Presentation on theme: "Acute Myeloid Leukaemia— phenotype and genotype"— Presentation transcript:
1Acute Myeloid Leukaemia— phenotype and genotype Barbara J. BainDepartment of HaematologySt Mary’s Hospital, London
2The phenotypic diagnosis A case of leukaemia was first clearly described in 1845 by John Hughes Bennett and another, 6 weeks later, by Rudolf VirchowThese were phenotypic diagnoses at autopsy, the blood being examined microscopicallyA few years later Virchow was the first to use the term “Leukhemia”
3Things moved onThe next one and a half centuries saw advances in the phenotypic diagnosis of leukaemia based onBetter stains and microscopesExamination of the blood and, later, the bone marrow during life
4Things moved on further Further advances improved the phenotypic diagnosis. These wereCytochemical stainsImmunophenotypingIntegration and codification of phenotypic diagnoses
5And further stillThe FAB classifications from the last quarter of the 20th century can be seen as the culmination of phenotypic diagnosisThe FAB group defined, and categorized and gave haematologists and, later, cytogeneticists throughout the world a common languagePhenotypic diagnosis had become quite sophisticated
6But meanwhile —Cytogenetic techniques were improving and with the introduction of chromosome banding there was a quantum leap in what could be recognizedThe incorporation of cytogenetic information into leukaemia classification started, e.g. MIC Group 1986.
7And furthermore — Molecular genetics was invented Now we have FISH, SKY, spectral karyotyping, CGHPCR and RT-PCRMicroarray analysis
8What does this mean for leukaemia diagnosis and classification? Can we move from a MIC to a MIC-M approachShould we do so?
9The WHO classification The WHO classification has taken an approach which is partly based on cytogenetic and molecular genetic analysisFirst, antecedent factors are consideredSecondly, genetic features are consideredThirdly, phenotype is used to categorize the remaining patients
10The WHO classification When appropriate, patients are first assigned to the category of therapy-related AML, regardless of whether they have recurring cytogenetic abnormalitiesThese cases are further categorized asAlkylating agent-relatedTopoisomerase II-interactive drug-relatedOther
11WHO and therapy-related AML This is, in part, a genetic classificationAlkylating agent-related AML is characterized by abnormalities of chromosomes 5 and 7, inv(3), t(3;3), t(6;9), t(8;16) and complex rearrangements
12WHO and therapy-related AML Topoisomerase II-inhibitor-related AML is characterized by balanced translocations with 21q22 (AML1) and 11q23 (MLL) breakpoints including t(3;21), t(8;21), t(4;11), t(9;11) and t(11;19)(q23;p13.1) [but not t(11;19)(q23;p13.3)]
13WHO and therapy-related AML Topoisomerase II-inhibitor-related AML is associated not only with t(8;21)(q22;q22) but also with other translocations usually found in de novo AML, e.g. t(15;17)(q22;q12) and inv(16)(p13q22)
14Where does therapy-related AML with recurrent cytogenetic abnormality belong? It may be important to classify such cases as therapy-related in order to accurately judge the magnitude of the problem of therapy-induced AML (and ALL)These cases might also be prognostically worse than de novo cases
15Where does therapy-related AML with recurrent cytogenetic abnormality belong? However—t-AML and de novo AML with the same cytogenetic abnormality have a lot of features in common and maybe the prognosis is not so very different
16Therapy-related AML with t(8;21)(q22;q22) Slovak et al. (2002) reported a median survival of < 3 years and a 5 year survival of < 30%However the treatment was not standardized and in the larger group of AML patients with a 21q22 bp a quarter of patients were untreated or undertreatedSlovak et al. (2002) Genes Chromosomes Cancer, 33, 379.
17Therapy-related AML with t(15;17)(q22;q21) Andersen et al. (2002) reported, for intensively treated patients, that there was:a 69% CR ratea median survival of 29 monthsa 5-year survival of 45%Andersen et al. (2002) Genes Chromosomes Cancer, 33, 395.
18Therapy-related AML with t(15;17)(q22;q21) n CR rate 4-yr EFS 4-yr OS34 97% 65% 85%‘secondary’% 68% 78%de novo‘Secondary’ = 15 surgery, 17 RT, 10 Chemo, 10 Chemo + RTPulsoni et al. (2002) Blood, 100, 1972
19Therapy-related AML with inv(16)(p13q22) Andersen et al (2002) reported , with intensive treatment:85% CR29 months median survival45% 5-year survivalAndersen et al. (2002) Genes Chromosomes Cancer, 33, 395.
20What should we do?We should follow the WHO classification but should note the presence of relevant cytogenetic abnormalitiesWe should recognize that topoisomerase II-inhibitor-related secondary AML is quite a different matter from t-AML related to alkylating agents
21WHO classification AML — with recurrent cytogenetic abnormalities AdvantagesCertain cytogenetic/molecular genetic categories are recognizedAML, e.g. with t(8;21) and inv(16) with less than 30% blasts is recognized
22WHO classification AML — with recurrent cytogenetic abnormalities DisadvantagesAcute promyelocytic leukaemia with classical and variant translocations are lumped togetherAll cases of AML with all 11q23 breakpoint and MLL rearrangement are lumped together
23Acute promyelocytic leukaemia and “variants” (i) Subtype Gene ATRA PMLresponse distribM3/M3v/t(15;17) PML-RARA Yes AbnormalM3-like/t(11;17) PLZF-RARA No Normal(q23;q21)M3-like/t(11;17) NuMA-RARA Probably Normal(q13;q21)M3-like/t(1;17) NPM-RARA Probably Normal
24Acute promyelocytic leukaemia and “variants” (ii) RARA and the normal cellRAR binds to RXR. In the absence of RA, RAR-RXR binds to RARE in the promoter of target genes, interacts with co-repressors, attracts HDACs, leading to chromatin condensation and repression of transcriptionIn the presence of RA, RAR-RXR is converted from a repressor to an activator since it now binds to co-activators and fails to bind to co-repressors
25Acute promyelocytic leukaemia and “variants” (iii) RARA and the promyelocytic leukaemia cellPML-RAR binds more strongly to co-repressors and does not dissociate in the presence of physiological levels of RAHowever, pharmacological levels of ATRA correct the situationHDAC inhibitors should enhance the action of ATRA and appear to do soJones and Saha (2002) Br J Haematol, 118, 714
26Acute promyelocytic leukaemia and “variants” (iv) RARA and the leukaemia cell of M3-like/t(15;17)/PLZF-RARA AMLPLZF is a transfer factor that binds to co-repressorsPLZF-RAR therefore binds to corepressors through two binding sites —dependent on RARA and independent of itPharmacological doses of ATRA don’t break the second bond and therefore cases are refractory to this therapyHowever HDAC inhibitors should enhance and appear to do so
27Acute promyelocytic leukaemia and “variants” (v) ConclusionNot all acute leukaemias involving the RARA gene represent the same diseaseSome respond to ATRA and some do notSome respond to arsenic trioxide and some do notA molecular classification can help us to predict or understand response to therapy
28Acute myeloid leukaemia with 11q23 breakpoints and MLL rearrangement Is this one disease or many?The results of the European 11q23 workshop and other published data suggest that this is many diseases
29Acute myeloid leukaemia with 11q23/MLL rearrangement n < 1 y ALLt(4;11) % 95 %t(6;11) % 10 %t(9;11) % 7 %t(10;11) % 20 %t(11;19)/MLL-ELL % nilt(11;19)/MLL-ENL % 66 %
30Acute myeloid leukaemia with 11q23/MLL rearrangement FAB t-AML/MDSt(4;11) M %t(6;11) M4/M5a nilt(9;11) M5a %t(10;11) M5a %t(11;19)/MLL-ELL M %t(11;19)/MLL-ENL M4/M5a nil
31Acute myeloid leukaemia with 11q23/MLL rearrangement ConclusionAcute leukaemia with 11q23/MLL involvement is many disease not oneThis does not yet have much therapeutic significance but maybe it will have in the future
32Are there other cytogenetic/ molecular genetic categories of AML we should recognize? M1/t(9;22)/BCR-ABL fusionFAB: M1 (occasionally M0, M2, M4)Usually no Auer rodsMainly de novo but occasionally after topoisomerase-II-interactive drugsPoor prognosis
33Are there other cytogenetic/ molecular genetic categories of AML we should recognize? M2 or M4Baso/t(6;9)/DEK-CAN fusionFAB: M2 (occasionally M4 or M1)May show basophilic differentiation and Auer rodsMainly de novo but occasionally after topoisomerase-II-interactive drugs or alkylating agentsPoor prognosis
34Are there other cytogenetic/ molecular genetic categories of AML we should recognize? M5/t(8;16)/MOZ-CBP fusionFAB: M5 or M4 with haemophagocytosisAbnormal coagulationde novo or secondary (topoisomerase-II-interactive drugs or alkylating agents)Poor prognosis
35Are there other cytogenetic/ molecular genetic categories of AML we should recognize? M7/t(1;22)/OTT-MAL fusionFAB: M7Mainly infants
36Are there other cytogenetic/ molecular genetic categories of AML we should recognize? Various/inv(3) or t(3;3)/EVI1 dysregulationAny category except M3; M7 over-representedPlatelet count often normal or even increasedTrilineage myelodysplasiaDe novo, secondary to alkylating agents or transformation of a MPD
37Can we recognize any purely molecular categories of AML?
38Can we recognize any purely molecular categories of AML? Yes
39AML with CEBPA mutations (i) Mutations in the CEBPA gene, encoding the CCAAT/enhancer binding protein a have now been identified in 7-10% of AMLCEBPa is exclusively expressed in myelomonocytic cells and is essential for neutrophilic differentiation
40AML with CEBPA mutations (ii) CEBPa negatively regulates MYC and positively regulates the genes encoding the receptors for M-CSF, G-CSF and GM-CSFCEBPa-deficient mice have granulopoiesis arrested at the myeloblast stage
41AML with CEBPA mutations (iii) CEBPa mutations were found in 15 of 134 patients studied prospectively and were an independent good prognostic featureSuch mutations, in the absence of FLT3 ITD, could lead to a patient being classified and treated as ‘good prognosis’Preudhomme et al (2002) Blood, 100, 2717
42What does the future hold? Is the future micro-arrays?
43What does the future hold? Clinical assessment and morphology will remain crucial, particularly for diagnosisCytochemistry will continue to decline in importance, but should not be neglectedImmunophenotyping will hang onMolecular diagnosis will lead to more accurate classification and scientifically-based more effective treatment