What Is Busulfan Used For?
Busulfan is a type of chemotherapy medication prescribed to treat chronic myelogenous leukemia, a form of cancer that affects the bone marrow and blood cells. This drug works by preventing DNA from replicating, a process needed in order for cancer cells to grow and multiply. Busulfan can also be used for treating other conditions, such as thrombocytosis and ovarian cancer.
Busulfan (Myleran®) is a prescription medication that belongs to a group of chemotherapy drugs known as alkylating agents. It is approved to treat chronic myelogenous leukemia, which is also sometimes called CML, chronic myelocytic leukemia, chronic granulocytic leukemia, or chronic myeloid leukemia.
Leukemia is a cancer that affects the blood and bone marrow. It occurs when the bone marrow makes large amounts of abnormal white blood cells called leukemia cells. The leukemia cells grow out of control and do not function like normal blood cells. Over time, leukemia cells can crowd out normal, healthy blood cells, leading to serious problems, such as bleeding, anemia, and infections.
There are several different types of leukemia. In general, leukemia types are classified by how quickly they get worse (chronic versus acute leukemia), and by the type of blood cell affected (lymphoid versus myeloid leukemia) (see Types of Leukemia for more information on the various kinds of leukemia).
Chronic leukemia progresses more slowly than acute leukemia. Lymphoid leukemia affects white blood cells called lymphocytes, while myeloid leukemia affects white blood cells called myelocytes. Therefore, CML is a slow-growing leukemia of the myelocytes. This type of leukemia usually occurs during or after middle age, and rarely occurs in children.
Most people with chronic myelogenous leukemia have an abnormal chromosome called the Philadelphia chromosome, which received its name because it was first discovered in Philadelphia. Chromosomes are the structures in cells that contain DNA. The Philadelphia chromosome forms when pieces of two different chromosomes break off and swap places. The shorter chromosome that results from this swap is called the Philadelphia chromosome.
The Philadelphia chromosome tells the bone marrow to make too much of an enzyme called tyrosine kinase. Tyrosine kinase causes the production of too many white blood cells, resulting in CML.
CML is divided into three phases, the chronic phase, accelerated phase, and blastic phase. These phases are primarily based on how many cells in the blood and bone marrow are immature blood cells (called blast cells).
In the chronic phase, very few cells in the blood and bone marrow are blast cells. A person may not have leukemia symptoms in this phase, or symptoms may be mild. As the number of leukemia cells increases, the disease moves into the accelerated phase, and symptoms are more noticeable. Finally, in the blastic phase, a large number of cells in the blood or bone marrow are blast cells. In this blastic phase, the leukemia has become quite aggressive, and symptoms may be significant.
Busulfan is considered a palliative treatment, which means it is used to relieve symptoms but cannot cure the cancer.
Busulfan can help people with chronic myelogenous leukemia achieve hematologic remission, which means white blood cells, red blood cells, and platelets have returned to normal levels, and the number of leukemia cells has decreased. Some studies suggest that up to 90 percent of people who have not been previously treated for their leukemia may achieve remission from this medication. The amount of time the remission will last will vary from person to person.
This medication is less effective in people who do not have the Philadelphia chromosome. It also does not appear to be beneficial for people in the blastic phase of CML.