Understanding CML

What is Chronic Myeloid Leukemia?

Chronic myeloid leukemia (CML) starts with an abnormal change, or mutation, in a cell’s DNA that creates a chromosome known as the Philadelphia (Ph) chromosome.

  • When the Ph chromosome is present in cells, a protein known as BCR-ABL is produced
  • The BCR-ABL protein causes the bone marrow to produce abnormal white blood cells
  • These abnormal cells are CML cells. Over time, they overtake healthy white blood cells in the bone marrow to cause leukemia

In CML, abnormal cells crowd out healthy cells in the bone marrow

Blood cells in CML.

CML is a progressive disease

There are 3 phases, or stages, of CML that represent different levels of progression. Ranging from least severe to most severe, the phases are:

Illustration of the three phases of CML: chronic phase, accelerated phase, and blast phase.
Man and woman sitting with a dog.

Not actual patients

Treating CML with TKI therapy

Many people with CML are treated with a type of targeted therapy known as a tyrosine kinase inhibitor, or TKI. The protein that causes CML, BCR-ABL, is a tyrosine kinase protein. The TKIs used to treat CML specifically inhibit BCR‑ABL. They help stop abnormal white blood cells, or CML cells, from forming in the body.

Monitoring your response to treatment

The goal of CML treatment is to keep your levels of BCR-ABL as low as possible. This can help reduce the number of CML cells in your body. Your doctor may do molecular or cytogenetic tests on cells from your bone marrow or blood to see how well a treatment is working.

One term your doctor may use to describe the results of these tests is log reduction. This is a measure of how much BCR-ABL levels have been lowered. Log reductions typically mean that a treatment is working well to control CML.


A 1-log reduction means there are 10 times fewer CML cells compared with the start of treatment (baseline). So the percentage of cells with BCR-ABL has been reduced to 10%


A 2-log reduction means there are 100 times fewer CML cells compared with the start of treatment (baseline). So the percentage of cells with BCR-ABL has been reduced to 1%

Why you may need to change your current treatment

An important goal of treating CML is to reduce the number of leukemia cells in the body. TKI treatments may work well to do this. However, in some cases after a period of time, CML may stop responding to a particular TKI treatment. This is known as treatment resistance.


If your CML becomes resistant to a TKI treatment, your doctor may recommend changing to a different TKI.


Another reason your doctor may recommend changing TKIs is intolerance to side effects caused by your current treatment.

Mutations and treatment resistance

Understand the role mutations may play in treatment resistance.

Results with ICLUSIG

How ICLUSIG may help treat resistant CP-CML

ICLUSIG dosing

Learn about once daily oral dosing with ICLUSIG