WHO CLASSIFICATION OF TUMOURS OF HAEMATOPOIETIC AND LYMPHOID TISSUES , WHO CLASSIFICATION OF TUMOURS OF HAEMATOPOIETIC AND LYMPHOID TISSUES , کتابخانه مرکزی دانشگاه علوم پزشکی تهران

WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues

https://redbook.streamliners.co.nz/MPD_WHO-classification_vardiman_blood2009.pdf

The 2008 revision of the World Health Organization (WHO) classification of myeloid neoplasms and acute leukemia: rationale and important changes

http://caprockhematology.com/Site/AML_and_ALL_files/AML%20Review%20Blood%202010.pdf

Diagnosis and management of acute myeloid leukemia in adults: recommendations from an international expert panel, on behalf of the European LeukemiaNet.

The origin and evolution of mutations in acute myeloid leukemia.

Background Myelodysplastic syndromes are clinically heterogeneous disorders characterized by clonal hematopoiesis, impaired differentiation, peripheral-blood cytopenias, and a risk of progression to acute myeloid leukemia. Somatic mutations may influence the clinical phenotype but are not included in current prognostic scoring systems. Methods We used a combination of genomic approaches, including next-generation sequencing and mass spectrometry–based genotyping, to identify mutations in samples of bone marrow aspirate from 439 patients with myelodysplastic syndromes. We then examined whether the mutation status for each gene was associated with clinical variables, including specific cytopenias, the proportion of blasts, and overall survival. Results We identified somatic mutations in 18 genes, including two, ETV6 and GNAS, that have not been reported to be mutated in patients with myelodysplastic syndromes. A total of 51% of all patients had at least one point mutation, including 52% of the patients with...

/pdf/clinical-effect-of-point-mutations-in-myelodysplastic-49qsko6mr5.pdf

Clinical effect of point mutations in myelodysplastic syndromes.

Myelodysplasia (MDS) and acute myeloid leukemia (AML) are heterogeneous, closely associated diseases arising de novo or following chemotherapy with alkylating agents, topoisomerase II inhibitors, or after radiotherapy. Whereas de novo MDS and AML are almost always subclassified according to cytogenetic characteristics, therapy-related MDS (t-MDS) and therapy-related AML (t-AML) are often considered as separate entities and are not subdivided. Alternative genetic pathways were previously proposed in t-MDS and t-AML based on cytogenetic characteristics. An increasing number of gene mutations are now observed to cluster differently in these pathways with an identical pattern in de novo and in t-MDS and t-AML. An association is observed between activating mutations of genes in the tyrosine kinase RAS-BRAF signal-transduction pathway (Class I mutations) and inactivating mutations of genes encoding hematopoietic transcription factors (Class II mutations). Point mutations of AML1 and RAS seem to cooperate and predispose to progression from t-MDS to t-AML. Recently, critical genetic effects underlying 5q-/-5 and 7q-/-7 have been proposed. Their association and cooperation with point mutations of p53 and AML1, respectively, extend the scenario of cooperating genetic abnormalities in MDS and AML. As de novo and t-MDS and t-AML are biologically identical diseases, they ought to be subclassified and treated similarly.

Genetics of therapy-related myelodysplasia and acute myeloid leukemia

The p14ARF, p15INK4B, and p16INK4A genes are important negative cell-cycle regulators often inactivated by deletions, mutations, or hypermethylation in malignancy. Hypermethylation of the three genes was studied in 81 patients with therapy-related myelodysplasia (t-MDS) or acute myeloid leukemia (t-AML) by methylation-specific PCR, and p15 methylation additionally by bisulfite genomic sequencing. In all, 55 patients disclosed p15 methylation, five patients showed p16 methylation, whereas p14 methylation was not observed. Methylation of p15 was closely associated with deletion or loss of chromosome arm 7q (P=0.0006). In t-MDS, the p15 methylation frequency and the p15 methylation density both increased significantly by stage (P=0.004 and 0.0002), and p15 methylation frequency increased with an increasing percentage of myeloblasts in the bone marrow (P=0.006). In a two-variable Cox model including the percentage of myeloblasts, p15 methylation was an independent prognostic factor (P=0.005). Methylation of p15 was less common in t-AML of subtype M5 than in other FAB subtypes (P=0.03). Methylation of p15 was unrelated to type of previous therapy, to latent period from start of therapy, to platelet count, and to p53 mutations. Inactivation of p15 and deletion of genes on chromosome arm 7q possibly cooperate in leukemogenesis.

Methylation of p15INK4B is common, is associated with deletion of genes on chromosome arm 7q and predicts a poor prognosis in therapy-related myelodysplasia and acute myeloid leukemia.

The Workshop identified 48 unselected patients with therapy-related myelodysplastic syndrome or acute myeloid leukemia (t-MIDS/t-AML) and inv(16), and 41 patients with t(15; 17) after chemotherapy (CT) and/or radiotherapy (RT) for a malignant or nonmalignant disease. The primary diseases were: breast cancer, 33 patients; lymphomas, 24 patients; various other solid tumors, 30 patients; and nonmalignant diseases, 2 patients. The general type of previous therapy was RT only in 10 patients with an inv(16) and in 12 patients with a t(15; 17), alkylating agents plus topoisomerase 11 inhibitors in 24 patients with an inv (16) and in 18 patients with a t(15; 17), topoisomerase 11 inhibitors only in 5 patients with an inv(16) and in 2 patients with a t(15; 17), alkylating agents only in 6 patients in each subgroup, and other types of chemotherapy in 3 patients in each subgroup. Most CT-treated patients (69%) also received RT. The latency period to development of t-MDS/t-AML was short: a median of 22 months in patients with inv(16) and 29 months in patients with t(15; 17). Twenty-six patients (54%) with an inv(16) and 17 patients (41%) with a t(15; 17) had additional cytogenetic abnormalities, which were unrelated to age and survival in both subgroups. Trisomy of chromosomes 8, 21, and 22 and del(7q) were the most frequent additional abnormalities in the inv(16) subgroup, whereas +8, -5, and del(16q) were most frequent in the t(15; 17) subgroup. The disease was overt t-AML in 38/48 patients (79%) with an inv(16) and in 38/41 patients (93%) with a t(15; 17). Thirty-three of 39 intensively treated patients (85%) with an inv(16) obtained a complete remission, whereas 24 of 35 intensively treated patients (69%) with a t(15; 17) obtained a complete remission. The median overall survival of intensively treated patients was 29 months in both cytogenetic subgroups. In the inv(16) subgroup, patients younger than 55 years of age had a longer survival when compared with older patients (P = 0.006). The study supports the observation that t-MDS/t-AML with inv(16) and t(15; 17) is often associated with prior therapy with topoisomerase 11 inhibitors; however, a notable finding was the high frequency of treatment with only radiotherapy, 29% of t(15; 17) and 21 % of inv(16). Response rates to intensive chemotherapy in this study were comparable to those of de novo disease. (Less)

Balanced chromosome abnormalities inv(16) and t(15;17) in therapy-related myelodysplastic syndromes and acute leukemia: Report from an international workshop

Alternative genetic pathways were previously outlined in the pathogenesis of therapy-related myelodysplasia (t-MDS) and acute myeloid leukemia (t-AML) based on cytogenetic characteristics. Some of the chromosome aberrations, the recurrent balanced translocations or inversions, directly result in chimeric rearrangement of genes for hematopoietic transcription factors (class II mutations) which disturb cellular differentiation. Other genetic abnormalities in t-MDS and t-AML comprise activating point mutations or internal tandem duplications of genes involved in signal transduction as tyrosine kinase receptors or genes more downstream in the RAS-BRAF pathway (class I mutations). The alternative genetic pathways of t-MDS and t-AML can now be further characterized by a different clustering of six individual class I mutations and mutations of AML1 and p53 in the various pathways. In addition, there is a significant association between class I and class II mutations possibly indicating cooperation in leukemogenesis, and between mutations of AML1 and RAS related to subsequent progression from t-MDS to t-AML. Therapy-related and de novo myelodysplasia and acute myeloid leukemia seem to share genetic pathways, and surprisingly gene mutations were in general not more frequent in patients with t-MDS or t-AML as compared to similar cases of de novo MDS and AML studied previously.

Alternative genetic pathways and cooperating genetic abnormalities in the pathogenesis of therapy-related myelodysplasia and acute myeloid leukemia.

Mutations of the FLT3, c-KIT, c-FMS, KRAS, NRAS, BRAF and CEBPA genes in the receptor tyrosine kinase (RTK)/RAS-BRAF signal-transduction pathway are frequent in acute myeloid leukemia (AML) We examined 140 patients with therapy-related myelodysplasia or AML (t-MDS/t-AML) for point mutations of these seven genes In all, 11 FLT3, two c-KIT, seven KRAS, eight NRAS and three BRAF mutations were identified in 29 patients (21%) All but one patient with a FLT3 mutation presented with t-AML (P=00002) Furthermore, FLT3 mutations were significantly associated with previous radiotherapy without chemotherapy (P=003), and with a normal karyotype (P=0004), but inversely associated with previous therapy with alkylating agents (P=0003) and with -7/7q- (P=0001) RAS mutations were associated with AML1 point mutations (P=0046) and with progression from t-MDS to t-AML (P=0008) Noteworthy, all three patients with BRAF mutations presented as t-AML of M5 subtype with t(9;11)(p22;q23) and MLL-rearrangement (P=001) In t-AML RAS/BRAF mutations were significantly associated with a very short survival (P=0017) Half of the patients with a mutation in the RTK/RAS-BRAF signal-transduction pathway (denoted 'class-I' mutations) simultaneously disclosed mutation of a hematopoietic transcription factor (denoted 'class-II' mutations) (P=0046) suggesting their cooperation in leukemogenesis

Mutations of genes in the receptor tyrosine kinase (RTK)/RAS-BRAF signal transduction pathway in therapy-related myelodysplasia and acute myeloid leukemia.

J Pedersen-Bjergaard

Papers

Genetics of therapy-related myelodysplasia and acute myeloid leukemia

Methylation of p15INK4B is common, is associated with deletion of genes on chromosome arm 7q and predicts a poor prognosis in therapy-related myelodysplasia and acute myeloid leukemia.

Balanced chromosome abnormalities inv(16) and t(15;17) in therapy-related myelodysplastic syndromes and acute leukemia: Report from an international workshop

Alternative genetic pathways and cooperating genetic abnormalities in the pathogenesis of therapy-related myelodysplasia and acute myeloid leukemia.

Mutations of genes in the receptor tyrosine kinase (RTK)/RAS-BRAF signal transduction pathway in therapy-related myelodysplasia and acute myeloid leukemia.