Search

BackgroundSecondary haemophagocytic lymphohistiocytosis (sHLH) is characterised by a hyper activation of immune system that leads to multiorgan failure. It is suggested that excessive immune response in patients with COVID-19 could mimic this syndrome. Some COVID-19 autopsy studies have revealed the presence of haemophagocytosis images in bone marrow, raising the possibility, along with HScore parameters, of sHLH.AimOur objective is to ascertain the existence of sHLH in some patients with severe COVID-19.MethodsWe report the autopsy histological findings of 16 patients with COVID-19, focusing on the presence of haemophagocytosis in bone marrow, obtained from rib squeeze and integrating these findings with HScore parameters. CD68 immunohistochemical stains were used to highlight histiocytes and haemophagocytic cells. Clinical evolution and laboratory parameters of patients were collected from electronic clinical records.ResultsEleven patients (68.7%) displayed moderate histiocytic hyperplasia with haemophagocytosis (HHH) in bone marrow, three patients (18.7%) displayed severe HHH and the remainder were mild. All HScore parameters were collected in 10 patients (62.5%). Among the patients in which all parameters were evaluable, eight patients (80%) had an HScore >169. sHLH was not clinically suspected in any case.ConclusionsOur results support the recommendation of some authors to use the HScore in patients with severe COVID-19 in order to identify those who could benefit from immunosuppressive therapies. The presence of haemophagocytosis in bone marrow tissue, despite not being a specific finding, has proved to be a very useful tool in our study to identify these patients.

BACKGROUND The significance of discrepant findings between histology (BMB) and flow cytometry (FC) in bone marrow (BM) examination at diffuse large B-cell lymphoma (DLBCL) diagnosis is uncertain. METHODS We performed a 5-year retrospective single-center study of patients diagnosed by DLBCL not otherwise specified (n = 82), divided into three groups according to BM infiltration at diagnosis: BMB-/FC- (75.6%), BMB+/FC+ (13.4%), and BMB-/FC+ (11%). RESULTS Median infiltration by FC analysis of the BMB-/FC+ group was 0.8% and if we considered BM infiltration as positive in all cases, 4/9 would be upstaged. Median follow was 33 months. Event-free survival (EFS) after 18 months was 82, 23, and 27% for BMB-/FC-, BMB-/FC+, and BMB+/FC+, respectively (p

Severe cases of Coronavirus Disease 2019 (COVID-19) can present with multiple neurological symptoms. The available neuropathological studies have described different lesions; the most frequent was the presence of neuroinflammation and vascular-related lesions. The objective of this study was to report the neuropathological studies performed in a medical institution, with abundant long intensive care unit stays, and their associated clinical manifestations. This is a retrospective monocentric case series study based on the neuropathological reports of 13 autopsies with a wide range of illness duration (13-108 days). A neuroinflammatory score was calculated based on the quantification of CD8- and CD68-positive cells in representative areas of the central nervous system. This score was correlated afterwards with illness duration and parameters related to systemic inflammation. Widespread microglial and cytotoxic T-cell activation was found in all patients. There was no correlation between the neuroinflammatory score and the duration of the illness; nor with parameters of systemic inflammation such as the peak of IL-6 or the HScore (a parameter of systemic macrophage activation syndrome). Two patients had global hypoxic ischaemic damage and five patients had subacute infarcts. One patient had many more brain vascular microthrombi compared to the others and multiple subacute pituitary infarcts. SARS-CoV-2 RNA was not detected with qRT-PCR. The proportion of brain lesions in severe COVID-19 patients could be related to illness duration. In our series, with abundant long hospitalisation stays, neuroinflammation was present in all patients and was more prominent between day 34 and day 45 after onset of symptoms. Clinical correlation showed that two patients with the highest neuroinflammatory scores had severe encephalopathies that were not attributable to any other cause. The second most frequent lesions were related to vascular pathology.

Diffuse follicular lymphoma (FL) variant is a rare condition that shows distinctive clinical, morphological, immunophenotypic, and molecular features that distinguish it from classical FL. Diffuse FL variant is characterized by a predominantly diffuse growth pattern, absence of the t (14;18) IGH/BCL2 translocation, CD23 expression, and presence of 1p36 deletion. Gene mutations involving STAT6 have been reported, with nuclear expression of STAT6 and phosphorylated STAT6 detected by immunohistochemistry. Patients frequently present with inguinal node involvement and low clinical stage. We describe the case of an 80-year-old female diagnosed with diffuse FL variant, presented with a classic diagnostic pattern and an unusual aggressive clinical onset.

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease whose prognosis is associated with clinical features, cell-of-origin and genetic aberrations. Recent integrative, multi-omic analyses had led to identifying overlapping genetic DLBCL subtypes. We used targeted massive sequencing to analyze 84 diagnostic samples from a multicenter cohort of patients with DLBCL treated with rituximab-containing therapies and a median follow-up of 6 years. The most frequently mutated genes were IGLL5 (43%), KMT2D (33.3%), CREBBP (28.6%), PIM1 (26.2%), and CARD11 (22.6%). Mutations in CD79B were associated with a higher risk of relapse after treatment, whereas patients with mutations in CD79B, ETS1, and CD58 had a significantly shorter survival. Based on the new genetic DLBCL classifications, we tested and validated a simplified method to classify samples in five genetic subtypes analyzing the mutational status of 26 genes and BCL2 and BCL6 translocations. We propose a two-step genetic DLBCL classifier (2-S), integrating the most significant features from previous algorithms, to classify the samples as N12-S, EZB2-S, MCD2-S, BN22-S, and ST22-S groups. We determined its sensitivity and specificity, compared with the other established algorithms, and evaluated its clinical impact. The results showed that ST22-S is the group with the best clinical outcome and N12-S, the more aggressive one. EZB2-S identified a subgroup with a worse prognosis among GCB-DLBLC cases.

In 2016, the WHO included haemoglobin values within normal ranges as a diagnostic criterion for Polycythaemia Vera (PV). Since then, concerns have arisen that a large number of patients are undergoing unnecessary screening for PV. To address this issue, we estimated the prevalence of JAK2 p.V617F in individuals with elevated haemoglobin or haematocrit and developed and validated a screening algorithm for PV. A total of 15,366 blood counts performed in seven non-consecutive days were reviewed, of which 1001 were selected for subsequent JAK2 p.V617F mutation screening. Eight (0.8%) new JAK2 p.V617F-mutated cases were detected. From ROC curves, a two-step algorithm was developed based on the optimal cut-off for the detection of the JAK2 p.V617F mutation. The algorithm was prospectively validated in an independent cohort of 15,298 blood counts. A total of 1595 (10.4%) cases met the criterion for haemoglobin or haematocrit, of whom 581 passed to step 2 (3.8% of the total). The JAK2 p.V617F mutation was detected in 7 of the 501 patients tested, which accounts for 0.04% of the total cohort and 0.4% of patients with erythrocytosis. In conclusion, this data show that our two-step algorithm improves the selection of candidates for JAK2 p.V617F testing.

BCR-ABL is an aberrant tyrosine kinase responsible for chronic myeloid leukemia (CML). Tyrosine kinase inhibitors (TKIs) induce a potent antileukemic response mostly based on the inhibition of BCR-ABL, but they also increase the activity of Natural Killer (NK) and CD8+ T cells. After several years, patients may interrupt treatment due to sustained, deep molecular response. By unknown reasons, half of the patients relapse during treatment interruption, whereas others maintain a potent control of the residual leukemic cells for several years. In this study, several immunological parameters related to sustained antileukemic control were analyzed. According to our results, the features more related to poor antileukemic control were as follows: low levels of cytotoxic cells such as NK, (Natural Killer T) NKT and CD8&plusmn, TCR&gamma, &beta, + T cells, low expression of activating receptors on the surface of NK and NKT cells, impaired synthesis of proinflammatory cytokines or proteases from NK cells, and HLA-E*0103 homozygosis and KIR haplotype BX. A Random Forest algorithm predicted 90% of the accuracy for the classification of CML patients in groups of relapse or non-relapse according to these parameters. Consequently, these features may be useful as biomarkers predictive of CML relapse in patients that are candidates to initiate treatment discontinuation.

Systemic mastocytosis is a rare and heterogeneous disease characterized by mast cell proliferation and activation. KIT is a transmembrane tyrosine kinase which plays a key role in mast cell growth, differentiation and survival. After interaction with its ligand, the stem cell factor, KIT dimerizes activating downstream pathways involving multiple tyrosine kinases (PI3K, JAK/STAT, RAS/ERK). Activating mutations in KIT are detected in most cases of systemic mastocytosis, being the most common KIT D816V. Therefore, since the emergence of tyrosine kinase inhibitors, KIT inhibition has been an attractive approach when facing mastocytosis treatment. Initial reports showed that only the rare KIT D816V negative cases were responsive to tyrosine kinase inhibitors. However, the development of new tyrosine kinase inhibitors such as midostaurin or avapritinib with activity against mast cells carrying the D816V KIT mutation, has changed the landscape of this disease.

Introduction. The boundaries between MDS and AML are still a matter of debate. In the 2001 WHO Classification, the myeloblast count distinguishing AML and MDS was lowered from 30% to 20% of the bone marrow (BM) cells or peripheral blood (PB) leukocytes. It was justified on the basis that treating patients with 20-29% BM blasts with intensive chemotherapy showed a similar outcome to those with > 30% BM blasts. However, the better knowledge of the biology of both diseases is showing that in several cases AML and high risk MDS share identical genetic profiles, as it is well known in AML with myelodysplasia- related changes (AML-MRC). Currently there are new therapeutic options, less toxic, and suitable for elderly people.The threshold of 20% BM blast is artificial, but it is still the main criterion used in clinical trials and also in real life to discriminate patients that probably belong to the spectrum of the same biological entity. Treatment of patients with MDS or AML is widely based in this relatively arbitrary condition. Objective: To study if the threshold of 20% bone marrow blasts, distinguishing MDS with excess of blasts type 2 (MDS EB 2) and AML, is reproducible among different observers. Methods. 120 bone marrow samples from patients previously diagnosed with MDS-EB-2, AML or therapy-related myeloid neoplasms (t-MN) according to 2016 WHO classification were included. The diagnosis of MDS required cytogenetics and/or FISH, and the cases with AML should have been classified following the 2017 ELN recommendations, regarding immunophenotyping, cytogenetics and molecular biology. The design of the study was established to include cases with Results. Finally 116/120 samples were considered suitable for the study. Regarding 2016 WHO categories, 55 cases showed MDS EB-2, 44 AML-MRC, 8 t-MN, 4 AML- NOS, 2 NPM1-mutated AML, 2 RUNX1-RUNX1T1 AML, 1 BCR-ABL1+ AML. Next generation sequencing was performed in 79 cases. Discordance was observed in 34/116 cases (29.3%). 14 cases with MDS-EB2 (1 NPM1+) were classified as AML-MRC by the second observer, 16 AML cases as MDS EB-2, 3 MDS EB-2 as MDS- EB1 and 1 AML as MDS- EB1. The genetic and /or molecular profile of the discordant cases was heterogeneous. Regarding the threshold of 20% BM blasts, discrepancies were 31/116 (26.7%, I Kappa test = 0.46, moderate agreement). The agreement between MDS-EB-2 and AML-MRC, with discordance in 28/98 cases (28.6%), was moderate-fair (Kappa test= 0.42). Conclusion. The threshold of 20% BM blasts did not accurately separate AML from MDS EB-2. Particularly less concordance was seen for AML-MRC. Incorporation of genetic and molecular characteristics to the morphologic diagnosis is needed to optimize the definition of both entities. Acknowledgment: Angel Cedillo, Secretaría Técnica AMHH. Disclosures Font Lopez: GILEAD: Membership on an entity's Board of Directors or advisory committees; CELGENE-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Loscertales: Janssen, Abbvie, Astra-Zeneca, Beigene, Roche, Gilead: Consultancy; Janssen, Abbvie, Roche, Gilead: Speakers Bureau. Cedena: Janssen, Celgene and Abbvie: Honoraria.

Introduction: Response to chemotherapy treatment both by cytology and by more sensitive techniques such as cytometry is one of the most influential parameters in the survival of patients with Acute Myeloid Leukaemia (AML). Patients with detectable minimal residual disease (MRD) or those with active disease (AD) after induction or prior to allogeneic transplantation (HCST) represent a high-risk group. Objectives: to analyse the impact of disease burden before HSCT in terms of Overall Survival (OS) and Event Free Survival (EFS) in a group of patients who received HSCT in a single institution. We also analysed the influence of disease burden at the end of induction (considering best response after 1 or 2 cycles) and its impact on those patients in Cytological Remission (CR) with MRD Methods: We analysed 103 patients who received HSCT in one centre between 2008 and 2020 in whom we knew disease status after induction and before HSCT. We divided the cohort into three groups according to preHSCT disease: Group 1) Patients in CR with MRD Results: The baseline characteristics of the population are reflected in table 1. Median follow-up was 13 months (0-140). One-year EFS (1y-EFS) was 49%. One-year OS (1y-OS) was 57.5%, with a 1y-IAR of 27%. We first analysed the impact on post-transplant survival according to the different groups. Group 1 had significantly better EFS than Group 2 (p=0.04) and Group 3 (p Conclusions: Patients with pre-transplant AD or MRD+ are a high-risk group due to a high incidence of post-HSCT relapse. Although patients with AD or CR with MRD+ after induction have a worse prognosis, those who achieve MRD- before HSCT have a similar survival to the MRD- group from the start of chemotherapy. Figure 1 Figure 1. Disclosures Garcia-Gutiérrez: Pfizer: Research Funding; Bristol-Myers Squibb: Consultancy; Incyte: Consultancy; Novartis: Consultancy.

Introduction Bone marrow (BM) examination at diffuse large B-cell lymphoma (DLBCL) diagnosis is essential in staging and has prognostic implication. According to the last recommendations (Cheson, et al. JCO 2014) BM biopsy (BMB) is only needed for those patients with a negative BM infiltration by positron emission tomography (PET) for whom identification of occult discordant histology - whose biological and prognostic implications are unknown - is clinically important. Despite its greater sensitivity, flow cytometry (FC) is secondary in BM assessment. Our aim was to compare PET, BMB and FC in the study of BM infiltration at DLBCL diagnosis. Methods Retrospective study in two hospitals in Madrid of patients diagnosed with DLBCL NOS from January 2014 to January 2020. A complete BM assessment including PET, BMB and FC was performed in all included patients. The hole series (n=102) was analysed separately according with BM infiltration by each technique, differences between biological, clinical and laboratory variables were studied applying descriptive statistics tests when appropriate (Fisher's exact test, chi-square test, Student's T test and Mann-Witney U test). Event-free survival (EFS) and overall survival (OS) were analysed with Kaplan-Meier estimator according to BM infiltration positive vs negative for each technique, using Cox proportional-hazard model for comparisons. Results BM infiltration was not assessed in 2 patients by BMB and in 4 patients by FC due to technical reasons. Analysing separately the series according to BM infiltration by each technique (PET+ 25 vs PET- 77, BMB+ 15 vs BMB- 85 and FC+ 16 vs FC- 82) the basal characteristics were comparable between groups, except from extranodal sites ≥2, Ann Arbor III-IV and elevated LDH level in groups with positive BM infiltration. The variables associated with worsen EFS in univariate analysis were age ≥80 years (HR 2.31; CI 95% 1.1-5.1), cell-of-origin (COO) non-GCB (HR 2.33; CI 95% 1.1-4.9), extranodal sites ≥2 (HR 2.39; CI 95% 1.2-4.7), Ann Arbor III-IV (HR 4.55; CI 95% 2.0-10.5), and elevated LDH level (HR 2.32; CI 95% 1.1-4.7). The variables statistically related with worsen OS were COO non-GCB (HR 2.91; CI 95% 1.2-6.8), extranodal sites ≥2 (HR 2.61; CI 95% 1.2-5.5), Ann Arbor III-IV (HR 5.97; CI 95% 2.1-17.3), elevated LDH level (HR 2.36; CI 95% 1.1-5.4), and elevated beta-2 microglobulin level (HR 3.82; CI 95% 1.1-12.9). Double-expressor phenotype did not demonstrated association with EFS or OS. Median infiltration by FC analysis was 0.9% (0.05-27). The series distribution among BM infiltration is presented in Figure 1. Median follow-up was 25 months (0.3-90). Survival curves according to BM infiltration by PET, BMB and FC are presented in Figure 2. Univariate analysis among the type of infiltration by each technique are presented in Table 1. Multivariate analysis included age ≥80 years, COO non-GCB, BM FC+ and IPI score 3-5; BM infiltration by FC demonstrated no association with EFS (HR 2.2; CI 95% 0.9-5.3) or OS (HR 2.5; CI 95% 0.9-6.5). Conclusions BM infiltration by PET at DLBCL NOS diagnosis has not survival implication, contrary to infiltration demonstrated by BMB or FC. Cases with positive infiltration by PET but negative by BMB and FC could be false positive in PET or false negative in BMB/FC. According to our results the patients with discordant lymphoproliferative disorder BM infiltration presented worse prognosis and FC is probably the most important technique in this regard. Disclosures No relevant conflicts of interest to declare.

Diffuse large B-cell lymphoma (DLBCL) is an aggressive and heterogeneous disease with variable prognosis associated with clinical features, cell-of-origin and genetic aberrations. The main problems for DLBCL patients are that a substantial percentage of them (30-40%) are refractory to treatment or relapse and the lack of accurate predictive markers that adequately determine which patients will benefit from immunochemotherapy. Several recent deep-sequencing studies have proposed new genetic subtypes based on the DLBCL genomic profile (Wright et al., 2020; Lacy et al. 2020) and associated with clinical outcome. However, a consensus and validated classification is still needed. The aim was to determine whether genetic alterations of individual genes or genes clustered in pathways are associated with clinical outcome in immunochemotherapy-treated patients. We used targeted massive sequencing to analyze 84 diagnostic samples from a multicentric cohort of patients with DLBCL treated with rituximab-containing therapies with a median follow up of 6 years. A two-step genetic classifier was built with mutation information from 27 genes and BCL2/BCL6 translocations, based on recently proposed genetic subtypes (Wright et al., 2020; Lacy et al. 2020). Logistic regression and Kaplan-Meier analyses for survival and risk of relapse were performed to assess the potential clinical value of the classifier. Moreover, this two-step classifier was validated in an external cohort and its specificity and sensitivity were tested to determine its accuracy in classifying patients compared to the previous approaches. We found that the most frequently mutated genes were IGLL5 (43%), KMT2D (33.3%), CREBBP (28.6%), PIM1 (26.2%), and CARD11 (22.6%). Mutations in CD79B, PRDM1, and NOTCH2 were associated with a higher risk of relapse after treatment, whereas patients with mutations in CD79B, ETS1, PRDM1, and TNFAIP3 had significantly shorter survival. Analyzing the impact of gene mutations on predefined gene sets related to lymphomagenesis revealed that mutations in genes involved in B-cell development, and BCR-PI3K and MAPK-ERK pathways were significantly associated with a higher risk of relapse and/or shorter overall survival. These results confirmed the current landscape of genetic alterations in DLBCL. According to the two-step classifier, we categorized the samples into MCD, BN2, EZB, ST2, and N1 genetic subgroups (Figure). We tested the accuracy of our classification in an external series (UK population-based Haematological Malignancy Research Network cohort [HMRN]) to determine its specificity and sensitivity compared with their own classification (Lacy et al. 2020) and the LymphGen algorithm (Wright et al., 2020). The comparison demonstrated (Wright et al., 2020; Lacy et al. 2020), a specificity and sensitivity higher than 85% for each subtype, except for BN2. This controversy may be explained by the fact that BN2 is less strongly defined than the other subtypes. We then tested their clinical impact and found the EZB and ST2 subtypes to have a better clinical course and a lower risk of relapse. The BN2 group had the worst clinical outcome of our series, unlike other published studies (Figure). These results were validated in the HMRN cohort, in which N1 showed a higher risk of relapse and shorter overall survival, whereas ST2 is the group with the most favorable outcome. Although N1 was not included for clinical outcome analysis in our cohort due to the small number of cases, the validation of our classifier defined N1 as the most aggressive subtype. In summary, we propose and validate a feasible genetic DLBCL classifier based on an optimized panel of genes that unifies previous genetic classification algorithms in such a way as to facilitate its implementation as part of pathology laboratories for routine patient management. This genetic classifier, combined with clinical data and other molecular characteristics, should eventually help develop improved risk models for DLBCL patients, and guide precision therapy. Figure Disclosures Perez Callejo: F. Hoffmann-La Roche: Current Employment, Current equity holder in publicly-traded company.

Chronic Lymphocytic Lymphoma (CLL) is a heterogeneous disease in which many important factors for its prognosis have been identified. The normal functioning of p53 is one of the most critical barriers against cancer; therefore, if it has a deletion and/or mutation, it is a robust biomarker for the therapeutic response in CLL. The possibility was raised that some germline single - nucleotide polymorphisms of TP53 in healthy populations may also affect p53 function. One of the most studied polymorphisms of the TP53 gene is codon 72 in exon 4, a CGC to CCC transition (R72P), due to its potential effect on cancer risk. As with many types of cancer, its association with a worse prognosis in CLL is unclear. We analyzed the relationship of the genotypes of the TP53 codon 72 polymorphism in a large cohort of patients with CLL, to demonstrate the association of codon 72 with the evolution of the disease. Using the IDIPHIM patient database, 558 patients with a diagnosis of CLL were included, with clinical data, immunophenotype studies, FISH, IgHV, and karyotype, at the time of diagnosis and during follow-up. The TP53 codon 72 Arg/Arg, Arg/Pro, and Pro/Pro genotypes were analyzed using RT-PCR and Sanger sequencing techniques. After analyzing the sample of patients, 321 patients with the Arg/Arg genotype, 202 with the Arg/Pro genotype, and 35 with the Pro/Pro genotype were found. In the comparative analysis of the three groups, the patients with the Pro/Pro genotype had a higher number of patients in advanced stages B and C. The latter had a significant association with Binet staging (p = 0.002) compared to the other groups. Likewise, patients with the Pro/Pro genotype had a higher incidence of Richter transformation, whose association was significant (p = 0.013). Also, the patients who were within the Pro/Pro genotype group showed a significant association (p = 0.030) with the Time to the first treatment (TFT), also observing that the group of patients with the Arg/Pro genotype had a more considerable time until your first treatment. 19.7% (110/558) had a second neoplasm, having a significantly higher association with the homozygous groups (Arg/Arg and Pro/Pro) than with the Arg/Pro group, which on the contrary, had fewer second neoplasms (p = 0.016) (see Table 1). Regarding the type of tumors, we found 14.5% of the bladder, 14.5% of the skin, 14.5% of the colon, 13.6% of the prostate, and 12.7% of the lung. No associations were found between Codon 72 and CD38+, ZAP70+, complex karyotype, IgHV, NOTCH-1, del 11q, 12+, p53, del 13q, TP53 mutation. Still, when forming a group between the p53 deletion and TP53 mutation, if significant differences were found (p = 0.023), Pro / Pro group had the highest percentage. The overall survival was 156.32 months (139.92 - 172.72), showing that patients with the Arg/Pro genotype live 40 months more significantly than the other groups (p = 0.028) (see Figure 1). Finally, in the multivariate analysis, age, complex karyotype, 11q deletion, p53 deletion, unmutated IgHV, and Pro/Pro genotype at codon 72 were identified as independent variables associated with an increased risk of death (see Table 2). In conclusion, the Pro/Pro genotype of TP53 Codon 72 has a potential role in the progression and the higher mortality of patients with CLL. Conversely, the Arg / Pro genotype was associated with a lower incidence of second malignancies and higher overall survival. Disclosures No relevant conflicts of interest to declare.

Introduction: Patients with Acute Myeloid Leukemia (AML) and positive Minimal Residual Disease (MRD) prior to allogeneic transplant are currently considered to be a group at high risk of relapse. Multiparameter flow cytometry is a standard technique to measure MRD, and generally we use a 0.1% threshold for positivity. The clinical significance of those patients with an MRD levels >0% but Material and methods: We performed a single-center retrospective analysis of 88 patients transplanted between 2012 and 2020. All patients achieved complete remission (CR) with or without hemoperipheral recovery prior to allogeneic transplant. We have divided our cohort into three groups according to MRD state by flow cytometry: Group 1 patients with negative MRD, Group 2 patients with MRD level >0% but Results: The baseline characteristics of our cohort are reflected in Table 1. We did not find statistical significant differences except for the response to induction. The median follow-up of the entire cohort was 13.5 months (range 6-43.5). The 4-year RFS (4y-RFS) was 47% and the 4-year OS (4y-OS) 50%. The 4y-RFS was 52.5% in Group 1 vs 59% in Group 2 vs 30% in Group 3. The 4y-OS was 60% in Group 1 vs 60% in Group 2 vs 31% in Group 3 (Image 1). The Hazard Ratio (HR) for RFS and OS comparing Group 1 vs Group 2 was 0.9 [95% CI ((0.3-2.5)] and 1.1 [95% CI (0.4-3)] respectively. The HR for the RFS and OS comparing Group 1 vs 3 was 1.2 [95% CI (0.9-1.7)] and 1.2 [95% CI (0.8-1.6)]. We have stratified patients according to the European LeukemiaNet risk classification. In Group 1, the 4y-RFS was 79% in patients with Favorable Risk (FR) vs 55% in those with Intermediate Risk (IR) and 53% in patients with Adverse Risk (AR) [HR 1.2, 95% CI (0.6-2.3)] and the 4y-OS was 79% vs 54% vs 53% respectively [HR 1.3, 95% CI (0.6-2.5)]. In Group 2, the 4y-RFS was 100% in those with FR vs 83% in IR vs 33% in AR [HR 3.9, 95% CI (0.4-30)] and the 4y-OS was 100% vs 82% vs 36% respectively [HR 4, 95% CI (0.5-32%)]. In Group 3, the 4y-RFS in patients with FR was 82% vs 0% in IR vs 0% in AR [HR 2.1, 95% CI (1.1-4.1)] and the 4y-OS was 82% vs 0% vs 0% respectively [HR 1.6, 95% CI (0.8-3.3)] (Image 2). Conclusions: In our cohort, positive MRD >0.1% prior to transplant identified a group with worse RFS and OS compared to those with negative MRD or positive MRD level >0% but 0.1% is especially relevant in the IR and AR groups of the European LeukemiaNet risk classification. In the AR subgroup even any detectable level of positive MRD could identify patients with unfavorable post-transplant OS and RFS outcomes. We must establish post-transplant strategies in these patients to improve survival. Disclosures Garcia-Gutiérrez: Pfizer: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding; Incyte: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding; Bristol-Myers Squibb: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding; Novartis: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding.

Introduction: Among Therapy-Related Myeloid Neoplasms (t-MNs), there are two large groups depending on the cytotoxic trigger. A first group arises after exposure to alkylating agents and / or radiation in the previous 5-10 years and it is associated with unbalanced chromosomal abnormalities, frequently with alterations in Cr 5, 7, complex karyotype and mutated TP53. The second arises after exposure to topoisomerase II inhibitors in the previous 1-5 years, and it is characterized by frequent balanced translocations and KMT2A rearrangement. In those cases with a latency time from cytotoxic exposure to T-MNs diagnosis greater than 10 years, there is doubt about whether they should be considered T-MNs or de novo leukemias. Material and methods: We performed a retrospective analysis of 34 patients with diagnosis of T-MNs treated in our center between 2013 and 2019. We have reviewed the cytogenetic alterations at diagnosis and alterations in TP53 and / or 17p and rearrangements in KMT2A. We divided the cohort into two groups based on the latency time of ≤10 years or> 10 years. The comparison between both groups was carried out using the chi2 test for qualitative variables and the t-student for quantitative variables. The Kaplan Meier method has been used for the calculation of Overall Survival (OS) and Event Free Survival (EFS) and the Cox regression model for the univariate and multivariate analysis. Results: The median follow-up of the global cohort was 8.5 months (0-74). The median OS of the global cohort was 10 months and the EFS was 8 months. In patients with a latency time ≤10 years the median OS was 12 months vs 9 months in those with latency >10 years, with a Hazard Ratio (HR) of 0.6 [95% CI (0.2-1.7), p = 0.3] and the EFS was 7 months vs 9 months respectively [HR 0.3, 95% CI (0.3-1.8), p = 0.7]. The baseline characteristics of the population are reflected in Table 1. A similar percentage of patients with complex or monosomal karyotype at diagnosis is observed in both groups, as well as alterations in TP53 and/or 17p. In the >10-year latency subgroup, there were no patients with prior exposure to Topoisomerase II Inhibitors. Within the Conclusions: Patients with a latency time from exposure to cytotoxic therapy to the diagnosis of T-MNs > 10 years, presented cytogenetic and molecular characteristics similar to those with an exposure time ≤10 years, as well as a similar OS and EFS. Regarding the cytogenetic characteristics at diagnosis of the general cohort, patients with monosomic karyotype and especially those with TP53 and/or 17p alterations had a worse prognosis. Disclosures Garcia-Gutiérrez: Incyte:Consultancy, Other: Travel, Accommodation, Expenses, Research Funding;Novartis:Consultancy, Other: Travel, Accommodation, Expenses, Research Funding;Bristol-Myers Squibb:Consultancy, Other: Travel, Accommodation, Expenses, Research Funding;Pfizer:Consultancy, Other: Travel, Accommodation, Expenses, Research Funding.

Lysosomal diseases (LD) are a group of about 70 rare hereditary disorders (combined incidence 1:5000) in which diverse lysosomal functions are impaired, impacting multiple organs and systems. The first clinical signs and symptoms are usually unspecific and shared by hundreds of other disorders. Diagnosis of LD traditionally relies on performing specific enzymatic assays, if available, upon clinical suspicion of the disorder. However, the combination of the insidious onset of LD and the lack of awareness on these rare diseases among medical personnel results in undesirable diagnostic delays, with unchecked disease progression, appearance of complications and a worsened prognosis. We tested the usefulness of a next‐generation sequencing‐based gene panel for quick, early detection of LD among cases of idiopathic splenomegaly and/or thrombocytopenia, two of the earliest clinical signs observed in most LD. Our 73‐gene panel interrogated 28 genes for LD, 1 biomarker and 44 genes underlying non‐LD differential diagnoses. Among 38 unrelated patients, we elucidated eight cases (21%), five with LD (GM1 gangliosidosis, Sanfilippo disease A and B, Niemann‐Pick disease B, Gaucher disease) and three with non‐LD conditions. Interestingly, we identified three LD patients harboring pathogenic mutations in two LD genes each, which may result in unusual disease presentations and impact treatment. Turnaround time for panel screening and genetic validation was 1 month. Our results underline the usefulness of resequencing gene panels for quick and cost‐effective screening of LDs and disorders sharing with them early clinical signs.

Introduction: Cytogenetic and molecular landscape at diagnosis and the depth of response to induction therapy are the most powerful prognostic tools available in patients with Acute Myeloid Leukemia (AML). Among the tests to measure Minimal Residual Disease (MRD), one of the most commonly used is flow cytometry. Nowadays, there is no consensus about optimal time for measurement and the threshold above which has greater prognostic value in AML, as well as its involvement in therapeutic management. Material and methods: We performed a single-center retrospective analysis of 62 patients diagnosed with AML between 2015 and 2019 that reached complete remission after first induction. Patients were stratified according to the European Leukemia Net (ELN) risk classification. MRD measurement was made in bone marrow samples with an 8-color flow cytometer (sensitivity 10-5), cut-off 0.1%. We divided our cohort in two groups according to MRD after induction: negative MRD (MRD-) and positive MRD (MRD+). The baseline characteristics of each group were compared using the Chi2 test. The survival analysis was performed through Kaplan-Meier method and the risk was calculated with Cox regression. The Overall Survival (OS) was defined as the period of time from diagnosis to death and the leukemia-free state (LFS) as the period of time from CR to either relapse or death. Statistical analysis were carried out using SPSS version 19.0. P Results: Baseline characteristics of the sample are represented in Table 1. The median follow-up was 15 months (1-45). The 3-year LFS for MRD- and MRD+ was 50% and 29% respectively (figure 1A) showing a hazard ratio (HR) of 2.02 (CI 95% 0.98-4.6, p=0.05). The 3-year OS was 50% and 36% for MRD- and MRD+ respectively (figure 1B) and HR was 1.3 (CI 95% 0.6-2.8, p=0.4). In MRD+ group according to ELN risk classification, the 3-year LFS was 100% vs 21% vs 19% for favorable, intermediate and adverse risk, respectively (p=0.01) with a HR of 2.1 (CI 95% 1.1-3.9, p=0.01) in the univariate analysis. The 3-year OS was 100% vs 24% vs 18% for each subgroup (p=0.03) with a HR of 2.1 (CI 95% 1.06-4.4, p= 0.03). Thirty-eight patients received consolidation with hematopoietic stem cell transplantation (HSCT), and MRD prior to HSCT was measured in 32 of 38, being positive in 10 patients. All cases with MRD+ before HSCT belonged to MRD+ after induction group (10/20) (p=0.03). In MRD+ group, the 3-year LFS was 36% among those who received HSCT vs 18% in those who did not (log rank p=0.02, HR 3.1 CI 95% 1.3-7.8 p=0.01). Conclusions: The persistence of MRD > 0.1% after first induction by flow cytometry has shown in our population the identification of a AML subgroup of high risk, specially relevant in the intermediate risk group of ELN classification. MRD+ leads to higher risk of relapse, and these patients benefit from more aggressive therapeutic strategies, including allogeneic HSCT. However, MRD+ group has more risk of MRD persistence prior to HSCT, the last being a knowing factor of relapse after allogeneic HSCT, what would justify more aggressive strategies after HSCT in these patients. Disclosures Piris-Villaespesa: Novartis: Honoraria, Other: Advisory Boards. García Gutiérrez:BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Incyte: Honoraria, Research Funding.

Background: After long-term treatment with tyrosine kinase inhibitors (TKIs), an important proportion of patients with chronic myeloid leukemia (CML) achieve and maintain a deep molecular response (DMR) that allows them to stop treatment indefinitely. However, approximately 50% of these patients on treatment-free remission (TFR) experience relapse by undetermined reasons. It has been described that TKIs may induce a potent antileukemic response that conditions the outcome of the discontinuation. Our objective was to analyze different immune parameters that could be used as biomarkers of safer treatment discontinuation. Objectives: To determine the modulation of immune biomarkers that could be related to current treatment with TKIs on patients with CML ("On TKI") or to successful TFR in patients that maintain DMR after treatment withdrawal ("Off TKI") or to relapse after TFR on patients that lost DMR. Materials & methods: We analyzed by flow cytometry the peripheral blood mononuclear cells (PBMCs) from 45 patients with CML "On TKI" for at least 9 months (imatinib (11), nilotinib (9), dasatinib (20) or bosutinib (5)), 17 patients "Off TKI" for at least 7 months who kept DMR at the moment of sampling (last TKI before TFR: imatinib (7), nilotinib (6), dasatinib(4)), 7 patients "Off TKI" for at least 1 year and 4 months who relapsed during TFR (samples from 3 patients were taken previous to TKI reintroduction (on relapse); samples from 4 patients were taken after they restarted treatment with TKIs ("On TKI" relapse), 4 patients with recent diagnosis of CML still untreated, and 20 healthy donors as basal control. Results: 1) Patients characteristics are shown in table 1. 2) Treatment with TKIs induced an increase of 8.6±1.2% ((p Conclusions: Characterization of the immune response developed in patients with CML due to treatment with different TKIs may be relevant to predict the success of treatment discontinuation. We have determined that the modulation of the expression of the following markers may be used as potential predictors of TFR outcome: CD56+7%; CD56+NKG2D+>24%; CD8+TCRgd+>7%; CD8-TCRgd+>4%; CD86+ This work was supported by NIH grant R01AI143567 and the Spanish Ministry of Economy and Competitiveness SAF2016-78480-R. Disclosures Garcia-Gutiérrez: Novartis: Honoraria, Other: Advisory Committees. Piris-Villaespesa:Novartis: Honoraria, Other: Advisory Boards.

INTRODUCTION: The 2016 update of the World Health Organization (WHO) classification criteria for Polycythemia Vera (PV) included a decrease of the hemoglobin threshold. This modification increases exponentially the individuals with potential PV. International groups have proposed diagnostic algorithms for the screening of individuals with potential PV. However, these algorithms are not based on the prevalence of JAK2V617F in this population, and to our concern has not been prospectively validated. Our aim is to develop and validate an algorithm based on previously reported prevalence of JAK2V617F in individuals with potential PV in our environment. METHODS: This study was designed in two phases: a first phase for the development of the algorithm and a second phase for the validation of the algorithm. Phase 1: from previous data collected from our group of JAK2 V617F prevalence in individuals with erythrocytosis according to WHO criteria we performed an area under the curve (ROC) analysis with optimal cutoff point in order to maximize sensibility and specificity of the collected variables. The thresholds for platelets and neutrophils were selected for being clinically relevant and with an AUC >0.8. With these two variables and their optimal cutoff point, a sequential 2-step-algorithm was designed (figure 1). Phase 2: for the validation of the algorithm, hemograms from outpatient individuals were selected, and the "2-step-algorithm" was applied. Therefore, if samples met the criteria for step 1 (hemoglobin > 16.5 g/dl for men or 16 g/dl for women or hematocrit >49 % for men or 48 % for women) then, the step 2 was applied (platelets > 248x103/ml or neutrophils>5.98x103/ml). Finally, all samples that passed the 2-step-algorithm, were tested for JAK2 V617F. With the chosen samples a JAK2 V617F qualitative PCR with a sensibility of at least >0.1% was performed. The positive results were validated and quantified in our reference laboratory, and those with an allele burden >1% were considered positive. RESULTS: A total of 15298 hemograms were initially selected. Of those, 1595 (10.4%) met the erythrocytosis criterion (step 1). 581 (36%) of these met the step 2 criteria and the JAK2 V617F PCR was performed in 501 samples. A total of 7 positive cases (1.4%) were found, none of which was previously diagnosed of myeloproliferative neoplasm. The median of hemoglobin and hematocrit was 16.3 g/dl and 50.3% respectively. Of the selected samples, 2 of them met the platelet criterion, 4 of them the neutrophils criterion and 1 of them met both. After reviewing clinical records, 43.8% of them were found to have cardiovascular events history history: 1 patient had atherosclerosis of the lower limbs, 1 had acute coronary syndrome and 1 had an ischemic stroke. Characteristics of JAK2V617F individuals are detailed in table 1. Comparing to step 1, the addition of step 2 increases the efficiency of the algorithm 1.75 times. In order to know the prevalence of JAK2 V617F clonal hematopoiesis in our environment, 300 unselected samples were tested. We found 1 positive result. However, after reviewing clinical records, this sample was found to belong to a patient with known myeloproliferative neoplasm. Thus, JAK2 V617F prevalence in our environment was considered CONCLUSION: This "2-step-algorithm" is a reproducible and validated tool for the screening of JAK2 V617F myeloproliferative neoplasms. Disclosures Piris-Villaespesa: Novartis: Honoraria, Other: Advisory Boards. Martinez-Lopez:Incyte: Honoraria, Other: Advisory boards; Novartis: Honoraria, Other: Advisory boards; BMS: Honoraria, Other: Advisory boards; VIVIA Biotech: Honoraria; F. Hoffmann-La Roche Ltd: Honoraria; Amgen: Honoraria, Other: Non-Financial Support ; Janssen: Honoraria, Other: Advisory boards and Non-Financial Support ; Celgene: Honoraria, Other: Advisory boards and Non-Financial Support .

Bosutinib is a second-generation tyrosine kinase inhibitor (2GTKI) approved at 400 mg once daily (QD) as first-line therapy in patients with chronic myeloid leukemia (CML) patients and at 500 mg QD in patients who are resistant to or intolerant of prior therapy. In clinical practice, bosutinib is often given to patients who have failed imatinib, nilotinib, and dasatinib (i.e., as fourth-line treatment), despite the limited data on its clinical benefit in this setting. We have retrospectively evaluated the results of bosutinib in a series of 62 CML patients who have failed to prior treatment with all three, imatinib, nilotinib, and dasatinib. Median time on TKI treatment before bosutinib start was 105 (9–163) months, and median duration on bosutinib was 9 months (1–30). Overall, probabilities to achieve complete cytogenetic response (CCyR) and major molecular response (MMR) were 25% and 24% respectively. After a median follow-up period of 14 months, the event-free survival and progression-free survival were 68 and 85%, respectively. Sixty-four percent of patients in CCyR at the time of bosutinib start were able to achieve MMR. In contrast, patients without CCyR, probabilities to obtain CCyR and MMR were 25% and 14%. Bosutinib was well tolerated in this heavily pretreated patients’ cohort. Pleural effusions and diarrhea were the most frequent grade II–IV side effects, leading to treatment discontinuation in 16% of patients. Bosutinib is an effective treatment option for patients who have failed previous 2GTKIs due to intolerance. However, efficacy seems to be related to the molecular response that the patient achieved prior to bosutinib.

Background: Bone marrow (BM) examination is essential in the staging of diffuse large B-cell lymphoma (DLBCL). The assessment of BM involvement includes both histology (gold-standard) and flow cytometry (FC), but few studies have compared BM biopsy (BMB) histologic findings with results of FC analysis of BM aspirate. Discordance between both techniques generates debate about the staging and the prognostic significance in these cases. Methods: We performed a retrospective single-center analysis of patients with DLBCL, not otherwise specified (NOS) diagnosed during a 4-year period (2014-2017). Patients were divided in three groups according to BM findings of BMB and FC at diagnosis. Standard FC was performed by 4-color flow panel until 2016 and by 8-color FC since then. We described main characteristics of each group at diagnosis and analyzed survival outcomes. We applied means of descriptive statistics and Pearson's chi-squared test, and analyzed survival outcomes according to Kaplan-Meier, using Cox regression for comparisons. Results: We analyzed 59 cases, which were divided in three groups: 40 cases (67.8%) presented both negative histology and FC (BMB-/FC-), 10 (16.9%) showed BM involvement using both histology and FC (BMB+/FC+) and 9 cases (15.3%) presented discordant results, all of them with negative histology and positive FC (BMB-/FC+). Clinical and biological characteristics of each group at diagnosis are presented in Table 1. Median infiltration by FC analysis of the BMB-/FC+ group was 0.8% (0.1-2.9) and 3/9 patients presented discordant immunophenotype of lymphoma cells between BM and node biopsy. If we considered BM infiltration as positive in all BMB-/FC+ cases, 4/9 (6.8% of all patients) would be upstaged. First-line treatment was homogeneous in all patients. With a median observation time of 18 months, progression-free survival (PFS) after 2 years was 67%, 22% and 22% with BMB-/FC-, BMB-/FC+ and BMB+/FC+, respectively (Figure 1A), with a multivariate hazard ratio (HR) of 1.9 (95% CI 1.2-2.9, p=0.004) and an univariate HR for FC+ (BMB-/FC+ and BMB+/FC+) vs FC- (BMB-/FC-) of 3.3 (95% CI 1.5-7.3, p=0.003). Two-year overall survival (OS) was 68%, 41% and 33% with BMB-/FC-, BMB-/FC+ and BMB+/FC+, respectively (Figure 1B); multivariate HR was 1.6 (95% CI 1.1-2.6, p=0.042) and univariate HR for FC+ vs FC- was 2.5 (95% CI 1.1-5.9, p=0.035). We found no significant difference between BMB-/FC+ and BMB+/FC+ in survival outcomes. Conclusions: In our series, the group with discordant BM infiltration (BMB-/FC+) presented worsen survival outcomes than BMB-/FC-. Such results should be validated in prospective studies because published series are retrospective and not focused specifically on DLBCL. BM infiltration detected by FC analysis but not by BMB could be considered as extranodal involvement at DLBCL NOS diagnosis. Disclosures García Gutiérrez: Novartis: Consultancy, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Research Funding, Speakers Bureau; Incyte: Consultancy, Research Funding, Speakers Bureau.

Introduction: The diagnostic criteria for polycythemia vera (PV) has recently been updated by the World Health Organization (WHO). The criterion for erythrocytosis has been modified downwards: hemoglobin (hb)> 16.5 g/dL or hematocrit (hto)> 49% in men and hb> 16 g/dL or hto> 48% in women. This reduction increases the potential number of patients that would be test for JAK2 V617F mutation if PV is suspected. The V617F mutation in the JAK2 gene is present in 95% of cases of PV. It is estimated that the prevalence of this mutation in the general population is around 0.2%. Our aims are to determine the prevalence of JAK2 V617F in individuals with erythrocytosis according to WHO2016 criteria and to find prognostic factors that could help to identify patients with PV. Methods: We prospectively studied all hemograms performed in our laboratory during 7 nonconsecutive days. Variables studied were hb, hto, leukocytes, neutrophils, platelets, MCV, MCH, MCHC and RDW. JAK2 V617F mutation was studied in all males that had hb> 16.5 g/dl or hto> 49% or females that had hb> 16 g/dl or hto> 48%. JAK2 V617F mutation was studied by PCR assay in which an amplification control fragment and the JAK2 mutant allele were simultaneously amplified. All positive samples were confirmed by quantitative real-time PCR in a reference laboratory. Positive results were considered when the JAK2 V617F allele ratio was ≥ 0.7. The variables collected were correlated with the result of the JAK2 test in a univariate way. The T-Student test was used for the quantitative variables and the Chi-square test for the categorical variables. For the cell count variables, the Mann-Whitney U test was used. Results: A total of 15366 HG were analyzed. 1271 (8.3%) met the inclusion criteria for erythrocytosis. JAK2 V617F was performed on 1001 samples (270 samples were not suitable for the PCR assay due to low quality). Twelve samples (1.2%) were positive for JAK2 V617F mutation. However, 5 samples were excluded due to a known diagnosis of myeloproliferative neoplasm. Therefore, finally prevalence of JAK2 V617 mutation in 996 patients that met WHO erythrocytosis criteria was 0.8% (8/996). Medians for all parameter studied for each group are shown in table 1. In order to find out parameters that could increase the incidence probabilities to identify patients with JAK2 V617F we performed an univariate analysis of the variables included, according to JAK2 mutational status. We found that patients with JAK2 V617F had higher levels of leukocytes, neutrophils, platelets and RDW than patients with negative JAK2 (p Conclusion: The prevalence of JAK2 V617F mutation in subjects with elevated Hb or hto according to WHO2016 criteria is increased with respect to that of the general population. Among this group of subjects, those with JAK2 V617F show significantly different levels of leukocytes, neutrophils, platelets, MCV, CMH and RDW. Interestingly, neutrophils, platelets and RDW show high sensitivity and specificity. Therefore, it is necessary to explore combinations of these parameters and their optimal cut-off points to elaborate efficient strategies for an early diagnostic approach. Disclosures Martinez Lopez: Bristol Myers Squibb: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau; Celgene: Research Funding, Speakers Bureau; Janssen: Research Funding, Speakers Bureau. García Gutiérrez:Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Incyte: Honoraria, Research Funding.

Chronic lymphocytic leukemia (CLL) is an incurable disease in need of new therapeutic strategies. The immunomodulatory agent, lenalidomide, has shown activity as salvage therapy for CLL. In this phase II trial, we combined lenalidomide with rituximab in 25 patients (range, 41-79) with refractory/relapsed CLL. Lenalidomide was administered orally on escalating doses, with cycle 1 doses of 2.5mg daily on days 1-7, 5mg on days 8-14, and 10mg on days 15-21 followed by 7days off. On cycle 2 and beyond, lenalidomide was administered at 20mg daily on days 1-21. Rituximab was administered at 375mg/m(2) intravenously on a weekly basis for the first cycle starting on day 15 for 4 doses, with each cycle being 28days. Treatment was continued until disease progression or toxicity. Overall response rate was 45.8% on intent-to-treat and 61.1% in evaluable patients (all partial responses). Median time to treatment failure was 14.3 months for evaluable patients, and median overall survival was not reached. The most common grade 3/4 toxicity was neutropenia (72% of patients). The most common nonhematologic toxicity was infection (29% of patients). Lenalidomide combined with rituximab showed activity in heavily treated refractory CLL with an acceptable toxicity profile.

There is a demand to understand B-cell lymphoma pathogenesis better, to identify new markers, and to define multiple lymphoproliferative disorders more accurately. MicroRNAs (miRNAs) are regulators of protein translation, comprising a group of more than 1500 short noncoding single-strand RNA molecules of approximately 22 nucleotides in length. They are easily detectable in fresh or paraffin-embedded diagnostic tissue and serum. Expression of individual miRNAs and miRNA signatures allows specific cell-differentiation stages to be identified, and is a powerful diagnostic and prognostic method. Here we review what is known about the pathogenic relevance of miRNAs, and use of miRNAs for the diagnosis and prognosis of B-cell lymphomas. Most of the published data concern chronic lymphocytic lymphoma and diffuse large B-cell lymphoma, and implicate miRNAs in the pathogenesis of these diseases. They identify miRNAs that could be used for diagnosis, prognosis, or prediction of response to specific therapies.

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the Western world. Pathogenic mechanisms involve multiple external events (such as microenvironmental and antigenic stimuli) and internal events (genetic and epigenetic alterations) that are associated with the transformation, progression and evolution of CLL. CLL is characterized by an accumulation of mature B cells in peripheral blood, bone marrow and lymphoid tissues. Extracellular stimuli play an important role in the development and maintenance of neoplastic cells. B-CLL cells proliferate and activate pathogenic signaling pathways in anatomical structures known as proliferation centers, which are usually more conspicuous in involved lymph nodes.1 Its clinical course is quite heterogeneous, whereby some patients progress rapidly and have short survival, whereas others have a more stable clinical course that may not need treatment for years. This work was supported by grants from the Ministerio de Economía y Competitividad (MINECO) (SAF2013-47416-R) Instituto de Salud Carlos III (ISCIII)- FEDER – MINECO- AES (CP11/00018, PI10/00621, RD012/0036/0060), and Asociación Española contra el Cancer (AECC). MS-B is supported by a Miguel Servet contract from ISCIII-FEDER (CP11/00018). Salary support to SG is provided by CP11/00018, from ISCIII-FEDER. JG-R is supported by a predoctoral grant from the Fundación Investigación Puerta de Hierro. Sí