Even if you've been living with Philadelphia chromosome–positive chronic myeloid leukemia (Ph+ CML) in chronic phase for a while, it's still helpful to understand the biology behind the disease and what's happening in your body.

A swap between chromosomes 9 and 22 creates the Ph chromosome

What causes Ph+ CML?

Ph+ CML is caused by an abnormal fusion gene called BCR-ABL1. It is the result of pieces of 2 chromosomes in the body trading places.

Here’s a brief overview:

• Each cell in the human body has 23 pairs of chromosomes
• In Ph+ CML, pieces from chromosomes 9 and 22 break off and swap places
• This can create a new abnormal chromosome known as the Philadelphia (Ph) chromosome
• The Ph chromosome creates the abnormal BCR-ABL1 fusion gene
• This abnormal gene then produces an abnormal protein called BCR-ABL

Here’s what happens in the bone marrow:

• The BCR-ABL protein sends too many signals to the bone marrow
• The bone marrow starts creating too many immature white blood cells (commonly referred to as blast cells)
• These cells, which your doctor may call leukemic cells, grow abnormally and do not become healthy white blood cells
• The leukemic cells start to grow and divide and build up, crowding out red blood cells and platelets in the bone marrow

Here’s what happens in the bloodstream:

• As the bone marrow becomes overcrowded with leukemic cells, these cells move into the bloodstream
• Over time, the leukemic cells crowd out healthy red blood cells, white blood cells, and platelets
• This can lead to serious health problems, including, but not limited to, a greater risk of infections, as well as anemia, bruising easily, and bleeding that takes longer to stop 

Doctors categorize Ph+ CML in phases instead of stages

While many types of cancer are categorized into stages, doctors assign 1 of 3 phases to Ph+ CML:

• Chronic phase: The first phase of Ph+ CML, when the number of white blood cells is higher than normal. Most adults are diagnosed in chronic phase
• Accelerated phase: The second phase of Ph+ CML, in which the number of immature white blood cells in the blood and bone marrow may increase rapidly
• Blast phase: The third and final phase of Ph+ CML. This phase has the highest number of immature blood cells in the blood and bone marrow

Learn about SCEMBLIX as a treatment option

By being your own advocate, you can work closely with your doctor to determine whether SCEMBLIX is right for you.

SCEMBLIX is a prescription medicine used to treat adults with:

• Philadelphia chromosome–positive chronic myeloid leukemia (Ph+ CML) in chronic phase (CP), previously treated with 2 or more tyrosine kinase inhibitors (TKIs). Learn More
• Ph+ CML in CP with the T315I mutation. Learn More

It is not known if SCEMBLIX is safe and effective in children.

Next: Understanding the T315I Mutation in Ph+ CML in Chronic Phase >