Having a treatment break for chronic myeloid leukaemia (CML)

Until recently, you took a targeted drug every day to treat CML. You stayed on treatment for life and you didn’t have any breaks in treatment. But now doctors know that it is safe for some people to stop treatment if their chronic myeloid leukaemia (CML) is under control.

Your doctor can talk with you about whether a treatment break might be an option for you.

What is a treatment break?

You usually take TKI drugs every day, for as long as it is controlling your leukaemia. You carry on taking it even if your tests don’t show any signs of leukaemia.

Researchers have been doing trials to see if it is safe to stop TKI treatment. This is called a treatment break. Or your doctor might call it treatment free remission.

Clinical trials show that it is safe for some people to stop their TKIs if they have been:

• on TKIs for around five years
• in remission for a long time - this means that tests have not shown any signs of leukaemia for at least 2 years (a deep molecular response)

Why do people have a break in treatment?

Your doctor will talk to you about this when you start treatment. There are different reasons why you might want to try and have a break. And it is more suitable for some people than others.

For example, some people want a break from treatment because they have been having some side effects from the drug.

It might also be an option for some women who want to start a family. It might be possible to plan for a treatment break so they have the opportunity to try and get pregnant.

Who can have a treatment break?

Your doctor might suggest you have a treatment break if:

• you have been taking TKIs for at least 3 to 5 years
• you have not had accelerated or blast phase leukaemia
• you have had a very good response to treatment which has lasted for at least 2 years
• you don’t have any extra chromosomal abnormalities – your doctor will talk to you about this
• your hospital has a laboratory that can provide the blood tests you need
• you are keen to have a break, you understand what it involves, and you are willing to have all the extra blood tests to monitor your CML

Stopping treatment

Your doctor might suggest reducing your dose of TKI for around 12 months before you stop completely. Or you might stop taking the TKI straight away.

You might have some side effects when you stop taking TKIs. Doctors call this withdrawal syndrome. Side effects include:

• aching muscles and joints
• feeling unwell

These symptoms are usually mild and pass quickly. Your doctor might suggest you take non-steroidal anti inflammatory drugs.  Rarely, you might need to restart taking TKIs.

Monitoring your CML on a treatment break

Your doctor will continue to look for signs of leukaemia in your blood when you stop the treatment. You have a regular PCR blood test to do look for the BCR-ABL1 gene.

After you stop treatment you might have PCR tests:

• monthly for the first 6 months
• every 6 weeks to 2 months for the next 6 months
• every 2 to 3 months after that

If your CML does come back, it is most likely to come back in the first 6 months after you stop treatment. The rest of the people who need to restart treatment, usually do so within the first 2 years. It is less common to need to restart after 2 years, although this can happen.

Having a break in treatment is still quite new. So far, none of the studies have followed up people on a treatment break for more than 10 years. So we don’t know how common it is for CML to come back after a long period of time. The doctors will continue to monitor you closely.

What happens if my CML comes back?

Your doctor will recommend you start treatment again if tests start to detect the BCR-ABL1 gene. This is a sign that your CML is coming back.

You restart TKI treatment if the doctors think your CML has come back. You usually restart the same drug as you were on before the treatment break. Or you might go on a different drug if you had side effects.

Your doctor does a blood test every 4 weeks to look for signs of leukaemia, until you go back into remission. The vast majority of people have a very good response when they restart the treatment. This means that after taking the TKI treatment again, the tests no longer show any signs of leukaemia. You are very likely to go back into remission. 

Can I have a second treatment break?

You might be able to try a second break in treatment if you have another good response to the treatment.