Abstract: Background: We have overcome the limitations of 40 years of ex vivo testing. The aim of this study is to determine the ability of Vivia's novel test to predict the complete remission (CR) rates after induction chemotherapy with cytarabine (Ara-C) and idarubicin (Ida) in 1st line AML. Material and Methods: Bone marrow samples from adult patients diagnosed with de novo AML in Spanish centers from the PETHEMA group were included. Whole marrow samples maintaining their Native Environment were incubated for 48h in well plates containing Ara-C, Ida, or their combination. Pharmacological responses are calculated using population models. Induction response was assessed according to the Cheson criteria (2003). Patients attaining a CR/CRi were classified as responders and the remaining as resistant. Results: 390 patient samples were used to calculate the dose response (DR) curves for Ara-C alone, Ida alone, and their synergism. For clinical correlation we used 142 patients with median 56 years. The strongest clinical predictor was the Area Under the Curve (AUC) of the DR of Ara-C, and the AUC of IDA. The GAM models revealed a significant relationship between the AUC of the concentration-effect curves of both, idarubicin and, particularly, Ara-C, with greater values associated to higher probabilities of post-induction resistance. The fitted Generalized Additive Method predictions of expected values for each patient were in turn related to overall survival when a discrimination value to define positive and negative test results that prioritized specificity over sensitivity was chosen based on equaling positive and negative predictive values (Fig 1A). Prioritizing specificity over sensitivity reflects the higher cost of false positive over false negative decisions: only in very rare instances, an effective treatment would be erroneously negated to a sensitive patient at the expense of overlooking a number of resistant patients. However, the later patients could take their chances on re-induction therapy. While for diagnostics sensitivity and specificity should both be optimized, for Personalized Medicine the positive and negative predictive values should be optimized preferentially because they define the patient response correlation. Fig 1B shows a table illustrating the correlation between clinical outcome (columns) and the test predictions (lines). From a diagnostic criteria (columns), clinically resistant patients (1st column) are not well predicted with a Sensitivity of 51%, while clinically sensitive patients (2nd column) are very well predicted with a Specificity of 94%. From a Precision Medicine criteria (Lines), patients predicted resistant (1st line) and well predicted with 80% positive predictive value, similar to patients predicted sensitive (2nd line) well predicted with 79% Negative Predictive Value. The test does not properly identify 23/142 that are clinically resistant and the test predicts as sensitive (bottom left quadrant right panel). This mismatched subgroup mimics the problems from molecular markers where a resistant clone present in a minority of leukemic cells cannot be detected yet drives the patient response. However, this group mismatch does not prevent a good correlation with the test predicted outcomes. Flow cytometry identified 2 clones in 75% of these 23 samples, and we revised all samples analyzing each of 2 clones separately whenever they were present. Results did not change by this clonal analysis, suggesting flow cytometry may not identify resistant clones. Future improvements of the test adding 16 concentrations to the dose response curves may be able to detect the presence and parameters of these resistant clones driving patient response. Conclusions: This novel test is able to predict the clinical response to Ida + Ara-C induction with overall correlation and predictive values of 80%, higher than ever achieved. It is significantly higher than the current clinical response rate of 66.7%. Thus this novel test may be valuable information to guide 1st line patient therapy. Figure 1. ROC curve and clinical correlation Figure 1. ROC curve and clinical correlation Disclosures Ballesteros: Vivia Biotech: Employment. Cordoba:Celgene: Research Funding. Ramos:GlaxoSmithKline: Honoraria; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria; Celgene Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Honoraria. Gaspar:Vivia Biotech: Employment. Gorrochategui:Vivia Biotech: Employment. Rojas:Vivia Biotech: Employment. Gomez:Vivia Biotech: Employment. Hernández:Vivia Biotech: Employment. Robles:Vivia Biotech: Employment.

Abstract: Introduction: Current recommendations for patients with low-risk polycythemia vera (PV) include hematocrit (Htc) control with phlebotomies and primary prophylaxis of thrombosis with low-dose aspirin. There is scarce information regarding the hematological control, the incidence of complications and the need for cytoreduction in PV patients treated with phlebotomies only. Methods: A total of 358 patients with low-risk PV ( & lt;60 years old and without history of thrombosis) from the Spanish Registry of Polycythemia Vera were included in the present study. PV-related symptoms and blood counts were collected at 6, 12, 18, 24, 36, 48 and 60 months from diagnosis while the patients were treated with phlebotomies only. The duration of the treatment with phlebotomies, the indication of starting cytoreduction and the incidence of thromboembolic and hemorrhagic events during the cytoreduction-free period was also analyzed. Results: Baseline characteristics at the time of diagnosis are described in Table 1. Table 2 summarizes the main hematological and clinical characteristics under treatment with phlebotomies. Inadequate control of the Htc ( & gt; 45%) was reported in 61-70% of the patients, leukocytosis & gt;15x10 9/l in 10% and thrombocytosis & gt;1000x10 9/l in 5%. In addition, about 20% of the patients had pruritus and 10% had microvascular symptoms. Of the 358 patients included, 275 (77%) required cytoreduction, 261 (73%) with hydroxyurea and 14 (4%) with IFN. The main indication of cytoreduction was thrombocytosis (20%), followed by age & gt;60 years old (15%) and microvascular symptoms (13%). Median duration of cytoreduction abstention was 4.7 (0.1-30.4) years being significantly longer in patients younger than 50 years (6 and 2 years for patients younger and older than 50 years, respectively, p & lt;0.0001). With a follow-up of 1659 person-years under phlebotomy only treatment, 14 thrombosis were observed (arterial n=9, venous n= 5), 12 hemorrhages (major n=4, minor n=8) and 4 solid tumors (1 melanoma and 3 non-cutaneous carcinomas). The incidence of complications during the cytoreduction-free period by person-years was: 0.8% for thrombosis, 0.2% for major hemorrhage and 0.2% for second neoplasia. The median follow-up until last visit including the time after starting cytoreductive therapy was 8.4 (0.2-39) years. Of 14 deaths observed, none occurred during the phlebotomy period. Half of the patients died from PV related reasons but the other 50% were not related. The median survival estimation by K-M was 36.5 years. Disease progression was documented in 27 (7.5%) patients, 26 of them to myelofibrosis, 1 to myelodysplastic syndrome and none to acute leukemia. Progression to myelofibrosis occurred during the cytoreduction-free period in 5 patients (1.4%) after a median of 5.8 years (Range: 4.9-8.9). Conclusions The incidence of thrombotic and hemorrhagic complications was very low in this series of low-risk patients treated with phlebotomies, even though only 30-40% of patients maintained the Htc & lt;45%. The data from the present study show that low-risk patients have different therapeutic needs than other PV patients and support the development of new treatment strategies. Representing the Spanish Group of Myeloproliferative Disorders. GEMFIN Figure 1 Figure 1. Disclosures Bellosillo: Qiagen: Consultancy, Speakers Bureau; Roche: Consultancy, Research Funding; Thermofisher Scientific: Consultancy, Speakers Bureau. Ferrer Marin: Cty: Research Funding; Incyte: Consultancy, Research Funding; Novartis: Speakers Bureau. Garcia Gutierrez: Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Consultancy, Honoraria, Research Funding.

Abstract: INTRODUCTION Anemia is the most frequent cytopenia in lower-risk MDS. Erythropoietic-stimulating agents (ESAs) are commonly used in these patients. The use of ÒclassicalÓ parameters (EPO and ferritin levels) and the revised IPSS (IPSS-R) has been proposed1 (SantiniÕs score) to predict response to ESAs and overall survival (OS) among patients with lower risk MDS by IPSS and a favorable Nordic group score2. OBJECTIVES The main objective of the study was to evaluate overall response rate (ORR) to ESAs and OS according to the proposed SantiniÕs score in an independent and large cohort of anemic lower risk MDS patients receiving treatment with ESAs. METHODS Data from 530 anemic patients with low/int1 risk IPSS de novo MDS (according to FAB and WHO criteria) and sufficient follow-up data available were recorded in Spresas3 (SPanish Registry of Erythropoietic Stimulating Agents Study from GESMD). Two hundred and twenty six patients (42.6% of the patients) were selected according to specific criteria regarding the published SantiniÕs score1: Hb level 〈 /=10 g/dL, serum erythropoietin (EPO) 〈 500 mU/mL and ESA (EPO alfa or B 40000-60000IU/week, or darbepoetin 150-300 ug/week). Applying 1 point to each of the following unfavorable variables for response to ESA, EPO 〉 200mU/mL(=1), serum ferritin (SF) 〉 350 ng/mL(=1) and IPSS-R very low=0, low=1, intermediate=2 and high=3) yielded a score ranging from 0 to 5. ESAs response rate and overall survival were analysed according to these score. Response to treatment was evaluated according to IWG 2006 response criteria and a multivariate logistic regression analysis was used to identify independent predictors of erythroid response (ER). OS were defined as the time between diagnosis and the corresponding event or last follow up (Feb 2015) and were analyzed using univariable and multivariable Cox proportional hazards regression methods. RESULTS Median age was 77 years (interquartile range [IQR] 25%-75%: 71-83 y), median Hb level at start of treatment was 10 g/dL (IQR25-75: 9-10), median EPO level was 90 (IQR25-75: 27,25-108) and median ferritin level was 338,5 (IQR25-75: 146,5-568,75). Among 139 patients with this data available, 85 patients (61,1%) were RBC transfusion dependent before ESAs treatment. Median time from diagnosis to ESAs treatment was 82 (IQR25-75: 27-353) days. According to the IPSS, 68.6% (N=155) and 31.4% (N=71) were in low and Int-1 risk groups, respectively. Regarding IPSS-R, 23% (N=52), 66.8% (N=151), 9.7% (N=22) and 0.4% (N=1) were in very low, low, intermediate and high risk, respectively. ORR to ESA treatment was 71.2% (N=161), with a median duration of response of 2.06 years. Prognosis factors of ER showed a trend toward to a higher ER among patients in the lower IPSS-R (P 〉 0.05), low IPSS (p=0.039) and lower EPO levels (p 〈 0.0001) while in multivariate analysis EPO level was confirmed as most significant variable associated to ER (p 〈 0.001). According to SantiniÕs score, 11.5%(N=26), 42.9%(N=97), 25.8%(N=81), 8%(N=18) and 1.8%(N=4) of the patients were in the 0, 1, 2 3 and 4 score. Erythroid response was better for patients in the lower scores, with response rates of 73.1%, 82.5%, 65.4%, 50% and 0%, for patients in 0, 1, 2, 3 and 4 score, respectively (p 〈 0.001, figure 1). After a median follow up of 3.1 years, median OS from diagnosis was 4.99 years. Interestingly, median OS from diagnosis was clearly related to SantiniÕs score (10.7 years, 6.7y, 4.9y, 3.7y and 6.7y for patients with 0, 1, 2, 3, and 4 points, respectively, p=0.041, Figure 2) whereas median OS from start of ESAs showed also some trend (p=0.26). CONCLUSIONS The present study confirms that SantiniÕs score is useful to identify patients with a higher probability of response to ESAs and better OS among lower risk MDS patients with an expected favorable response to ESA according to Nordic group score. Spresas study was partly supported by Janssen 1.-Santini et al, Blood 122(13), 2013. 2.-Hellstršm-Lindberg, Br J Haematol 120(6), 2003. 3.-D'ez Campelo, EHA 2015 meeting, P244. Disclosures Díez Campelo: Novartis: Research Funding, Speakers Bureau; Janssen: Research Funding; Celgene: Research Funding, Speakers Bureau. Off Label Use: Use of erythropoietic stimulating agents for anemia in patients with myelodysplastic syndromes. Ramos:JANSSEN: Honoraria, Membership on an entity's Board of Directors or advisory committees; AMGEN: Consultancy, Honoraria; NOVARTIS: Consultancy, Honoraria; CELGENE: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Falantes:Celgene: Honoraria. Garcia:Celgene: Research Funding. Sanz:JANSSEN CILAG: Honoraria, Research Funding, Speakers Bureau.

Abstract: Abstract 300 Background: Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of diseases characterized by clonal expansion of malignant T-cells in the skin. The two predominant clinical forms of CTCL are mycosis fungoides (MF) and Sezary syndrome (SS). Tumor-stage MF has an unfavorable prognosis with a 10-year survival of approximately 40%. The molecular pathogenesis of CTCL is still basically unknown, although some data suggest that signalling from T-cell receptor (TCR) is a driving force. However, the molecular mechanisms responsible for this activation have not been fully clarified. Methods: Based on the hypothesis that TCR activation may depend, at least in part, on somatic mutations, we have investigated this in a selection of genes belonging to TCR, or related pathways, such as NFkB, JAK/STAT, by means of deep sequencing. A Target Enrichment method using SureSelect system (Agilent) has been used to enrich in exons and regulatory regions of 524 genes belonging to these pathways. DNA from 2 tumoral-MF, 5 erythrodermic-MF and 4 SS patients, both normal and tumoral, were processed and sequenced with Genome Analyzer GA2 (Illumina) (PE-42bp). Sequencing data were first checked by FastQC and aligned to the human reference genome (GRCh37) using BWA and BFAST alignments. Somatic variants were identified using GATK. Thus, SNPs available at dbSNP 135 (hg19) and 1000 Genomes Project were filtered out from VCF output files. The GATK-QUAL field was employed for ranking selected somatic variants. Biological impact predictions for detected variants were obtained from Ensembl Variant Effect Predictor. Putative variants were manually reviewed and validated by capillary sequencing. Immunohistochemical analysis for NFAT, p50, p52 and STAT·p was also performed. qPCR-genotyping for specific variants was performed in a new cohort of 60 CTCL patients including SS and tumoral MFs. Results: Several mutations were found in essential genes belonging to pathways implicated in the Treg and Th17 regulatory pathways, NFkB and JAK/STAT, among others. PLCG1 was found mutated in three samples, two of them sharing the same mutation affecting one of the PLCG1 protein catalytic domains. This mutation was further analyzed by qPCR-genotyping in the new series of patients, being detected in 20% of samples. PLCG mutated cases showed a strong paraffin immunostaining for nuclear NFAT, p50 and p52. Additionally, immunological studies performed by flow cytometry in CTCL cell lines show aberrant coexpression of TH17 and Treg phenotypes. Conclusions: Activation of the TCR in CTCL might be partially dependent on the acquisition of somatic mutations in the coding region of genes known to play an essential role in T-cell differentiation processes and acquisition of TH17 and Treg phenotypes. Especially relevant is the finding that the catalytic domain of PLCG1 is frequently mutated in tumoral MF samples. Disclosures: No relevant conflicts of interest to declare.

Abstract: Activating mutations in PLCG1 are a frequent finding in tumoral CTCL samples. This raises the possibility of targeted therapies against PLCG1 signaling pathway, using calcineurin inhibitors.

Abstract: Background: Since survival in AL mainly depends on the extent of organ involvement of patients at presentation, early diagnosis and risk stratification are key to improve patients' outcome. Therefore, together with surrogates of organ involvement, biomarkers identifying patients with MGUS or MM at greater risk of developing AL would be highly valuable to prevent organ damage, to maximize therapeutic efficacy and to improve outcomes in AL. Aim: To investigate the value of multidimensional flow cytometry (MFC) for simultaneous fast diagnostic screening of plasma cell (PC) clonality and risk stratification, as well as to identify immunophenotypic markers useful for the selection of patients with monoclonal gammopathies candidates for monitoring of pre-symptomatic organ damage related to AL. Methods: We used MFC to characterize a large series of patients with newly-diagnosed (ND) AL (N=94) vs MGUS (N=20) and NDMM (N=52), as well as age-matched healthy adults (HA, N=30). For each patient with AL, automated risk stratification was performed using principal component analysis (PCA) based on the relative frequency of bone marrow (BM) PCs, plus the percentage of clonal and normal PCs within the whole BM PC compartment, vs a database containing information on the same three parameters from a total of 1,774 patients, including 497 MGUS and 1,227 NDMM. In parallel, immunophenotypic protein expression profiles (iPEP) of AL patients were clustered using t-SNE, and the comparison between the iPEP of clonal PCs from patients with AL vs MGUS and MM cases was performed using canonical-correlation analysis (CCA). To identify additional immunophenotypic hallmarks of AL, the BM cellular composition in HA, MGUS, AL and MM patients was compared using 2-dimensional minimum spanning tree (MST) force-directed classification to determine the distance among individual cases. Results: PC clonality was detected by MFC in 93/94 (99%) AL patients, whereas an M-component was detectable in 96% of cases by electrophoresis, immunofixation and sFLC. PCA as defined above, identified AL patients displaying an MM-like (n=6) and an MGUS-like (n=38) signature, as well as 49 cases with an intermediate signature between the MGUS and MM reference datasets. Multivariate analysis of baseline prognostic factors for survival, including patients' age, number of organs involved, Mayo staging, the percentage of BM PCs based on cytomorphology and eligibility for ASCT, showed that having an intermediate- or an MM-like profile had an independent adverse effect on patients' progression-free (PFS) and overall survival (OS) (HR:3.4; P≤.02). t-SNE based on the iPEP of clonal PCs revealed two major clusters of AL patients with significantly different PFS, defined by opposite patterns of expression for CD45, CD56 and CD138 (P≤.02). CCA of tumor iPEP showed partial overlap between AL vs MGUS and MM, with progressively higher percentages of cases with a CD38lo, CD45-ve, CD81-ve and CD138lo iPEP being observed from MGUS to AL and MM. In contrast, AL patients displayed significantly lower reactivity for CD56 (P≤ .03). Further characterization of the BM cellular composition allowed the systematic assessment of 16 cell populations and 18 phenotypic parameters that, by MST, mapped AL in between MGUS and MM. Of note, while AL patients displayed a predominantly-clonal PC compartment in the absence of an MM-like tumor PC expansion, the percentage of B-cell precursors was consistently lower in AL patients than in HA, MGUS and MM (P=.004). Thus, using optimal cut-off values to discriminate between AL vs MGUS and MM, we built a scoring model based on the presence of 〈 100% CD56+ve clonal PCs, 〈 0.1% B-cell precursors, 〉 80% clonal PCs within total BM PCs and 〈 2% BM PCs. Overall, a significant (P 〈 .001) association was found between a progressively higher score and the diagnosis of AL, with a 74% accurate classification based on ROC analysis (AUC of 0.74; 95% CI = 0.66 - 0.82; P 〈 .001) of the performance of the scoring model. Conclusions: We demonstrate the value of MFC for fast diagnostic screening of PC clonality in AL and simultaneous automated patient risk-stratification, based on the BM tumor burden and PC phenotype. In addition, our results also provide new immunophenotypic markers for the identification of patients with monoclonal gammopathies that are candidates for monitoring of pre-symptomatic organ damage related to AL. Disclosures Puig: Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; Celgene: Honoraria, Research Funding. Ocio:Array Pharmaceuticals: Research Funding; Sanofi: Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Pharmamar: Consultancy; BMS: Consultancy; AbbVie: Consultancy; Janssen: Consultancy, Honoraria; Seattle Genetics: Consultancy; Mundipharma: Research Funding; Takeda: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Oriol:Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. De La Rubia:Ablynx: Consultancy, Other: Member of Advisory Board. Martinez Lopez:Janssen: Research Funding, Speakers Bureau; Celgene: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau; Bristol Myers Squibb: Research Funding, Speakers Bureau. Mateos:Amgen: 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; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, 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; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Lahuerta:Janssen: Honoraria; Celgene: Honoraria; Amgen: Honoraria.

Abstract: Background: Alemtuzumab (Campath®/Mabcampath®, anti-CD52 humanized monoclonal antibody) has recently been shown to be effective in the treatment of diverse hematological malignancies. Mycosis fungoides (MF) and Sezary Syndrome (SS) are low grade cutaneous T-cell lymphoma with indolent course and multiple relapsed. Aim: We describe our experience from three centers in South America with refractory/relapsed MF/SS patients treated with Alemtuzumab as monotherapy. Methods: From July 2005 to April 2006 a total of 13 patients were recruited from 2 centers in Lima-Perú and one center in Caracas-Venezuela with histopathology diagnosed of advanced refractory/relapsed MF (10pts) or SS (3pts); median age 60 years old (range: 36–72); 9 pts. were male. Median number of previous therapies 2.5 (range: 2–7). Treatment scheduled was planned as follow: Alemtuzumab 30 mg i.v. tiw per 8 weeks with a gradually escalated doses during the first week (3,10, 30 mg). Trimethoprim/sulphamethoxazole and acyclovir as prophylaxis were given. Median Alemtuzumab total dose was 429 mg (range: 123–706) over a median time of treatment of 6.2 weeks (range:3–15). The first nine pts. received the planned schedule dose; 2 pts. received Alemtuzumab 30 mg i.v. tiw for 4 weeks and then 30 mg i.v. weekly and the last 2 recruited pts. received Alemtuzumab 10 mg iv. tiw for 4 weeks them after 10 mg i.v. biw and finally 10 mg i.v. weekly. CMV monitoring with pp65 was performed in the first five pts. and qualitative PCR in 3 pts. Results: Twelve patients were evaluable for response. Overall response rate (ORR) was 75% (9/12), with three patients achieving complete remission (CR) and six patients with partial response (PR); three patients with progressive disease (PD) during treatment. Responses were seen in 6/9 (75%) MF pts. and 3/3(100%) SS pts. Regarding clinical presentation: 4 over 4 (100%) eritrodermic forms responded and 5 over 8 (62%) tumoral forms responded. Response duration and CMV reactivation were described in table 1. Hematological toxicity was grade 1–2 neutropenia in three pts. and grade 1–2 thrombocytopenia in three pts. One pt. developed urosepsis caused by E. Coli. and 1 pt. had genital herpes. No cardiac toxicity was reported. Kaposi sarcoma progression was discovered in one pt. One pt. died with CMV pneumonitis, three months after treatment, 1 pt. died at two months during treatment for a neurology event Conclusion: Alemtuzumab as monotherapy shows promising clinical activity with sustained response in patients with advanced MF and SS. New studies should be address the Alemtuzumab impact in these malignancies with reduced doses or even combined therapies. Table 1. Outcomes, follow-up and CMV status Alemtuzumab (TD, mg) Response Follow-up (m) CMV Status TD=total dose, NE=no evaluable, AD=active disease, m=months, R=reactivation, F=fever, P=Pneumonitis 123 NE AD, 14 m R with F 313 PD Died, 8 m 706 PD AD, 8 m 403 CR Relapse at 6 m R with F 253 CR Relapse at 3 m. R with F 493 PR PR at 8 m, and death 123 PR Relapse at 3 m R no F 163 PD AD, 3 m R no F 673 CR Relapse at 30 m 673 PR Relapse at 14 m 673 PR Death at 2 m 673 PR PR, 30 m 673 PR PR, 3 m and death R with P

Abstract: BACKGROUND AND OBJECTIVES. Post transplantation High dose Cyclophosphamide (PTCY) used in haploidentical hematopoietic transplantations, has a high effectivity in acute Graft versus Host Disease (aGVHD), and chronic Graft versus Host Disease prophylaxis (cGVHD), however it is associated with high relapse rates. On the other hand, Anti-T-Lymphocyte Globulin (ATG-Fresenius ®) is also effective as immunosuppressive (IS) drug, but its benefit on Overall Survival (OS) and Relapse Free Survival (RFS) is unclear. The aim of this study was to compare the effectiveness of two GVHD prophylaxis regimes used in high risk transplantation: PTCY used in Haploidentical transplantation and ATG used for peripheral blood, non-related, related and mismatched donors. The primary endpoint was to evaluate the incidence of aGVHD and cGVHD, and its severity in both groups. As secondary endpoints we analyse the OS, RFS and GRFS (recorded adverse events include grade 3-4 aGVHD, systemic therapy-requiring cGVHD, relapse or death during median follow-up). We also consider transplantation related mortality (TRM) and post-transplantation complications. PATIENTS AND METHODS. We retrospectively analyse 111 allo-transplantations performed at our institution between 2012 and 2017. We analyse two cohorts: 49 haploidentical transplantation with PTCY (50 mg/kg, on day +3, +4) followed by Tacrolimus and Mycophenolate; and 62 peripheral blood related, non-related and mismatched with low dose ATG Fresenius (7mgr/Kg on days -3, -2, -1) associated with Tacrolimus/Cyclosporine starting on day -1 with a short course Methotrexate (on day +1, +3, +6) or Mycophenolate. Mycophenolate was stopped on day +28 and Cyclosporine or Tacrolimus were tapered on day +50. RESULTS. There were no differences in patients' age (49 vs 51), sex or pre-transplantation HCTI-score ≥ 3 (30 vs 26) between PTCY and ATG groups. We found differences between diagnosis (lymphoproliferative disorders (16 vs 4, p= 0.003), high DRI-score (18 vs 11, p = 0.04), number of previous transplantations (12 vs 5, p= 0.02), reduced intensity conditioning regimen (36 vs 20, p 〈 0.001) and bone marrow as stem cells source (38 vs 9, p 〈 0.001) between PTCY and ATG groups. The median time to neutrophil engraftment ( 〉 500/uL) was similar: 17 days [13-34] for PTCY and 16 days [9-33] for ATG. Median time to platelet recovery was higher in PTCY cohort (33 vs 18 days, p= 0.016). There were 3 secondary graft failures in PTCY group vs 4 graft failures in ATG (3 primary, 1 secondary). The were no differences in grade 2 - 4 aGVHD incidence between groups (PTCY:30.6% vs ATG:36.4%), but we found differences in grades 3 - 4 aGVHD (PTCY:4.1% vs ATG: 9%, p=ns). The global incidence of any NIH grade cGVHD was 56.1% in PTCY vs 66% in ATG group. Mild, moderate and severe cGVHD incidence were 31.7%, 19.5% and 4.8% for PTCY vs 28%, 26% and 12% in ATG (p=ns). The median duration of IS in alive patients with cGVHD was 6.5 months [3-19] in PTCY patients and 10 [3-34] in ATG group. Among moderate and severe forms, the median IS duration was 10 and 5 months in PTCY group vs 13 and 12 months in ATG respectively. PTCY cohort developed more non-infectious complications, especially, cardiac, lung, digestive and neurologic complications, (p=0.086), however there were not differences in infectious complications (Table 1). TRM was similar between groups, 18.4% for PTCY vs 22.5% for ATG, (p=0.250). We didn´t find differences in early toxic mortality ( 〈 100 days): 16.3% for PTCY and 14.5% for ATG (p=0,421). With a median follow-up of 27 months in alive patients (28 months for PTCY and 22 months for ATG) we report an 67.8 % and 61% OS at 12 and 24 months for PTCY and 68.8% and 59.9% for ATG (Log Rank=0.971). Relapse free survival at 12 and 24 months was 61% and 57.9% for PTCY and 69% and 54% for ATG (Log Rank=0.839). GRFS at 12 and 24 months was 46.5% and 42.9% for PTCY patients and 40.7% and 33% for ATG patients, (Log Rank = 0.433). CONCLUSIONS. Regardless the different scenarios between transplantation cohorts, the use of PTCY and low dose ATG are equally effective in the prophylaxis of severe forms of aGVHD and cGVHD, offering similar GRFS. PTCY shows higher early toxicity but a similar rate of infectious events. In order to validate these results, it would be necessary to carry out a randomized controlled trial. Disclosures No relevant conflicts of interest to declare.

Abstract: Abstract 1415 Background: Chronic myeloid leukemia (CML) is one of the best examples of a disease that can be targeted by molecular therapy however, the success of new designed drugs is largely restricted to the chronic phase of the disease. If not cured at this stage, CML invariably progresses and transforms into an acute-type leukemia undegoing a blast crisis, that is characterized by a rapid expansion of myeloid or lymphoid differentiation-arrested blast cells leading to short median survival. To investigate the genetic changes associated with CML progression under tyrosin-kinase inhibitor treatment, and to determine whether clonal evolution contributes to blast crisis, we performed whole-exome sequencing of an individual patient at three different times of the CML progression: chronic phase (CP), complete hematological remission (CHR) and blast crisis (BC). Methods and Case Description: We collected genomic DNA from bone marrow cells (tumor DNA) at three disease evolution points and from epithelial cells (germline DNA). The sequence capture, enrichment and elution was performed according to manufacturer's instructions and protocols (SureSelect, Agilent). Each eluted-enriched DNA sample was sequenced on an Illumina GAIIX as paired-end 75b reads. The bioinformatics analysis of sequencing data was based on a pipeline which includes alignment, annotation, and filtering of the somatic variants, all linked to a coverage/depth statistical analysis. Validation of somatic mutations was done by capilary sequencing. The patient, a 65 year-old men, showed at diagnosis a classic CML with a 45,XY,t(9;22)(q34;q11.2),rob(13;14)(q10;q10)c [20]. He was treated with Imatinib (400 mg/day) achieving complete hematological and cytogenetic remission after 12 months of treatment. Real-time qRT-PCR demonstrated molecular response: BCR/ABL1 ratio decreased from 53% to 13% within the first year. Unfortunately, the disease progressed at month 14 to a blast crisis with a complex karyotype that did not respond to 2nd line treatment (Dasatinib + Idaurobinice-AraC) and the patient died of the disease 18 months after diagnosis. Results: After discarding the variants present in the matched normal DNA and in the dbSNP132 database, we obteined a total of 3123, 7678 and 3306 single nucleotide substitutions (SNSs) and small insertions and deletions (indels) for CP, CHR and BC, respectively. Next, we selected only those variants within coding regions that, passing depth and quality controls, were predicted to produce non-synonymous amino acid changes. This resulted in 27, 30 and 26 SNSs for CP, CHR and BC, respectively, (Fig. 1). Among those SNSs, we validated mutations in genes known to be involved in CML (such as ASXL1 and TP53) as well as in genes that have not been described so far in the disease (such as UBE2G2, ZEB2 and IKZF3). TP53 mutation (p.E286K) was found in the three phases of CML progression. However, ASXL1 (p.G679*), UBE2G2 (p.D35V), ZEB2 (p.L420R) and IKZF3 (p.E272K) were present only in the CP and BC-CML. On the other hand, only 7%, 42% and 6% of the mutated gene were exclusively found in CP, CHR and BC, respectively (Fig. 1). The evaluation of the number of mutated reads for each gene allowed us to study clonality and clonal evolution patters during CML progression. 93% of the selected SNSs that were present in the CP were also seen in BC (only 46% during CHR). In fact, the percentages of reads of the mutant alleles identified for the most relevant genes were the same (around 50%) both at CP and at BC. Conclusions: Whole-exome sequencing allowed to identify a large number of mutated genes, even at the chonic phase of CML, that harbour clear prognostic and predictive significance (TP53, IKZF3, absence of ABL1 mutations). The study of the mutation profile through the disease progression indicated that, at least in this patient, the number and the type of mutations were rather similar at CP and BC. Disclosures: No relevant conflicts of interest to declare.