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We studied the impact of HLA mismatching on the outcome of 318 consecutive patients who received an unmanipulated haploidentical bone marrow transplant, followed by post-transplant cyclophosphamide (PTCy). The number of HLA-mismatched antigens was tested for its impact on overall survival (OS) and nonrelapse mortality (NRM), whereas HLA mismatches in the graft-versus-host (GVH) direction were tested for prediction of graft-versus-host disease (GVHD and relapse. Finally, we studied whether graft rejection correlated with the number of HLA mismatched antigens in host-versus-graft (HVG) direction. Two hundred thirty-one donor–recipient pairs (72%) had 4/8 mismatches at the -A, -B, -C, -DRB1 HLA loci. HLA mismatches did not predict the 2-year OS (hazard ratio, .83; P = .58) and NRM (subhazard ratio, 1.08; P = .93). The cumulative incidence of acute GVHD (P = .13), 1-year chronic GVHD (P = .84), and relapse rate (P = .26) did not correlate with univectorial GVH mismatches. Similarly, no correlation was observed between the amount of HLA mismatch in the HVG direction and graft rejection. In multivariate analysis advanced disease at transplant was the strongest predictor of survival, NRM, relapse, and graft rejection. In conclusion, the degree of HLA mismatching should not be used as a criterion to select family haploidentical donors when using bone marrow as stem cell source and PTCy for GVHD prophylaxis.

Disease relapse remains an unmet medical need for patients with Hodgkin lymphoma (HL) receiving an allogeneic hematopoietic cell transplantation (HCT). With the aim of identifying patients at high risk for post-transplant relapse, we retrospectively reviewed 41 HL patients who had received haploidentical (haplo) nonmyeloablative (NMA) HCT with high dose post-transplant cyclophosphamide (PT-Cy) for graft-versus-host (GVHD) prophylaxis. Primary refractory disease, relapse within 6 months from autologous stem cell transplantation, age, pretransplant chemotherapy, HCT comorbidity index (HCT-CI), sex mismatch, tumor burden and pretransplant fluorodeoxyglucose positron emission tomography (FDG-PET) status, assessed by Deauville score, were analyzed as variables influencing outcomes. All but 1 patient engrafted: median time to neutrophil and platelet recovery was 15 (interquartile range, 13 to 23) days and 19 (interquartile range, 12 to 28) days, respectively. Cumulative incidence of severe (grade III to IV) acute graft-versus-host disease (GVHD) and 3-year moderate-severe chronic GVHD was 2.4% and 11.8%, respectively. The 3-year overall (OS), progression free (PFS), and graft relapse-free survival (GRFS) were 75.6%, 43.9%, and 39%, respectively. On multivariate analysis, 3-year OS was significantly worse in patients with HCT-CI ≥3 (hazard ratio [HR], 5.0; 95% confidence interval [CI], 1.1 to 21.8; P = .03). Three-year relapse rate, 3-year PFS, and 3-year GRFS were significantly worse in patients with HCT-CI ≥3 (HR, 3.5; 95% CI, 1.3 to 9.3; P = .01; HR, 3.3; 95% CI, 1.2 to 9.0; P = .02; and HR, 4.2; 95% CI, 1.7 to 9.9; P = .001, respectively) and in patients with a Deauville score ≥4 on pretransplant FDG-PET (HR, 4.4; 95% CI, 1.6-12.4; P = .005, HR, 3.8; 95% CI, 1.5 to 9.7; P = .005; and 3.2; 95% CI, 1.3 to 7.9; P = .01, respectively). On univariate analysis, 3-year NRM was significantly worse only in patients with a HCT-CI ≥3 (HR, 17.6; 95% CI, 1.4 to 221.0). Among relapsed or refractory HL patients undergoing haplo NMA HCT with PT-Cy, pretransplant FDG-PET with a Deauville score ≥4 and HCT-CI ≥3 identified patients at high risk of relapse. Moreover, an HCT-CI ≥3 was associated with higher NRM and lower OS.

We compared the clinical value of minimal residual disease (MRD) monitoring by cytofluorimetric methods, Wilms tumor gene 1 (WT1) expression and the study of nucleophosmin gene (NPM) mutations in a series of 26 patients with NPM-mutated de novo acute myeloid leukemia (NPM-AML) who achieved complete hematological remission after conventional chemotherapy. The relapse risk was significantly lower only in patients achieving a NPM molecular complete response (NPM mol-CR) and confirmed NPM mol-CR (non-detectable NPM mutations in two consecutive marrow samples). The disease-free survival (DFS) of patients achieving a = 4-log reduction in NPM value after induction therapy was 12.6 % and 50%, respectively, at 36 months (p = 0.009). The attainment of a confirmed NPM-CR had a significant influence on overall survival (OS at 36 months was 64.3% and 11.9% in patients obtaining or not obtaining confirmed NPM-CR, respectively, p < 0.03). We confirm that NPM-molecular relapse (NPM-rel) is always followed by hematological relapse (H-rel), but longitudinal studies of NPM mutations may predict an impending H-rel earlier than flow cytometric- or WT1-based methods.

We report the final results of a prospective trial testing the combination of fludarabine, Ara-C and idarubicin (FLAI) followed by low-dose gemtuzumab ozogamicin (FLAI-GO) in 85 patients aged 60 years or more with CD33+ acute myeloid leukaemia (AML). Median age was 68 years (60-82); karyotype was unfavourable in 21 patients (24 %), intermediate in 63 (74 %) and favourable in 1 (2 %). There were five therapy-related deaths. Of the 80 evaluable patients, 47 achieved complete response (CR) (58 %); CR rates were 65 and 32 % in good-intermediate/poor karyotype patients, respectively. Median length of CR was 7 months (3-76). The cumulative incidence of relapse was 84 % with an actuarial survival of 50.3 % at 1 year and 14.4 % at 2 years. The study control population is an unselected consecutive historic cohort of 104 patients treated with the FLAI regimen, who were matched for age and prognostic factors. CR rates after FLAI-GO and FLAI were comparable. However, patients with de novo AML and intermediate-favourable karyotype receiving GO had a significantly lower risk of relapse at 2 years as compared to patients not receiving GO (n = 77) (40 vs 80 %, p = 0.01) and significantly better disease-free survival (p = 0.018) and overall survival (p = 0.022).

Fifty uniformly treated adult AML patients were analyzed with respect to pre-treatment and post-induction risk factors. Forty-two patients achieving complete hematological remission were assessed for minimal residual disease (MRD) by WT1 gene expression; 34 by flow-cytometry (flow-MRD). Patients who were flow-MRD negative had a better 3-year disease-free (DFS; 79.5% vs. 27.3%; p=.032) compared with patients who were still positive after induction. Interestingly, DFS of flow-MRD positive patients was not related to the amount of flow-detected clone population (≥ or

Introduction Allogeneic hematoopoietic stem cell transplantation (HSCT) is the only today available curative treatment for Myelodysplastic Syndrome (MDS) patients. Wide approach to transplant has been hampered by HLA compatible donors availability, advanced diseases, donor and patients advanced age. In the recent years improvement of haploidentical HSCT has offered to many patients the opportunity to undergo this curative approach. The Genova transplant team included haplo HSCT for MDS in his standard operative procedure since 2011. Therefore this unselected consecutive patients cohort offers the possibility to verify feasibility of haplo HSCT in MDS patients. Patients and Methods. Form August 2011 since March 2016 thirty (30) consecutive patients were transplanted from an haploidentical donor in our center. All of them were lacking an HLA identical family donor and an 8/8 matched unrelated donor. Table 1 reports patients and disease characteristics. All donors were haploidentical family member. Conditioning regimen was myeloablative for 10 patients and reduced intensity for 20 patients as previously reports (Raiola et al Biol Blood Marrow Transplant. 2013; 1:117-22). Patients received a median of 3.1 x10e8 /kg (range 1.1 -6) un-manipulated marrow derived nucleated cells. Graft versus host disease (GvHD) prophylaxis consisted in post transplant cyclophosphamide 50 mg/kg , on day+3 and +5 , cyclosporine (from day 0) , and micophenolate (from day +1). Data are expressed and median with a range unless indicated. Disease free survival and GvHD rate are calculated with the methods of Kaplan and Meier. Results Hematologic recovery was complete in 28 (93%) patients. The median times to neutrophil (>500/μL) and platelet recovery (>20,000/μL) was 18 days (range, 14-24 days) and 25 days (range, 12 - 51 days), respectively. Two patients had autologous recovery and were successfully re-transplanted with the same protocol. The incidence of acute GVHD grade II-IV was 15%. No early death was registered. Two patients died, in complete remission of MDS, at 389 (chronic GVHD + sepsis) and 1123 (interstitial pneumonitis) days after transplant, respectively. Seven patients relapsed at median time from transplant of 188 days (range 139 - 560 days). All relapsed patients subsequently died by disease progression. The incidence of chronic GVHD was 20% (6 patients, severe in 5). At the time of this report of the 21 surviving patients (all in remission by MDS) two are under chronic GvHD treatment. With a median follow up of 20.5 months (range 4 - 54) the 3 years probability disease free survival is 69% (95%, CI 51-87). Discussion Haploidentical transplant, together with conventional donor approach, offers the majority of patients the possibility to undergo HSCT. The data here presented demonstrated feasibility of the procedure in advanced disease patients even by an haploidentical donor. In our knowledge no similar results are achievable by today available or experimental medical therapy. HSCT transplantation, even from haploidentical donor, should be offered to all MDS patients presenting with this indication. Disease relapse is the most important cause of transplant failure. Disclosures Angelucci: Novartis oncology, celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Background. In recent years, the number of Hodgkin Lymphoma (HL) patients submitted to reduced intensity haploidentical allogeneic transplant (RIC haplo SCT) consistently increased. [Sureda et al. Curr Treat Options Oncol 2014] However, with a post alloSCT relapse rate so high as 40-60%, disease control after autoSCT relapse remains a clear unmet medical need. In respect of improving transplant outcome identification of factors influencing outcomes are warranted Methods.We reviewed outcomes obtained in 44 consecutive HL patients who received RIC haplo SCT between September 2009 and June 2015 at our institution. The donor was haploidentical relative in all cases. All patients had received at least 3 conventional chemotherapy lines before RIC haplo SCT; most of them (72%) were refractory to front-line chemotherapy and all but one had received an autologous SCT. All patients received the same reduced intensity conditiong regime, and GvHD prophilaxis with post-transplant cyclophosphamide (Raiola et al. BBMT 2008). The median age was 31years (range 18-60). Deauville five-points scale were used to interpretate the results of pre-transplant positron-emission tomography (PET) studies, with a threshold of 4 or above considered positive. Survival curve and GvHD incidence were calculated with the method of Kaplan and Meier. Cox regression model was performed to identify pre-transplant factors influencing outcomes. Results. All patients engrafted but 1 who showed autologous recovery. The median day for 500 neutrophils was 15 days (13-23). Three patients died in remission at 8 (cGvHD), 16 (myocarditis) and 51(pneumonia) months from SCT, respectively. Three years non relapse mortality = 8%. Risk of grade II-IV acute GvHD and 3-year chronic GvHD were 22 and 21%, respectively. With a median follow-up for surviving patients of 38 months (range 13-83), 21 relapsed (47%). All relapsed patients were treated with further therapy, mainly immuno-chemotherapy and donor lymphocyte infusion (DLI). The 3-year overall (OS) and progression free survival (PFS) were 77% and 39%, respectively. Pre-transplant PET status was the only factor influencing outcomes of the procedure (OR 5.4; 95% CI 1.7 - 16.6). In the 41 patients with available pre-transplant PET status, 19 were positive and 22 negative. Outcomes accordingly to pre-transplant PET status are shown in the following table. Conclusions.Pre-transplant PET status is a factor influencing outcomes of relapsed/refractory HL submitted to RIC haplo SCT. Grade II-IV aGvHD was markedly reduced in patients with metabolic remission at time of transplantation. Table Table. Disclosures Angelucci: Novartis oncology, celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Chronic myeloid leukemia (CML) is a hematological disease accounting for about 15-20% of all adult leukemias. The clinical and biologic advances achieved in such a malignancy, represent one of the best successes obtained by translational medicine. Indeed, identification of the fusion oncogene BCR-ABL has allowed using of small molecule inhibitors of its tyrosine kinase activity which, in turn, have literally revolutionized the treatment of CML. Importantly the successfully clinical management was also realized on appropriate diagnosis, disease monitoring as well as early identification of such mutations causing drug resistance. Notably the recent availability of refined laboratory equipments represented by the Next Generation Sequencing (NGS) and genomic analyses has further contributed to gain ground towards the cure of this tumor. These issues are discussed here together with an overview on how patients treated with tyrosine kinase inhibitors should be monitored.

Treatment of Hodgkin’s lymphoma (HL) is perceived to be relatively straightforward. Consequently, patients are not usually referred to hemato-oncologically specialized centres and are treated locally instead. Comprehensive findings beyond prospective controlled trials are therefore lacking. Clinical data of 209 patients who had received a HL diagnosis were collected. A total of 7 patients received radiotherapy (RT) alone (3%), 75 (35%) were treated with a combination of chemotherapy (CT) and RT and 127 patients received CT alone [mainly doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD)]. Complete response (CR) following first-line treatment was achieved in 178 patients (85%) and in 195 (93%) after salvage treatment. Favorable disease (p=0.000359), limited-stage disease (p=0.0003), involvement of lymph nodes above the diaphragm (p=0.05) and absence of mediastinal bulky tumor involvement positively affected the CR rate following first-line treatment. Out of the 195 patients that achieved CR, 31 relapsed. Male gender (p=0.043) and age over 45 years (p=0.047) were significantly associated with an increased incidence of relapse. Age at diagnosis was the key factor affecting long-term outcome. The event-free survival (EFS) projected at 120 months was 80 and 57% for patients younger and older than 45 years, respectively (p=0.022). The overall survival (OS) projected at 120 months was 92 and 38% for patients younger and older than 45 years, respectively (p=0.00561). A second neoplasia was diagnosed in 8 patients. The development of a tumor in 4 cases (breast, lung and thyroid cancer) was likely RT-related. Only 1 patient not receiving RT developed acute myeloid leukemia. The EFS and OS of the 141 early-stage patients treated with CT + RT (n=62) or with CT alone (n=79) were not statistically different.

Background Natural Killer (NK) cells have been widely studied due to their non-major histocompatibility complex (MHC)-restricted cytotoxicity towards transformed or virally infected target cells. In the setting of hematopoietic stem cell transplantation (HSCT), donor NK cells may be "alloreactive" as their killer immunoglobuline-like receptors (KIRs) do not recognize their ligands on recipient human leukocyte antigen (HLA) class I molecules (i.e. KIR-ligands), leading to NK activation. NK alloreactivity can often occur in haploidentical HSCT (Haplo-HSCT), by means of KIR/KIR-L mismatch in graft versus host (GvH) direction, contributing to graft-versus leukemia (GvL) effect, clearing residual leukemic blasts. In the last decade, several studies have shown that NK cells alloreactivity plays a role in T-depleted Haplo-HSCT leading to higher disease free survival rates for patients transplanted from NK-alloreactive donors; recent studies have also shown that donors having KIR B haplotypes (characterized by the presence of more activating KIR) or expressing KIR2DS1 correlated with a better clinical outcome of transplantation. Thus, these NK cell features might be positively considered in the donor selection strategy. Materials and Methods: We analyzed NK-alloreactivity in the setting of unmanipulated Haplo-HSCT with post-transplant cyclophosphamide for patients affected by acute myeloid leukemia or myelodisplastic syndromes. 101 consecutive patients transplanted from September, 2010 to October, 2014 were enrolled, with the big majority of donors and patients studied for HLA-genotype and KIR. Results: Disease status at HSCT was the most relevant factor affecting outcome (p =2) or who had KIR2DS1 was not associated with better outcome (p 0.67 and p 0.89, respectively). We observed an high expression of CD56 and inhibitory receptors such as NKG2A on surface of NK cells in post-HSCT samples, suggesting that NK-cell function could be inhibited in unmanipulated haploidentical setting. Conclusions NK alloreactivity seems not to play a role in preventing leukemia relapse in unmanipulated haploidentical transplantation with post-transplantation. The different immunosuppressive approach of this Haplo-HSCT setting compared to T-depleted Haplo-HSCT, with concomitant use of cyclosporine from early transplant days, which has been shown to interact and possibly inhibit NK cells in vivo, and post transplant cyclophosphamide effects, selectively killing activated T-cell and inducing long-term tolerance, could affect NK efficacy. Further studies are needed to better understand the complexity of this intriguing issue, leading to a more complete definition of NK cell functions in this Haplo-HSCT setting. Disclosures No relevant conflicts of interest to declare.

Background and aims Myelodisplastic syndromes (MDS) are a group of hemopoietic disorder characterized by an impaired blood cell production, morphologic dysplasia and peripheral cytopenias; they are the most common hematologic neoplastic disorder and its diagnosis relays on morphologic evaluation, associated to a karyotypic assay. In order to predict the outcome of patients affected from these disorders, knowing that the order of survival can be extremely variable, several prognostic index were developed such as International Prognostic Score Sistem (IPSS) or the most usefull WHO-Prognostic Score Sistem (WPSS). On the contrary of acute leukemia, these disorders have not a biomolecular profile evalutation of intrinsic markers able to stratify patients in different prognostic risk groups. The aim of our study is to assess the risk of leukemic evolution, in MDS patients, on the basis of the levels expression of WT1 and BAALC at disease diagnosis, and to evaluate the leukemia free survival (LFS) at 6-12-24-36 months of follow up, among the different risk category according to IPSS and irrespectively of treatment. Materials and method In five years we analized 102 patients with a diagnosis of MDS divided according to the WHO classification such as follows: 38 AR, 1 AR with del(q5), 21 aREB-1, 23 AREB-2, 3 chronic myelomonocitic leukemia, 1 RARS, 1 MDS, 11 RCMD, 1 5q- syndrome, 2 suspected MDS. According to IPSS 58 belonged to the low risk category, 21 to the intermediate-1, 23 to the intermediate-2/high risk. Cytogenetic assay showed 20 people with an abnormal karyotype, 8 of them fallen into the high risk class and 12 into the intemediate risk. Low risk and intermediate-1 patients were treated only with supportive care; high risk patients were treated with hypomethylating agents. Iron chelation were used when necessary. Lenalidomide was used in the only case of 5 q- syndrome Samples of bone marrow were analized with Real-Time quantitave PCR and levels of WT1 and BAALC expression were determinated. Molecular datas were analized with X-square Test and a significant association was recorded between overexpression of the genes evaluated (WT1 higher than 100 copy numbers and BAALC higher than 1000 copy numbers) and the probability of develop acute myeloid leukemia ( AML ). Results Nine out of 102 patients showed an isolated WT1 hyperexpression (3 of them developed an AML ), in 15 cases we reported an isolated BAALC overexpression (3 of them developed an AML ), while 13 out 18 patients ( 72% ) with combined WT1 and BAALC overexpression developed AML within an average time of 6 months; instead only 5% of patients, which expressed low levels of WT1 and BAALC, developed AML within the interval of observation. In particulary a combined high expression of WT1 and BAALC were strongly associated with an high risk to develop leukemia and a short LFS, especially in INT-1 subset. After that we calculated the LFS, divided for the risk category at 6-12-24-36 months of follow up. Patients with combined overexpression of WT1 and BAALC showed a LFS of 40% at 6 months of follow up and 0% at 24 months. Conclusion MDS have a great variable survival, and the current approach to these diseases relays on morphological evaluation, karyotypic assay and need of transfusional support; gene expression could be a promising system to predict the prognosis in these patients. Analysis of gene expression, which belong to AML evaluation, allows to divide patients in several risk groups; furthermore is not the single gene evaluation that is more predictable but a combined assay. With this method, which seems to be more realiable than IPSS, we could find that a great percentage of patients with levels of WT1>100 and BAALC >1000, indipendently from karyotypic status and treatment, developed AML and have a shorter LFS than the population with WT1 Disclosures: No relevant conflicts of interest to declare.

Abstract 2535 Background and aims. Detection of minimal residual disease (MRD) has a relevant prognostic value in Acute Myeloid Leukemia (AML). MRD, when used as early treatment response assessment, allows identification of true low-risk and high-risk patients, who may profit alternative chemotherapy approach. In the present retrospective study, we evaluated the impact of MRD assessed by 4-color flow cytometry and WT1 RQ-PCR gene expression in a cohort of AML patients treated at our institution. Methods. Bone marrow samples of 50 adult AML patients (45 de novo and 5 secondary) with available karyotype (K), FLT3-ITD and NPM-A genes mutational status were assessed for MRD after induction. All included patients had a baseline WT1 expression greater than 1000 copies/Ablx104 (range 1060–346060; lab references for normal values 0–500). Fludarabine-based regimen was used as induction; one course of intermediate dose Ara-C 2g/sqm plus idarubicin, followed by 3 courses of intermediate dose Ara-C (2g/sqm) as further consolidation therapy. WT1 log reduction (DWT1) was used to assess the WT1 clearance (DWT1 = logWT1diagnosis – logWT1 post induction). A positive flow MRD was defined by the presence of no less than 25 clustered leukemic cells/105 total events - threshold of 2.5 × 10−4 residual leukemic cells. In patients submitted to bone marrow transplantation (BMT) only the first consolidation course was administered and disease free survival (DFS) was censored at the date of BMT. Results. Two (4%) patients had favorable, 40 (80%) intermediate, and 5 (10%) poor risk K (3 had no metaphases); 14 (28/%) carried FLT3-ITD mutation: among them 8 carried NPM-A mutation too, while 6 were wild type. After the first induction regimen 42 of 50 (84%) patients achieved a complete remission (CR). Patients with a negative flow MRD (32%) had 3 years DFS of 69.5%, whereas those with a positive flow MRD (68%) had a DFS of 27.3% (p = 0.032). Patients with a DWT1 > 1.5 log (65%) had a 3-years DFS of 58.3%, whereas those with a DWT1 ≤ 1.5 log (35%) had a DFS at 1 and 2-years of 13,5% and 0%, respectively (p < 0.001). All patients with a negative flow MRD had also a DWT1 > 1.5 log, whereas 12 (52%) of those who achieved a DWT1 > 1.5 log were still positive by flow MRD. Fourteen (28%) patients with a high risk (HR) profile at diagnosis (poor risk K, intermediate K with FLT3-ITDpos/NPM-Aneg, AML secondary to therapy or previous haematological disorder), 6 were no responder to induction, whereas no one of 8 patients in CR reached a negative MRD status in both test with a very poor outcome (projected DFS 4.8 months). MRD assessment using both flow and DWT1 allow to discriminate no-HR profile patients in three prognostic group: good (flow MRD neg) intermediate (flow MRD pos and DWT1 > 1.5 log) and adverse prognosis (flow MRD pos and DWT1 ≤ 1.5 log) with a projected DFS of 70.5 months, 38.2 months and 4.2 months, respectively (p < 0.001). Conclusions. DWT1 identified patients who would relapse better than flow, whereas a negative flow MRD was the best predictor of long DFS. Using both test in combination with baseline biologic parameters enabled the definition of discrete prognostic categories (Fig 1). Outcome of patients with DWT1 ≤ 1.5 log was very poor and comparable with that of patients with HR profile at diagnosis. In these patients forecast a cure is very difficult with the current treatment option and clinical trials with new drugs should be used already in up-front setting. Disclosures: No relevant conflicts of interest to declare.

Abstract 4675 The prognostic value of WT1 expression at diagnosis is still controversial. It has been retrospectively evaluated in 99 consecutive non pretreated non M3 AML patients who had undergone a complete prognostic work up at diagnosis and had received intensive chemotherapy. Biological markers were evaluated on fresh marrow samples collected at diagnosis. WT1 expression was evaluated using TaqMan Gene Expression Assays as described. All patients received induction therapy with combination of fludarabine, Ara-C and anthracycline ± low dose gemtuzumab ozogamicin (n. 59) or with a conventional combination of Ara-C and anthracycline (n. 40) A conventional post-induction chemotherapy including intermediate dosage Ara-C was administered to all responding patients. Univariate comparisons between patients in CR vs non CR were performed using chi-square analysis or Fisher's exact test for categorical variables and t-test for continuous variables. P values < 0.05 were considered statistically significant. Analyses were performed using SPSS. The prognostic impact of WT1 expression was evaluated using quartiles as cut off point and selecting the one with the lowest p value. The event free survival and OS were calculated using the Kaplan Meier method. Non CR after the first induction course, relapse and death due to any cause were considered events. OS and EFS duration were calculated from start of treatment. The impact of multiple predictor variables was assessed by multivariate analyses according to the Cox regression model for OS and EFS while for the evaluation of RC was used the Logistic regression model. Median age of patients was 59 years (range 17-81). Cytogenetic alterations were prognostically favorable in 3 patients and belonged to the intermediate prognostic group in 77 patients (normal karyotype in 75 patients and +8 in two). Nineteen patients had a poor prognosis cytogenetics. For statistical analyses we considered two karyotipic groups: unfavorable (19 patients) and not unfavorable (80 patients). CRs were 60/99 (60%), of which 40 in 51 patients aged 60 or less (78%) and 20 in 48 older than 60 years (41%). Twenty-six patients relapsed, 54 are alive, 45 have died, with a median follow up of 360 days (range 20-2300). In Table 1 are reported clinical indicators of outcome being patients grouped according to the percentile of WT1 expression with the lowest p value (75th). Statystical analysis showed that all WT1 quartiles were balanced for other prognostic factors, such as cytogenetics, BAALC expression, FLT3 and NPMA and B mutations, age, blast count and therapy. The lack of consense on the role of WT1 level at diagnosis in the prognostic stratification indicate that further clinical studies are required. The clear correlation between the level of WT1 transcript and the tumor burden explains why WT1 is used in the follow up of leukemic patients as universal marker of residual disease, also in patients with specific chimeric products. On the contrary, the biological explanation of the prognostic impact of WT1 transcript level at diagnosis remains uncertain. Over the years WT1 gene has been considered as an oncogene or a tumor suppressor gene. In our experience the protective influence of high WT1 expression cannot be explained with an association with good prognosis biological features (such as mut NPM and / or low BAALC). The positive prognostic value of high WT1 expression might be implicated either with WT1 antioncogenic function, or with the stimulating effect of WT1 oncogene on leukemic cellular cycle, possibly associated with an enhanced response to chemotherapy.Table 1WT1 2400 N./N.pts (%)p univ,p multiv.*RR (95% CI)CR (all karyotypes)41/ 75 (54)19/24 (82)0,0260.063.364 (0.927-12.202)CR (int/good karyot.)36/59 (61)19/210.010,0276.649 (1.240-35.645)CR (denovo AML int kar)31/45 (69)14/15 (98)0.020,03412.557 (1.218-129.446)CR (denovo, N.K.)26/40 (65)15/16 (94)0.0250.0413.430 (1.111-162.318)EFS at 24 months (all karyotypes)8%6%0.0020.050.486 (0.235-1.007)EFS at 24 months (int / good karyot.)9%64%0.0010.0230.360 (0.150-0.866)EFS at 24 months (de novo, N.K.)5%70%0.0010.0070.227 (0.077-0.671)OS (all karyot)15%55%0,110,660.837 (0.371-1.890)OS (int/good kar.)18%63%0,050,180.507 (0.186-1.381)Table 1 legend: * for multivariate analysis age, karyotype, FLT3, NPM mutation, BAALC expression, denovo/secondary disease were considered. Disclosures: No relevant conflicts of interest to declare.

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