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The T315I mutation in CML: what it rules out and what remains | CION Cancer Clinics
A T315I mutation rules out imatinib, dasatinib, nilotinib and bosutinib, because the altered BCR-ABL protein shuts them out at any dose. It does not rule out treatment. Ponatinib and asciminib were designed to work against it, and a stem cell transplant is discussed for some people. Which route suits you depends on your phase of disease, heart health and fitness. 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 does a T315I mutation rule out?
- Which treatments are ruled out, and which remain?
- What treatments can still work with T315I?
- What usually happens once T315I is found?
- What do the terms around T315I mean?
- What do families fear about a T315I result that is not true?
- What can this page not tell you about your own situation?
- Common questions about the T315I mutation
The short answer
What does a T315I mutation rule out?
A T315I mutation rules out imatinib, dasatinib, nilotinib and bosutinib, because none of them can attach to the altered BCR-ABL protein. It does not rule out treatment. Ponatinib, asciminib and, for some people, a stem cell transplant still work against CML with this change.
Why this one change blocks so many tablets
The letters T315I describe one swapped building block at position 315 of the BCR-ABL protein. That spot acts like a gatekeeper at the entrance of the pocket where most TKIs fit. The swap narrows the entrance, so the first and second generation tablets are shut out together. Ponatinib was built to slip past it. Asciminib avoids the pocket entirely and attaches somewhere else on the protein.
What the result changes straight away
If you are on one of the tablets it rules out, your haematologist will plan a change rather than wait for the next test. Staying on a tablet that cannot reach the leukaemia gives resistant cells time to grow. Your team will also look at which phase your CML is in, because that shapes how urgent the next step is and whether a transplant should be discussed now.
Keep taking your current tablet until your team gives you a clear plan for the change. Do not stop it on your own.At a glance
Which treatments are ruled out, and which remain?
Ruled out by T315I
Still open to discuss
Imatinib, the first generation TKI
Ponatinib, a third generation TKI built for it
Dasatinib and nilotinib
Asciminib, which attaches at a different site
Bosutinib
Stem cell transplant, for people fit enough
Raising the dose of a ruled-out tablet
Clinical trials of newer medicines, where available
Not sure whether this applies to you?
Ask an oncologistThe options
What treatments can still work with T315I?
Each has trade-offs. The right one depends on your phase of disease, your heart and your overall fitness.
Ponatinib
A strong TKI with good activity against T315I. It raises the risk of clots, blocked arteries and high blood pressure, so your heart and blood pressure are checked closely.
May not suit
- People with past heart attack or stroke
- Uncontrolled high blood pressure
Asciminib
Works on a different part of the protein. It is used for T315I in chronic phase in several countries, and blood counts and pancreas tests are watched.
Ask your team about access and cost in India.Stem cell transplant
Replaces your blood-forming cells with a donor's. It is the one route that can remove CML for the long term, but it carries serious risks.
Usually discussed when
- Tablets are not controlling the disease
- CML has moved beyond chronic phase
Clinical trials
Newer medicines for resistant CML are being studied. Your haematologist can tell you whether a suitable trial is open.
After the result
What usually happens once T315I is found?
-
The result is confirmed and explained
Your haematologist goes through the report with you and checks it against your BCR-ABL trend and your history of tablets.
-
The phase of CML is checked
Blood counts and sometimes a bone marrow test show whether the disease is still in chronic phase or has moved on.
-
Heart and general health are reviewed
Blood pressure, heart tests, sugar and cholesterol help decide whether ponatinib is safe or another route is wiser.
-
A new plan is agreed
The case is discussed at a tumour board, and the new treatment is explained with its side effects and costs.
-
Transplant is discussed if relevant
Siblings may be asked for a donor match test, and a referral to a transplant centre may be made early, before it is urgent.
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Words you will hear
What do the terms around T315I mean?
- Gatekeeper mutation
- Another name for T315I, because it sits at the entrance to the pocket where most TKIs fit.
- Allosteric inhibitor
- A medicine, like asciminib, that attaches away from that pocket and changes the protein's shape from outside.
- Allogeneic transplant
- A stem cell transplant using cells from a donor, often a matched brother or sister or an unrelated volunteer.
- HLA typing
- A blood test that checks how closely a possible donor matches you.
- Accelerated or blast phase
- More advanced stages of CML where the plan is usually more intensive.
Commonly believed
What do families fear about a T315I result that is not true?
"T315I means nothing works any more."
It rules out four tablets, not all treatment. Ponatinib and asciminib were developed for exactly this situation, and transplant is another route for people who are fit enough.
"A higher dose of the old tablet will push through."
It will not. The altered protein blocks these tablets at any dose, and raising it only adds side effects. Never change your dose on your own.
"We missed doses, so this is our fault."
Missed doses can let resistant cells grow, but T315I also appears in people who took every tablet on time. Blame does not help. A clear plan and steady dosing from here on does.
"Transplant is the only real option, so we must rush."
For many people in chronic phase, a tablet that works against T315I is tried first. Transplant is planned carefully, not in a panic, and the team will tell you if timing is urgent.
Being straight with you
What can this page not tell you about your own situation?
It cannot tell you how your CML will respond to the next treatment, or what the outlook is for you. That depends on the phase of disease, whether other mutations are present, your age, fitness and heart health, and how BCR-ABL moves on the new treatment.
Where evidence is thinner
The newer options have been used for fewer years than imatinib, and studies in people with T315I are smaller. Access to some medicines in India is still changing, so what is possible for you may depend on availability and cost. Ask whether a scheme or insurer covers your treatment, and check the current rules. If a medicine is hard to obtain, say so early, so the team can plan around it rather than leave a gap.
What to ask at your next appointment
Ask what phase your CML is in, which of the remaining options suits your heart and health, and whether a transplant should be discussed now. Ask how often BCR-ABL will be checked on the new treatment, and whom to call if a side effect worries you.
CION's haematology team, led by Dr. Basudev Pokhrel, reviews resistant CML at a tumour board and coordinates referral to transplant centres where needed.Questions we are asked
Common questions about the T315I mutation
Is T315I the worst mutation to have?
It is the one that rules out the most tablets, which is why it worries people. But treatments designed for it now exist. How serious it is for you depends more on your phase of disease and overall health than on the mutation name alone. Your haematologist can explain your own picture.
How did I get the T315I mutation?
It arises inside the leukaemia cells by chance. A small group of cells may carry it early, and when a tablet clears the other cells, this group becomes visible. It is not inherited, not caught from anyone, and not caused by food or anything you did.
Can T315I be treated with tablets alone?
For many people in chronic phase, yes. Ponatinib or asciminib can bring BCR-ABL down. If tablets do not control it, or the disease has moved beyond chronic phase, a stem cell transplant is usually discussed. Your team will explain which path suits you.
Does CION do stem cell transplants?
CION's haematology team evaluates your case, presents it at a tumour board and coordinates referral and care with qualified transplant centres. Ask the team which centres they work with, what the assessment involves and how your care is shared before and after the transplant.
Is ponatinib safe for my father, who has heart disease?
It may not suit him, because it raises the risk of clots and blocked arteries. His haematologist will look at his heart history and tests and may prefer another route, or involve a heart specialist. This is a decision for his team, made with full information.
Can the T315I mutation go away?
It can become undetectable if a treatment that works against it clears those cells. That does not mean it cannot come back. BCR-ABL is tracked on regular blood tests, and the mutation test may be repeated if the level starts to rise.
Are these medicines available in India?
Availability and cost are changing. Some are available but expensive, and access schemes or trials may help. Ask your team what can be obtained, whether Aarogyasri, PM-JAY, CGHS, ECHS, EHS or insurance may contribute, and check current rules, since they change.
Should my brothers and sisters get tested now?
Not for the mutation, which is not inherited. If a transplant may be needed, siblings may be asked for HLA typing to see if they match. Your haematologist will say when this is worth doing, and it is often sensible to start early rather than wait.
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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
- Blood Cancer 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
BCR-ABL Mutation Testing After TKI FailureHow the mutation is found and reportedFirst, Second and Third Generation TKIs ComparedWhere ponatinib and asciminib sit among the tabletsWhen CML Progresses to Blast CrisisWhat changes if the disease moves beyond chronic phaseChronic Myeloid Leukaemia (CML)The full CML guide
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Has a T315I mutation been found?
Share the report with us. CION's haematology team will review your options and help coordinate the next step, including transplant referral where needed.