan RQ-PCR and the GeneXpert based assay. We analyzed 100 peripheral blood samples from CML patients with both methods. First of all, we performed a comparison in terms of quality of the ABL control gene. We found that: 87/100 (87%) samples evaluated with the TaqMan standard assay had the control gene transcript value more than 1000 copies; 100/100 (100%) samples evaluated with the GeneXpert had the control gene transcript value more than 1000 copies; Thereafter, we analyzed the concordance of the two methods in the quantification of the target gene BCR-ABL. We considered for this analysis only samples with a good quality of the ABL control gene (> 1000 copies) and we subdivided them in two groups:,: patient who achieved a major molecular response (MMR) and patients who did not achieve a MMR. The MMR wass defined as the achievement of a ratio BCR-ABL/ABLx100 78/87 (90%) patients analyzed with the standard TaqMan assay achieved a MMR; 9/87 (10%) patients did not achieve a MMR if analyzed with the standard TaqMan protocol; 69/87 (79%) patients analyzed with the GeneXpert achieved a MMR; 18/87 (21%) patients didn't achieve a MMR if analyzed with the GeneXpert. In conclusion, our preliminary results showed that GeneXpert assay may be a valid alternative to conventional and traditional TaqMan RQ-PCR methods, allowing a better standardization of the molecular techniques used for the monitoring of minimal residual disease in CML patients. Supported by European LeukemiaNet, AIL, AIRC, FIRB 2006, PRIN 2008, Ateneo RFO grants, Project of integrated program (PIO), Programma di Ricerca Regione – Università 2007 – 2009. Disclosures: Martinelli: Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Pfizer: Consultancy. Rosti: Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria. Baccarani: Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria.

Abstract 1028 Poster Board I-50 Background: Outcome of elderly acute myeloid leukemia (AML) patients is dismal. Targeted-therapies might improve current results by overcoming drug-resistance and reducing toxicity. In particular, the farnesyl-transferase inhibitor Tipifarnib (Zarnestra®), and the proteasome inhibitor Bortezomib (Velcade®), appeared synergistic in AML cells ex vivo, and their association was shown to be safe in vivo in a phase I trial by our group. Aim We conduced a phase II study aiming to assess efficacy and toxicity of Tipifarnib-Bortezomib association in AML patients >18 years, unfit for conventional therapy, or >60 years, in relapse. Furthermore, we aimed to identify biological features potentially predictive of clinical response. In particular, we focused on the RASGRP1/APTX ratio, which was previously found to be effective in predicting treatment response in patients treated with Tipifarnib alone. Methods: Bortezomib (1.0 mg/m2) was administered as weekly infusion for three consecutive weeks (days 1, 8, 15). Tipifarnib was administered at dose of 300-600 mg BID for 21 consecutive days. Response was assessed at the end of each cycle (28 days). Patients' withdrawn was planned in case of progression or stable disease after six cycles. Real-time quantitative-PCR (q-PCR) was used for RASGRP1/APTX quantification. Results: Eighty patients were enrolled (47 male). Median age was 71 years (43-89) and WBC at diagnosis was 4.2 × 109/L (0.5- 42.1). Thirty-two out of 80 patients had a secondary-AML, 14 had a high risk cytogenetic and 42 were previously untreated. Seventy-five patients actually initiated the treatment, 62 completed at least the first cycle while 13 early dropped out for non-leukemia related adverse event. Nine patients achieved complete remission (CR), 1 patients obtained a partial response (PR) and in 2 cases an hematological improvement (HI) was documented for an overall response rate (ORR) of 19%. Eighteen had progressive disease (PD) and the remaining showed stable disease (SD). Median time to response was 112 days, corresponding to 4 cycles (range 2-14). Marrow response (CR+PR) was significantly associated with overall survival (OS) (p8 (p8 and Conclusion: We conclude that the clinical efficacy of the combination Tipifarnib-Bortezomib was similar to what reported for Tipifarnib alone. However, noteworthy, we could confirm that the RASGPR1/APTX BM or PB level is an effective predictor of response. Though higher RASGRP1/APTX is relatively rare (∼10% of cases), Tipifarnib (±Bortezomib) may represent an important option in a subset of high risk/frail AML patients. Acknowledgments: Supported by BolognAIL, AIRC, European LeukemiaNET, COFIN, FIRB 2006, Fondazione del Monte di Bologna e Ravenna. Disclosures: No relevant conflicts of interest to declare.