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Genetic changes in MDS
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MDS is a heterogeneous disease with few unifying features
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Spectrum of MDS Differentiation Asymptomatic,IPSS low Low/Int-1
Symptomatic,IPSS Int-2/High Risk BM function Transfusion Transfusion Apoptosis Proliferation and Blasts IPSS Using risk factors such as age and blast count patients are stratified into prognostic risk groups. This has recently been revised to improve accuracy but these models still do not take into account the emerging molecular information. Greenberg, Blood 1997, Malcovati,JCO 2009,Greenberg Blood 2012
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Gross genomic changes are detected by cytogenetics
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MDS cytogenetic studies
Unlike ph+ CML or JAK2 positive PRV MDS has no specific defining molecular
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Mutations alter proteins
Small genetic changes can only be detected at the molecular level. Met Lys Leu His His Trp Lys Phe Asp * ATG AAG TTA CAT CAT TGG AAA TTT GAT TGA ATG AAG TTA CAT GAT TGA AAA TTT GAT TGA Met Lys Leu His Asp * Lys Phe Asp *
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Point Mutations in MDS BRAF TET2 RUNX1 TP53 U2AF1 DNMT3A SF3B1 SRSF2
Tyrosine Kinase Pathway Transcription Factors Others NPM1 KRAS BRAF RUNX1 JAK2 TP53 GATA2 ETV6 Cohesins GNAS/GNB1 RNA helicases NRAS RTK’s PTPN11 BCOR EP300 WT1 PHF6 CBL Epigenetic Dysregulation Splicing Factors DNMT3A EZH2 U2AF1 ZRSF2 SF3B1 IDH 1 & 2 SETBP1 PRPF40B TET2 U2AF2 SRSF2 UTX ASXL1 PRPF8 SF1 ATRX SF3A1
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Many mutations are very rare
Haferlach et al., Leukemia Feb;28(2):241-7 Only 5 genes are mutated in >10% of patients Target present on the KCH panel
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KCH: Myeloid Gene Panel (MGP)
24 genes mutations panel: Transcription factors and cell cycle regulators RUNX1 TP53 GATA2 ETV6 CEBPA NPM1 Epigenetic modifications TET2 IDH1 IDH2 DNMT3A KDM6A ASXL1 EZH2 Spliceosome component SF3B1 U2AF1 SRSF2 ZRSR2 Signaling NRAS KRAS FLT3 CBL JAK2 KIT Cohesin complex STAG2 Research use only: clinical importance is yet to be determined
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The challenge for the laboratory
Integrating genomic analysis into diagnostic, prognostic and therapeutic systems for patients.
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Therapy response / outcome
Lenalidomide (Revlimid) TP53mut do not achieve complete cytogenetic response in del5q MDS (Jadersten JCO, Austin Kulasekararaj BJH) 5’Azacytidine (Vidaza) TET2mut may respond better TET2mut and DNMT3Amut may respond better ASXL1 and SF3B1 status also modulate response
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Finally Genetic testing is more widely available:
Cheaper, simpler, faster Mutations help in the certainty of diagnosis. Incorporation into prognostic models such as IPSS The era of biomarker-based therapy may not be too distant
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Acknowledgments LMH laboratory KCH:
Department of Hematological Medicine, King’s College London Prof G Mufti Prof Judith Marsh Dr Austin Kulaesekararaj Dr Robin Ireland LMH laboratory KCH: Dr Steve Best Dr Aytug Kizilors Sara Ribeiro Tashna Smith
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