ALBERT

Beschreibung: BACKROUND: Hodgkin Lymphoma (HL) is characterized by a high degree of response to chemotherapy and an overall favorable outcome in responding patients. Despite the efficacy of first line therapy, however, about 30% of patients affected by HL eventually relapse or are refractory (R/R) to first or second line therapy followed by autologous hemopoietic stem cell transplantation (ASCT). Recently, the clinical application of immune checkpoint inhibitors (CI), in particular the PD-1 targeting antibody Nivolumab, has dramatically improved the prognosis of patients affected by advanced phase solid tumours. In HL, Nivolumab has shown good activity in the difficult setting of patients relapsing after ASCT; however, complete response (CR) rate was less than 20%. Many studies in the solid tumours field have shown that the efficacy of CI is strictly related to the host degree of immune competence, which is greatly impaired in heavily pre-treated HL patients who received ASCT. Therefore, there is a strong rationale in enhancing the activity of the CI with the co-infusion of autologous lymphocytes (ALI), that have been collected in the early phase of therapy, and that are functionally activated. AIMS OF THE STUDY: Primary endpoint of this prospective trial was the evaluation of the efficacy of ALI in combination with pre-emptive CI administration early post ASCT in patients affected by R/R HL. Secondary pre-clinical endpoint was the study of the peripheral blood lymphocyte subpopulation, pre and post adoptive immune cell therapy and CI administration. METHODS: HL patients under the age of 60 with active R/R disease who have already failed at least two chemotherapy lines and Brentuximab (BV) were eligible for the trial. All enrolled patient underwent early lymphocyte apheresis, with a target cell dose of 5x107 CD3+/kg. All patients then received ASCT with FEAM conditioning. After ASCT, the first ALI was delivered 7 days after engraftment. ALI dosing was incremental, one logarithm at each step, starting from 1x104/kg in the first infusion to a maximum of 1x107/kg in the fourth and last infusion. Each ALI was followed after 48 hours by the administration of Nivolumab 240 mg flat dose. The second ALI dose was administered at 14 days after the first one. The third and the fourth were given every 21 days. Lymphocyte subpopulations were extensively studied on peripheral blood samples before and after each ALI and each Nivolumab administration, by 8-colours flow cytometry. Clinical response was evaluated 21 days after completion of the fourth ALI + Nivolumab. RESULTS: Six R/R HD patient have completed treatment so far and one is currently being treated. All patients failed to achieve CR with chemotherapy and then progressed during BV therapy. PET scan before ASCT showed progressing disease in all patients, with multiple-extra nodal involvement in 5 of them. All patients achieved complete hematological engraftment after a median of 10 days (8-12) from ASCT. Overall, infusion of ALI resulted in significantly higher lymphocyte counts at day 90, as compared to HL patients receiving the same conditioning without ALI (p

Beschreibung: Abstract 2500 Wilms' tumor gene 1 (WT1) is a tumor suppressor gene coding for a zinc finger transcriptional factor which was found overexpressed in acute myeloid leukemias (AML). In AML WT1 functions as an oncogene rather than a tumor suppressor. This may depend on the unbalanced expression of its different isoforms derived from alternative splicing in exon 5 (EX5+/−) or the presence of KTS in exon 9 ( KTS+/KTS-). In normal hematopoietic cells the physiological ratio between KTS+/KTS- isoforms is 1:1. KTS are inserted between the third and fourth zinc fingers thus influencing the DNA binding and therefore the transcriptional activity. The aim of the study was to investigate the possibility of an unbalanced ratio between the isoforms thus leading to the disruption of WT1 function. In addition we correlated KTS+ isoform with clinical and biological features. Methods: we analyzed KTS+/KTS- isoforms in 120 AML patients ( 102 BM samples, 18 PB), 63 chronic phase CML patients (48 BM and 15 PB). In addition we evaluated 5 samples of selected blast cells from AML patients. In a subset of 38 adult acute myeloid leukemia (AML) patients we measured all WT1 isoforms (A[EX5 -/KTS -], B[+/−], C[-/+] and D[+/+]. Quantitative PCR was used for the WT1 isoforms detection and measurement. Results: KTS+ isoform is significantly overexpressed with a ratio KTS+/KTS− 2:1 in both AML and CML patients and it is confirmed in blast cell samples. In the subgroup of patients analyzed for the expression pattern of all WT1 isoforms we detected a significant overexpression of isoform D (EX5+/KTS+) (median value 821) while the isoform A (EX5−/KTS−) is the less represented ( median value 303). In this subgroup the expression of KTS+ isoforms (B+D) is higher than KTS- ( A+C) with a median value of 642 compared to 421. The ratio of WT1 isoforms was not significantly different among FAB subgroups or according to cytogenetic risk, FLT3 (fms-like tyrosine kinase receptor-3) internal tandem duplication or exon 17 mutation, NPM (nucleophosmin) gene mutations and BAALC (brain and acute leukemia, cytoplasmic) gene expression. Conclusion: Although WT1 is overexpressed in AML and CML patients it lacks its typical tumor suppressor function. In this study we have demonstrated the overexpression of WT1 KTS+ isoforms. In addition we have previously demonstrated that KTS+ isoform does not have transcriptional activity since it is mainly localized within the cytoplasm. In conclusion, WT1 is overexpressed in AML but the unbalanced ratio between the isoforms may probably influence the transcriptional activity. Any possible correlation between the unbalanced ratio of WT1 isoforms and clinical outcome requires further prospective studies to be established. Disclosures: No relevant conflicts of interest to declare.

Beschreibung: 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.

Beschreibung: BACKROUND Hodgkin lymphoma (HL) is a lymphoid malignancy of B-cell origin with a high long-term survival. Despite the efficacy of frontline therapy, about 30% of patient will show relapse or refractory disease (R/R). In this patient population, the treatment of choice consists of salvage chemotherapy followed by intensive conditioning regimen and autologous stem cell transplantation (ASCT). However 30-50% of patients receiving salvage chemotherapy fail to achieve at least PR and further therapy with Brentuximab-Vedotin (BV) may be administered to induce a clinical response. Nonetheless, therapeutic options for truly refractory patients are still limited. Recently, immune-check point inhibitors have shown promising results in HL patients relapsed after ASCT. Anti-PD1 Nivolumab is currently approved with this indication. Unfortunately,expected CR rate is only about 20%.Thus, we reasoned that earlier administration of Nivolumab, as post-ASCT consolidation, might improve its efficacy. However, several reports have highlighted the importance of patient immune-competence, which is severely impaired in heavily pre-treated lymphoma patients undergoing ASCT, to achieve durable response with anti-PD1 immunotherapy. AIMS OF THE STUDY Here we report the preliminary results of a prospective trial investigating the feasibility, and the efficacy, in terms of both immunological recovery andclinical response,ofthe reinfusion of autologous lymphocytes (ALI), early after ASCT, concomitant with anti-PD1 consolidation immunotherapy in very high-risk HD patients. METHODS Patients under the age of 60 with high risk HD identified by PET2 or PET6 positivity following ABVD were scheduled for a pre-emptive lymphocyte apheresis with a target of 5x107 CD3+/kg. Patients who failed to achieve at least PR with salvage chemotherapy proceeded to ASCT with FEAM conditioning followed by early Nivolumab and ALI.The first ALI was performed 7 days after engraftment; the second ALI was administered at day +14 after the first dose whereas the third and the fourth doses were given every 21 days. ALI dosing was incremental, one logarithm at each infusion, starting from 1x104CD3+ cells/kg in the first infusion to a maximum of 1x107/kg in the fourth and last infusion. Each ALI was followed within 48 hours by the administration of Nivolumab 240 mg flat dose. Toxicity was evaluated and graduated according to CTCAE-EORTC standards. Circulating lymphocyte subpopulationswere extensively studied before and after each ALI and each Nivolumab administration by 12-colours flow cytometry. Clinical response was evaluated 21 days after completion of the fourth ALI + Nivolumab. PRELIMINARY RESULTS Four R/R HD patients have completed the treatment and3are currently under treatment. All patientshad failed to achieve CR with first and second line chemotherapy. PET scan before ASCT showed progressing disease in all patients despite BV therapy, with multiple-extra nodal involvement in 3 of them. Study patients underwent ASCT with FEAM conditioning and achieved complete engraftment after a median of 10 days (8-12). ALI induced faster T-cell recovery (p

Beschreibung: Background: Therapy-related acute myeloid leukemia (t-AML) or AML evolving from a myelodisplastic syndrome are characterized by a low response rate to conventional chemotherapy and high relapse rate with poor overall survival (OS) despite intensive treatment and allogeneic stem cell transplantation consolidation (HSCT). CPX-351 is a dual-drug liposomal encapsulation of cytarabine and daunorubicin, in a fixed synergistic 1:5 molar ratio. CPX-351 has been approved by FDA for the treatment of patients affected by t-AML or AML with myelodisplasia-related changes (MRC-AML) based on the results of a randomized phase III trial where the drug was compared with conventional 3+7 induction (Lancet et al, JCO 2018). Notably, CPX-351 proved to increase survival probabilities in comparison with standard chemotherapy even among patient achieving complete remission (CR) and proceeding to HSCT, suggesting that CPX-351 may allow deeper responses. However, few information is available on minimal residual disease (MRD) assessment after CPX-351 treatment, or on the impact of molecular alterations on response probability. Aims: The aim of this study was to evaluate the clinical activity of CPX-351 in a real life setting, with particular focus on molecular characterization at diagnosis and MRD evaluation in responding patients. Methods: Seventy five patients were enrolled in a compassionate use program (CUP) in 37 Italian Hematology Centers. CUP started on December 2018 and closed on June 2019. Data collection began on July 2019 and was completed, at the time of writing, for 25/75 patients, enrolled in 9 Centers. Median age was 69 years (56-73), 10 patients were female. Molecular and MRD analysis were performed in each Center as per internal standard. MRD was assessed in most Centers with multicolor flow cytometry. NPM1 mutation was found in 2/22 assessed patients, FLT3-ITD in 3/22, with low allelic burden in 2/3 patients. TP53 mutations have been found in 4/12 patients.Four patients had complex Karyotype, one had isolated del(7q) whereas the remaining 19 had normal karyotype. Six patients had t-AML; 15 patients were previously diagnosed with MDS and 5 of them had already received hypomethilating agents for a median of 5 cycles (2-49). European Leukemia net risk score was low in 2 (8%), intermediate in 12 (48%) and high in 11 (44%) patients. Most patients (20/25) had relevant comorbidities upon enrollment, mostly COPD, diabetes and/or hypertension. As per CUP inclusion criteria, all patients had normal left ventricular function at the time of enrollment (defined by a normal ejection fraction). Results: Induction-related mortality was 2/25 (8%). Fourteen patients experienced grade 〉1 extra hematological adverse event during induction (mainly infections). Alopecia was observed in 4/25 patients (16%).Response was assessed in 20 patients:2 patients died during induction and 3 patients were not yet evaluated for response at the time of analysis. CR or CRi was observed in 19/22 (86.3%). MRD was performed in 11 patients, with 4 of them achieving flow MRD negativity after first cycle (defined as

Beschreibung: BACKGROUND AND AIMS Allogeneic bone marrow transplantation (BMT) offers the greatest chance of cure for high-risk acute myeloid leukemia (AML) patients. Persistence of disease or high levels of pre BMT minimal residual disease (MRD) have been reported to predict relapse risk after BMT. Multicolor flow cytometry (MFC) is the most common tool to evaluate MRD, whereas WT1 gene expression is the most widely applicable and standardized molecular MRD marker in AML. The aim of this study was to analyze the role of pre-BMT combined MFC-molecular MRD assessment as predictor for the post-transplant relapse risk. MATERIALS AND METHODS We retrospectively analyzed the outcome of 224 consecutive AML patients receiving allo-BMT in 1st or 2nd CR. Pre-BMT marrow samples were analysed for WT1 expression and MFC as MRD evaluation. Median age at transplant was 44 years. Disease phase was CR1 in 161 (72%) and CR2 in 63 patients (28%). BMT conditioning wasmyeloablative in 163 (73%), whereas 61 patients (27%) received reduced intensity conditioning. Stem cell source was HLA-identical sibling in 79 (35%),haploidentical in 59 (27%) and alternative donor in 86 (38%).Median follow-up was 64 months (95% CI 50.3 - 77.3 months). Cumulative Incidence of Relapse (CI of relapse) at various time-points was calculated in competing risk analysis by takingin account non relapse mortality as competing event. Overall Survival (OS) was calculated from the time of BMT until death by any cause or last follow-up. A positive MFC MRD was defined by the presence of no less than 25 clustered leukemic cells/105 total events (threshold of 2.5x10-4 residual leukemic cells) at four-color flow-cytometry. WT1 copy number/Abl copy number 500x104 was used as cut-off value for abnormal WT1 expression. RESULTS Relapse occurred in 62 patients (27.7%). Three-year estimate of CI of relapse was 25.9% (median not reached). The CI of relapse was significantly affected by occurrence of acute GVHD (lower for grade ≥2, p

Beschreibung: Background The use of 5-azacytidine (AZA) as front line therapy in elderly, frail patients with acute myeloid leukaemia (AML) has entered in clinical practice. Our retrospective therapeutic experience with AZA in 52 AML patients is presented and compared with intensive chemotherapy (FLAI-GO). Materials and methods We retrospectively analysed the outcome of 52 elderly AML patients treated with AZA as front line therapy from June 2010 to June 2016. We compared the outcome with that of a cohort of a 55 partially matched AML patients who had received FLAI-GO from September 2004 to January 2010. The two populations were comparable for sex, karyotype, FLT3 mutational status, LDH levels, WT1 and BAALC expression levels. The two cohorts significantly differed for median age (76.5 and 71 years for AZA and FLAI go, respectively), percentage of patients older than 70 years (77% vs 58%), secondary disease (75% vs 31%), mean leukocytes count (8850/mmc vs 2800/mmc ). Relevant comorbidities were present in both arms. AZA was administrated monthly (75 mg/mq5+2 schedule) until disease progression or toxicity (mean 7 courses range 1-27). FLAI-GO consisted inFludarabine30 mg/mq,Cytarabine1000 mg/mq,Idarubicin5 mg/mq(day 1-2-3) andGemtuzumabozogamicin(3 mg /mq) on day 4. Those achieving CR after induction received an identical consolidation cycle, those not in CR were treated with salvage therapy (MEC, MEA, MINI ICE or low dose chemotherapy). Results Early death rate was comparable between the two arms (5/52 for AZA 3/55 for FLAI-GO). CR rate was lower in patients treated with AZA (12,8 %) compared with those receiving FLAI-GO (52%). No factors influenced theprobability of achieving CR in AZA arm (sex, disease onset, karyotype, WBC count, age, blasts, LDH, WT1 and BAALC levels) although none of the 3 patients with FLT3-ITD mutation showed any kind of response. In FLAI-GO arm the only factor which impacted on response rate was sex (CR rate was 69.2% and 34.6% in women and male, respectively, p=0,025). We observed a lower probability of CR in patients with higher bone marrow blast burden (CR rate of 80% with blasts 30%) and in patients with elevated BAALC (75% CR with BAALC 1000). The 1 and 2 years OS were 46 and 21 % in all patients (median 11 months),with no differences in AZA (45,9% and 26,2% ) and FLAI-GO arm ( 46,3% and 17,8%). In AZA group karyotype, FLT3 mutational status, WT1 expression significantly impacted on OS. In multivariate analysis only FLT3-ITD mutation retained its prognostic impact on OS (p = 0.02) . Achieving CR after AZA induction did not deeply modify OS probability, as there was no significant difference between patients in CR or not after AZA (even with a trend in favour of patients with CR). Non responders (NR) had a 1 year OS of 40% (median 9 months); patients with CR had a 1 year OS of 83.3% (median 47 months). Patients with an haematological improvement (HI) had a 1 year OS of 48% . In FLAI-GO arm the variables significantly influencing OS were: type of response (NR patients had a 2 years OS of 0% whereas CR patients had a 2 yeas OS of 38%), sex, WBC; neither karyotype, expression of BAALC , disease status, FLT3-ITD, WT1 expression, NPM1 mutation, blasts , age over 70 or LDH had a prognostic impact on OS. In multivariate analysis the only factor which impacted the survival was the achievement of CR to induction chemotherapy (p=0,000). Infection rate was 28/52 in AZA arm and 40/55 in FLAI-GO arm. The hospitalization rate was significantly lower in AZA arm compared to FLAI-GO (8.5 days vs 27 days in the first 30 days; 11.3 vs 51 in the first 90 days; 15 vs 64.5 in the first 180 days). Conclusions In our study AZA has shown to be well tolerated in a group of elderly frail patients until recently eligible only for best supportive care or low dose chemotherapy. AZA is less effective than FLAI-GO in inducing CR in all subgroups of patients but this doesn't translate into a lower OS. In the AZA arm the achievement of CR (or PR) is not fundamental for the duration of survival, unlike what has been observed in the FLAI-GO treated cohort. Our study suggests that some subgroups of patients may benefit more from AZA and others more from aggressive approaches; patients with low BAALC levels and with FLT3 mutation seem to benefit from FLAI-GO. Larger prospective trials evaluating clinical, cytogenetic and molecular risk factors in patients receiving AZA or chemotherapy will help to tailor the best therapy for each patient. Disclosures Gobbi: Novartis: Consultancy, Research Funding; Gilead: Honoraria; Celgene: Consultancy; Mundipharma: Consultancy, Research Funding; Janssen: Consultancy, Honoraria; Takeda: Consultancy; Roche: Honoraria.

Beschreibung: Background: HSCT has greatly improved the prognosis of patients affected by hematological malignancies leading to more long-term survivors. However, long-term survivors are at increased risk of developing complications; cardiovascular complications are relatively rare but, on the other hand, it seems quite common to develop cardiovascular risk factors like: arterial hypertension (AH), diabetes, dyslipidemia. Aims of the study: to observe the incidence and outcome of patients developing cardiovascular risk factors (CVRF) and cardiovascular events (CVE) after allo-HSCT, eventually identifying patient and HSCT-related risk factors for CVE (CVE predictors). Materials and methods: We retrospectively analyzed 300 patients undergoing allo-HSCT from January 2006 to December 2009. Patients were considered long-term survivors and suitable for the analysis if they were alive at 2 years after HSCT. Following variables were recorded: diagnosis, sex, age at time of HSCT, comorbidities and pre-existing risk factors, BMI, previous chemotherapy with anthracyclines, donor type, disease status at time of HSCT, conditioning regimens with or without total body irradiation (TBI), onset of acute or chronic graft versus host disease (aGVHD and cGvHD), treatment with high doses corticosteroids after HSCT. We observed incidence and outcome of early (within 2 years) and late (after 2 years) CVRF and CVE in long-term survivors; CVE were divided in non-serious (grade1-2) and serious (grade 3-4) if they required or not hospitalization. Dichothomius variables were compared with Chi-Square test or Fisher's exact test. Continuous variables were compared with Student's T-Test. Median Follow-Up duration was estimated with Kaplan Meier reverse survival method. Multiple linear regression models were built for multivariate analysis of CVE incidence. A two-sided p value

Beschreibung: Background Conventional induction therapy of acute myeloid leukemia (AML) is still largely based on the combination of cytarabine (ARA-C) and daunorubicin. In the last two decades alternative drug combinations have been tested in order to improve complete remission (CR) rate and quality of remission. Fludarabine has been shown to enhance ara-CTP accumulation in leukemic blasts and to inhibit DNA repair mechanisms, thus providing a rationale for combination with DNA damaging agents. In our institution a fludarabine containing induction regimen (FLAI-5) is being used since more than 15 years. Patients and methods Eighty-four consecutive non M3 AML patients (age 17-72 years) treated in our center between 2006 and 2013 were retrospectively analyzed. Median follow-up was 42 months. Induction regimen included fludarabine 30 mg/sqm and ARA-C 2g/sqm on days 1 to 5 plus idarubicin 10 mg/sqm on days 1-3-5, with or without gemtuzumab ozogamicin (3mg/sqm) on day 6. Patients achieving complete remission received a second course including ARA-C 2g/sqm on days 1 to 5 and IDA at an increased dose of 12 mg/sqm on days 1-3-5. Patients were stratified in prognostic risk groups according to a comprehensive score based on karyotype, de-novo or secondary disease, NPM and FLT3 status. High-risk and selected intermediate-risk patients underwent allogeneic bone marrow transplantation (BMT) in first complete remission if a donor was available. The other patients were scheduled to receive at least 2 and up to 4 courses of consolidation therapy with 4 days of ARA-C (2g/sqm, daily). Patients features, CR rate and overall survival (OS)analysis are summarized in Table 1. Results and Discussion Six patients (7%) died during first induction mainly because of infective or hemorrhagic events. Of the remaining 78 patients, 63 patients achieved CR (81%) and 15 did not respond (19%). FLAI-5 was generally well tolerated, with negligible non-hematological toxicity; median time to neutrophil and platelet recovery was 18 and 17 days, respectively. Most patients were able to receive subsequent therapy at full dose and in a timely manner; 33/63 CR patients underwent BMT whereas 21/30 (70%) non-transplanted patients received the full programmed therapy. In the whole cohort, 3 years OS was 50.9% (median 38 months). Factors affecting CR rates and OS are summarized in Tab.1. In a large randomized trial Burnett et al showed that FLAG-Ida favorably compared with other induction schedule. However the longer disease free survival and the lower relapse rate observed in the FLAG-Ida arm did not translate in a higher OS mostly due to the severe hematological toxicities following the second course. Our results are comparable to those recently published and show that the administration of fludarabine only in the first course may significantly reduce hematological toxicity therefore allowing patients to proceed along the consolidation program or undergo allo-BMT in a good performance status. Besides, we were able to increase IDA dose (10 and 12mg/sqm in first and second course, respectively, compared to 8 mg/sqm used in the FLAG-Ida combination). Our results show that FLAI-5 induction regimen followed by a second ARA-C and IDA containing course is an effective and well tolerated therapy for younger AML patients and confirm that CR rate and OS are mainly affected by comprehensive risk group, WBC count at diagnosis and NPM status. Abstract 2266. Table 1: Patients features and CR/OS analysis CR after 1st cycle/Tot.(%) p(univ.) p(multiv.) Median OS(months) OS 36 months (%) p(univ.) P(multiv.) All Patients 63/78 (81) - - 38 50.9 - - Age 〈 45 yrs 28/34 (82) 1.000 - NR 53.4 0.121 0.105 〉 45 yrs 35/44 (80) 15 49.2 Karyotype Favorable 3/3 (100) 0.093 0.248 NR 100 0.003 0.775 Intermediate 52/61 (85) NR 60.9 Sfavorable 8/13 (62) 7 0 NPM Wild type 36/50 (72) 0.003 0.001 32 45.1 0.270 0.541 Mutated 26/26 (100) 65 66 FLT3 Wild type 48/60 (80) 0.721 - 65 56.3 0.249 0.658 FLT3 ITD 14/16 (88) 14 35 Disease Onset De novo 57/67 (85) 0.031 0.213 65 56.1 0.001 0.809 Secondary 6/11 (55) 7 21.4 WBC at diagnosis 30.000/mmc 22/31 (71) 14 39.4 Comprehensive Risk Group Good 17/17 (100) 0.009 0.983 NR 81.2 0.000 0.001 Intermediate 31/37 (84) NR 63.5 Poor 15/24 (63) 9 14.4 Mylotarg FLAI 44/54 (82) 1.000 - 34 49.1 0.676 - MY-FLAi 19/24 (79) 65 52 Figure 1: OS according to risk group Figure 1:. OS according to risk group Disclosures No relevant conflicts of interest to declare.

Beschreibung: BACKGROUND AND AIMS Non high risk acute promyelocytic leukemia (APL) patients, as defined by WBC count at diagnosis, have nowadays a very good prognosis when treated with ATRA plus chemotherapy based protocols, with high rate of complete molecular remission after consolidation therapy. However, a small proportion of patients (roughly 10-15%) will eventually relapse, despite the achievement of molecular CR. In the past years, some groups showed that relapse risk could be predicted by testing for some gene alterations, such as FLT3-ITD, or by break point cluster region (BCR) analysis. However, those results were not confirmed in prospective trials. We retrospectively applied a simple 3 gene based molecular panel to low-intermediate risk acute promyelocytic patients, alongside with BCR analysis, in order to develop a risk score. MATERIALS AND METHODS Fifty-nine low/intermediate risk APL patients, treated with the Italian age-adapted AIDA protocol from January 1st 2004 to December 31st 2014 in our center were retrospectively included in this study. Median age was 47 years (range 19-88), 16 patients were older than 60 years (27%). BCR analysis was available in all patients, 41 patients showed BCR1/2, whereas 18 patients had BCR3 (30%). Molecular profile included determination of FLT3-ITD mutation, WT1 and BAALC gene expression levels and was available in 38/59 patients (64%); bone marrow sample of diagnosis is available for all other 21 patients for further analysis. Cut-off values for WT1 (20000/abl x 104) and BAALC (450/abl x 104) were arbitrarily chosen after pre-analysis and comparison with our published data. Five patients had FLT3-ITD mutation (13%), 18 (45%) patients had higher WT1 expression levels and BAALC was overexpressed in 9 (24%) patients. Pre-analysis showed that FLT3-ITD, low WT1 levels, high BAALC levels but not the presence of BCR3 were associated with higher relapse risk. A molecular score including those 3 genes was built: 16 patients had no risk factors (42%), 17 patients had one risk factor (45%), 5 had two risk factors (13%). RESULTS Fifty-four patients survived induction, all of them achieved CR, in 52 PML/RARα transcript was undetectable after last consolidation therapy. The two patients with molecular persistence of disease received further therapy and then achieved molecular CR. Nine patients (15%) relapsed after a median follow-up of 56 months, 45 patients are alive at the time of analysis (76%). Relapse risk was influenced only by the presence of at least one molecular risk factor (p