Cristalina Fernández

Prognostic value of minimal residual disease (MRD) in acute myeloid leukemia (AML) with favorable cytogenetics [t(8;21) and inv(16)]

Most patients with acute myeloid leukemia (AML) and t(8;21) or inv(16) have a good prognosis with current anthracycline- and cytarabine-based protocols. Tandem analysis with flow cytometry (FC) and real-time RT-PCR (RQ-PCR) was applied to 55 patients, 28 harboring a t(8;21) and 27 an inv(16), including one case with a novel CBFbeta/MYH11 transcript. A total of 31% (n=17) of CR patients relapsed: seven with t(8;21) and 10 with inv(16). The mean amount of minimal residual disease (MRD) detected by FC in relapsed and nonrelapsed patients was markedly different: 0.3 vs 0.08% (P=0.002) at the end of treatment. The mean number of fusion transcript copies/ABLx104 also differed between relapsed and non-relapsed patients: 2385 vs 122 (P=0.001) after induction, 56 vs 7.6 after intensification (P=0.0001) and 75 vs 3.3 (P=0.0001) at the end of chemotherapy. Relapses were more common in patients with FC MRD level >0.1% at the end of treatment than in patients with ⩽0.1%: cumulative incidence of relapse (CIR) was 67 and 21% (P=0.03), respectively. Likewise, using RQ-PCR, a cutoff level of >10 copies at the end of treatment correlated with a high risk of relapse: CIR was 75% for patients with RQ-PCR >10 compared to 21% for patients with RQ-PCR levels ⩽10 (P=0.04). Combined use of FC and RQ-PCR may improve MRD detection, and provide useful clinical information on relapse kinetics in AML patients.

Acute myeloid leukemia with MLL rearrangements: clinicobiological features, prognostic impact and value of flow cytometry in the detection of residual leukemic cells.

The MLL gene, located at 11q23 band, is frequently disrupted by different chromosomal rearrangements that occur in a variety of hematological malignancies. MLL rearrangements are associated with distinct clinical features and a poor prognosis. The aim of this study was to analyze the incidence and the prognostic significance of MLL rearrangements in a consecutive series of adult AML patients and to determine the immunophenotypic features of these cases. The identification of abnormal immunophenotypes could be used for the detection of minimal residual disease (MRD). Ninety-three adult patients with de novo acute myeloid leukemia (AML) were analyzed by Southern blot in order to detect MLL rearrangements (MLL+). RT-PCR and genomic long-range PCR were performed to further characterize MLL partial tandem duplication (PTD) in those patients in whom conventional karyotype did not show 11q23 chromosomal translocations. All the patients were homogeneously immunophenotyped at diagnosis. MLL rearrangements were detected in 13 (14%) patients. Four patients (5%) showed 11q23 translocations by karyotypic conventional analysis. Nine patients (10%) revealed PTD of MLL and one patient showed a MLL cleavage pattern. The MLL+ patients usually expressed myeloid and monocytic antigens CD33 (12/13 cases), CD13 (9/13), CD117 (9/13), CD64 (11/13) and in some cases CD14 (4/11). HLA-DR was also positive in (12/13). Eight out of 13 cases expressed the stem cell marker CD34. Only one patient revealed lymphoid marker reactivity (CD7) and CD56 was expressed in 5/13 cases. All the MLL+ patients showed at least one aberrant phenotype at diagnosis, which allowed us to set out a simple panel for the MRD studies. Twenty-seven samples from eight patients in morphologic complete remission (CR) were analyzed using the aberrant immunologic combinations detected at diagnosis. Phenotypically abnormal cells were detected in all the patients who subsequently relapsed, whereas only one patient with MRD+ remained in CR. Owing to the high level of residual leukemic cells, the MLL+ patients showed a short CR duration and a poor survival. In conclusion, immunophenotyping may be a suitable approach to investigating MRD status in AML patients with PTD of the MLL gene.

Donor CTLA-4 genotype influences clinical outcome after T cell-depleted allogeneic hematopoietic stem cell transplantation from HLA-identical sibling donors.

CTLA-4 (cytotoxic T-lymphocyte antigen-4) plays a pivotal role in inhibiting T cell activation through competitive interaction with B7 molecules and interruption of costimulatory signals mediated by CD28. Polymorphisms on the CTLA-4 gene have been previously associated with autoimmune diseases, predisposition to leukemic relapse, and with graft-versus-host disease (GVHD) or relapse after allogeneic transplant. As CTLA-4 is expressed on T-lymphocytes, the aim of this study was to determine whether the donor CTLA-4 CT60 genotype also influences clinical outcome even after T cell depletion with CD34-positive selection. We studied 136 patient-donor pairs. Overall survival (OS) was worse for those patients who received grafts from a donor with the CT60 AA genotype rather than from a donor with the AG or GG genotype (35.6% vs 49.4%; P = .043). This association was confirmed through multivariate analysis, which identified the donor CT60 genotype as an independent risk factor for OS (P = .008; hazard ratio [HR]: 2.24, 95% confidence interval [CI]: 1.23-4.08). The donor CT60 AA genotype was also associated with lower disease-free survival, this being related to an increased risk of relapse (P = .001; HR: 3.41, 95% CI: 1.67-6.96) and a trend toward higher transplant-related mortality. These associations were stronger when considering only patients in the early stage of disease. Our results suggest that graft-versus-leukemia (GVL) activity after T cell depletion is conditioned by the donor CTLA-4 genotype.

Co-existence of JAK2 V617F and CALR mutations in primary myelofibrosis

In December 2013 mutations were described in the calreticulin (CALR) gene in 67–71% and 56–88% of patients with JAK2 V617F and MPL negative essential thrombocythemia (ET) and primary myelofibrosis (PMF), respectively [1,2]. Since this discovery, not only have CALR mutations been recommended to be included in the diagnostic algorithm for myeloproliferative neoplasms [3], but also CALR exon 9 mutations have been recognized to have clinical utility, as patients with these mutations have a better outcome than JAK2 V617F positive patients [4,5]. CALR mutations have also been reported to be mutually exclusive from JAK2 V617F or MPL mutations [1,2], so the majority of retrospective studies do not test for CALR mutations in JAK2 V617F or MPL positive patients. Recently, some series have described patients harboring mutations in both JAK2 V617F and CALR genes [5–7], but the true frequency of patients with “double-positive” disease is unknown, as mutations in JAK2 V617F, MPL and CALR are not routinely studied in all patients. For this reason, the objective of this study was to establish the true frequency of patients with double-positive PMF. Peripheral blood or bone marrow samples were obtained from 73 patients (45 males, median age 69 years) diagnosed with PMF according to the World Health Organization (WHO) classification [8]. Written informed consent for sample collection was received from all participants. DNA was extracted from blood or bone marrow samples collected in ethylenediaminetetraacetic acid anticoagulant using a QiaAmp DNA Blood Mini Kit (Qiagen, Hilden, Germany) and diluted with double-distilled water. In compliance with the Declaration of Helsinki this study was approved by the Institutional Review Board of the Hospital Germans Trias i Pujol. In all patients JAK2 V617F, MPL and CALR mutations were studied. To detect the presence of JAK2 V617F mutation, an allele-specific polymerase chain reaction (PCR) with TaqMan probes was used. We employed Sanger sequencing to detect MPL exon 10 mutations. Moreover we screened for insertions or deletions in the CALR gene with 6-carboxyfluorescein (6-FAM) labeled primers spanning exon 9 as previously described [1]. We confirmed and described the CALR mutation type with Sanger sequencing. A total of 46 out of 73 (63%) patients were JAK2 V617F positive, and among the 27 JAK2 V617F negative patients, five had MPL mutations (18.5%). Twelve patients out of 73 (16.5%) had a CALR mutation (eight type 1, one type 2 and three different from the 36 described). One patient harbored both JAK2 V617F and CALR mutations (c.1142_1144del) (Figure 1), the other 11 patients being JAK2 V617F and MPL negative. The biological implication of this mutation is unknown, as it implies the deletion of one amino acid but the reading frame does not change, and the somatic nature of this alteration could not be confirmed in constitutional DNA as the patient died of acute myocardial infarction in October 2011. In our series, 85% of patients carried a JAK2 V617F, MPL or CALR mutation, and a single patient had JAK2 V617F and CALR double-positive disease, representing 1.4% of the cohort studied. The patient with double-positive disease was an 86-yearold male with hemoglobin of 142 g/L, white blood cell count 11.7  109/L, platelet count 1170  109/L and a history of rectorrhagia. A diagnosis of PMF was made on the basis of the clinical characteristics, morphology and JAK2 V617F mutation status (allele burden of 60.58%). To date, and taking into account the present study, only four patients have been described (two with ET and two with PMF) with concurrent JAK2 V617F and CALR exon 9 mutations [5–7]; however, this percentage could be underLeukemia & Lymphoma, October 2015; 56(10): 2973–2974

Pentasomy 21 with two isochromosomes 21 in a case of acute myeloid leukemia without maturation

Here, we report a 72-year-old male patient with acute myeloid leukemia (AML) without maturation. Cytogenetic study of a bone marrow culture revealed the following karyotype: 47,XX,+21,+i(21)(q10)x2. Fluorescence in situ hybridization study with a locus specific probe for 21q22 verified a pentasomy of 21q as a sole clonal cytogenetic abnormality. To our knowledge, this is the first report of pentasomy 21q in AML without Down syndrome.

Frequency of ABL gene mutations in chronic myeloid leukemia patients resistant to imatinib and results of treatment switch to second-generation tyrosine kinase inhibitors

BACKGROUND AND OBJECTIVES Tyrosine kinase inhibitors (TKI) have improved the management of patients with chronic myeloid leukemia (CML). However, a significant proportion of patients do not achieve the optimal response or are resistant to TKI. ABL kinase domain mutations have been extensively implicated in the pathogenesis of TKI resistance. Treatment with second-generation TKI has produced high rates of hematologic and cytogenetic responses in mutated ABL patients. The aim of this study was to determine the type and frequency of ABL mutations in patients who were resistant to imatinib or had lost the response, and to analyze the effect of second-generation TKI on their outcome. PATIENTS AND METHODS The presence of ABL mutations in 45 CML patients resistant to imatinib was evaluated by direct sequencing and was correlated with the results of the cytogenetic study (performed in 39 cases). The outcome of these patients after therapy with nilotinib or dasatinib was analyzed. RESULTS ABL mutations were detected in 14 out of 45 resistant patients. Patients with clonal cytogenetic evolution tended to develop mutations more frequently than those without clonal evolution. Nine out of the 15 patients with ABL mutation responded to a treatment switch to nilotinib (n=4), dasatinib (n=2), interferon (n=1) or hematopoietic stem cell transplantation (n=2). CONCLUSION The frequency of ABL mutations in CML patients resistant to imatinib is high and is more frequent among those with clonal cytogenetic evolution. The change to second-generation TKI can overcome imatinib resistance in most of the mutated patients.

Highly variable mutational profile of ASXL1 in myelofibrosis

Somatic mutations in ASXL1 seem to have a negative prognostic impact in patients with several myeloid neoplasms, including myelofibrosis (MF). The aim of this work was to determine the prevalence and profile of ASXL1 mutations in MF.

Linfocitosis B policlonal persistente: estudio de 35 casos

BACKGROUND AND OBJECTIVES Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare entity, presenting especially in adult smoker women. It is characterized by an increase of serum IgM, DR7-HLA haplotype, cytogenetic abnormalities and multiple IgH/BCL-2 rearrangements. To date, it has not been elucidated whether this is a benign or premalignant disorder. We analyzed the PPBL characteristics with especial attention to its evolution. PATIENTS AND METHODS Thirty-five PPBL patients from 5 hospitals in Catalonia were retrospectively analyzed. A simultaneous morphologic review of the blood smears was performed by members of the GCCH in a 16 multiple-observer optic microscope. Clinical and biological data were also analyzed. RESULTS PPBL presents in the majority of cases with persistent polyclonal B-cell lymphocytosis and affects primarily smoker women. The morphologic hallmark, in absence of viral infections, is the presence of activated lymphocytes with bilobulated and/or cleaved nuclei, and nuclear pockets in the ultrastructural study. Increased serum IgM, HLA-DR7 haplotype, chromosomal abnormalities such as i(3)(q10) and multiple IgH/BCL-2 rearrangements were detected. Thirty-four out of 35 patients are alive after a median follow up of 70.7 months. One patient died because of lung adenocarcinoma and another developed a follicular lymphoma without relation to PPBL. CONCLUSIONS PPBL has an asymptomatic and stable evolution, although it frequently presents genetic abnormalities. It remains unknown whether it is a premalignant entity, similar to monoclonal gammopathies of unknown significance. Hence, accurate cytologic diagnosis and follow-up are essential.