ETP-ALL (Early T-cell precursor acute lymphoblastic leukemia)

ETP-ALL is currently defined by a distinctive phenotype characterized by a lack of expression of the T-lineage cell surface markers CD1a and CD8, weak or absent expression of CD5 and aberrant expression of one or more myeloid or stem cell markers (Coustan-Smith et al., 2009).
Early T-cell precursors (ETPs) are immature progenitors that have recently immigrated from the bone marrow to the thymus and which retain a multilineage differentiation potential (T-lymphoid, natural killer, dendritic and myeloid cell differentiation potential).

There is currently no consensus on the prognosis of ETP-ALL. Initial prognostic studies between 2009 and 2012 reported a negative prognostic impact on response rate and survival (Coustan-Smith et al., 2009, Inukai et al., 2012; Ma et al., 2012) and a higher risk of relapse (Allen and al., 2013).

Immunophenotyping:

ETP-ALL cases are currently identified through the phenotype of blast cells : CD1a-, CD8-, CD5- /weak, and positivity for one or more stem cell and/or myeloid antigens (CD117, CD34, HLA-DR, CD13, CD33, CD11b, and/or CD65). ETP-ALL typically also express CD2, CD7 and cytoplasmic CD3 and may express CD4.

                                                                                                                     CASE 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In case 1 blasts are gated from CD45 population in red. these blasts are positive for cCD3 , MPO , CD7, CD34CD117, CD38, CD2, CD11B and CD13dim while negative for CD5, CD33, HLA-DR, CD123, CD1a, CD56, CD19, CD22, CD16 and Tdt.

 

 

 

 

                                                                                                                     CASE 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In case 2 blasts are gated from CD45 population in red. these blasts are positive for cCD3, CD7, CD34, CD33, CD117dim, CD2, CD11B, HLA-DR  while negative for CD5, CD1a, CD56, CD19, CD65, cCD79a, CD8 and CD4.

 

 

 

REFERENCES

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  2. Ludwig WD, Raghavachar A, Thiel E. Immunophenotypic classification of acute lymphoblastic leukaemia. Baillieres Clin Haematol. 1994;7(2):235-262.

  3. Ludwig WD, Reiter A, Loffler H, et al. Immunophenotypic features of childhood and adult acute lymphoblastic leukemia (ALL): experience of the German Multicentre Trials ALL-BFM and GMALL. Leuk Lymphoma. 1994;13 Suppl 1:71-76.

  4. Borowitz MJ, Chan JKC. T Lymphoblastic Leukemia/Lymphoma. In: Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and LymphoidTissues. Lyon: IARC; 2008:176-178.

  5. Coustan-Smith E, Mullighan CG, Onciu M, et al. Early T-cell precursor leukaemia: a subtype of very high-risk acute lymphoblastic leukaemia. Lancet Oncol. 2009;10(2):147-156.

  6. Zhang J, Ding L, Holmfeldt L, et al. The genetic basis of early T-cell precursor acute lymphoblastic leukaemia. Nature. 2012;481(7380):157-163.

  7. Bell JJ, Bhandoola A. The earliest thymic progenitors for T cells possess myeloid lineage potential. Nature. 2008;452(7188):764-767.

  8. Conter V, Valsecchi MG, Buldini B, et al. Early T-cell precursor acute lymphoblastic leukaemia in children treated in AIEOP centres with AIEOP-BFM protocols: a retrospective analysis. Lancet Haematol. 2016;3:e80-e86.

  9. Coustan-Smith E, Mullighan CG, Onciu M, et al. Early T-cell precursor leukaemia: a subtype of very high-risk acute lymphoblastic leukaemia. Lancet Oncol. 2009;10:147-156.

  10. Patrick K, Wade R, Goulden N, et al. Outcome fro children and young people with Early T-cell precursor acute lymphoblastic leukaemia treated on a contemporary protocol, UKALL 2003. Br J Haematol. 2014;166:421-424.

  11. Wood BL, Winter SS, Dunsmore KP, et al. T-lymphoblastic leukemia (T-ALL) shows excellent outcome, lack of significance of the early thymic precursor (ETP) immunophenotype, and validation of the prognostic value of end-induction minimal residual disease (MRD) in children's oncology group (COG) study AALL0434. Blood. 2014;124:1.

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