TP53 Mutations in Blood Cancers

by Kamran Mirza MBBS PhD FCAP
April 4, 2026

If your blood, bone marrow, or molecular test report mentions a TP53 mutation or a 17p deletion, these findings both relate to the same gene — TP53 — which produces one of the most important proteins in the body’s system for preventing cancer. In blood cancers, losing the function of this gene is associated with more aggressive disease, a greater tendency to resist standard treatments, and a poorer outlook in most settings. TP53 changes are found across many blood cancers — including chronic lymphocytic leukemia (CLL), acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), multiple myeloma, and mantle cell lymphoma — and what the finding means in terms of treatment depends significantly on which disease you have. This article explains how TP53 works, why losing its function matters, how the test is done, and what a positive result means across different blood cancers.

What the test looks for

Every cell in your body contains two copies of the TP53 gene — one inherited from each parent. The TP53 gene encodes a protein called p53, which acts as a guardian inside cells. Its job is to detect when a cell’s DNA has been damaged — by radiation, toxic chemicals, errors during cell division, or any other cause — and then decide what to do about it.

When p53 detects serious DNA damage, it does one of two things. It either pauses the cell’s growth to give it time to repair the damage before dividing again, or, if the damage is too severe to repair, it triggers the cell to destroy itself — a controlled process called programmed cell death. This makes p53 one of the body’s most important defenses against cancer. Without it, damaged cells that should be destroyed are instead free to keep dividing, passing their damaged DNA on to daughter cells and accumulating the kind of errors that drive cancer.

In blood cancers, TP53 can be inactivated in two different ways:

TP53 mutation. A mutation is a change in the gene’s code that either stops the p53 protein from being made or produces a faulty version that cannot perform its job. Most TP53 mutations found in blood cancers produce a faulty protein rather than no protein at all — meaning the defective version of p53 is still present inside the cell, but it can no longer respond to DNA damage.
17p deletion. The TP53 gene sits on the short arm of chromosome 17, in a region called 17p. When a piece of chromosome 17 is deleted — lost entirely from the cell — the copy of TP53 that lived on that piece disappears with it. A 17p deletion removes one of the cell’s two copies of the gene entirely.

Both of these changes reduce or eliminate p53 function. In many cases, both occur together in the same cancer cell — a mutation inactivates one copy of TP53 while a deletion removes the other. When both copies are lost, the cell has no functional p53. This is called biallelic loss — meaning both copies (alleles) of the gene are gone — and it is associated with the most aggressive behavior and the greatest resistance to treatment.

Understanding whether a patient has a TP53 mutation, a 17p deletion, or both — and whether one or both copies of the gene are affected — is now a standard part of risk assessment in several blood cancers.

Why is the test done

TP53 testing is performed because the result directly impacts treatment selection. In blood cancers, losing TP53 function does not just make the disease more aggressive — it also makes it resistant to many treatments that work well in patients whose p53 is intact.

Many standard chemotherapy drugs and some targeted therapies work partly by triggering damaged cancer cells to destroy themselves — the same programmed cell death that p53 normally controls. When p53 is absent or broken, cancer cells can no longer respond to this signal, even when a drug has damaged their DNA. The drug delivers the hit, but without p53 to pull the trigger, the cell keeps dividing. This is why TP53-mutated or 17p-deleted blood cancers often do not respond as expected to standard treatment, and why choosing the right therapy from the start matters.

In CLL in particular, identifying a 17p deletion or TP53 mutation changes the treatment approach fundamentally — away from chemotherapy-based regimens and toward targeted drugs that work by a completely different mechanism, one that does not depend on p53 at all.

How the test is performed

Two different types of tests are used to assess TP53 status, and each looks for different things. Both are often performed together, because either one alone can miss half the picture.

FISH testing for 17p deletion

Fluorescence in situ hybridization (FISH) uses small pieces of fluorescently labeled DNA designed to bind to specific regions of the chromosome. For TP53 testing, FISH uses a probe that binds to the 17p region where the TP53 gene is located. In a normal cell, two signals appear — one for each copy of chromosome 17. In a cell with a 17p deletion, only one signal appears because one copy of the gene is gone.

FISH detects deletions but cannot detect mutations — it tells you whether a copy of the gene is physically missing, but not whether the remaining copy is working correctly. This is why a FISH result showing no 17p deletion does not rule out TP53 dysfunction.

Sequencing for TP53 mutation

Next-generation sequencing (NGS) reads the genetic code of the TP53 gene in detail and can identify mutations — changes in the code that alter or destroy the p53 protein’s function. This test detects mutations but cannot detect deletions. A cancer cell could have a normal-looking TP53 gene sequence in the copy that remains, and still have lost the other copy entirely through deletion — which is why sequencing and FISH complement each other.

In many centers, both tests are now performed together as part of standard molecular profiling in blood cancers. The result of both tests together — not either one alone — gives the complete picture of TP53 status.

How results are reported

TP53 results may appear in your report in several ways, depending on which tests were performed:

17p deletion detected by FISH. The report will describe the percentage of cancer cells in which one copy of the 17p region was absent. A commonly used threshold is 10% or more of cells showing deletion, which is considered clinically significant in CLL. The percentage can also indicate how large a proportion of the cancer cases carry this change.
TP53 mutation detected. The report will name the specific mutation—for example, “TP53 p.R175H” or “TP53 c.817C>T”—and describe the type of change it is. The variant allele frequency (VAF) — the proportion of tested cells carrying the mutation — is usually included. A high VAF means most cancer cells carry the mutation; a low VAF may indicate a smaller subpopulation of cells carrying it, which can still be clinically significant.
Biallelic TP53 loss. When both a mutation and a deletion are present, the report may explicitly state that biallelic loss has been detected, or your hematologist will interpret the combined result this way. This finding — losing both working copies of the gene — carries the most significant implications.
No TP53 mutation detected / 17p deletion not detected. A negative result means neither change was found in the cells tested. In most blood cancers, this is associated with a better treatment response.

What the result means

The implications of a TP53 result depend on which blood cancer you have. The sections below address the most common contexts.

Chronic lymphocytic leukemia (CLL)

In CLL, 17p deletion and TP53 mutation are among the most important prognostic factors across the disease. They are found in about 5–10% of patients at the time of first diagnosis, but become more common as the disease progresses, rising to approximately 30–40% of patients at the time of relapse. This pattern reflects how TP53 loss confers a survival advantage to cancer cells, allowing them to outgrow cells with intact p53 over time.

In CLL, the key treatment implication is straightforward: chemotherapy-based regimens — including fludarabine, cyclophosphamide, and chlorambucil — do not reliably work in patients with 17p deletion or TP53 mutation and should generally be avoided. These drugs work by damaging cancer cell DNA, hoping that p53 will then trigger cell death. Without functional p53, that trigger cannot be pulled.

Instead, patients with 17p deletion or TP53 mutation are treated with targeted drugs that bypass p53 entirely:

BTK inhibitors — ibrutinib (Imbruvica), acalabrutinib (Calquence), and zanubrutinib (Brukinsa) — work by blocking a signaling protein called Bruton’s tyrosine kinase (BTK), which CLL cells depend on for survival. These drugs do not require p53 to work. They are effective in TP53-deficient CLL and are currently the standard first-line treatment for patients with this finding.
Venetoclax (Venclyxto/Venclexta), when combined with obinutuzumab or rituximab, works by blocking the BCL-2 protein that CLL cells use to avoid programmed cell death. This also bypasses p53 — venetoclax opens a different door to cell death, one that does not rely on the p53 pathway. It is highly effective in TP53-deficient CLL, either as initial treatment or at relapse.

With these targeted therapies, outcomes for TP53-deficient CLL have improved substantially compared to the chemotherapy era. However, response durability and long-term outcomes remain somewhat shorter than in patients without TP53 loss, and resistance can develop. Your hematologist will discuss which targeted therapy is most appropriate for your situation and how long-term monitoring will work.

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS)

In AML and MDS, TP53 mutations are found in approximately 5–10% of AML cases overall, but in a much higher proportion — up to 30–40% — of patients whose AML has developed after prior treatment with chemotherapy or radiation (called therapy-related AML). TP53 mutations in AML and MDS are strongly associated with a complex karyotype — a pattern in which the cancer cells have many simultaneous chromosomal abnormalities, not just the TP53 change alone. This combination is among the highest-risk presentations in AML and MDS.

TP53-mutated AML and MDS are resistant to many standard chemotherapy regimens. Standard intensive induction chemotherapy achieves remission in a lower proportion of TP53-mutated patients than in patients without the mutation, and remissions that are achieved tend to be shorter.

Several treatment approaches are used or under study in this setting:

Hypomethylating agents — azacitidine and decitabine — are lower-intensity treatments that work by altering how genes are read inside cancer cells, rather than by directly damaging DNA. They are less dependent on p53 for their effect and are the most commonly used treatments for TP53-mutated MDS and for older or less fit patients with TP53-mutated AML.
Venetoclax combined with azacitidine has become a standard option for older adults with AML. Its activity in TP53-mutated AML is more limited than in TP53-intact AML, but it is still used in many patients.
Stem cell transplantation remains the only treatment with the potential for long-term remission in TP53-mutated AML and MDS, but achieving a deep enough remission to proceed to transplant safely can be difficult, and outcomes after transplant are also less favorable than in lower-risk disease.
Eprenetapopt (APR-246) is an investigational drug designed specifically for TP53-mutated cancers. It works by refolding the misshapen p53 protein into a functional shape. Early clinical trial results in TP53-mutated MDS showed promising response rates when combined with azacitidine. However, longer-term data are still being gathered. This drug is not yet widely approved but represents an important area of active research.

If you have TP53-mutated AML or MDS, your hematologist will discuss which treatment approach is most appropriate given your overall health, your fitness for intensive treatment, and whether a stem cell transplant is a realistic option for you.

Multiple myeloma

In multiple myeloma, 17p deletion — which removes one copy of the TP53 gene — is found in approximately 7–10% of newly diagnosed patients and is one of the features used to classify myeloma as high-risk. Its presence, particularly when combined with other high-risk chromosomal changes, is associated with shorter periods of remission after treatment and shorter overall survival compared to standard-risk myeloma.

TP53 mutations are less common than 17p deletion in myeloma at diagnosis but become more frequent as the disease progresses and relapses, suggesting — as in CLL — that TP53 loss confers a growth advantage to cancer cells over time.

Knowing that myeloma carries a 17p deletion or a TP53 mutation influences several aspects of management:

Patients are classified as high-risk and typically receive more intensive initial treatment, often including stem cell transplantation when they are eligible, followed by maintenance therapy with drugs such as lenalidomide or daratumumab.
Regular monitoring is more frequent because the risk of early relapse is higher.
At relapse, treatment decisions take TP53 status into account alongside other factors, and participation in clinical trials is often encouraged, given the limited effectiveness of standard approaches in heavily TP53-altered myeloma.

Mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive type of blood cancer that starts in B lymphocytes — the cells that normally make antibodies. TP53 testing is now considered standard practice at the time of MCL diagnosis in most specialist centers, because the result directly and significantly affects the treatment recommended from the start.

TP53 mutations are found in approximately 10–20% of newly diagnosed MCL cases. Like CLL, MCL cells with TP53 mutations are resistant to standard chemotherapy-based regimens. This is not simply because TP53-mutated MCL is more aggressive — it is because chemoimmunotherapy depends on p53 to pull the trigger on cancer cell death after DNA damage. Without working p53, that trigger cannot be pulled. Studies have consistently shown that patients with TP53-mutated MCL who receive standard chemotherapy have much shorter periods without the cancer getting worse, and shorter overall survival, compared to patients without the mutation. In a large real-world analysis of 645 MCL patients, median overall survival was approximately 8.3 years in TP53-mutated patients compared to approximately 14.2 years in TP53-unmutated patients.

The preferred treatment approach for TP53-mutated MCL avoids chemotherapy and instead combines drugs that work through p53-independent mechanisms. The most studied combination is called BOVen — zanubrutinib (a BTK inhibitor), obinutuzumab (an antibody that targets B cells), and venetoclax (a BCL-2 inhibitor). In a phase 2 study of 25 previously untreated patients with TP53-mutated MCL, this chemotherapy-free combination achieved an overall response rate of 96% and a complete response rate of 88%. At two years, 72% of patients were still free of disease progression — a result that compares very favorably with historical outcomes from chemotherapy-based treatment in this group. Treatment in this study was discontinued after 24 cycles in patients who achieved a complete response with no detectable remaining disease, an approach called minimal residual disease-guided treatment stopping.

BTK inhibitors — including ibrutinib, acalabrutinib, and zanubrutinib — are active in TP53-mutated MCL and are a cornerstone of treatment in this setting. Venetoclax adds to this by blocking BCL-2, a protein that cancer cells use to avoid programmed cell death, through a route that does not require p53. When the two approaches are combined, the result is a treatment that targets MCL cells from two independent directions, neither of which depends on p53.

For patients with TP53-mutated MCL that has relapsed or stopped responding to initial treatment, CAR-T cell therapy — a treatment in which the patient’s own immune cells are genetically modified to recognize and attack the cancer — has shown meaningful activity. In systematic reviews, CAR-T therapy achieved complete response rates of approximately 85% in relapsed TP53-mutated MCL. However, two-year survival rates of approximately 44% reflect that long-term disease control remains difficult in this group.

Despite these advances, TP53-mutated MCL remains one of the most challenging subgroups in lymphoma, and clinical trials continue to seek better long-term outcomes. If you have MCL and a TP53 mutation, your hematologist will discuss which treatment approach is most appropriate given your overall health and whether a clinical trial is available that you might benefit from.

Other blood cancers

TP53 mutations are also found in diffuse large B-cell lymphoma and in Richter transformation — a change that can occur when CLL converts into a more aggressive lymphoma. In both settings, TP53 loss signals more aggressive disease and reduced treatment sensitivity. The specific treatment implications depend on the diagnosis and will be discussed by your hematologist or oncologist.

TP53 mutations are not inherited in most blood cancers

It is natural to wonder, when you hear that a gene called a “tumour suppressor” is mutated, whether this means the change was inherited and might affect your children or relatives.

In blood cancers, TP53 mutations are almost always somatic — meaning they developed inside a blood-forming cell during your lifetime and are not present in the rest of your body’s cells. They are not inherited, cannot be passed to your children, and do not carry hereditary implications for your family.

This is different from germline TP53 mutations, which are inherited from birth, present in every cell in the body, and cause a rare hereditary condition called Li-Fraumeni syndrome, associated with a wide range of cancers from childhood onward. Germline TP53 mutations are tested through a blood or saliva sample that reflects the DNA in all cells, not just cancer cells. They are a separate and much rarer situation from somatic TP53 mutations found in blood cancer cells. If there is any concern about a possible hereditary risk, your medical team can clarify this and, if needed, arrange a referral to a genetic counselor.

What happens next

For patients with mantle cell lymphoma, a TP53 mutation result means standard chemotherapy-based treatment is unlikely to be recommended, and your hematologist will discuss a chemotherapy-free combination approach — most likely incorporating a BTK inhibitor and venetoclax — or enrolment in a clinical trial. If your MCL has relapsed, CAR-T cell therapy or other options will be discussed.

For patients with CLL, a positive 17p deletion or TP53 mutation result means chemotherapy-based treatment should be avoided from the outset, and your hematologist will recommend a BTK inhibitor or venetoclax-based regimen instead. This guidance applies whether you need treatment now or in the future — the result is documented and will inform treatment decisions throughout your care.

For patients with AML or MDS, TP53 status is one of several factors used to determine treatment intensity and to assess whether stem cell transplantation is appropriate. Your hematologist will discuss how the result fits into the overall picture of your disease and what the treatment plan will be.

For patients with multiple myeloma, a 17p deletion result places you in the high-risk category. Your hematologist will explain what this means for the intensity and duration of treatment, the frequency of monitoring, and what to watch for.

For any blood cancer in which TP53 testing has not yet been performed, it is worth asking your hematologist whether it is indicated and when the result is expected. The result can have a meaningful effect on treatment choice, and knowing it before the first treatment decision is made is important.

Questions to ask your doctor

Do I have a TP53 mutation, a 17p deletion, or both — and have both types of testing been done?
If I have both a mutation and a deletion, does that mean both copies of the TP53 gene are affected?
How does the TP53 result change my treatment options compared to what they would be without this finding?
For CLL patients: Does this mean chemotherapy should be avoided, and which targeted therapy is being recommended?
For mantle cell lymphoma patients: does a TP53 mutation mean I should avoid chemotherapy, and is a BTK inhibitor plus venetoclax combination or a clinical trial recommended?
For AML/MDS patients: am I a candidate for stem cell transplantation, and is there a clinical trial I should consider?
For myeloma patients: how does the high-risk classification change my treatment plan or monitoring schedule?
Is there any possibility that this TP53 mutation is inherited, and should I see a genetic counselor?
Will my TP53 status be retested if my disease progresses or comes back?