Stem cell and bone marrow transplant for chronic myeloid leukaemia (CML)

A stem cell transplant allows you to have high doses of chemotherapy. The chemotherapy kills the leukaemia cells. But it also damages the normal bone marrow cells.

After the chemotherapy, you have new stem cells into your bloodstream through a drip. The cells find their way back to your bone marrow. Your body then starts making blood cells again and your bone marrow slowly recovers. The new cells also help destroy any remaining cancer cells. 

When do you have a stem cell transplant for CML?

Stem cell transplant used to be a common treatment for CML. These days, it is less common. This is because targeted cancer drugs work very well at controlling most people's leukaemia. 

You might have a stem cell transplant if:

• your CML is no longer responding to targeted cancer drugs, such as imatinib, nilotinib, dasatinib, ponatinib or asciminib
• your CML progresses from chronic phase to accelerated phase 
• you have blast phase CML

This type of transplant can cause severe side effects. So it often isn't a treatment option if you are older or have other health problems. 

What are stem cells?

Stem cells are very early cells made in the bone marrow. Bone marrow is a spongy material that fills the bones.

These stem cells develop into 3 different types of blood cells. They are:

• red blood cells - contain haemoglobin and carry oxygen around the body
• white blood cells - part of your immune system and help fight infections
• platelets - help clot the blood and stop bleeding

What’s the difference between a stem cell transplant and a bone marrow transplant?

A stem cell transplant uses stem cells from the bloodstream. This is also called a peripheral blood stem cell transplant (PBSCT). 

A bone marrow transplant uses stem cells directly from the bone marrow.

Stem cell transplants are the most common type of transplant. Doctors don't often use bone marrow transplants any more.  This is because:

• it’s easier to collect stem cells from the bloodstream than bone marrow
• your treatment team can usually collect more cells from the bloodstream
• blood counts tend to recover quicker following a stem cell transplant

In CML, you usually have the stem cells from someone else (a donor). This is known as an allogeneic transplant or allograft.

You might have stem cells from:

• a brother or sister (sibling match)
• a person unrelated to you whose stem cells are similar to yours (matched unrelated donor or MUD)
• cord blood stem cells (umbilical cord)

In some situations, you might have stem cells from a half match - for example, from one of your parents. This is called a haploidentical match.

Having a stem cell transplant

Having high dose treatment

You usually have the high dose chemotherapy over about 5 or 6 days. You might have whole body radiotherapy at the beginning or the end of the chemotherapy.

You have your high dose chemotherapy through a central line. This type of line runs up under your skin to a large vein close to your collarbone.

You can have anti sickness medicines and antibiotics through your central line too. And your nurses can take blood samples from your line.

Having the stem cells

After your high dose treatment, you have your donor's stem cells back through a drip. 

The cells flow through your central line into your bloodstream. You might need another small plastic tube in your vein called a cannula, if the cells don't flow easily.

You are awake while you have the drip. It's like having a blood transfusion. It usually takes a couple of hours at the most.

Side effects of a stem cell transplant

The possible side effects of having a stem cell transplant are caused by high dose treatment. These treatments lower the number of the different blood cells. Side effects include:

• increased risk of getting an infection 
• tiredness and lacking energy
• increased risk of bleeding
• sickness and diarrhoea