What testing should be done to confirm an acute myeloid leukemia diagnosis?

What testing should be done to confirm an AML diagnosis? So first of all, one has to do a bone marrow, aspirate, and biopsy. So that's standard. And then the hematopathologist will look at the smear and at the biopsy and identify these blasts. And we will call it AML if there are certain markers positive, so-called myeloid markers. So how is that being done in the old days? More by staining with antibodies on the slide. And for many years, this is done by flow cytometry. We will explain what that is. So we have a very vast panel of markers on these cells that we can identify with so-called monoclonal antibodies. So these are antibodies that bind to receptors on the surface of the leukemic cell. And we can quantitate that. How many of these receptors do we have per cell? So this is called immunophenotyping. And this will tell us the cell of origin, perhaps, and how mature, how differentiated the leukemic cell is, and are these really myeloid leukemias. So not so long ago, the false diagnostics was about 30%. So 30% of patients were not correctly diagnosed. And that has vastly improved because of the use of flow cytometry. So the diagnosis of acute myeloid leukemia was imperfect two or three decades ago. And up to 30% of patients who came to MD Anderson had to be reclassified. So that number is way down now because of the wide use of flow cytometry, where we are checking for antigens expressed on the surface of the leukemic cells to make sure these are myeloid cells and not lymphoid cells or some other cells. So we have a very vast panel of antibodies, reagents, that are labeled with a fluorescent marker. And this can be quantitated by flow cytometry. So that's the next important step. And pathologists always use these markers to call it AML and subtypes of AML. The next testing now is molecular. So it started with chromosome analysis, so-called cytogenetics. It's still very, very useful. So we are looking at chromosomes and changes in chromosomes, breaks in chromosomes, fusion of different chromosomes. For instance, BCIABL, which is two genes that are fused and they give rise to a 922 translocation, which is found in chronic myeloid leukemia, but also in some acute myeloid leukemias. Other abnormalities would be trisomy 8. So chromosome 8 is not present in two copies, but in three copies. Other changes would be short arm of chromosome 17, losses of pieces of chromosome 5 and 7, or the entire loss of chromosome 5 and 7, and so on. So it's very complicated in the end, but not all patients have all these abnormalities. And it gives us a very good idea already about the prognosis based on these chromosome analyses. So the next step then is DNA sequencing. So we have a panel of right now 81 mutations that we are looking at routinely. One could also sequence the entire exome, that means all the expressed, all the genes, but that is too cumbersome. And so we have a panel of 81 genes, which covers the vast majority of what is known to be mutated in AML. So now we're looking at mutations. I mentioned already FLIC3 mutation, which comes in different flavors, which are important for the specific drugs that we use. There are so-called IDH mutations. We have drugs specifically for these mutations. There are mutations in genes like Rangs1, like P53 again, which I said is the worst. And so we have a whole panel of mutations, and they help us nailing down the diagnosis. And now we are classifying the AMLs increasingly more based on mutations. This is directly correlated with prognosis. And to make a bad prognosis group into a good prognosis group, we need targeted treatments. And I mentioned the FLIC3 leukemias, which were very bad before and have vastly improved by quite a number of targeted therapies. All this takes a long time. All this takes 20 years. Each drug has a history of 20 years at least, from the development to early clinical trials, and if successful, then to FDA approval. So these things don't happen overnight. There's a lot of preclinical work, a lot of chemistry, a lot of optimization of drugs involved. But in the end, we have an ever increasing number of specific therapies that are usually targeted to particular mutations, but not all of them. So that, I think, is the diagnostic workup which leads directly to treatment decisions. There's one more technique called FISH fluorescence in cytohybridization, which we also pioneered 30 years ago, and it's used routinely and detects chromosomal abnormalities that cannot be detected by conventional microscopy of chromosomes.