Preleukemia: one name, many meanings.

Definition of preleukemia has evolved. It was first used to describe the myelodysplastic syndrome (MDS) with a propensity to progress to acute myeloid leukemia (AML). Individuals with germline mutations of either RUNX1, CEBPA, or GATA2 can also be called as preleukemic because they have a markedly increased incidence of evolution into AML. Also, alkylating chemotherapy or radiation can cause MDS/preleukemia, which nearly always progress to AML. More recently, investigators noted that AML patients who achieved complete morphological remission after chemotherapy often have clonal hematopoiesis predominantly marked by either DNMT3A, TET2 or IDH1/2 mutations, which were also present at diagnosis of AML. This preleukemic clone represents involvement of an early hematopoietic stem cells, which is resistant to standard therapy. The same clonal hematopoietic mutations have been identified in older 'normal' individuals who have a modest increased risk of developing frank AML. These individuals have occasionally been said, probably inappropriately, to have a preleukemia clone. Our evolving understanding of the term preleukemia has occurred by advancing technology including studies of X chromosome inactivation, cytogenetics and more recently deep nucleotide sequencing.

Preleukemia: the normal side of cancer.

PURPOSE OF REVIEW: In the present review, we will define the preleukemic state. We aim at increasing awareness and research in the field of preleukemia that will nurture targeted therapy for the earlier steps of leukemia evolution. RECENT FINDINGS: Emerging evidence supports the role of hematopoietic stem/progenitor cells carrying recurrent leukemia-related mutations as the cell of origin of both myeloid and lymphoid malignancies. The preleukemic stem cells can maintain at least to some extent their functionality; however, they have increased fitness endowed by the preleukemic mutations that lead to clonal expansion. SUMMARY: The latent preleukemic period before overt leukemia presents can take years, and the majority of carriers will never develop leukemia in their lifetime. The preleukemic state is not rare, with greater than 1% of individuals having acquired one or more of the recognized preleukemic lesions. The high frequency of such abnormalities in the population may be the cost of growing old; however, another view could be that in order to survive to old age, the hematopoietic system must adapt to create robust hematopoietic stem/progenitor cells with an increased fitness and clonal expansion. Hence, leukemia does not necessarily start as a disease, but rather as a need, with the normally functioning preleukemic hematopoietic stem cells trying to maintain health for years but in time succumbing to their own acquired virtues.

GATA1-mutant clones are frequent and often unsuspected in babies with Down syndrome: identification of a population at risk of leukemia.

Transient abnormal myelopoiesis (TAM), a preleukemic disorder unique to neonates with Down syndrome (DS), may transform to childhood acute myeloid leukemia (ML-DS). Acquired GATA1 mutations are present in both TAM and ML-DS. Current definitions of TAM specify neither the percentage of blasts nor the role of GATA1 mutation analysis. To define TAM, we prospectively analyzed clinical findings, blood counts and smears, and GATA1 mutation status in 200 DS neonates. All DS neonates had multiple blood count and smear abnormalities. Surprisingly, 195 of 200 (97.5%) had circulating blasts. GATA1 mutations were detected by Sanger sequencing/denaturing high performance liquid chromatography (Ss/DHPLC) in 17 of 200 (8.5%), all with blasts >10%. Furthermore low-abundance GATA1 mutant clones were detected by targeted next-generation resequencing (NGS) in 18 of 88 (20.4%; sensitivity ∼0.3%) DS neonates without Ss/DHPLC-detectable GATA1 mutations. No clinical or hematologic features distinguished these 18 neonates. We suggest the term "silent TAM" for neonates with DS with GATA1 mutations detectable only by NGS. To identify all babies at risk of ML-DS, we suggest GATA1 mutation and blood count and smear analyses should be performed in DS neonates. Ss/DPHLC can be used for initial screening, but where GATA1 mutations are undetectable by Ss/DHPLC, NGS-based methods can identify neonates with small GATA1 mutant clones.

Prognostic significance of combined MN1, ERG, BAALC, and EVI1 (MEBE) expression in patients with myelodysplastic syndromes.

Overexpression of MN1, ERG, BAALC, and EVI1 (MEBE) genes in cytogenetically normal acute myeloid leukemia (AML) patients is associated with poor prognosis, but their prognostic effect in patients with myelodysplastic syndromes (MDS) has not been studied systematically. Expression data of the four genes from 140 MDS patients were combined in an additive score, which was validated in an independent patient cohort of 110 MDS patients. A high MEBE score, defined as high expression of at least two of the four genes, predicted a significantly shorter overall survival (OS) (HR 2.29, 95 % CI 1.3-4.09, P= .005) and time to AML progression (HR 4.83, 95 % CI 2.01-11.57, P< .001) compared to a low MEBE score in multivariate analysis independent of karyotype, percentage of bone marrow blasts, transfusion dependence, ASXL1, and IDH1 mutation status. In a validation cohort of 110 MDS patients, a high MEBE score predicted shorter OS (HR 1.77; 95 % CI 1.04-3.0, P= .034) and time to AML progression (HR 3.0, 95 % CI 1.17-7.65, P= .022). A high MEBE expression score is an unfavorable prognostic marker in MDS and is associated with an increased risk for progression to AML. Expression of the MEBE genes is regulated by FLI1 and c-MYC, which are potential upstream targets of the MEBE signature.

Survival, prognostic factors and rates of leukemic transformation in 381 untreated patients with MDS and del(5q): a multicenter study.

Myelodysplastic syndromes (MDS) with del(5q) are considered to have a benign course of the disease. In order to address the issue of the propensity of those patients to progress to acute myeloid leukemia (AML), data on 381 untreated patients with MDS and del(5q) characterized by low or intermediate I International Prognostic Scoring System (IPSS) risk score were collected from nine centers and registries. Median survival of the entire group was 74 months. Transfusion-dependent patients had a median survival of 44 months vs 97 months for transfusion-independent patients (P<0.0001). Transfusion need at diagnosis was the most important patient characteristic for survival. Of the 381 patients, 48 (12.6%) progressed to AML. The cumulative progression rate calculated using the Kaplan-Meier method was 4.9% at 2 years and 17.6% at 5 years. Factors associated with the risk of AML transformation were high-risk World Health Organization adapted Prognostic Scoring System (WPSS) score, marrow blast count >5% and red-cell transfusion dependency at diagnosis. In conclusion, patients with MDS and del(5q) are facing a considerable risk of AML transformation. More detailed cytogenetic and molecular studies may help to identify the patients at risk of progression.

Leukemic presentation of ALK-negative anaplastic large cell lymphoma in a patient with myelodysplastic syndrome.

A 50-year-old woman with a history of aplastic anemia developed cervical lymphadenopathy and atypical lymphocytosis. Atypical cells of lymph nodes were positive for CD3 and CD30 but negative for anaplastic lymphoma kinase (ALK). Bone marrow examination showed trilineage myelodysplasia. She was diagnosed with ALK-negative anaplastic large cell lymphoma (ALCL) with leukemic transformation and myelodysplastic syndrome (MDS) which presumably developed from aplastic anemia. The lymphoma was resistant to intensive chemotherapies, ultimately leading to death. Leukemic presentation of ALK-negative ALCL as an initial manifestation is extremely rare, and the progression of the disease may be influenced by MDS through alteration of immune functions.

Immunophenotypic signatures of benign and dysplastic granulopoiesis by cytomic profiling.

BACKGROUND: The role of flow cytometry (FCM) in diagnosing myelodysplastic syndromes (MDS) remains controversial, because analysis of myeloid maturation may involve subjective interpretation of sometimes subtle patterns on multiparameter FCM. METHODS: Using six-parameter marker combinations known to be useful in evaluating the myeloid compartment in MDS, we measured objective immunophenotypic differences between non-neoplastic (n = 25) and dysplastic (n = 17) granulopoiesis using a novel method, called Fisher information nonparametric embedding (FINE), that measures information distances among FCM datasets modeled as individual high-dimensional probability density functions, rather than as sets of two-dimensional histograms. Information-preserving component analysis (IPCA) was used to create information-optimized "rotated" two-dimensional histograms for visualizing myelopoietic immunophenotypes for each individual sample. RESULTS: There was a consistent trend of segregation of higher-grade MDS (RAEB and RCMD) from benign by FINE analysis. This difference was accentuated in cases with morphologic dysgranulopoiesis and in cases with clonal cytogenetic abnormalities. However, lower grades of MDS or cases that lacked morphologic dysgranulopoiesis showed much greater overlap with non-neoplastic cases. Two cases of reactive left shift were consistently embedded within the higher-grade MDS group. IPCA yielded two-dimensional histogram projections for each individual case by relative weighting of measured cellular characteristics, optimized for preserving information distances derived through FINE. CONCLUSIONS: Objective analysis by information geometry supports the conclusions of previous studies that there are immunophenotypic differences in the maturation patterns of benign granulopoiesis and high grade MDS, but also reinforces the known pitfalls of overlap between low-grade MDS and benign granulopoiesis and overlap between reactive granulocytic left shifts and dysplastic granulopoiesis.

The immunoglobulin gene repertoire of low-count chronic lymphocytic leukemia (CLL)-like monoclonal B lymphocytosis is different from CLL: diagnostic implications for clinical monitoring.

In the revised National Cancer Institute Working Group (NCI-WG)/International Workshop on Chronic Lymphocytic Leukemia (IWCLL) guidelines for CLL, CLL-like monoclonal B lymphocytosis (MBL) is defined as the presence of less than 5 x 10(9)/L B lymphocytes in the peripheral blood. However, the concentration of MBL in the blood is extremely variable. MBL in subjects with lymphocytosis require treatment at a rate of 1.1% per year and present immunoglobulin (IG) gene features and similar to good prognosis CLL. Little is known about low-count MBL cases, accidentally found in the general population. We analyzed IGHV-D-J rearrangements in 51 CLL-like MBL cases from healthy individuals, characterized by few clonal B cells. Seventy percent of the IGHV genes were mutated. The most frequent IGHV gene was IGHV4-59/61, rarely used in CLL, whereas the IGHV1-69 gene was lacking and the IGHV4-34 gene was infrequent. Only 2 of 51 (3.9%) MBL cases expressed a CLL-specific stereotyped HCDR3. Therefore, the IG gene repertoire in low-count MBL differs from both mutated and unmutated CLL, suggesting that the detection of MBL in an otherwise healthy subject is not always equivalent to a preleukemic state. Detailed IG analysis of individual MBL may help to identify cases that necessitate continuous clinical monitoring to anticipate disease progression.

Transient pancytopenia preceding acute lymphoblastic leukemia with positive Philadelphia chromosome.

Transient pancytopenia preceding acute lymphoblastic leukemia (pre-ALL) is a rare but well-known occurrence usually affecting children and adolescents. Though pre-ALL in a few adults has ever been reported, the association of this preleukemic syndrome with positive Philadelphia chromosome and P190(BCR-ABL) is extremely rare. To the best of our knowledge, this is the first report of adult B-cell type pre-ALL with positive Philadelphia chromosome and P190(BCR-ABL) published in the literature. We report the case of a 49-year-old woman who was diagnosed with B-cell type ALL associated positive Philadelphia chromosome and P190(BCR-ABL) preceded by transient pancytopenia. The clinical, morphologic, immunophenotypic and molecular features of this patient are described and the literature reviewed.

Ocular complications in myelodysplastic syndromes as preleukemic disorders.

PURPOSE: To identify ocular complications in patients with myelodysplastic syndromes (MDS), who have a propensity to progress to acute myeloid leukemia (AML). METHODS: Forty-one patients with MDS were the subjects in this retrospective study, and 21 patients with AML were selected as controls. Reviewing their clinical records, we verified that corneal ulcer, iridocyclitis, vitreous hemorrhage, retinal hemorrhage, and optic neuritis had been evaluated using slit-lamp assessment and opthalmoscopy in all the patients. In this study, the MDS patients were classified into those with refractory anemia (RA) and those with refractory anemia with excess blasts (RAEB). RESULTS: Ocular complications were found in 19 (46.3%) of the 41 patients with MDS, comprising corneal ulcer (two cases), iridocyclitis (five), vitreous hemorrhage (one), retinal hemorrhage (ten), cotton wool spots (one), and optic neuritis (two). (Some patients had more than one ocular complication.) Ocular complications were identified in 12 of the 21 (57.1%) patients with AML. There was no significant difference in frequency of ocular complications between MDS and AML (P = 0.4892). In MDS, retinal hemorrhage was associated with significantly reduced platelet counts (P = 0.0063). The frequency of ocular complications was significantly higher in MDS-RAEB than in MDS-RA (P = 0.0478). Retinal hemorrhage was significantly more frequent in patients with MDS-RAEB than in patients with MDS-RA (P = 0.0433). CONCLUSION: Ocular complications in MDS patients should be carefully examined as prognostic factors for progression to acute leukemia.

Clonal lymphocytes in persons without known chronic lymphocytic leukemia (CLL): implications of recent findings in family members of CLL patients.

Several genetic abnormalities have been characterized in chronic lymphocytic leukemia (CLL) but these are predominantly secondary events and the initiating phenomena in the etiology of the disease are yet to be established. Studies of inherited susceptibility have identified the early oncogenic events in both familial and "sporadic" forms of several malignant disorders, and this may also be possible in CLL. However, the utility of linkage analysis in identifying a predisposition locus for the disease is limited because large multigenerational families segregating CLL are rare, while the more frequent small nuclear CLL families contain insufficient numbers of affected individuals. The power to detect predisposition gene(s) could be greatly increased by extending the number of affected individuals within a particular family, for example, by identifying family members with subclinical levels of disease. High-sensitivity flow cytometry techniques, developed to monitor disease in CLL patients undergoing treatment, have allowed accurate enumeration of subclinical levels of CLL cells in healthy individuals from the general population and CLL families. Emerging evidence confirms the phenotypic, genotypic, and clinical associations between the aberrant cells in healthy individuals and those in CLL patients. The data suggest that inherited factors increase the susceptibility to both indolent and aggressive CLL, and they provide unbiased demonstration that the age of onset in CLL families is younger than in the general population.

Identification of preleukemic precursors of hyperdiploid acute lymphoblastic leukemia in cord blood.

Previous studies involving identical twins with concordant leukemia and retrospective scrutiny of archived neonatal blood spots have shown that common chromosome translocations of pediatric leukemia frequently arise before birth. The IGH/TCR clonotypic sequences used as surrogate molecular markers suggest this is also likely to be true for hyperdiploid acute lymphoblastic leukemia (ALL). Yet evidence that hyperdiploidy itself is an early or initiating event occurring prenatally has been limited. Now, however, we can provide direct evidence of this from our identification of CD34+/CD19+ B-lineage progenitor cells with triploid chromosomes in the stored cord blood of an individual who subsequently developed hyperdiploid ALL.

Lack of circulating megakaryoblasts in newborn peripheral blood: development and validation of a sensitive flow cytometric detection method.

It is currently thought that approximately 1% of children with Down syndrome will develop a "premalignant" syndrome known as transient myeloproliferative disorder (TMD). Prospective, population-based studies of the incidence of TMD in Down syndrome infants is lacking. Although most cases of TMD resolve by 1 year of age, data suggest that 10% to 20% of Down syndrome patients with TMD develop AML-M7 (megakaryoblastic leukemia). To identify the true incidence of TMD in the Down syndrome population, a sensitive, rapid, and cost-effective method of quantifying circulating megakaryoblasts in large numbers of patients was needed. In this pilot study, the authors tested the hypothesis that there are fewer than 1% megakaryoblasts of nucleated cells circulating in the blood of normosomic infants. Four-antigen flow cytometry was used to establish the percentage of megakaryoblasts present in each of 100 cord blood samples collected blindly from "normosomic" live births. There was a mean percentage of 0.017% megakaryoblasts in 100 cord blood samples from normosomic infants. Flow cytometry proved to be a sensitive, rapid, and reproducible method for the quantification of megakaryoblasts. Less than 1% of circulating nucleated cells in the blood of newborn infants are megakaryoblasts, providing a comparison population for the authors' larger proposed incidence study.

Clinical and laboratory features of preleukemia patients.

OBJECTIVE: To explore prospective diagnostic criteria for preleukemia. METHODS: A case control study was done comparing the discrepancies on clinical and laboratory features between patients with preleukemia and those with chronic aplastic anemia (CAA) or atypical paroxysmal nocturnal hemoglubinuria (a-PNH). RESULTS: There were eight variables of significance: (1) lymphocytoid micromegakaryocytes in the bone marrow; (2) immature granulocytes in the peripheral blood; (3) > or = 2.0% myeloblasts in the bone marrow; (4) positive periodic acid schiff (PAS) stained nucleated erythrocytes; (5) myeloid differentiation index > or = 1.8; (6) typical colonal karyotypic abnormalities; (7) negative sister chromatid differentiation; (8) cluster/colony ratio of granulocyte-macrophage colony-forming units (CFU-GM) > 4.0. The following criteria were assigned: A: to meet variable one and at least two of the other seven variables and B: to meet at least four of the eight variables. All of the patients with preleukemia met either A or B and none of the patients with CAA or a-PNH did. CONCLUSIONS: Preleukemia is different from CAA or a-PNH. It has its own clinical and laboratory features, which may be useful for its prospective diagnosis.

Elevated plasma level of differentiation inhibitory factor nm23-H1 protein correlates with risk factors for myelodysplastic syndrome.

We measured plasma nm23-H1 level (nm23-H1), a differentiation inhibitory factor, by an enzyme-linked immunosorbent assay (ELISA) in patients with aplastic anemia (AA) and myelodysplastic syndrome (MDS). The nm23-H1 in AA was not significantly elevated when compared to normal subjects (6.66 +/- 1.20 ng/ml vs 5.13 +/- 0.81 ng/ml; P = 0.274). In contrast, MDS patients had significantly high levels of nm23-H1 compared not only to normal subjects (11.16 +/- 1.42 vs 5.13 +/- 0.81 ng/ml; P = 0.0004) but also to those of the AA group (11.16 +/- 1.42 ng/ml vs 6.66 +/- 1.20 ng/ml; P = 0.018). In the MDS group of patients, no significant difference was observed in the nm23-H1 levels between patients with refractory anemia (RA) and RA with excess blasts (RAEB)/RAEB in transformation (10.71 +/- 1.61 ng/ml vs 9.24 +/- 2.66 ng/ml; P = 0.672). Of the patients with RA, patients with low risk according to the International Prognostic Scoring System (IPSS) had significantly low levels of nm23-H1 compared to those of IPSS INT-1 level cases (6.40 +/- 1.36 ng/ml vs 13.05 +/- 2.50 ng/ml; P = 0.0028), suggesting that nm23-H1 may be useful as a prognostic marker for MDS, especially in low risk patients.

[The characteristics of the pre- and leukemic stages of chronic myeloproliferative diseases in persons suffering as a result of the Chernobyl catastrophe]. / Kharakteristika pre- i leikemicheskoi stadii khronicheskikh mieloproliferativnykh zabolevanii u lits, postradavshikh vsledstvie chernobyl'skoi katastrofy.

Clinical, morphological and cytogenetic investigations were done in those patients with leukocytosis having become victims of the Chernobyl catastrophe. Of these (n = 10), six patients demonstrated chromosomal abnormalities. In the study made at a later date in six patients with cytogenetic abnormalities, five patients were found to have chronic myeloproliferative disorders, with four cases presenting with chronic myeloid leukemia and one patient having osteomyelofibrosis.