What type of cells are affected in acute myeloid leukemia?

A very interesting question. AML is considered a stem cell disease. Stem cell means a hematopoietic stem cell, so a stem cell that gives rise to all the different blood components. White cells, red cells, platelets, and stem cells are affected to different degrees. So there are leukemias that are very early in the stem cell hierarchy, and then there are leukemias that are generated in a more mature cell, like in a blast or promyelocyte cell. And in the old days, the leukemias were classified based on what cell was transformed. And the transformation we will talk about are very immature stem cell-like leukemias, and then there are more mature leukemias that affect monocytes or promyelocytes. And speaking of promyelocytes, there's one subtype called APL, acute promyelocytic leukemia, which is clinically very different from the others. This had the worst prognosis when I started, with a cure rate of 30%. And now the cure rate worldwide is between 80% and 90%. So it matters, obviously, what kind of leukemia you have. So that's an easy classification based on the cell of origin. But what is leukemia? That's a real question, right? So leukemia is not just proliferation division of the cells. It is considered also to be the inability to differentiate into the mature cells. So in case of AML, which affects mostly the myeloid cells and two-degree erythroid cells, but not lymphoid cells, that would be called ALL, acute lymphoblastic leukemia. So in the acute myeloid leukemias, the cells cannot mature to make good white cells. That means granulocytes that you have in your bloodstream, they fight infections. So there are three different factors that play a role. Increased production, the inability to mature, to differentiate to cells that are obviously needed by us. And third, the inability to die. So that is a very important component. And more recently, we have exploited that therapeutically. And Dr. Konop-Levra will talk about it later. So the inability to die, to undergo apoptosis is a key feature of acute myeloid leukemia. So I hope that answers the question of what type of cells are affected. The more immature the leukemia, the closer to a stem cell, the worse the outcome. So that has been established also over the years, but that does not have a direct therapeutic consequence at this point, at least.