Current Classifications of Acute Myeloid Leukemia


Expert perspectives on current classification strategies in acute myeloid leukemia and how these guidelines make use of molecular markers.


Jorge E. Cortes, MD: I’d like to ask Dr Kasner, in this classification, what are the subsets that you think were in attention because they’re more frequent, or they’re more challenging? Which ones would you highlight as the ones to pay the most attention? Of course, they’re all important, but which ones do you find particularly challenging or common?

Margaret T. Kasner, MD: I think we need to step back a second because you mentioned FAB [French-American-British classification], which was how we classified a long time ago, and since then, the WHO, World Health Organization, has led our classification systems. This year we have a unique challenge, which is that we now have 2 classification systems. In addition to the fifth WHO classification system, we also have the International Classification Consensus, or ICC. Talking for a moment about their similarities and differences leads to where we should focus because I think the goal of these is to help us focus. One of the things that’s interesting is that the ICC merged all the AMLs [acute myeloid leukemias] defined by the differentiation markers, which is what you were talking about, the sort of M0 all the way through M7, into an AML, NOS category. But that’s not that important. You don’t need to focus on that. What you need to focus on is defined cytogenetic abnormalities. Those are things like what defines acute promyelocytic leukemia, which is the PML-RARA fusion and the long list of the core-binding factors and other genetic abnormalities that are well defined. The ICC said that some of them are so important that you only need 10% blasts if you have one of these translocations to be called AML. It’s AML. Now, both maintained 20% blasts for other settings, including AML with the BCR-ABL translocation, which used to think of as some form of CML [chronic myeloid leukemia], but now can be called AML. [It] then became an expanded classification of AML with myelodysplastic-related changes, which no longer focused on morphology, but on MDS [myelodysplastic syndromes]-related gene mutations. This is an important place for us to focus in terms of subtypes. I don’t need to read the list to you, but the important thing is that the ICC and the WHO agree on everyone except for [INAUDIBLE]. They’re saying to us, pay attention. These are important, and honestly, generally poor prognostic indicators for our patients, and we must pay attention to these things. The other thing that they said was that prior cytotoxic therapy is now a qualifier, but not a subtype. Why is this important? Because we’ve always known that if you had chemotherapy from breast cancer, but you got a core-binding factor leukemia, that the biology was most important, not that you had had previous chemotherapy. Again, they’re saying to us, the biology is what’s important. These abnormalities, FLT3, the most common for a prognosis abnormality that we see in our clinics. I think that the new classification systems are pushing us to look at what is important, which is the molecular abnormalities and the biology of the disease, and much less about what we used to classically think of as sub-categorizations by things like morphology.

Transcript edited for clarity.

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