Targeted therapy is the use of medicines that take aim on parts of cancer cells that make them different from normal cells. They do this without affecting most normal, healthy cells. The medicines are different from standard chemotherapy medicines. And they often have less severe side effects.

The types of targeted medicines used to treat chronic myeloid leukemia (CML) are called tyrosine kinase inhibitors (TKIs). These medicines block a substance called kinase protein inside leukemia cells. The protein is made as a result of the cells having the abnormal BCR-ABL gene. This protein helps the leukemia cells grow.

TKIs used to treat CML include:

• Imatinib

• Dasatinib

• Nilotinib

• Bosutinib

• Ponatinib

In most cases, TKIs are the first treatment used for CML. These medicines often work well at keeping the CML under control for long periods of time. It’s not  yet clear if they can cure the leukemia. Your healthcare provider will monitor your CML during treatment with blood tests or other tests. If one of these medicines does not work or stops working over time, the dose of the medicine might be increased. Or another TKI may be used.

The medicine is taken as pills or capsules, once or twice a day. Make sure to take these medicines exactly as your healthcare team tells you. Taking these medicines every day gives them the best chance to treat your leukemia. It's likely you will need to take these pills for a very long time to keep the CML under control.

Be sure to tell your healthcare provider about all other medicines you take. This includes over-the-counter medicines and supplements such as herbs and vitamins. Some medicines and supplements can change the way targeted therapy medicines work.

During treatment, you’ll have blood tests. These are done to check for a decrease in your levels of white or red blood cells or platelets. These tests will happen more often at the start of treatment. 

Side effects of TKIs depend on the medicine, and may include:

• Bloating or swelling from fluid retention

• Diarrhea

• Itchy skin rashes

• Muscle pain

• Nausea

• Tiredness (fatigue)

• Belly (abdominal) pain 

• Lower blood cell counts, which can increase your risk of infections, bleeding, and brusing

Side effects from these medicines tend to be mild. But in some cases, they can cause more severe side effects, such as:

• Fluid buildup around the heart or lungs, which can cause trouble breathing

• Changes in heart rhythm

• High blood pressure

• Liver damage

Ponatinib can also cause serious blood clots. This medicine may be used only if the other TKIs are no longer working, or if the leukemia cells have a certain gene change.

It's important to know which medicines you're taking. Write down your medicines. Ask your healthcare team how they work and what side effects they might have.

Talk with your healthcare providers about what side effects to watch out for, and when you should call your healthcare team. Make sure you know what number to call with questions, even on evenings and weekends.

It may be helpful to keep a diary of your side effects. Write down any physical, thinking, and emotional changes. A written list will make it easier for you to remember your questions when you go to your appointments. It will also make it easier for you to work with your medical team to make a plan to manage your side effects.