Minimally Differentiated Acute Myeloid Leukemia (AML-M0): Comparison of 25 Cases With Other French-American-British Subtypes

UNC2025, a MERTK Small-Molecule Inhibitor, Is Therapeutically Effective Alone and in Combination with Methotrexate in Leukemia Models

Purpose: MERTK tyrosine kinase is ectopically expressed in 30% to 50% of acute lymphoblastic leukemias (ALL) and more than 80% of acute myeloid leukemias (AML) and is a potential therapeutic target. Here, we evaluated the utility of UNC2025, a MERTK tyrosine kinase inhibitor, for treatment of acute leukemia.Experimental Design: Preclinical in vitro and in vivo assays using cell lines and primary leukemia patient samples were used to evaluate antileukemic effects of UNC2025.Results: UNC2025 potently inhibited prosurvival signaling, induced apoptosis, and reduced proliferation and colony formation in MERTK-expressing ALL and AML cell lines and patient samples. Approximately 30% of primary leukemia patient samples (78 of 261 total) were sensitive to UNC2025. Sensitive samples were most prevalent in the AML, T-ALL, and minimally differentiated (M0) AML subsets. UNC2025 inhibited MERTK in bone marrow leukemia cells and had significant therapeutic effects in xenograft models, with dose-dependent decreases in tumor burden and consistent two-fold increases in median survival, irrespective of starting disease burden. In a patient-derived AML xenograft model, treatment with UNC2025 induced disease regression. In addition, UNC2025 increased sensitivity to methotrexate in vivo, suggesting that addition of MERTK-targeted therapy to current cytotoxic regimens may be particularly effective and/or allow for chemotherapy dose reduction.Conclusions: The broad-spectrum activity mediated by UNC2025 in leukemia patient samples and xenograft models, alone or in combination with cytotoxic chemotherapy, supports continued development of MERTK inhibitors for treatment of leukemia. Clin Cancer Res; 23(6); 1481-92. ©2016 AACR.

Flow cytometric maturity score as a novel prognostic parameter in patients with acute myeloid leukemia

The European LeukemiaNet (ELN) classification is widely accepted for risk stratification of patients with acute myeloid leukemia (AML). In order to establish immunophenotypic features that predict prognosis, the expression of single AML blast cell antigens has been evaluated with partly conflicting results; however, the influence of immunophenotypic blast maturity is largely unknown. In our study, 300 AML patients diagnosed at our institution between January 2003 and April 2012 were analyzed. A flow cytometric maturity score was developed in order to distinguish "mature" AML (AML-ma) from "immature" AML (AML-im) by quantitative expression levels of early progenitor cell antigens (CD34, CD117, and TdT). AML-ma showed significantly longer relapse-free survival (RFS) and overall survival (OS) than AML-im (p < 0.001). Interestingly, statistically significant differences in RFS and OS were maintained within the "intermediate-risk" group according to ELN (RFS, 7.0 years (AML-ma) vs. 3.3 years (AML-im); p = 0.002; OS, 5.1 years (AML-ma) vs. 3.0 years (AML-im); p = 0.022). Our novel flow cytometric score easily determines AML blast maturity and can predict clinical outcome. It remains to be clarified whether these results simply reflect an accumulation of favorable molecular phenotypes in the AML-ma subgroup or whether they rely on biological differences such as a higher proportion of leukemia stem cells and/or a higher degree of genetic instability within the AML-im subgroup.

Prognostic value of IDH1 mutations identified with PCR-RFLP assay in acute myeloid leukemia patients

BACKGROUND

Somatic mutations in isocitrate dehydrogenase 1 (IDH1) gene occur frequently in primary brain tumors. Recently theses mutations were demonstrated in acute myeloid leukemia (AML). So far, assessment of these mutations relied on the DNA sequencing technique.

AIM OF THE WORK

The aim of this study was to detect somatic mutations in IDH1 gene using mismatched primers suitable for endonuclease based detection, without the need for DNA sequencing, and to estimate its prognostic value, on patients with de novo AML.

METHODS

Residual DNA extracted from pretreatment bone marrow (BM) samples of 100 patients with de novo AML was used. The polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP) was adapted to IDH1gene, codon 132 mutations screening.

RESULTS

The frequency of IDH1 mutations was 13%. In the non-acute promyelocytic leukemia group (non-APL), IDH1 mutations were significantly associated with FLT3-ITD negative patients (p=0.03). Patients with IDH1 mutations did not achieve complete remission (CR). There was a trend for shorter overall survival (OS) in patients with IDH1 mutation compared to those with wild type (p=0.08).

CONCLUSION

IDH1 mutations are recurring genetic alterations in AML and they may have unfavorable impact on clinical outcome in adult AML. The PCR-RFLP method allows for a fast, inexpensive, and sensitive method for the detection of IDH1 mutations in AML.

TdT expression in acute myeloid leukemia with minimal differentiation is associated with distinctive clinicopathological features and better overall survival following stem cell transplantation

The diagnostic criteria for acute myeloid leukemia (AML), not otherwise specified, with minimal differentiation (AML-M0, French-American-British classification), have been refined in the 2008 World Health Organization (WHO) classification. Terminal deoxynucleotidyl transferase (TdT) expression in AML-M0 has been proposed by others as a surrogate for RUNX1 (runt-related transcription factor 1) mutations, a mutation associated with distinct gene expression profiles in AML-M0. In this study, we investigated the significance of TdT expression in AML-M0 cases defined using the 2008 WHO classification criteria. Demographic, laboratory and clinical information were obtained from the hospital medical records. Statistical analysis was performed using Student's t-test, log-rank test and Fisher's exact test. The study group included 30 AML-M0 patients (male:female=19:11; median age: 60 years). In all, 10 cases of AML-M0 were positive for TdT(+) and 20 cases were negative for TdT(-). Patients with TdT+ AML-M0 had higher peripheral blood and bone marrow blast counts compared to patients with TdT- AML-M0 (P=0.01). TdT expression in AML-M0 was not associated with a distinct immunophenotype. Monoclonal IgH and TCR gene rearrangements were frequent, but independent of TdT expression in AML-M0. TdT expression in AML-M0 correlated with trisomy 13 and inversely correlated with aberrations of chromosomes 5 and 17. Among six patients with AML-M0 who received a stem cell transplant, overall survival was significantly longer for the three TdT+ patients compared with the three TdT- patients (P=0.03). In the TdT+AML-M0 subgroup, the three patients with stem cell transplant had better overall survival compared with five patients who did not receive stem cell transplant (P=0.01). We conclude that AML-M0, as currently defined in the 2008 WHO classification, can be divided into two groups based on TdT expression. Although there is a need to assess a greater number of patients, our results suggest that TdT positivity in AML-M0 identifies a subset of patients with a better prognosis after stem cell transplant.

Functions and uses of immunohistochemical stains in cutaneous infiltrates of hematopoietic origin: a review for the practicing dermatologist

BACKGROUND

Immunohistochemical stains, particularly those for cutaneous lymphomas, have similar-sounding names, which may lead to confusion among dermatologists who are not well versed in the terminology of the tools used for pathologic diagnosis. Also aiding in this is the fact that some familiar stains are constantly investigated for novel utility in different tumors, and a plethora of new stains regularly emerge in the peer-reviewed literature.

OBJECTIVE

To review the major stains encountered in dermatopathologic reports for cutaneous lymphomas. A select number of other stains are reviewed that are either new and under investigation in several cutaneous processes or have a new use described in recent reports.

METHODS

The peer-reviewed literature was searched and analyzed for the accepted purposes of using these markers.

RESULTS

All pertinent findings for these immunostains are reported with the purpose of educating the dermatology community.

CONCLUSION

This review serves as a reference to clarify potentially confusing immunohistochemical stains.

Congenital acute leukemia with initial indolent presentation--a case report

BACKGROUND

Congenital acute leukemia is a rare event, presenting usually as an aggressive disease with a poor prognosis. A differential diagnosis is the transient myeloproliferative disorder observed in Down syndrome. We describe the case of an apparently healthy newborn male child presenting with normal peripheral blood (PB) counts but with a blast population on differentials. The child's condition and the blast population remained unchanged during the first year of life.

METHODS

Bone marrow and PB were morphologically analyzed. Multiparametric flow cytometry was performed at the time of diagnosis and repeated at 1 year. These studies were completed by cytogenetic and molecular analyses.

RESULTS

Bone marrow contained 40% of undifferentiated blasts. Multiparametric flow cytometry showed low expression of CD38, HLA-DR, and CD33 markers. All other markers were negative. Constitutional and blast cell karyotypes were normal. Fluorescence in situ hybridization analysis showed no rearrangement. Molecular studies were negative. The blast percentage remained stable during several months. After 1 year, the PB counts showed thrombocytopenia, with an increase of blast cells exhibiting the same phenotype. Clinically, an enlarged spleen was found. The child did not respond to chemotherapy and only partially to gemtuzumab ozogamicin. A cord blood cell transplantation was finally performed. With a follow-up of 12 months, the child is doing well.

CONCLUSIONS

To our knowledge, this is the first case of congenital acute leukemia with initially indolent course in a newborn without Down syndrome. This observation emphasizes the importance of a careful follow-up.

Gene expression profiling of minimally differentiated acute myeloid leukemia: M0 is a distinct entity subdivided by RUNX1 mutation status

Minimally differentiated acute myeloid leukemia (AML-M0) is defined by immature morphology and expression of early hematologic markers. By gene expression profiling (GEP) and subsequent unsupervised analysis of 35 AML-M0 samples and 253 previously reported AML cases, we demonstrate that AML-M0 cases express a unique signature that is largely separated from other molecular subtypes. Hematologic transcription regulators such as CEBPA, CEBPD, and ETV6, and the differentiation associated gene MPO appeared strongly down-regulated, in line with the primitive state of this leukemia. AML-M0 frequently carries loss-of-function RUNX1 mutation. Unsupervised analyses revealed a subdivision between AML-M0 cases with and without RUNX1 mutations. RUNX1 mutant AML-M0 samples showed a distinct up-regulation of B cell–related genes such as members of the B-cell receptor complex, transcription regulators RUNX3, ETS2, IRF8, or PRDM1, and major histocompatibility complex class II genes. Importantly, prediction with high accuracy of the AML-M0 subtype and prediction of patients carrying RUNX1 mutation within this subtype were possible based on the expression level of only a few transcripts. We propose that RUNX1 mutations in this AML subgroup cause lineage infidelity, leading to aberrant coexpression of myeloid and B-lymphoid genes. Furthermore, our results imply that AML-M0, although originally determined by morphology, constitutes a leukemia subgroup.

Contrasting antigenic maturation patterns in M0-M2 versus M3 acute myeloid leukemias

Acute myelogenous leukemia (AML) is divided into 8 FAB subgroups based on differentiation and maturation properties of the neoplastic cells. Acute promyelocytic leukemia (APL), or M3 AML, is associated with disseminated intravascular coagulation (DIC). Flow cytometric immunophenotyping differentiates among the AML subtypes. Key markers in this classification include the myeloid antigens CD13 and CD33 and the hematopoietic precursor markers CD34 and HLA-DR. The present study analyzes and compares differences in the expression of these markers in 27 M0-M2 cases and 8 M3 cases. The M0-M2 cases generally expressed all four antigens. CD13 and CD33 were positively expressed in 23 (85.2%) and 21 (77.8%) of the 27 cases, respectively. CD34 and HLA-DR were present in 25 (92.6%) and 26 (96.3%) of the 27 cases, respectively. Analysis of the M3 cases revealed a different immunophenotype as CD13 and CD33 were each positive in all 8 (100%) M3 AML cases while CD34 and HLA-DR were negative in 6 (75%) and 8 (100%) of the 8 M3 cases, respectively. In contrast to expression of the early markers CD34 and HLA-DR in the M0-M2 group, these were negative in the M3 cases which were characterized by heterogeneous CD13 and generally homogeneous and bright CD33 expression.

Minimally differentiated acute myeloid leukemia (FAB AML-M0) is associated with an adverse outcome in children: a report from the Children's Oncology Group, studies CCG-2891 and CCG-2961

To assess the impact of minimally differentiated acute myeloid leukemia (AML-M0) morphology in children, we analyzed 2 sequential Children's Cancer Group AML clinical trials. We compared presenting characteristics and outcomes of 82 CCG-2891 and CCG-2961 patients with de novo, non-Down syndrome (DS) AML-M0 with those of 1620 patients with non-M0 AML, and of 10 CCG-2891 patients with DS-associated AML-M0 with those of 179 with DS-associated non-M0 AML. Morphology and cytogenetics were centrally reviewed. The non-DS AML-M0 children had a lower white blood cell (WBC) count (P = .001) than their non-M0 counterparts and a higher incidence of chromosome 5 deletions (P = .002), nonconstitutional trisomy 21 (P = .027), and hypodiploidy (P = .002). Outcome analyses considering all children with non-DS AML demonstrated no significant differences between M0 and non-M0 patients. Analyses restricted to intensive-timing CCG-2891 and CCG-2961 demonstrated comparable complete response (CR) rates (79% and 78%) between non-DS M0 and non-M0 patients. Overall survival (OS) from diagnosis (38% +/- 14% versus 51% +/- 3%; P = .160) was not significantly different between the 2 groups. OS from end of induction (45% +/- 17% versus 63% +/- 3%; P = .038), event-free survival (EFS; 23% +/- 11% versus 41% +/- 3%; P = .018), and disease-free survival (DFS; 31% +/- 14% versus 52% +/- 3%; P = .009) were inferior in the M0 group. There was no significant outcome difference between DS-associated AML-M0 and non-M0 children. This study suggests that intensively treated non-DS-associated AML-M0 children have an inferior outcome compared with children with non-M0 AML.

Further correlations of morphology according to FAB and WHO classification to cytogenetics in de novo acute myeloid leukemia: a study on 2,235 patients

In routine diagnostic procedures of acute myeloid leukemia (AML), the French-American-British (FAB) and World Health Organization (WHO) classifications both play a central role. Some morphologic subtypes are specifically associated to distinct cytogenetic and molecular aberrations; however, such close correlations do not exist for the majority of entities. We evaluated cytogenetics in 2,235 patients at diagnosis of AML with the FAB subtypes M0-2, M4, and M5-7. The cytogenetic patterns of these subtypes showed differences with respect to the clonal aberration rate and the incidence of complex aberrant karyotypes. The frequency of numerical gains and losses and of structural losses and the incidence of 11q23/MLL rearrangements differed. Thus, cytomorphology of AML may be helpful to support or even initiate other diagnostic procedures, e.g., interphase fluorescence in situ hybridization and polymerase chain reaction. In conclusion, the central role of morphology as defined by the FAB and WHO classification in AML at diagnosis is still justified in combination with other techniques.

Clinical implications of blast immunophenotypes in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are malignant disorders of hematopoietic cells. For many neoplasms, immunophenotype data of the neoplastic cells provide valuable information in clinical practice. However, the clinical values of immunophenotype data have not yet been firmly established for MDS. Since MDS blasts are not predominant in the bone marrow and peripheral blood, which makes reliable immunophenotyping of blasts difficult, we used a newly developed density-centrifugation reagent to generate blast-enriched MDS samples for phenotyping. The key findings of our study, which phenotyped blasts from 116 patients with MDS or acute leukemia transformed from MDS, were the following. (1) MDS blasts were usually CD34( + )CD38( + )HLA-DR( + )CD13( + )CD33( + )CD2(-)CD3(-)CD5(-)CD8(-)CD19(-)CD20(-) in flow cytometric analysis and often lacked myeloperoxidase in cytochemistry, regardless of the MDS subtype. (2) MDS blasts showed asynchronous expression of antigens (expression of both stem cell antigens and antigens of mature myeloid cells). (3) During disease progression of MDS, phenotypic clonal evolution (transition from blasts with a relatively mature phenotype to blasts with a more immature phenotype) occurred in at least some cases. (4) CD7-positivity was an independent variable associated with a short survival in MDS. Further studies of blast immunophenotypes will deepen our understanding of MDS and hopefully improve the clinical approach to these intractable disorders.

C-type lectin-like molecule-1: a novel myeloid cell surface marker associated with acute myeloid leukemia

Acute myeloid leukemia (AML) has a poor prognosis due to treatment-resistant relapses. A humanized anti-CD33 antibody (Mylotarg) showed a limited response rate in relapsed AML. To discover novel AML antibody targets, we selected a panel of single chain Fv fragments using phage display technology combined with flow cytometry on AML tumor samples. One selected single chain Fv fragment broadly reacted with AML samples and with myeloid cell lineages within peripheral blood. Expression cloning identified the antigen recognized as C-type lectin-like molecule-1 (CLL-1), a previously undescribed transmembrane glycoprotein. CLL-1 expression was analyzed with a human anti-CLL-1 antibody that was generated from the single chain Fv fragment. CLL-1 is restricted to the hematopoietic lineage, in particular to myeloid cells present in peripheral blood and bone marrow. CLL-1 is absent on uncommitted CD34(+)/CD38(-) or CD34(+)/CD33(-) stem cells and present on subsets of CD34(+)/CD38(+) or CD34(+)/CD33(+) progenitor cells. CLL-1 is not expressed in any other tissue. In contrast, analysis of primary AMLs demonstrated CLL-1 expression in 92% (68 of 74) of the samples. As an AML marker, CLL-1 was able to complement CD33, because 67% (8 of 12) of the CD33(-) AMLs expressed CLL-1. CLL-1 showed variable expression (10-60%) in CD34(+) cells in chronic myelogenous leukemia and myelodysplastic syndrome but was absent in 12 of 13 cases of acute lymphoblastic leukemia. The AML reactivity combined with the restricted expression on normal cells identifies CLL-1 as a novel potential target for AML treatment.

Cytogenetic profile in de novo acute myeloid leukemia with FAB subtypes M0, M1, and M2: a study based on 652 cases analyzed with morphology, cytogenetics, and fluorescence in situ hybridization

In about 55% of acute myeloid leukemia (AML) cases, chromosome aberrations are detectable by cytogenetics. Close correlations between cytomorphology and cytogenetics have been reported. To determine a pattern of cytogenetic abnormalities within the French-American-British (FAB) subtypes AML M0, M1, and M2, we analyzed 48 AML M0, 179 AML M1, and 425 AML M2 and compared cytogenetic data to a cohort of 1,062 AML M3/3v, M4, M4eo, M5a/5b, M6, and M7. Cytogenetic abnormalities were significantly more frequent in AML M0 (71%) compared to M1 (49%), M2 (53%), and the total cohort (56%; P < 0.02). While +8 was the most common numeric abnormality in all FAB subtypes, +13, +14, and +11 were associated with AML M0-M2. The only recurring balanced translocation that was associated with one of these FAB subtypes was t(8;21) in M2 (12.5%) and, rarely, M1 (1.7%) (M0, 0% and M3-7, 0.09%; P=0.001). To evaluate the frequency of cytogenetically undetectable abnormalities, we performed fluorescence in situ hybridization (FISH) analyses in 273 AML M0-M2 with normal karyotype using probes for ETO, ABL, MLL, TEL, RB, P53, AML1, and BCR. In two cases we identified numerical aberrations of RB only in interphases nuclei. In seven additional cases, TEL and MLL abnormalities were found. In conclusion, t(8;21), +11, +13, and +14 are strongly associated with AML M0, M1, and M2. The FISH screening analyses identified abnormalities in an additional 3% in normal karyotypes.

Initial human myeloid/dendritic cell progenitors identified by absence of myeloperoxidase protein expression

Myeloperoxidase (MPO) represents an early-appearing and highly reliable intracellular myeloid lineage marker molecule. MPO protein can be detected in a subset of human hematopoietic bone marrow progenitor cells and in granulomonopoietic (GM) cells. However, other myeloid-related cell types such as epidermal Langerhans-type dendritic cells (LC) lack MPO. Therefore, human myeloid progenitors might be subdivided based on MPO protein expression into functional subsets. Here we identified two consecutive myelopoietic cell stages, i.e., early myeloid progenitors that lack MPO, as well as their immediate MPO+ progeny. MPO- myeloid progenitors possess previously described granulomonocyte (GM) progenitor-associated cell-surface characteristics (CD34+CD45RA+CD13+lin-). They are specifically recruited and can be expanded in cultures of CD34+ cord blood cells in response to early-acting hematopoietic cytokines. Furthermore, cell fractions enriched in MPO- myeloid progenitors efficiently developed along Langerhans-type dendritic cell (LC) and granulomonocytic (GM) lineages, whereas progeny enriched in MPO+ cells showed diminished LC potential. In line with this, peripheral blood progenitors, known to possess LC differentiation potential, lacked MPO expression. We conclude that differential expression of MPO therefore further characterizes cells with myeloid or LC potential.

The prognostic significance of antigen expression in leukaemia

Numerous immunophenotypic features have been examined for their potential prognostic significance in predicting treatment outcome in leukaemias. These include immunophenotypic subgroups of acute lymphoblastic leukaemia (ALL) and immature acute myeloid leukaemia, expression of individual surface antigens or combined immunophenotypic features, and more recently, molecules mediating the multidrug resistance phenotype or being involved in the regulation of drug-induced apoptosis. Most previous studies investigating the prognostic significance of antigen expression in leukaemia have not used the information provided by multiparameter flow cytometry and have chosen rather arbitrary cut-off points for marker positivity. Moreover, given significant associations between immunophenotypic features and genetic abnormalities in leukaemic cells, immunophenotyping as an independent predictor of treatment outcome has been questioned. Thus, except for lineage assignment of leukaemic blasts and definition of maturational status in ALL, information provided by immunophenotyping is currently not applied to risk-classification systems or used for planning patient treatment in leukaemia. We review some of the recent findings regarding the prognostic impact of distinct immunophenotypic features in acute leukaemias and myelodysplastic syndrome.

Low expression of the myeloid differentiation antigen CD65s, a feature of poorly differentiated AML in older adults: study of 711 patients enrolled in ECOG trials

CD65s appears when the progenitor antigen CD34 disappears, suggesting that this sialylated carbohydrate antigen marks a turning point in normal myeloid differentiation. We characterized acute myeloid leukemia (AML) with low CD65s expression (CD65s(low) AML) in 711 patients entered on seven Eastern Cooperative Oncology Group AML treatment trials (1986-1999). Of those, 198 (28%) qualified as having CD65s(low) AML. Morphologically, CD65s(low) AML was more common in FAB subgroups with minimal differentiation, M0/M1 (P=<0.0001). Early precursor antigens CD34, CD117 and terminal transferase were more frequent in CD65s(low) than CD65s(high) AML (P=<0.0001). Myeloperoxidase was present in fewer CD65s(low) myeloblasts, and the more mature myeloid antigens, CD15 and CD11b, were rarely detected (P=<0.0001). Yet, the two diagnoses did not differ in the distribution of cytogenetic prognostic groups or the occurrence of the multidrug-resistance mediator, P-glycoprotein. CD65s(low) AML patients were significantly older than CD65s(high) cases (P<0.0001). Furthermore, the incidence of CD65s(low) cases increased with age, from 20% in patients under the age of 50 years to 67% in patients older than 80 years (P<0.0001). Overall, complete remission (CR) rate and overall survival were comparable in CD65s(low) and CD65s(high) AML. However, among patients >55 years of age, CD65s(low) AML had a decreased CR rate of 33 vs 44% in CD65s(high) AML (P=0.055). Thus, CD65s(low) AML represents immunophenotypically undifferentiated disease and occurs predominantly in older adults. Although not statistically significant, the observed association between low CD65s expression and decreased CR rate only in patients over the age of 55 is intriguing.

The percentage of myeloperoxidase-positive blast cells is a strong independent prognostic factor in acute myeloid leukemia, even in the patients with normal karyotype

To examine whether the percentage of myeloperoxidase (MPO)-positive blast cells is useful as a prognostic factor for acute myeloid leukemia (AML), cytochemical analysis of MPO was performed in 491 patients who were registered to the Japan Adult Leukemia Study Group-AML92 study. Patients were divided into two using the percentage of MPO-positive blast (high [>or=50%] and low (<50%)). Complete remission rates were 85.4% in the former and 64.1% in the latter (P=0.001). The overall survival (OS) and the disease-free survival (DFS) were significantly better in the high MPO group (48.3 vs 18.7% for OS, and 36.3 vs 20.1% for DFS, P<0.001, respectively). Multivariate analysis showed that both karyotype and the percentage of MPO-positive blast cells were equally important prognostic factors. The high MPO group still showed a better survival even when restricted to the intermediate chromosomal risk group or the patients with normal karyotype (P<0.001). The OS of patients with normal karyotype in the high MPO group was almost equal with that of the favorable chromosomal risk group. The percentage of MPO-positive blast cells is a simple and highly significant prognostic factor for AML patients, and especially useful to stratify patients with normal karyotype.

Prognostic significance of CD7+CD56+ phenotype and chromosome 5 abnormalities for acute myeloid leukemia M0

Myeloid/natural killer (NK) cell precursor acute leukemia is an entity of acute leukemia characterized by poor prognosis and a CD7+CD56+ myeloid antigen+ phenotype without light-microscopic myeloperoxidase reactivity. This disease shares several clinical characteristics with acute myeloid leukemia (AML) M0. To clarify the relationship between these 2 leukemias, we analyzed 105 cases of AML M0. Among them, 17 were CD7+ and CD56+, 77 were negative for either antigen, and 11 could not be determined. CD7+CD56+ AML M0 showed onset at significantly lower patient age (median 46 versus 63 years, P = .004). The disease localization and the hematological manifestations were significantly different: CD7+CD56+ AML showed more frequent extramedullary involvement, fewer circulating leukemic blasts, less anemia, and less thrombocytopenia than did AML M0. The cytogenetic aberrations were also unique, because no 5q abnormalities were found in CD7+CD56+ M0. The prognosis of CD7+CD56+ M0 was poor in patients younger than 46 years (P = .03). Multivariate analysis showed that the CD7+CD56+ phenotype was a significant prognostic factor for AML M0, as well as age, circulating blast percentage, and chromosome 5 abnormalities These findings suggest that AML M0 consists of heterogeneous subgroups to be managed separately, and CD7+CD56+ M0 constitutes a distinct subtype of AML M0.

Human acute stem cell leukemia with multilineage differentiation potential via cascade activation of growth factor receptors

The morphologic, immunophenotypic, genotypic, genomic, and functional features of an undifferentiated acute leukemia with stem cell features are reported. At light and electron microscopy, the leukemic population was represented by primitive progenitor cells with no evidence of differentiation. The blasts were CD34(+), AC133(+), CD71(-), HLA-DR(-), CD38(-/dim+), CD90(+), CD117(dim+), flt3(+); did not express B, T, or myeloid-associated antigens; and showed a germline configuration of the immunoglobulin and T-cell receptor. Genomic profiling documented the expression of early stem cell and myeloid-associated genes. Receptors for early-acting hemopoietic growth factors (HGFs) were detected, while receptors for unilineage HGF were not expressed. Incubation with the flt3 or Kit ligand induced the expression of unilineage HGF receptors, allowing these cells to respond to their respective ligands. Growth without differentiation was sustained only in the presence of early-acting HGF, namely flt3 ligand, while early and unilineage HGF gave rise to all types of hemopoietic colonies.

The immunophenotype of 325 adult acute leukemias: relationship to morphologic and molecular classification and proposal for a minimal screening program highly predictive for lineage discrimination

Bone marrow cells of 325 adults with acute leukemia were immunophenotyped using a panel of monoclonal antibodies proposed by the European Group for the Immunological Characterization of Leukemias (EGIL). Of these, 97.2% could be assigned clearly to myeloid or lymphoid lineage (254 acute myeloid leukemias [AMLs], 48 B-cell lineage acute lymphoblastic leukemias [ALLs], 14 T-cell lineage ALLs), 1.8% as biphenotypic, and less than 1% as undifferentiated. Immunologic subtyping of ALLs revealed an association between early precursor phenotypes and coexpression of myeloid antigens, particularly CD15/CD65s coexpression and pre-pre-B cell-specific phenotypes and genotypes. The common ALL phenotype was associated with BCR-ABL translocation. Among AMLs, CD2 coexpression was almost exclusively restricted to French-American-British subtypes M3 variant and M4Eo and related molecular aberrations. The most valuable markers to differentiate between myeloperoxidase-negative AML subtypes M0 and ALLs were CD13, CD33, and CD117, typical of M0, and intracytoplasmic CD79a, intracytoplasmic CD3, CD10, and CD2, typical of B cell- or T cell-lineage ALL. Our results confirm excellent practicability of the EGIL proposalfor immunologic classification of acute leukemias. For myeloperoxidase-negative AMLs, we suggest a scoring system based on markers most valuable to distinguish between AML-M0 and ALLs.

Acute myeloid leukaemia M0: haematological, immunophenotypic and cytogenetic characteristics and their prognostic significance: an analysis in 241 patients

Haematological, immunophenotypic and cytogenetic characteristics were analysed in 241 patients with acute myeloid leukaemia (AML) M0, including 58 children. Children < 3 years and adults between 60 and 70 years of age were most frequently affected. Immunophenotyping showed a heterogeneous phenotype. Anti-myeloperoxidase was positive in about half of the patients. Cytogenetic data were available from 129 (54%) patients. A normal karyotype was found in only 24%. Most of the abnormalities were unbalanced and the chromosomes 5, 7, 8 and 11 were the most frequently affected. Survival data were available from 152 treated patients (63%). The median overall survival for all patients was 10 months, 20 months for children (n = 36), 10 months for the young adult group (n = 50) and 7 months for the elderly patients (n = 66) (P = 0.09). Karyotype was not a prognostic factor influencing survival. AML M0 shows the immunological characteristics of early progenitor cells, but the expression of the different markers and cytogenetic abnormalities is heterogeneous. The prognosis is poor compared with other de novo AML and similar to that of AML with multilineage dysplasia or AML following myelodysplastic syndromes.

Cytochemical staining and flow cytometry methods applied to the diagnosis of acute leukemia in the pediatric population: an assessment of relative usefulness

BACKGROUND

Cytochemical staining has been used in the diagnosis of acute leukemia for more than 20 years. The general availability of flow cytometers and an extensive panel of antibody reagents useful for characterizing blood cell lineage question the usefulness of continuing routine use of the cytochemical staining for the diagnosis of acute leukemia.

PATIENTS AND METHODS

Test results were evaluated in 122 (n = 122; 112 with acute lymphocytic leukemia and 10 with acute myeloid leukemia) patients selected from among 320 patients with acute leukemia at Texas Children's Hospital in 1997 and 1998. Results were selected for review if the clinical encounter represented the initial diagnostic work-up and if data were available from cytochemical staining and flow cytometry studies.

RESULTS

Cell lineage classification derived from flow cytometry and cytochemical stains were in agreement in all cases. Definitive diagnoses were feasible using flow cytometry results alone in 120 of 122 patients (98.4%) as compared with only 99 of 122 patients (81.2%) when only cytochemical staining results were considered. In two patients with inconclusive flow cytometry results, cytochemical staining alone provided information sufficient for diagnosis.

CONCLUSIONS

Results from this study indicate that with few exceptions, flow cytometry studies alone provide sufficient information for diagnosis and management of acute leukemia in children. Nevertheless, cytochemical staining should be available for those cases in which flow cytometry results fail to allow a definitive diagnosis. A modified testing protocol is recommended.

CD2- CD4+ CD56+ hematodermic/hematolymphoid malignancy

BACKGROUND

CD2- CD4+ CD56+ lymphoid malignancy has been only rarely reported the last 5 years. It is characterized by a high incidence of cutaneous involvement, cytologically agranular cells, aggressive clinical course, and negative Epstein-Barr virus (EBV) involvement.

OBSERVATION

We describe a Japanese patient with a unique hematolymphoid malignancy characterized by an involvement of skin, nasopharyngeal region, bone marrow, lymph node, and a CD4+ CD43+ CD56+ CD2- CD3- CD8- and terminal deoxynucleotidyl transferase phenotype. Clinically, the cutaneous eruptions were purplish, hard, multiple nodules. Histologically, a massive proliferation of atypical pleomorphic cells with medium-sized nuclei were observed throughout the dermis. No clonal rearrangement of T-cell receptor (TCR)-beta gene or immunoglobulin heavy chain J gene was found, and no positive identification of EBV by in situ hybridization for EBV-encoded small nuclear RNA was found. The patient underwent high-dose chemotherapy with autografting of peripheral blood stem cells; however, the tumors quickly relapsed.

CONCLUSION

We gathered data from 17 cases of lymphoid malignancy from the literature sharing immunophenotypic and genotypic features similar to those of our case, including CD2- CD4+ CD56+ and germline rearrangement of TCR. Although the cellular origin could not be decided, this malignancy was found to have 100% affinity for skin, a short course, and poor prognosis.

BP1, a new homeobox gene, is frequently expressed in acute leukemias

Aberrant expression of homeobox genes has been described in primary leukemia blasts. We recently cloned a new cDNA, BP1, which is a member of the homeobox gene family. BP1 expression was investigated in bone marrow samples from acute myeloid leukemia (AML), acute T cell lymphocytic leukemia (ALL) and pre-B cell ALL. Expression levels of two apparent isoforms of BP1, DLX7 and DLX4, were measured in the same samples. They are weakly if at all detectable in normal bone marrow, PHA-stimulated T cells or B cells. BP1 RNA was highly expressed in 63% of AML cases, including 81% of the pediatric and 47% of the adult cases, and in 32% of T-ALL cases, but was not found in any of the pre-B ALL cases. Coexpression of BP1, DLX7 and DLX4 occurred in a significant number of leukemias. Our data, including co-expression of BP1 with c-myb and GATA-1, markers of early progenitors, suggest that BP1 expression occurs in primitive cells in AML. Analysis of CD34+ and CD34- normal bone marrow cells revealed BP1 is expressed in CD34- cells and virtually extinguished in CD34+ cells. Ectopic expression of BP1 in the leukemia cell line K562 increased clonogenicity, consistent with a role for BP1 in leukemogenesis. The presence of BP1 RNA in leukemic blasts may therefore be a molecular marker for primitive cells and/or may indicate that BP1 is an important upstream factor in an oncogenic pathway.

Immunophenotyping of leukemia

Modern immunophenotyping of hematological malignancies by flow cytometry is assisted by a wide array of easily accessible monoclonal antibodies, by antibodies conjugated to diverse fluorochromes, and by reliable techniques for cell membrane permeabilization. Simultaneous assessment of multiple surface and intracellular markers at diagnosis reduces the number of cells required, helps the identification of the malignant cells and determines the degree of immunophenotypic heterogeneity of the malignant cell population. A few critical markers are sufficient to establish the lineage association in the majority of cases of acute and chronic leukemias and lymphomas. More extensive immunophenotyping can provide information about the cells' stage of differentiation, assess the expression of prognostically important features, and determine clonality. The identification of leukemia-associated immunophenotypes can be used for monitoring minimal residual disease during therapy. The presence of cells expressing these phenotypes in patients who are in clinical remission is associated with an increased risk of relapse.

Immunohistochemistry can be used to subtype acute myeloid leukemia in routinely processed bone marrow biopsy specimens. Comparison with flow cytometry

Flow cytometry (FC) is the preferred method of immunophenotyping acute myeloid leukemia (AML). However, there are situations in which FC is unavailable and in which immunohistologic staining of bone marrow biopsy specimens can be used to provide immunophenotypic information. To evaluate immunohistologic staining and to confirm its value, we selected 80 newly diagnosed cases of AML that were classified according to French-American-British (FAB) criteria and confirmed by flow cytometric analysis for this study. Paraffin-embedded bone marrow specimens were stained using a panel of antibodies that included CD34 (QBEND10), antimyeloperoxidase (anti-MPO), antihemoglobin, factor VIII-related antigen, and 3 epitopes of CD68 (HAM56, KP1, and PG-M1). Our findings suggest that with the use of the paraffin-reactive antibodies CD34 (QBEND10), MPO, CD68 (PG-M1), antihemoglobin, and factor VIII-related antigen, immunohistochemistry can be used to subclassify AML. Comparison of immunohistochemical results with FC immunophenotyping suggests that there is significant concordance in the results for markers that can be used with both techniques, indicating that the sensitivity and specificity of both methods is comparable (P > .53 in all cases).

A novel t(11;12)(q23-24;q24) in a case of minimally-differentiated acute myeloid leukemia (AML-M0)

Acute myeloid leukemia with minimal signs of myeloid differentiation (AML-M0) is a recent addition to the FAB group classification. Chromosome data is scarce, but existing reports describe a high incidence of complex karyotypes and myelodysplastic syndrome-like chromosome alterations, while single chromosome translocations have rarely been reported. We describe the case of a 60-year-old woman diagnosed with AML-M0 with a novel translocation t(11;12)(q23-24;q24) as the sole karyotypic marker. Fluorescence in situ hybridization analysis to assess MLL gene splitting did not show rearrangement of this oncogene.

Minimally differentiated acute myeloid leukemia (AML M0): clinico-biological findings of 29 cases

Twenty-nine cases of minimally differentiated acute myeloid leukemia or AML M0 identified among 441 AML diagnosed in the last 12 years are reported. In all cases, flow cytometric analysis using a large panel of monoclonal antibodies and cytogenetic and molecular studies (IgH, TcRbeta, BCR/ABL, AML1/ETO and CBFB-MYH11 rearrangements) were performed. Of the 29 patients, 27 were treated with intensive chemotherapy based on GIMEMA protocols. We noted a greater incidence of older (over 60 years) and male patients (52% and 65%, respectively). CD33, CD13, CD7 and TdT were expressed in 79.3%, 82.7%, 58.6% and 42.8% of cases, respectively. Antigenic MPO was present in 17 of 22 cases (77.3%). Most cases expressed CD34 (93.1%), HLA-DR (93.1%), CD117 (80%) and CD45RA (87%). CD45RO and CD90 were consistently negative. In all cases, we observed an up-expression of bcl-2 and a down-expression of CD95 with an inverse trend between the two markers (r -5253; p 0.03). Karyotypic abnormalities were demonstrated in 53.6% of cases. Of these, 6 involved chromosomes 5, 7 and 8, t(9;22), confirmed by the BCR/ABL transcript, was detected in one case. Rearrangements of the TcRbeta and IgH chains were observed in 3 and 2 cases, respectively. No AML1/ETO and CBFB-MYH11 transcripts were found. Twelve out of 27 patients (44%) achieved a complete remission (CR) (in 2 cases after rescue therapy). Seven early (range 1-9 months) and one late (32 months) relapses were observed. Five patients are alive, but only the 4 who underwent bone marrow transplantation are in persistent first CR. In conclusion, AML M0 is a subtype of AML antigenically well detectable, endowed with many adverse parameters (older age, TdT and CD34 expression, resistance to apoptosis, unfavorable cytogenetic abnormalities) and poor prognosis. A very aggressive consolidation treatment can be useful to improve the outcome.

Flow cytometric immunophenotypic characterization of pediatric and adult minimally differentiated acute myeloid leukemia (AML-M0)

We reviewed the clinicopathologic and immunophenotypic profiles of 7 pediatric and 11 adult minimally differentiated acute myelogenous leukemias (AML-M0). We also compared and evaluated myeloperoxidase in leukemic blasts using standard cytochemical and polyclonal antibody immunohistochemical stains. No distinctive clinical findings were noted in either patient group; however, thrombocytopenia typically was more prominent in adults. Adult AML-M0 also was associated with an immature myeloid profile (CD34+, terminal deoxynucleotidyl transferase positive, CD13+, and CD33+), in contrast with pediatric AML-M0, which usually lacked terminal deoxynucleotidyl transferase or CD34 but expressed bright CD33 with weak or negative CD13. Coexpression of the T-cell-associated antigen CD7 was observed in both groups. Antibody immunohistochemical stains were more sensitive than cytochemical stains for detection of myeloperoxidase activity and a useful adjunct for establishing a diagnosis of myeloid leukemia in paraffin-embedded marrow tissues.

Acute minimally differentiated myeloid leukemia (M0) with inv(3)(q21q26)

We describe a 55-year-old Japanese man with acute minimally differentiated myeloid leukemia (M0) with an inversion in the long arm of chromosome 3, i.e., inv(3)(q21q26). Patients with this chromosomal abnormality usually show normal or elevated platelet counts. However, our case had a low platelet count with megakaryocytic dysplasia at diagnosis. Furthermore, the 3q21q26 aberration is generally detected in patients with acute myelogenous leukemia (AML) or myelodysplastic syndrome. To the best of our knowledge, it has also been reported in two cases of AML-M0 with 3q21q26 and this is the third case of AML-M0 with 3q21q26. Thus it is suggested that there is some relationship between this type of karyotype abnormality and leukemogenesis and/or thrombopoiesis.

Expression of the C-kit receptor (CD117) is a feature of almost all subtypes of de novo acute myeloblastic leukemia (AML), including cytogenetically good-risk AML, and lacks prognostic significance

Because of conflicting reports on the prognosis of patients with c-kit receptor positive AML and lacking correlations with cytogenetic analyses, we prospectively evaluated the c-kit receptor expression in 917 AML patients (750 adult patients; 167 children) using flow cytometry and compared the results to the immunophenotype, morphological and cytogenetic findings as well as clinical outcome. Expression of the c-kit receptor was present in 63% of all AML investigated. Among these an immature immunophenotype was more frequent and 30% had a CD34+/CD15- and 37% a CD34+/CD14- phenotype, whereas only 9% and 10% showed these phenotypes in the c-kit receptor negative group, respectively. C-kit receptor expression ranged average in M0 and M1 subtypes (69% versus 70%) but was less pronounced among M5 subtypes (21%). Results of karyotyping were available in 280 patients. C-kit receptor expression occurred in 37 of 42 (88%) patients with favorable cytogenetic abnormalities such as t(8;21), t(15;17) or inv(16) which exceeded the expression rate in patients with intermediate risk, poor risk or other abnormalities. Information about the clinical outcome was available in 228 patients treated according to the protocols of two German multicenter trials (AML-BFM, AMLCG). We found no difference of CR-rate or event-free survival (EFS) in adults with or without c-kit receptor expression. Children with c-kit receptor negative AML had a lower CR-rate and EFS, but also a lower median age and a higher frequency of M5 subtype as compared to children with c-kit receptor expression. In conclusion, analysis of c-kit receptor expression may help to identify phenotypically immature AML but fails to identify myeloid differentiation of leukemic blasts in approximately one third of patients. We found no evidence of an adverse prognosis in AML patients with c-kit receptor expression. Analysis for c-kit receptor expression does not appear to add information to established prognostic parameters in AML.

AML-M0: a review of laboratory features and proposal of new diagnostic criteria

In 1991, the FAB group published a proposal to designate acute leukemias with minimal signs of myeloid differentiation as AML-M0. This proposal was meant to offer a provisional basis for the study of immature myeloid forms, with the understanding that it was susceptible to changes and improvements with new information derived from the laboratory. Since then there have been a number of reports detailing the biological and clinical features of patients with AML-M0. In this article we review the laboratory data acquired from various sources and suggest a partial modification of diagnostic criteria.

Therapeutic Options in the Management of Acute Myelogenous Leukemia in Adults

BACKGROUND: The treatment of acute myelogenous leukemia has evolved in recent years due to advances in supportive care, the identification of prognostic factors, and the careful evaluation of chemotherapeutic modalities in randomized clinical trials. METHODS: The classification and prognostic features are reviewed, and the results from clinical trials have been evaluated with an emphasis on randomized trials and on both remission induction and postremission phases of management. RESULTS: The combination of an anthracycline and standard-dose Ara-C form the basis of remission induction. High-dose Ara-C has greater toxicity. For postremission therapy, high-dose Ara-C improves results in those with good risk features or normal cytogenetics. Acute promyelocytic leukemia management includes all-trans-retinoic acid. CONCLUSIONS: Once a patient relapses from a nontransplant approach, high-dose therapy and allogeneic marrow transplantation are considered. Autologous stem cell transplantation cures some patients who do not have a donor.