Leukemias
Acute promyelocytic leukemia (APL)
Also called Acute promyelocytic leukemia with PML::RARA fusion
If you or someone you love has just heard this diagnosis, start here. This guide explains what the condition is, how it is usually treated and whether a transplant plays any part.
Acute promyelocytic leukemia (APL) is a distinct form of AML, usually driven by a PML::RARA gene fusion. It can cause dangerous bleeding, but prompt treatment with differentiation medicines allows many people to recover without a stem cell transplant.
Other names and abbreviations
APL, AML-M3, PML-RARA AML, Acute promyelocytic leukaemia, FAB M3
In short
- APL is a type of acute myeloid leukemia (AML). It can cause dangerous bleeding, so it needs expert care right away.
- Many people are treated with two medicines, ATRA and arsenic trioxide. Some people with higher-risk APL also get chemo.
- A transplant is usually not needed. If APL comes back, some people may have one, using their own cells or sometimes a donor's cells.
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Underlined words open a short explanation. See all terms
Where transplant fits
TransplantA treatment that gives a patient healthy blood-forming stem cells through a vein. The cells travel to the bone marrow and replace faulty marrow or marrow damaged by treatment. They can come from the patient or a donor. is generally unnecessary in first remissionA decrease in or disappearance of the signs of a disease. In complete remission, no signs can be found, but some disease cells may still be in the body.. Selected relapsedWhen a disease comes back after a period of getting better. Relapsed disease has returned after treatment helped for a time. APL may use autologous rescueComing from the patient's own body. In an autologous transplant, the patient's own stem cells are collected and stored, then given back after high-dose treatment. It does not use a donor. after molecular remission or an allogeneic transplantComing from another person. In an allogeneic, or donor, transplant, the stem cells come from a relative or an unrelated volunteer whose cells are a close enough match to the patient's. for persistent or further-relapsed disease; only the allogeneic procedure requires a donor.
Treatment depends on the exact diagnosis, disease stage, prior treatment and the person’s health.
Key facts
- Who it affects
- APL occurs in children and adults and is often diagnosed at a younger age than AML overall.
- How common
- About 5 to 8 in every 100 cases of AMLShare of acute myeloid leukemia (AML) cases that are APL, as summarized in the U.S. National Cancer Institute's adult AML treatment summary (PDQ, updated March 2025), which notes APL occurs mostly in adults in midlife Source: How common
- Cells used in a transplant
- The patient’s own collected cells for autologous rescue; donated blood-forming cells only when an allogeneic procedure is selected.
- Where a donor fits
- Limited transplant role
The condition
What it is
APL affects immature myeloid cellsHaving to do with the bone marrow, or with certain blood-forming cells made there. Also called myelogenous. Acute myeloid leukemia (AML) is a fast-growing cancer that starts in these cells. called promyelocytes. In the form described here, a PML::RARA fusion disrupts their normal development. This genetic finding distinguishes APL from other AML and explains why its main medicines work differently.
APL can develop in children and adults. Blood and marrowThe soft, spongy tissue in the center of most bones. Red bone marrow holds the blood-forming stem cells that make red blood cells, white blood cells and platelets. testing identifies the abnormal cells, and molecular or chromosome testing confirms the fusion. Suspected APL requires immediate specialist care because bleeding complications can develop before all test results are available.
Marked as affected: granulocytes.
- Blood stem cell, In the bone marrow
- Myeloid line
- Red blood cells
- Platelets
- Granulocytes, Affected
- Monocytes
- Lymphoid line
- B cells
- Plasma cells, Develop from B cells
- T cells
- NK cells, Natural killer cells
- Myeloid line
What causes it
PML::RARA usually forms when parts of chromosomes 15 and 17 rearrange in a blood-forming cell. This is generally an acquired change, not something passed from a parent to a child.
Most people have no identifiable cause. APL can occasionally follow previous cancer treatment. It cannot be caught from another person. Other rare rearrangements can resemble APL, but their response to treatment may differ and requires precise diagnosis.
Symptoms and effects
APL can reduce normal red cells and plateletsTiny pieces of cells in the blood that help form clots to slow or stop bleeding. They are made in the bone marrow. Too few platelets can cause easy bruising and bleeding., causing tiredness, breathlessness, bruising or bleeding. It can also disrupt the clotting system, so serious bleeding and abnormal clotting may occur together.
During treatment, differentiation syndrome is another possible emergency: maturing leukemia cells can trigger inflammation, fluid retention and breathing difficulties. The care team monitors for this and provides prompt treatment when needed.
Diagnosis and treatment
How APL is diagnosed
A blood count and a look at the blood under a microscope (a blood smear) can raise the first suspicion of APL. Clotting tests, such as fibrinogen and prothrombin time, show whether the blood's clotting system is disturbed.
Care does not wait for the final test result. European expert guidelines say a person with suspected APL is admitted to the hospital right away and treated as a medical emergency. A medicine called ATRA and transfusionsPutting blood, or parts of blood such as red cells or platelets, into a person's bloodstream through a vein. Some people with blood disorders need regular transfusions. to support clotting start at once. Clotting tests are then repeated at least daily until the clotting problem has cleared.
Specialist labs confirm APL by finding the PML::RARA gene change, ideally in a bone marrow sample. Fast tests, such as FISH or a stain for the PML protein, can give an early answer. A PCR test is run alongside them. It shows the exact form of the gene change, and it is later used to track whether any leukemia is left.
A standard chromosome test can miss the gene change. European guidelines say it is the test most likely to give a false-negative result, which is why faster, more sensitive tests are used as well.
How blood counts can look in acute promyelocytic leukemia (APL): red blood cells low and platelets low.
- Red blood cells: Low
- Platelets: Low
Each lab has its own usual range, and it changes with age. The drawing shows only the direction a count often moves, not how far, and one person’s results can look different.
How it is treated
All-trans retinoic acid (ATRA) helps abnormal promyelocytes mature. Arsenic trioxide is also a central treatment. Many patients receive ATRA with arsenic; higher-risk disease may require additional treatment to control the leukemia-cell count, including chemotherapy in some protocols.
Treatment includes intensive support for bleeding and clotting abnormalities. After the initial response, consolidation and molecular testing help establish whether the PML::RARA signal has cleared and whether it returns.
Transplant is generally unnecessary in first remission. In relapse, treatment depends on what was given before and the molecular response. An autologous transplant, using the person’s own collected cells, may be considered after molecular remission. Allogeneic transplantation may be considered when disease persists or for selected further relapses.
Kinds of treatment described for acute promyelocytic leukemia (APL): supportive care, medicines, a donor stem cell transplant (for a few people) and a transplant with the person’s own cells (for some people).
After diagnosis, the options described here
Supportive care
Transfusions to support clotting start at once, as part of intensive support for bleeding and clotting problems.
Medicines
ATRA helps the abnormal cells mature and arsenic trioxide is also a central treatment, with chemotherapy for some higher-risk APL.
Donor stem cell transplant, For a few people
May be considered when APL persists or for selected further relapses.
Transplant with the person’s own cells, For some people
If APL comes back, a transplant with the person’s own collected cells may be considered once tests no longer find the leukemia signal.
These are the kinds of treatment this page describes, not a plan. Which ones fit, in what order and whether they are combined differs from person to person.
When transplant specialists are usually consulted
A transplant is not part of first treatment for APL. If APL comes back, European expert guidelines say the main aim is a deep (molecular) remission as a bridge to transplant. They name a transplant of the person's own cells as the first choice when tests no longer find the PML::RARA signal. A donor transplant is recommended when that signal does not clear. The same guidelines note a UK report that questions whether every person in second remission needs a transplant.
Read the guidanceDaily life and the donor’s role
Living with the condition and treatment
The early days may involve hospitalization, frequent blood tests and transfusions even while medicines are beginning to work. Later treatment can include repeated clinic visits and molecular monitoring. A good early response does not make follow-up unnecessary.
ATRA and arsenic have side effects that need monitoring, including differentiation syndrome; arsenic can also affect heart rhythm and electrolytes. The treatment team explains which symptoms need an urgent call and how follow-up fits around home, school or work.
The role of a blood stem cell donor
A registry donor is not part of the usual first-line APL treatment. An autologous transplant also does not use a registry donor.
For a person who needs allogeneic transplantation after relapse, a relative or unrelated donor may be considered, with alternative graftThe blood-forming stem cells given to a patient in a transplant. In a donor transplant, the graft comes from the donor's bone marrow or blood, or from donated cord blood. options assessed by the transplant team. Most people with APL are treated without a donor transplant.
Looking ahead
Looking ahead
Outlook for APL
Researchers now call APL the most curable type of acute myeloid leukemia. In a large Italian-German trial, 99.2% of adults with lower-risk APL treated with ATRA and arsenic trioxide were alive about four years later. St. Jude, a children's cancer hospital, reports that more than 9 in 10 patients treated for APL are considered cured.
The hardest time is the start. Bleeding in the brain or lungs is the most common cause of death, both before and soon after treatment begins. Studies that count everyone diagnosed, not just people in trialsA research study that tests how well a new medical approach works in people. Trials can test new ways to screen for, prevent, diagnose or treat a disease., find more early deaths than trials do. Two things raise this early risk: older age and a white blood cell count above 10,000 per microliter at diagnosis. That high count is also what makes APL high-risk.
After the first weeks, care teams use PCR tests to check that the PML::RARA signal clears and stays gone. In lower-risk APL treated with ATRA and arsenic trioxide, relapse is uncommon. When APL does come back, arsenic trioxide brings many people into a second remission.
About these numbers. Each one says which group of people it comes from, and the place and years where the source gives them. It describes what happened across that group, not what will happen to any one person. And a figure measured among people who had a transplant is not the same as the number of people who need one.
- 99.2%Alive at 50 months (about 4 years)
Adults aged 18 to 71 with newly diagnosed lower-risk APL (white count 10,000 per microliter or less) randomly assigned to ATRA and arsenic trioxide in the Italian-German APL0406 trial, enrolled 2007 to 2013 (final results published 2017)
Read the source: Alive at 50 months (about 4 years) - 98.0% (standard risk); 96.4% (high risk)Event-free 2 years after diagnosis (alive, with no relapse or treatment failure)
154 children and young people aged 1 to 21 treated with ATRA and arsenic trioxide in the Children's Oncology Group AAML1331 trial at 85 centers in the U.S., Canada and Australia, enrolled 2015 to 2019 (published 2022)
Read the source: Event-free 2 years after diagnosis (alive, with no relapse or treatment failure) - 87.9%Alive 3 years after diagnosis, counting every eligible patient
1,233 eligible people newly diagnosed with APL at all 57 hematology centers in Zhejiang Province, China, 2015 to 2019, including the 8.2% who died within 30 days of diagnosis (population-based study, published 2021)
Read the source: Alive 3 years after diagnosis, counting every eligible patient
Trial figures describe people who were well enough to enroll and start treatment. They cannot predict how any one person will do.
Common questions
Is acute promyelocytic leukemia curable?
Yes, most of the time. Researchers now call APL the most curable type of acute myeloid leukemia (AML). The main danger is bleeding in the first days and weeks, which is why APL is treated as an emergency. The outlook section on this page gives the figures, with the groups they describe. Group results cannot predict one person's outcome.
Why is APL treated as a medical emergency?
APL can disturb the blood's clotting system, so serious bleeding, and sometimes clotting, can happen suddenly. Bleeding in the brain or lungs is the most common cause of death before and soon after treatment starts. For this reason, European expert guidelines say a person with suspected APL should be admitted to the hospital right away. A medicine called ATRA and transfusions to support clotting start at once, before genetic tests confirm the diagnosis. Studies that count everyone diagnosed find more early deaths than clinical trials do.
How is APL different from other types of AML?
APL is a form of acute myeloid leukemia (AML) in which young white blood cells called promyelocytes build up. It is caused by a gene change called PML::RARA. This change sets APL apart from other AML and explains why its main medicines, ATRA and arsenic trioxide, work so well. Many people with lower-risk APL are treated with these two medicines without chemotherapy. APL makes up about 5 to 8 in every 100 cases of AML, and it commonly disturbs blood clotting.
Does APL need a bone marrow transplant?
Usually not. A transplant is not part of first treatment for APL, because ATRA and arsenic trioxide work so well. In a large trial, fewer than 2 in 100 adults with lower-risk APL treated this way had their leukemia come back within about four years. If APL does return, it is treated again. European guidelines say a transplant using the person's own cells is usually the first choice if tests then no longer find the PML::RARA signal. A donor transplant is recommended when the signal does not clear.
Can children get acute promyelocytic leukemia?
Yes. APL makes up about 7 in every 100 cases of AML in children. St. Jude says it is rare before age 3 and is most often diagnosed in children of Hispanic or Mediterranean descent. Children are treated with ATRA and arsenic trioxide, and those with high-risk APL may also get chemotherapy. In a Children's Oncology Group trial, 98% of children with standard-risk APL and 96% with high-risk APL were alive with no relapse or treatment failure two years after diagnosis.
For your next appointment
Acute promyelocytic leukemia (APL)
From the Jada Bascom Foundation disease library, jadabascomfoundation.org. Printed .
Questions to bring to your care team
- Is this APL low risk or high risk, based on the white blood cell count at diagnosis, and how does that change the treatment plan?
- Which clotting tests are you checking each day, and what signs of bleeding or clotting should we report right away?
- Will treatment use ATRA and arsenic trioxide alone, or is chemotherapy also needed, and how long will treatment last?
- How and when will you test for the PML::RARA signal after treatment, and what would happen if it came back?
- What is the goal of each treatment you are suggesting?
- What would make a transplant worth considering later on?
- Are there clinical trials that might fit?
- Where can our family find support during treatment?
A one-page list to take to the next appointment, with room for notes.
Supporting someone with a diagnosisSupport for patients and families
These independent organizations offer information and support. JBF is not affiliated with them.
- Acute Leukemia Advocates Network (ALAN) A worldwide network of acute leukemia patient organizations; its member list helps families look for a group in their country.Worldwide
- Leukaemia Care UK charity with a free helpline, support groups and practical help for people affected by leukemia, with a page on APL.United Kingdom
- Leukemia Research Foundation US nonprofit offering peer support, an online community and mentoring for people with leukemia and their families, plus patient education.United States
Sources and further reading
- Acute Myeloid Leukemia Treatment (PDQ), Health Professional Version
NCI, Accessed 2026-09-05 - AML in Adults
EBMT Handbook / NCBI Bookshelf, Accessed 2026-09-05 - WHO fifth-edition classification: Myeloid and Histiocytic/Dendritic Neoplasms
WHO classification authors / Leukemia, Accessed 2026-09-05 - Indications for haematopoietic cell transplantation and CAR-T: 2025 EBMT practice recommendations
EBMT / Bone Marrow Transplantation, Accessed 2026-09-05 - Stem Cell and Bone Marrow Transplants for Cancer
NCI, Accessed 2026-09-05 - Childhood Acute Myeloid Leukemia Treatment (PDQ), Health Professional Version
National Cancer Institute, Updated 2025-04-15; accessed 2026-09-26 - Sanz MA et al. Management of acute promyelocytic leukemia: updated recommendations from an expert panel of the European LeukemiaNet
Blood (American Society of Hematology) / European LeukemiaNet, 2019; accessed 2026-09-26 - Platzbecker U et al. Improved outcomes with retinoic acid and arsenic trioxide compared with retinoic acid and chemotherapy in non-high-risk APL: final results of the randomized Italian-German APL0406 trial
Journal of Clinical Oncology (via Europe PMC), 2017; accessed 2026-09-26 - Kutny MA et al. Assessment of arsenic trioxide and all-trans retinoic acid for the treatment of pediatric APL: a report from the Children's Oncology Group AAML1331 trial
JAMA Oncology (via PubMed Central), 2022; accessed 2026-09-26 - Zhu HH et al. Early death and survival of patients with acute promyelocytic leukemia in ATRA plus arsenic era: a population-based study
Frontiers in Oncology (via PubMed Central), 2021; accessed 2026-09-26 - Park JH et al. Early death rate in acute promyelocytic leukemia remains high despite all-trans retinoic acid
Blood (via PubMed Central), 2011; accessed 2026-09-26 - Acute Promyelocytic Leukemia (APL)
St. Jude Children's Research Hospital, Accessed 2026-09-26
This information explains a condition and its treatments. It cannot diagnose an illness or recommend treatment for an individual. Your care team can explain how the evidence applies to you. Written and source-checked by the Jada Bascom Foundation. Each page lists the published sources it draws on.
Ways to help
Help another family understand.
Most people with acute promyelocytic leukemia (APL) are treated without a registry donor. A clear explanation can help the next family who hears this diagnosis, and many people with other blood cancers and blood disorders need a donor who is a stranger.
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More in the library
Keep learning
Interactive storyWhy matching is hard: leukemiaHow leukemia affects blood production, when a donor transplant may help, and how inherited HLA markers shape the search for a suitable donor.Begin the storyPart of 2 diagnosis guides, each explaining how its subtypes fit together: Leukemia and Types of blood cancer.
