Treatments for acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML). It is treated slightly differently than other AML subtypes but will still have induction, consolidation and maintenance phases of treatment.

Induction is the first phase of treatment. The goal of induction is to kill all the leukemia cells (blast cells, or blasts) in the blood and lessen the number of leukemia cells in the bone marrow to normal. Targeted therapy may also be used if the cancer cells have certain genetic mutations.

Consolidation is the second phase of treatment, given after induction. The purpose is to continue to rid the body of leukemia cells that are still around but can't be seen. Chemotherapy is given in cycles with rest periods. Targeted therapy may also be used for certain genetic mutations.

Maintenance is a third phase of treatment. It follows consolidation and involves low-dose chemotherapy for a longer period of time.

The specific drugs and treatments used in the different phases of APL treatment depend on whether you are low or high risk or have any cardiac issues.

Low risk is if you have a white blood cell (WBC) count less than or equal to 10,000/mm³.

High risk is a WBC count greater than 10,000/mm³.

Induction is the first phase of treatment given for newly diagnosed APL. Induction treatment is also called remission induction therapy. The goal of induction treatment for APL is to treat all the leukemia cells in the blood and bone marrow and bring about a complete remission, or complete response.

Your healthcare team will suggest induction treatments based on your needs and work with you to develop a treatment plan. Induction treatment usually involves all-trans retinoic acid (ATRA) along with chemotherapy. ATRA is a drug derived from vitamin A. It must be followed by other chemotherapy drugs or given with other chemotherapy drugs to bring about remission, which might take about 2 months.

Chemotherapy uses anticancer drugs to destroy cancer cells. The chemotherapy drugs used in combination will depend on whether the cancer is low or high risk. The targeted therapy drug gemtuzumab ozogamicin (Mylotarg) may also be used.

Induction treatment for APL may include:

• ATRA and arsenic trioxide (ATO)
• ATRA and idarubicin or daunorubicin (Cerubidine)
• ATRA, idarubicin or daunorubicin and ATO
• ATRA, ATO and gemtuzumab ozogamicin
• ATRA and idarubicin or daunorubicin with or without cytarabine

A bone marrow biopsy is usually done about a month or 2 after treatment starts. Once APL is in remission, consolidation therapy can start.

Find out more about chemotherapy for AML and targeted therapy for AML.

Consolidation is the second phase of treatment given for APL. Consolidation treatment starts once APL is in remission. Consolidation treatment is also called post-remission therapy. The goal of consolidation treatment for APL is to treat any leukemia cells that are still in the blood or bone marrow once remission is reached. It is done to maintain complete remission and prevent relapse.

Your healthcare team will suggest consolidation treatments based on your needs and work with you to develop a treatment plan. Consolidation usually involves the same drugs as induction. It usually lasts several months, depending on the drugs being used.

Chemotherapy uses anticancer drugs to destroy cancer cells. The chemotherapy drugs used in combination will depend on whether the cancer is low or high risk. The targeted therapy drug gemtuzumab ozogamicin may also be used.

Consolidation treatment for APL may include:

• ATRA and arsenic trioxide (ATO)
• ATRA and gemtuzumab ozogamicin
• ATO and gemtuzumab ozogamicin
• ATRA and idarubicin, mitoxantrone or daunorubicin
• ATRA and ATO with or without gemtuzumab ozogamicin
• ATO, ATRA and idarubicin or daunorubicin, with or without cytarabine

Find out more about chemotherapy for AML and targeted therapy for AML.

Maintenance is a third phase of treatment given for APL. The goal of maintenance treatment for APL is to prevent leukemia cells from coming back (called relapse). Not all treatment plans for APL need to include maintenance therapy.

Maintenance treatment is usually given for 1 to 2 years. The most common drug combinations used for maintenance include:

• ATRA
• ATRA and methotrexate
• ATRA and mercaptopurine

Find out more about chemotherapy for AML.

Relapsed, or recurrent, APL means the leukemia has come back after treatment and remission.

Refractory APL means the leukemia did not respond to treatment. Complete remission has not been reached because the chemotherapy did not kill enough leukemia cells.

Both relapsed and refractory APL need more treatment to reach complete remission.

Your healthcare team will suggest treatments based on your needs and work with you to develop a treatment plan. Some factors considered for your treatment include:

• your age
• your health
• how long the leukemia was in remission
• treatments you had before

Treatments used for relapsed or refractory APL include:

• chemotherapy with daunorubicin, idarubicin or mitoxantrone
• ATO with or without ATRA
• ATO, ATRA and chemotherapy (daunorubicin, idarubicin or mitoxantrone) or targeted therapy (gemtuzumab)

Stem cell transplant may also be considered for APL if a second remission is reached.

Find out more about chemotherapy for AML, targeted therapy for AML and stem cell transplant for AML.

Supportive therapy is important during every phase of APL treatment. It is used to treat the complications that usually happen with treatments for APL and the disease itself.

Supportive therapies given during treatment for relapsed or refractory APL may include:

• antibiotics and antifungals to treat infections
• growth factors to help the bone marrow recover from chemotherapy (chemotherapy can affect the bone marrow so it doesn’t make enough healthy blood cells, which can increase the risk for infection)
• transfusions of red blood cells, platelets, fresh frozen plasma and cryoprecipitate (a product that replaces clotting factors)

Find out more about supportive therapy.

Differentiation syndrome is a complication caused by ATRA, and it may also happen with ATO. It is most often seen during the first cycle of treatment with these drugs.

The symptoms of differentiation syndrome include:

• fever
• weight gain
• swelling caused by a buildup of fluid in the body (called edema)
• buildup of fluid around the lungs (called pleural effusion)
• buildup of fluid around the heart (called pericardial effusion)
• breathing problems
• low blood pressure

If the symptoms of differentiation syndrome are mild, you can usually keep taking ATRA or ATO. Doctors will also prescribe a steroid, such as dexamethasone (Decadron, Dexasone), to help manage side effects.

If differentiation syndrome is severe, doctors will stop giving ATRA or ATO and give steroids until the symptoms completely go away. If steroid treatment doesn't work, doctors may try chemotherapy to relieve symptoms of differentiation syndrome.

Talk to your doctor about clinical trials open to people with AML in Canada. Clinical trials look at new ways to prevent, find and treat cancer. Find out more about clinical trials.