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BCR-ABL mutation testing after a TKI stops working | CION Cancer Clinics
A BCR-ABL mutation test is a blood test that reads the faulty CML gene for small changes that stop a TKI from fitting. It is usually sent when BCR-ABL is not falling as expected or is rising again. The result helps your haematologist avoid tablets unlikely to work, and a T315I finding points towards ponatinib, asciminib or an early transplant discussion. At CION Cancer Clinics, every leukaemia, MDS and MPN case is reviewed by our haematologist and discussed at a tumour board before a plan is agreed.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
- What is a BCR-ABL mutation test, and why is it done?
- Who is usually offered mutation testing?
- How is the test actually done?
- What do the words on a mutation report mean?
- How can a result change the choice of tablet?
- What do people misunderstand about mutation testing?
- What can a mutation result not tell you?
- Common questions about BCR-ABL mutation testing
The short answer
What is a BCR-ABL mutation test, and why is it done?
A BCR-ABL mutation test is a blood test that looks for small changes in the faulty CML gene that can stop a TKI from working. It is usually sent when BCR-ABL is not falling as expected, or is rising again, so your haematologist can pick a tablet that still has a good chance of working.
How a gene change causes resistance
Every TKI works by fitting into a pocket on the faulty BCR-ABL protein, like a key in a lock. A mutation is a tiny spelling change in the gene that alters the shape of that pocket. Some changes stop one tablet from fitting while others still fit well. A few, like T315I, block almost all the older tablets at once.
Why it matters before choosing the next tablet
Without the test, the next TKI is an educated guess. With it, your team can avoid a tablet the result says is unlikely to help, and move sooner to one that fits. That saves months on a treatment that may not work, and it tells the team whether a transplant discussion should start early. It also helps the team explain to you, in plain terms, why one tablet was chosen over another.
Not everyone whose treatment is failing has a mutation. A normal result means other reasons, such as missed doses or clashing medicines, need a careful look.When it is sent
Who is usually offered mutation testing?
It is a targeted test, sent when the answer will change the plan.
Missing a response checkpoint
If BCR-ABL has not fallen enough by the time your haematologist expected, the test helps explain why.
Losing a response you had
A clear, confirmed rise in BCR-ABL after it had been low is one of the commonest reasons to test.
A single small rise is usually repeated before any test is sent.Disease moving beyond chronic phase
If CML shows signs of accelerated or blast phase, testing helps guide urgent decisions about treatment and transplant.
Usually not needed
The test is not routine at diagnosis for most people in chronic phase, and not needed when a switch is only for side effects.
Also unlikely to help when
- BCR-ABL is already very low
- Doses have been missed often
Not sure whether this applies to you?
Ask an oncologistFrom sample to report
How is the test actually done?
A blood sample
An ordinary blood draw from your arm is usually enough. A bone marrow sample is only needed if your team wants other information at the same time.
Sent to a specialist lab
Not every laboratory does this test. The sample is often sent to a specialist molecular lab, so ask your team where it is going and when results are expected.
The gene is read
The lab reads the part of BCR-ABL where TKIs attach, using either Sanger sequencing or next-generation sequencing, and compares it with the normal code.
The report is explained
Your haematologist reads the result alongside your BCR-ABL trend and your history, then explains what it means for the choice of tablet.
On your report
What do the words on a mutation report mean?
- Kinase domain
- The part of the BCR-ABL protein where TKIs attach. Most resistance mutations sit here.
- T315I
- A change at one exact spot that blocks imatinib, dasatinib, nilotinib and bosutinib. Only a few treatments still work.
- Sanger sequencing
- An older reading method. It finds a mutation only when many of the leukaemia cells carry it.
- NGS
- Next-generation sequencing. It can find much smaller groups of cells carrying a change, earlier.
- No mutation detected
- None was found at the level the method can see. It does not prove no resistant cells exist.
- Compound mutation
- Two changes in the same gene copy. This can make resistance harder to overcome.
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Result to decision
How can a result change the choice of tablet?
What the report finds
What it usually means for the plan
No mutation detected
Look at missed doses and clashing medicines; a switch may still help
A change that affects one second generation tablet
Another second generation tablet may be preferred
T315I found
Ponatinib or asciminib considered; transplant often discussed
Compound or several mutations
Specialist review, often with a transplant centre
Commonly believed
What do people misunderstand about mutation testing?
"A mutation means I passed on a faulty gene to my children."
No. These changes happen only inside the leukaemia cells during your life. They are not in your eggs or sperm and are not inherited. Your children do not need testing because of your result.
"The tablet caused the mutation, so it was the wrong tablet."
Resistant cells can exist in small numbers from early on. The tablet clears the sensitive cells, which can let the resistant ones show. That is not a mistake in the original choice.
"A normal mutation report means the treatment is fine."
If BCR-ABL is still rising, something is wrong even without a mutation. Your team will look at missed doses, other medicines and repeat tests.
"We should test every year just to be safe."
Testing while BCR-ABL is low rarely finds anything useful. The test earns its place when response is slipping.
Being straight with you
What can a mutation result not tell you?
It cannot tell you how long you will live or how well the next tablet will work. It narrows the choice. Your response on the new tablet, tracked on BCR-ABL tests, is what shows whether it is working.
Its limits are technical too
If BCR-ABL is low, the lab may not have enough material to read. Sanger sequencing can miss a small resistant group that NGS would find. Results from different labs may be reported in different ways, so bring the full report, not only the summary line.
What to ask your haematologist
Ask which method was used, whether a mutation was found, and which tablets the result rules in or out. Ask whether a transplant discussion is needed now or later, and where that would happen.
If you are the son or daughter helping
Keep the reports in one folder, in date order, with the mutation report on top. Write down the names of every tablet your parent has taken and why each one was stopped. That single page often saves a long appointment. If the result is hard to take in, ask the team to explain it again at the next visit. Nobody expects you to understand a gene report on the first reading.
CION's haematology team arranges this test through specialist laboratories, reviews the result with a tumour board and coordinates referral to transplant centres when needed.Questions we are asked
Common questions about BCR-ABL mutation testing
Is the mutation test the same as my regular BCR-ABL test?
No. Your regular BCR-ABL test measures how much of the faulty gene is in your blood. The mutation test reads the gene's code to look for changes that affect which tablets work. Both use a blood sample, but they answer different questions and are sent at different times.
Do I need to stop my tablet before the test?
No. The test is done while you are on your current treatment, and you should keep taking your TKI exactly as prescribed unless your haematologist tells you otherwise. Stopping on your own can lower the value of the result and put your control at risk.
How long do results take?
It varies by laboratory, because the sample is often sent to a specialist lab. Your team will tell you the expected wait. If a decision is urgent, for example when the disease is moving beyond chronic phase, ask whether the sample can be prioritised.
Which is better, Sanger or NGS?
NGS can find smaller groups of resistant cells, so it may pick up a change earlier. Sanger is older and more widely available. Both can guide the choice of tablet. Your haematologist chooses based on what is accessible and how urgent the decision is.
My report found T315I. Is there anything left to try?
Yes. T315I rules out most older TKIs, but ponatinib and asciminib are designed to work against it, and a stem cell transplant may be discussed. Your haematologist will explain which options suit your health and phase of disease, and where each would be given.
Can a mutation disappear?
It can become undetectable when a tablet that works against it clears those cells. That does not mean the change is gone for good. Your team keeps watching BCR-ABL and may repeat the mutation test if the level rises again.
Does insurance or Aarogyasri cover the test?
Cover varies. Some schemes and insurers pay for molecular tests as part of approved treatment, others do not. Ask the team to check Aarogyasri, PM-JAY, CGHS, ECHS, EHS or your insurer before the sample is sent, and confirm the current rules, since they change.
Should my brothers and sisters be tested too?
Not for the mutation, which is not inherited. Siblings may be asked for a different blood test, HLA typing, if a transplant is being considered, to see whether they could be a donor. That is a separate conversation your haematologist will start if it applies.
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Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
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Sources
- National Cancer Institute — Chronic Myeloid Leukemia Treatment (PDQ) - Patient Version
- American Cancer Society — Chronic Myeloid Leukemia (CML)
- Leukemia & Lymphoma Society — Chronic Myeloid Leukemia
- Cancer Research UK — Chronic myeloid leukaemia (CML)
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
T315I Mutation: What It Rules OutWhat a T315I result means for treatmentReading Your BCR-ABL Report and the IS ScaleThe regular test that shows when response slipsWhat Happens If You Miss a MilestoneThe usual trigger for mutation testingSwitching TKI: Reasons and What ChangesHow the next tablet is chosen and started
Talk to us
Has your BCR-ABL level started rising?
Send us your reports. CION's haematology team will explain whether a mutation test is needed and what the result could change.