Recurrent genetic defects on chromosome 5q in myeloid neoplasms.

BACKGROUND: Deletion of chromosome 5q (del(5q)) is the most common karyotypic abnormality in myeloid neoplasms. MATERIALS AND METHODS: To define the pathogenic molecular features associated with del(5q), next-generation sequencing was applied to 133 patients with myeloid neoplasms (MDS; N = 69, MDS/MPN; N = 5, sAML; N = 29, pAML; N = 30) with del(5q) as a sole abnormally or a part of complex karyotype and results were compared to molecular features of patients diploid for chr5. FINDINGS: A number of 5q genes with haploinsufficient expression and/or recurrent somatic mutations were identified; for these genes, CSNK1A1 and G3BP1 within the commonly deleted 5q region and DDX41 within a commonly retained region were most commonly affected by somatic mutations. These genes showed consistent haploinsufficiency in deleted cases; low expression/mutations of G3BP1 or DDX41 were associated with poor survival, likely due to decreased cellular function. The most common mutations on other chromosomes in patients with del(5q) included TP53, and mutations of FLT3 (ITD or TKD), NPM1 or TET2 and were mutually exclusive. Serial sequencing allowed for definition of clonal architecture and dynamics, in patients with exome sequencing allelic imbalance for informative SNPs facilitated simultaneous approximation of clonal size of del(5q) and clonal burden for somatic mutations. INTERPRETATION: Our results illuminate the spectrum of molecular defects characteristic of del(5q), their clinical impact and succession of stepwise evolution.

Cell intrinsic and extrinsic factors synergize in mice with haploinsufficiency for Tp53, and two human del(5q) genes, Egr1 and Apc.

Therapy-related myeloid neoplasms (t-MN) are a late complication of the successful use of cytotoxic therapy for patients with cancer. A heterozygous deletions of the long arm of chromosome 5 [del(5q)], observed in 40% of patients, is associated with prior exposure to alkylating agents, and a high frequency of TP53 loss or mutation. In previous studies, we demonstrated that haploinsufficiency of 2 del(5q) genes, Egr1, and Apc, individually play a role in the pathogenesis of hematologic disease in mice. We now show that loss of one copy of Egr1 or Tp53 in an Apc haploinsufficient background (Apc (del/+)) accelerated the development of a macrocytic anemia with monocytosis, early features of t-MN. The development of anemia was significantly accelerated by treatment of mice with the alkylating agent, N-ethyl-N-nitrosourea (ENU), regardless of the levels of expression of Egr1 and Tp53. Transplantation of either wild type; Egr1(+/-); Tp53(+/-); Apc(del/+); or Egr1(+/-), Apc(del/+) bone marrow cells into lethally irradiated Apc(del/+) recipients resulted in rapid development of anemia that was further accelerated by administration of ENU to recipients, demonstrating that the Apc(del/+)-induced anemia was cell extrinsic and potentiated by ENU mutagenesis. These data emphasize the synergistic role of cell intrinsic and cell extrinsic (microenvironment) factors in the pathogenesis of t-MN, and raise awareness of the deleterious effects of cytotoxic therapy on the stromal microenvironment.

TP53 mutations in myelodysplastic syndrome are strongly correlated with aberrations of chromosome 5, and correlate with adverse prognosis.

This study aimed to determine the incidence/prognostic impact of TP53 mutation in 318 myelodysplastic syndrome (MDS) patients, and to correlate the changes to cytogenetics, single nucleotide polymorphism array karyotyping and clinical outcome. The median age was 65 years (17-89 years) and median follow-up was 45 months [95% confidence interval (CI) 27-62 months]. TP53 mutations occurred in 30 (9.4%) patients, exclusively in isolated del5q (19%) and complex karyotype (CK) with -5/5q-(72%), correlated with International Prognostic Scoring System intermediate-2/high, TP53 protein expression, higher blast count and leukaemic progression. Patients with mutant TP53 had a paucity of mutations in other genes implicated in myeloid malignancies. Median overall survival of patients with TP53 mutation was shorter than wild-type (9 versus 66 months, P < 0.001) and it retained significance in multivariable model (Hazard Ratio 3.8, 95%CI 2.3-6.3,P < 0.001). None of the sequentially analysed samples showed a disappearance of the mutant clone or emergence of new clones, suggesting an early occurrence of TP53 mutations. A reduction in mutant clone correlated with response to 5-azacitidine, however clones increased in non-responders and persisted at relapse. The adverse impact of TP53 persists after adjustment for cytogenetic risk and is of practical importance in evaluating prognosis. The relatively common occurrence of these mutations in two different prognostic spectrums of MDS, i.e. isolated 5q- and CK with -5/5q-, possibly implies two different mechanistic roles for TP53 protein.

Impact of adjunct cytogenetic abnormalities for prognostic stratification in patients with myelodysplastic syndrome and deletion 5q.

This cooperative study assessed prognostic factors for overall survival (OS) and risk of transformation to acute myeloid leukemia (AML) in 541 patients with de novo myelodysplastic syndrome (MDS) and deletion 5q. Additional chromosomal abnormalities were strongly related to different patients' characteristics. In multivariate analysis, the most important predictors of both OS and AML transformation risk were number of chromosomal abnormalities (P<0.001 for both outcomes), platelet count (P<0.001 and P=0.001, respectively) and proportion of bone marrow blasts (P<0.001 and P=0.016, respectively). The number of chromosomal abnormalities defined three risk categories for AML transformation (del(5q), del(5q)+1 and del(5q)+ ≥ 2 abnormalities) and two for OS (one group: del(5q) and del(5q)+1; and del(5q)+ ≥ 2 abnormalities, as the other one); with a median survival time of 58.0 and 6.8 months, respectively. Platelet count (P=0.001) and age (P=0.034) predicted OS in patients with '5q-syndrome'. This study demonstrates the importance of additional chromosomal abnormalities in MDS patients with deletion 5q, challenges the current '5q-syndrome' definition and constitutes a useful reference series to properly analyze the results of clinical trials in these patients.

Impact of drug-eluting versus bare-metal stents on mortality in patients with anemia.

OBJECTIVES: Our aim was to assess the incidence of all-cause mortality in patients with anemia undergoing percutaneous coronary intervention (PCI) receiving drug-eluting stents (DES) or bare-metal stents (BMS). BACKGROUND: Anemia has been associated with poor clinical outcomes in patients undergoing PCI. However, it is unknown whether stent selection (DES or BMS) has a differential outcome in this high-risk group. METHODS: Anemia was defined as a hematocrit below 36% for female subjects and below 40% for male subjects as defined by the World Health Organization. All patients undergoing PCI with DES or BMS alone from March 2003 to June 2007 were included. The primary end point was all-cause mortality. Anemia was further characterized using mean corpuscular volume as microcytic, normocytic, or macrocytic. RESULTS: A total 11,181 patients underwent PCI over a 4.5-year interval; of these, 2,172 met our inclusion criteria. There were a total of 429 deaths. The majority of patients had normocytic anemia (n = 1,931). Of the 3 anemia subtypes, macrocytic anemia (DES 26%, BMS 44%) had the highest mortality followed by normocytic (DES 17%, BMS 25%) and microcytic (DES 13%, BMS 18%) anemia, respectively. All-cause mortality was significantly lower with DES in unadjusted and multivariable adjusted Cox proportional models (adjusted hazard ratio: 0.66, 95% confidence interval: 0.54 to 0.82; p < 0.001). CONCLUSIONS: In an adjusted analysis, the use of DES as compared with the use of BMS was associated with decreased mortality in patients with anemia. Additionally, among anemia subtypes, macrocytic anemia had the highest mortality.

Microcytosis in agnogenic myeloid metaplasia: prevalence and clinical correlates.

Microcytosis is a characteristic laboratory feature for both iron deficiency anemia and thalassemia. It is also infrequently seen in "anemia of chronic disease" that accompanies a spectrum of chronic conditions including rheumatoid arthritis, polymyalgia rheumatica, diabetes mellitus, connective tissue disease, and protracted infection. In addition, there is a well established but pathogenetically obscure association of microcytosis with Hodgkin's lymphoma, Castleman's disease, and renal cell carcinoma. In the current study, we show that microcytosis is a frequent laboratory feature in agnogenic myeloid metaplasia and investigate its clinical relevance in the particular setting.

Azathioprine-induced fatal macrocytic anemia in rabbits.

Azathioprine (AZA) is used clinically sometimes at high doses for short-term therapy to treat acute rejection of kidney allograft or to desensitize hypersensitive patients to it. The delayed consequences of this approach had not been well investigated. Therefore, in this study we have investigated the delayed consequences of high-dose short-term AZA administration in rabbits. Our results showed that oral administration of AZA (10 mg/kg/day) to rabbits for two weeks induced reversible thrombocytosis and delayed fatal macrocytic anemia. Moreover, neither the hemoglobin level nor the white blood cell count was affected by AZA. The solvent of AZA had no effect on blood cell counts and hemoglobin levels. We can conclude that although high-dose AZA therapy may not induce immediate and significant changes in blood picture, delayed fatal macrocytosis may occur.

Murine Hertwig's anemia: premature death after normal bone marrow transplantation is radiation dose-dependent.

Marrow transplantation therapy in mice with heritable blood disorders usually leads to rapid blood cell normalization, but is sometimes followed by pancytopenia and premature death. This is especially true in mice with Hertwig's anemia (an/an). Unlike the +/+ recipients, 100% of whom survive for over a year, 66% of the mutant mice die by 6 months posttransplantation, and the rest die soon thereafter. It is not clear whether premature death is due to the radiation dose (10 Gy) or to the fact that the F1 mutant mice receive parental-type cells known to induce hybrid resistance. In the present report, experiments were designed to determine whether the F1-an/an host is more sensitive to radiation and/or resistant to continued expansion of the parental-type +/+ cells. The mutant mice are, indeed, more sensitive to irradiation, with an LD100/30 of 7 Gy as compared with an LD100/30 of 10 Gy for the +/+ mice. The times of anemia onset and death for mutant mice implanted with +/+ cells postirradiation is also radiation dose-dependent. Further evidence that death is due to host radiation damage rather than F1 hybrid resistance was provided by transplanting cells from three morbid 10 Gy-irradiation recipients into unirradiated, anemic, stem cell-deficient, F1-W/Wv secondary hosts. All recipients were repopulated by the original parental cells, were cured of their anemia, and survived for 52 weeks posttransplantation. The an/an mouse's heightened susceptibility to radiation damage appears to be the major factor in early death after transplantation therapy.

Development of adult bone marrow stem cells in H-2-compatible and -incompatible mouse fetuses.

Bone marrow of normal adult mice was found, after transplacental inoculation, to contain cells still able to seed the livers of early fetuses. The recipients' own hematopoietic stem cells, with a W-mutant defect, were at a selective disadvantage. Progression of donor strain cells to the bone marrow, long-term self-renewal, and differentiation into myeloid and lymphoid derivatives was consistent with the engraftment of totipotent hematopoietic stem cells (THSC) comparable to precursors previously identified (4) in normal fetal liver. More limited stem cells, specific for the myeloid or lymphoid cell lineages, were not detected in adult bone marrow. The bone marrow THSC, however, had a generally lower capacity for self-renewal than did fetal liver THSC. They had also embarked upon irreversible changes in gene expression, including partial histocompatibility restriction. While completely allogeneic fetal liver THSC were readily accepted by fetuses, H-2 incompatibility only occasionally resulted in engraftment of adult bone marrow cells and, in these cases, was often associated with sudden death at 3-5 mo. On the other hand, H-2 compatibility, even with histocompatibility differences at other loci, was sufficient to ensure long-term success as often as with fetal liver THSC.

Deaths from severe megaloblastic anaemia in hospitalised patients.

In a series of 128 consecutive patients dying from severe megaloblastic anaemia, over half the deaths occurred within one week of hospitalisation and one third were sudden and unexpected. Congestive cardiac failure was extremely common in these patients and was often associated with pleural effusions. Just over half the patients were examined at autopsy and of these 42% had pleural effusions and 15% had pericardial effusions. The cause of the latter is unclear as is their clinical significance, nevertheless this condition has not previously been reported in the megaloblastic anaemias and may well play a part in the fatal outcome in such patients. Blood transfusion was administered to over half the patients, usually in the form of whole blood. It is recommended that transfusions be used sparingly, and consist of cells or preferably exchange transfusion, the latter being of particular value in the elderly or in those with pre-existing cardiac failure.