Alberto Bosi

Prospective identification of high-risk polycythemia vera patients based on JAK2(V617F) allele burden.

The aim of this study was to determine whether the burden of JAK2V617F allele correlated with major clinical outcomes in patients with polycythemia vera (PV). To this end, we determined JAK2 mutant allele levels in granulocytes of 173 PV patients at diagnosis. The mean (±s.d.) mutant allele burden was 52% (±29); 32 patients (18%) had greater than 75% mutant allele. The burden of JAK2V617F allele correlated with measurements of stimulated erythropoiesis (higher hematocrit, lower mean cell volume, serum ferritin and erythropoietin levels) and myelopoiesis (higher white cell count, neutrophil count and serum lactate dehydrogenase) and with markers of neutrophil activation (elevated leukocyte alkaline phosphatase and PRV-1 expression). As compared to those with less than 25% mutant allele, patients harboring greater than 75% JAK2V617F allele were at higher relative risk (RR) of presenting larger spleen (RR 4.7; P<0.001) or suffering from pruritus (RR 3.1; P<0.001). In these patients, the risk of requiring chemotherapy (RR 1.8; P=0.001) or developing major cardiovascular events (RR 7.1; P=0.003) during follow up were significantly increased. We conclude that a burden of JAK2V617F allele greater than 75% at diagnosis points to PV patients with high-risk disease.

Impact of calreticulin mutations on clinical and hematological phenotype and outcome in essential thrombocythemia.

Mutations in the calreticulin (CALR) gene were recently discovered in patients with essential thrombocythemia (ET) lacking the JAK2V617F and MPLW515 mutations, but no information is available on the clinical correlates. In this series, CALR mutations were found in 15.5% of 576 World Health Organization-defined ET patients, accounting for 48.9% of JAK2 and MPL wild-type (wt) patients. CALR-mutated patients were preferentially male and showed higher platelet count and lower hemoglobin and leukocyte count compared with JAK2- and MPL-mutated patients. Patients carrying the CALR mutation had a lower risk of thrombosis than JAK2- and MPL-mutated patients; of interest, their risk was superimposable to patients who were wt for the above mutations. CALR mutation had no impact on survival or transformation to post-ET myelofibrosis. Genotyping for CALR mutations represents a novel useful tool for establishing a clonal myeloproliferative disorder in JAK2 and MPL wt patients with thrombocytosis and may have prognostic and therapeutic relevance.

Clinical implications of the JAK2 V617F mutation in essential thrombocythemia.

istic upmodulation of CD20 and downmodulation of CD10, comparable to the immunophenotypic modulation observed in vivo. In contrast, the viable 7-AAD-negative cells retained their original immunophenotype (Figure 2e, f). For each antibody, the MFI differed between the viable and dead cells, but within these two populations the MFI was not affected by the type and dose of the cytotoxic agents to which the cells were exposed (data not shown). Further analysis of dead and viable cells showed that dead cells had a higher MFI for each isotype control antibody than viable cells. This increase in background staining was comparable to the upmodulation of CD20 on CD20-negative leukemic cells observed in day 15 and 28 samples. Altogether, these data indicate that the immunophenotypic modulation observed in vitro is due to the induction of cell kill, resulting in a higher aspecific staining and a decreased expression of membrane antigens. Our data suggest that in ALL patients undergoing treatment, immunophenotypic modulation is caused by drug-induced cell death, resulting in loss of membrane antigens and higher aspecific staining. Our data are in agreement with a recent study, which showed that the loss of expression of lineage antigens (such as CD19) is a common feature of lymphocytes undergoing apoptosis and that the MFI for different antigens might drop to undetectable levels during different stages of apoptosis. Antigens coexpressed on the same cells showed different degrees of loss in the different stages of apoptosis, suggesting that it is a specific, active process, rather than a general degradation of cell components. Our observation that immunophenotypic modulation is due to apoptotic cells also explains why ALL blast cells in resistant patients show no modulation. In conclusion, our data indicate that immunophenotypic modulation in ALL patients undergoing treatment can (at least in part) be explained by the induction of cell death. As the presence of these dying cells may still be clinically relevant, usage of strict gating procedures, based on the exact immunophenotype of the blast cells at diagnosis, should be avoided for the analysis of MRD.

Characteristics and clinical correlates of MPL 515W>L/K mutation in essential thrombocythemia.

Among 994 patients with essential thrombocythemia (ET) who were genotyped for the MPLW515L/K mutation, 30 patients carrying the mutation were identified (3.0%), 8 of whom also displayed the JAK2V671F mutation. MPLW515L/K patients presented lower hemoglobin levels and higher platelet counts than did wild type (wt) MPL; these differences were highly significant compared with MPLwt/JAK2V617F-positive patients. Reduced hemoglobin and increased platelet levels were preferentially associated with the W515L and W515K alleles, respectively. MPL mutation was a significant risk factor for microvessel disturbances, suggesting platelet hyperreactivity associated with constitutively active MPL; arterial thromboses were increased only in comparison to MPLwt/JAK2wt patients. MPLW515L/K patients presented reduced total and erythroid bone marrow cellularity, whereas the numbers of megakaryocytes, megakaryocytic clusters, and small-sized megakaryocytes were all significantly increased. These data indicate that MPLW515L/K mutations do not define a distinct phenotype in ET, although some differences depended on the JAK2V617F mutational status of the counterpart.

EZH2 mutational status predicts poor survival in myelofibrosis.

We genotyped 370 subjects with primary myelofibrosis (PMF) and 148 with postpolycythemia vera/postessential thrombocythemia (PPV/PET) MF for mutations of EZH2. Mutational status at diagnosis was correlated with hematologic parameters, clinical manifestations, and outcome. A total of 25 different EZH2 mutations were detected in 5.9% of PMF, 1.2% of PPV-MF, and 9.4% of PET-MF patients; most were exonic heterozygous missense changes. EZH2 mutation coexisted with JAK2V617F or ASXL1 mutation in 12 of 29 (41.4%) and 6 of 27 (22.2%) evaluated patients; TET2 and CBL mutations were found in 2 and 1 patients, respectively. EZH2-mutated PMF patients had significantly higher leukocyte counts, blast-cell counts, and larger spleens at diagnosis, and most of them (52.6%) were in the high-risk International Prognostic Score System (IPSS) category. After a median follow-up of 39 months, 128 patients (25.9%) died, 81 (63.3%) because of leukemia. Leukemia-free survival (LFS) and overall survival (OS) were significantly reduced in EZH2-mutated PMF patients (P = .028 and P < .001, respectively); no such impact was seen for PPV/PET-MF patients, possibly due to the low number of mutated cases. In multivariate analysis, survival of PMF patients was predicted by IPSS high-risk category, a < 25% JAK2V617F allele burden, and EZH2 mutation status. We conclude that EZH2 mutations are independently associated with shorter survival in patients with PMF.

Identification of patients with poorer survival in primary myelofibrosis based on the burden of JAK2V617F mutated allele.

A total of 186 patients with primary myelofibrosis (PMF) were genotyped for JAK2V617F at diagnosis aimed at analyzing the correlation of mutational status and mutated allele burden with outcome variables, including time to anemia, leukocytosis, leukopenia, thrombocytopenia, massive splenomegaly, leukemia, and with overall survival. A total of 127 JAK2V617F-mutated patients (68% of whole series) were divided in quartiles of V617F allele burden. After a median follow-up of 17.2 months, 23 patients died, 15 because of leukemia. A JAK2V617F mutated status did not impact on the rate of leukemia transformation or overall survival. Patients in the lower quartile had shorter time to anemia and leukopenia and did not progress to large splenomegaly. Furthermore, survival was significantly reduced in the lower quartile compared with upper quartiles and JAK2 wild-type patients. In multivariate analysis, factors associated with reduced survival were age, a blast count more than 1%, and a JAK2V617F burden within first quartile. Causes of death in the lower quartile were represented mainly by systemic infections. We conclude that a low JAK2V617F allele burden at diagnosis is preferentially associated with a myelodepletive rather than myeloproliferative phenotype and represents an independent factor associated with shortened survival in patients with PMF.

WHO classification and WPSS predict posttransplantation outcome in patients with myelodysplastic syndrome: a study from the Gruppo Italiano Trapianto di Midollo Osseo (GITMO).

We evaluated the impact of World Health Organization (WHO) classification and WHO classification-based Prognostic Scoring System (WPSS) on the outcome of patients with myelodysplastic syndrome (MDS) who underwent allogeneic stem cell transplantation (allo-SCT) between 1990 and 2006. Five-year overall survival (OS) was 80% in refractory anemias, 57% in refractory cytopenias, 51% in refractory anemia with excess blasts 1 (RAEB-1), 28% in RAEB-2, and 25% in acute leukemia from MDS (P = .001). Five-year probability of relapse was 9%, 22%, 24%, 56%, and 53%, respectively (P < .001). Five-year transplant-related mortality (TRM) was 14%, 39%, 38%, 34%, and 44%, respectively (P = .24). In multivariate analysis, WHO classification showed a significant effect on OS (P = .017) and probability of relapse (P = .01); transfusion dependency was associated with a reduced OS (P = .01) and increased TRM (P = .037), whereas WPSS showed a prognostic significance on both OS (P = .001) and probability of relapse (P < .001). In patients without excess blasts, multilineage dysplasia and transfusion dependency affected OS (P = .001 and P = .009, respectively), and were associated with an increased TRM (P = .013 and P = .031, respectively). In these patients, WPSS identified 2 groups with different OS and TRM. These data suggest that WHO classification and WPSS have a relevant prognostic value in posttransplantation outcome of MDS patients.

Second Allogeneic Bone Marrow Transplantation in Acute Leukemia: Results of a Survey by the European Cooperative Group for Blood and Marrow Transplantation

PURPOSE Leukemic relapse is the most frequent cause of treatment failure after allogeneic hematopoietic stem-cell transplantation (HSCT). To identify prognostic factors affecting the outcome of second HSCT, we performed a retrospective study on patients with acute leukemia (AL) undergoing second HSCT who reported to the Acute Leukemia Working Party of the European Cooperative Group for Blood and Marrow Transplantation registry. PATIENTS AND METHODS One hundred seventy patients who received second HSCTs for AL experienced relapse after first HSCTs were performed from 1978 to 1997. Status at second HSCT, time between first and second HSCT, conditioning regimen, source of stem cells, treatment-related mortality (TRM), acute graft-versus-host disease (aGVHD), leukemia-free survival (LFS), overall survival (OS), and relapse were considered. RESULTS Engraftment occurred in 97% of patients. Forty-two patients were alive at last follow-up, with a 5-year OS rate of 26%. The 5-year probability for TRM, LFS, and relapse was 46%, 25%, and 59%, respectively. Grade > or = 2 aGVHD occurred in 59% of patients, and chronic GVHD occurred in 32%. In multivariate analysis, diagnosis, interval to relapse after first HSCT > 292 days, aGVHD at first HSCT, complete remission status at second HSCT, use of total-body irradiation at second HSCT, acute GVHD at second HSCT, and use of bone marrow as source of stem cells at second HSCT were associated with better outcome. CONCLUSION Second HSCT represents an effective therapeutic option for AL patients relapsed after allogeneic HSCT, with a 3-year LFS rate of 52% for the subset of patients who experienced relapse more than 292 days after receiving the first HSCT and who were in remission before receiving the second HSCT.

Treatment of refractory chronic GVHD with rituximab: a GITMO study

The anti-CD20 chimaeric monoclonal antibody Rituximab has recently been shown to induce significant clinical response in a proportion of patients with refractory chronic graft-versus-host disease (cGVHD). We now report 38 patients, median age 48 years (22–61), receiving Rituximab for refractory cGVHD, assessed for clinical response and survival. Median duration of cGVHD before Rituximab was 23 months (range 2–116), the median number of failed treatment lines was 3 (range 1 to ⩾6) and the median follow-up after Rituximab was 11 months (1–88). Overall response rate was 65%: skin 17/20 (63%), mouth 10/21 (48%), eyes 6/14 (43%), liver 3/12 (25%), lung 3/8 (37.5%), joints 4/5, gut 3/4, thrombocytopaenia 2/3, vagina 0/2, pure red cell aplasia 0/1 and, myasthenia gravis 1/1. During the study period 8/38 died: causes of death were cGVHD progression (n=3), disease relapse (n=1), infection (n=3), sudden death (n=1). The actuarial 2 year survival is currently 76%. We confirm that Rituximab is effective in over 50% of patients with refractory cGVHD and may have a beneficial impact on survival.

Anaemia characterises patients with myelofibrosis harbouring MplW515L/K mutation

The clinical and haematological phenotype of patients with myelofibrosis harbouring MPLW515L/K mutation has not been thoroughly investigated. Of 217 myelofibrosis subjects, 18 (8·2%) had an MPL mutation, four of which (22%) co‐existed with JAK2V617F mutation. When compared with MPL wild‐type patients, irrespective of JAK2V617F status, those with MPLW515L/K, were more frequently female, were older (61 years vs. 57 years; P = 0·02), presented with more severe anaemia (haemoglobin, 101 g/l vs. 121 g/l; P = 0·002) and were more likely to require regular transfusional support (P = 0·012). These data indicate that MPL mutation in myelofibrosis characterises patients with more severe anaemic phenotype.