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Chronic Myeloid Leukaemia (CML): BCR-ABL, TKI Tablets and Long-Term Outlook
By Dr. Gajendra Kumar Himanshu
Chronic Myeloid Leukaemia (CML) is a type of blood cancer that is usually caused by an abnormal gene called BCR-ABL1. This gene makes a protein that causes abnormal white blood cells to keep growing. For most people with chronic-phase CML, daily tablets called tyrosine kinase inhibitors (TKIs) are the main treatment. With regular treatment and check-ups, many people can live for many years with good control of the disease.
In this blog, we are talking about Chronic Myeloid Leukaemia (CML), how the BCR-ABL1 gene causes the disease, why TKI tablets are important in treatment and how doctors check whether the treatment is working. We will also discuss symptoms, CML phases, side effects, treatment changes and the long-term outlook.
Why it is important to understand CML
A diagnosis of CML can sound frightening because it is a type of leukaemia. However, treatment has changed greatly over the past few decades. For many people diagnosed in the chronic phase, targeted medicines can keep the disease under control for a long time. National Cancer Institute notes that with oral TKIs, survival for many patients can approach normal life expectancy.
CML is different from acute leukaemias because it often develops more slowly. Many people have no clear symptoms when it is first found, and the condition may be discovered during a routine blood test.
What is Chronic Myeloid Leukaemia?
CML starts in the bone marrow, where blood cells are made. In most cases, a change between chromosomes 9 and 22 creates what is called the Philadelphia chromosome. This change leads to the abnormal BCR::ABL1 gene.
The BCR::ABL1 gene makes an abnormal protein called tyrosine kinase. This protein keeps sending signals that tell leukaemia cells to grow and multiply.
What does BCR-ABL mean?
BCR-ABL1 is more than just a name on a test report. It is an important marker that helps doctors confirm CML and follow the disease during treatment.
Doctors can measure BCR::ABL1 levels with molecular tests such as quantitative PCR. This helps them know how much of the disease is still present and whether the treatment is working well.
What are the symptoms of CML?
CML may not cause any symptoms in the beginning. When symptoms do appear, they may be mild and can look like other common health problems.
Common symptoms
Possible symptoms of CML include unusual tiredness, weight loss, fever, night sweats, low appetite and a feeling of fullness or pain under the left side of the ribs. This can happen when the spleen becomes enlarged.
Because these symptoms are not only seen in CML, a blood test may be the first sign that something is wrong. More tests are then done to confirm the diagnosis.
How is CML diagnosed?
Doctors usually start with a complete blood count and a physical examination. If the blood test shows changes that may suggest CML, doctors check for the BCR::ABL1 gene or the Philadelphia chromosome.
Molecular testing
Molecular tests such as PCR can find BCR::ABL1 very accurately. Cytogenetic tests and FISH may also be used to look for the chromosome change.
A bone marrow test may be advised in some cases, especially when doctors need more information about the phase of CML or other chromosome changes.
What are the phases of CML?
CML is usually divided into three phases. These phases are based on the number of immature blood cells and other signs of the disease.
Chronic phase
Most people are diagnosed in the chronic phase. At this stage, CML usually responds well to standard treatment.
Accelerated and blast phases
Accelerated-phase and blast-phase CML are more advanced forms of the disease. Treatment can become more difficult and may include a different TKI, a combination of treatments or a stem cell transplant, depending on the patient’s condition.
How do TKI tablets treat CML?
TKIs are the main targeted therapy for most people with chronic-phase CML. These medicines block the abnormal BCR::ABL1 tyrosine kinase protein.
By blocking this protein, TKIs reduce the signals that help CML cells grow and multiply.
Which TKI medicines are used?
Depending on the patient’s condition, doctors may prescribe medicines such as imatinib, dasatinib, nilotinib, bosutinib or asciminib.
Ponatinib may be used in selected cases, including some patients whose disease does not respond well to other TKIs or who have certain BCR::ABL1 mutations.
The same TKI is not right for every patient. Doctors look at the CML phase, treatment response, other health problems, possible side effects and interactions with other medicines before choosing a treatment.
How do doctors know if CML treatment is working?
Regular check-ups are an important part of CML treatment. Doctors check blood counts, but molecular testing is especially important because it shows the amount of BCR::ABL1 in the blood.
A lower BCR::ABL1 level usually means the disease is responding well to treatment. A deeper molecular response generally shows better disease control.
What happens if the TKI is not working well?
When the response is not good enough, doctors may first check whether the patient is taking the medicine regularly. They may also look for other medicines that could affect the TKI.
More tests may be done to find out why the treatment is not working well. The doctor may then change to another TKI. Mutation testing can also help guide treatment when resistance is suspected.
What are the side effects of TKI treatment?
TKIs are targeted medicines, but they can still cause side effects. The side effects can be different for each medicine.
Some people may have tiredness, nausea, muscle cramps, swelling, skin changes or changes in blood counts.
Why regular follow-up matters
Many side effects can be managed by changing the dose, switching to another treatment or giving supportive care.
Patients should not stop taking their TKI on their own. Missing treatment may allow CML to become less controlled.
Regular follow-up also helps doctors find treatment problems early and manage them before they become more serious.
Can someone with CML stop TKI tablets?
For most people, TKI treatment continues for many years and sometimes for decades.
However, some adults with chronic-phase CML who have had a deep and stable molecular response for a long time may be considered for a planned treatment stop. This is called a treatment-free remission attempt.
It is not suitable for everyone. It must be done under a specialist’s care with regular molecular tests.
Stopping treatment without medical advice is not recommended. If CML returns after a planned treatment stop, restarting treatment can often bring the disease back under control. Regular monitoring is still very important.
What is the long-term outlook for CML?
The outlook for people with CML has improved greatly because of TKI treatment. With modern oral TKI medicines, many patients with chronic-phase CML can have long-term disease control, and survival can come close to normal life expectancy.
The outlook can still depend on the CML phase, response to treatment, BCR::ABL1 results, age, overall health and whether the disease becomes resistant to treatment.
Most people with chronic-phase CML respond well to treatment, but regular long-term follow-up is still needed.
You can also read more about blood cancer treatment and supportive care through our blogs.
Consult Today
If you have been diagnosed with CML or your blood report shows an unusually high white blood cell count, speaking with an experienced haematologist can help you understand the diagnosis and treatment plan.
At Oncare Cancer Hospital, patients can discuss BCR-ABL1 testing, TKI treatment, molecular monitoring, side effects and long-term follow-up with the specialist team based on their individual condition.
Disclaimer
This information is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Always discuss decisions about CML testing, TKI medicines or any change in treatment with a certified cancer healthcare provider.
Frequently Asked Questions
Yes, CML is a serious blood cancer. However, modern targeted treatment has greatly improved disease control and long-term outcomes, especially for people diagnosed in the chronic phase.
BCR-ABL1 is an abnormal gene caused by a chromosome change that is commonly seen in CML. It makes a protein called a tyrosine kinase that causes abnormal blood cells to keep growing.
Yes. TKI medicines that target BCR::ABL1 are the main treatment for most people with chronic-phase CML.
Many people with chronic-phase CML can live for many years with effective TKI treatment and regular follow-up. The outlook can be different for each person depending on the disease phase, treatment response and overall health.
Written and Verified by:
Dr. Gajendra Kumar Himanshu Exp: 10 Yr
Medical Officer
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