You spelled it right. I am studying to be a Medical Laboratory Technician. So I will tell some of the things I can remember. When it stops responding to treatments that means that the leukemia has gotten so bad that it can not get any better. There are so many types of leukemias categorized under acute and chronic leukemia. One example of leukemia is Acute Lymphocytic Leukemia(L1), which is most common in children, and is when the predominant cell being made is lymphocytes. Some leukemias have a longed life expectancy than others, from a couple months to years, so it really depends. Patients die from leukemia because there bone marrow is making white blood cells or other cell lines at a fast pace causing cells to spill over into the bloodstream, crowding out other cells that are needed for everyday function such as red blood cells. Crowding out can cause thrombocytopenia, which means that lack of platelets, which stops bleeding. And it also causes lack of rbc's leading to less oxygen being transported to the rest of the body. These patients experience excruciating bone pain due to the large cells being proliferated in the bone marrow. Infections and hemorrahages usually result in death because their bodies just breakdown after awhile. I hope this information is helpful.
I have a link if you want more info about leukemias.