FLT3 is a gene change, or mutation, in leukemia (blood cancer) cells. It’s the most common genetic change in acute myeloid leukemia (AML), a type of leukemia that starts in the bone marrow and often moves into the blood.
The FLT3 gene contains instructions for a protein called FLT3, which helps white blood cells grow. A mutation in this gene encourages the growth of too many abnormal white blood cells.
There are two types of this mutation:
- FLT3-ITD: involving multiple copies of the gene in a row
- FLT3-TKD: involving a single change or gene deletions
People with the FLT3 mutation have a very aggressive form of leukemia that’s more likely to return after it’s treated. Around
In the past, AML treatments weren’t very effective against cancers with the FLT3 mutation. But new drugs that specifically target this mutation are improving the outlook for people with this AML subtype.
AML is divided into subtypes based on how the cancer cells look and what gene changes they have. Some types of AML, including those with the FLT3 mutation, are more aggressive than others and need different treatment.
The FLT3 gene helps regulate cell survival and reproduction. The gene mutation causes immature blood cells to multiply uncontrollably.
As a result, people with the FLT3 mutation have a less promising outlook compared with other types of AML. Their disease is more likely to return, or relapse, after treatment. They also tend to have a lower survival rate than people without the mutation.
AML usually causes symptoms quickly. These symptoms may include:
- easy bruising or bleeding
- bleeding gums
- unexplained weight loss
- pale skin
These symptoms are typically caused by another condition instead of by cancer. Still, if you have any symptoms of AML, it’s important to talk with your doctor.
FLT3 mutations occur more often in people under
In general, other risk factors for AML include:
The College of American Pathologists and the American Society of Hematology recommend that everyone who is diagnosed with AML gets tested for the FLT3 gene mutation.
Your doctor will have you tested in one of the following ways:
- Blood test. Blood is drawn from a vein in your arm and sent to a lab.
- Bone marrow aspiration or biopsy. A needle is inserted into your bone. The needle removes a small amount of liquid bone marrow.
The blood or bone marrow sample is then tested to see if you have the FLT3 mutation in your leukemia cells. This test will show whether you’re a good candidate for drugs that specifically target this type of AML.
Until recently, people with the FLT3 mutation were mainly treated with chemotherapy, which wasn’t very effective at improving survival rates. A new group of drugs called FLT3 inhibitors is improving the outlook for people with the mutation. Researchers are also investigating other treatments for the condition.
The FLT3 inhibitor midostaurin (Rydapt) was the first drug approved for FLT3, and the first new drug approved to treat AML in over 15 years. Doctors give midostaurin together with chemotherapy drugs such as cytarabine and daunorubicin.
Midostaurin works by blocking FLT3 and other proteins on leukemia cells that help them grow. You take it by mouth twice per day.
A 2017 study involving 717 people with the FLT3 gene published in The New England Journal of Medicine looked at the effects of treatment with this new drug. Researchers found that adding midostaurin to chemotherapy prolonged survival compared with an inactive treatment (placebo) plus chemotherapy.
The 4-year survival rate was 51 percent among people who took midostaurin, compared with just over 44 percent in the placebo group. The median length of survival (the point at which half of the participants were still alive) was more than 6 years in the treatment group, versus just over 2 years in the placebo group.
According to the same study, the group that received midostaurin had higher rates of anemia and rash than the group that received a placebo.
Midostaurin is given in combination with chemotherapy. Other possible side effects of the treatment include:
- fever and low white blood cells (febrile neutropenia)
- sores or redness in the mouth
- muscle or bone pain
- high blood sugar levels
Your doctor will monitor you for side effects while you’re on this drug and offer you treatments to help manage them.
Midostaurin is considered a first-generation FLT3 inhibitor. Second-generation FLT3 inhibitors target FLT3 more specifically and powerfully.
In 2018, the
Other FLT3 inhibitors are still in clinical trials to see if they work, including crenolanib and quizartinib.
Your doctor may recommend a stem cell transplant if you have FLT3-mutated AML that’s in remission (decreased symptoms). It uses stem cells either from a donor or from your body (in which case they’ll have been treated to kill leukemia cells) and then injects them into your blood. This may reduce the chance of the cancer returning.
Additionally, researchers are looking at whether different combinations of drugs might be more effective in people with this mutation.
Having the FLT3 mutation if you have AML is often linked to a less positive outcome. However, targeted medications like FLT3 inhibitors are helping improve the outlook. New drugs and combinations of drugs may extend survival even more in the years to come.
If you’re diagnosed with AML, your doctor will test you for FLT3 and other gene mutations. Knowing as much as possible about your condition can help your doctor find the most effective treatment for you.