What is the treatment protocol for acute lymphoblastic leukemia?

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Once a person has been diagnosed with ALL, a healthcare team can formulate a treatment plan. Treatment plans for ALL generally consist of three steps:

• induction
• consolidation
• maintenance

According to the American Cancer Society, treatment for ALL usually takes around 2 years. The intensity of a person’s treatment can depend on the severity or type of ALL they have.

A child with ALL may receive different treatments than an adult with ALL.

A person can talk with a doctor about the treatments that may work best for them.

Learn more about ALL here.

Induction treatment aims to get a person’s ALL into complete remission. Complete remission is when a person has no traces of ALL following treatment. A person achieves this by having:

• bone marrow that contains less than 5% blast cells
• a normal red blood cell count
• no signs or symptoms of ALL

However, a small amount of ALL cells may remain in the body following complete remission. If these cells replicate, a person can have a relapse of ALL. A person who has relapsed ALL will require further treatment.

During the induction phase of ALL treatment, a person will generally receive chemotherapy. Induction chemotherapy usually lasts around one month. A person may receive a combination of different chemotherapy drugs, which usually include:

• vincristine
• dexamethasone or prednisone
• an anthracycline drug, such as doxorubicin or daunorubicin

A person may receive additional chemotherapy drugs depending on their outlook. These drugs include:

• cyclophosphamide
• L-asparaginase
• high doses of methotrexate or cytarabine (ara-C)

People over 65 years old may have the same chemotherapy drugs but at different doses.

If a person has ALL with the Philadelphia chromosome, they may require additional treatment. The Philadelphia chromosome is an abnormal fusion of two genes. This gene fusion creates abnormal proteins that help ALL cells grow.

Doctors can treat Philadelphia-positive ALL using targeted therapy. Targeted therapy is a treatment that targets specific cancer cells.

Central nervous system (CNS) prophylaxis

A review from 2020 notes that doctors find that leukemia has reached the brain and spinal cord in 3–5% of cases at initial diagnosis. This increases to 30–40% at relapse. For this reason, doctors often prescribe treatment, or prophylaxis, during induction that prevents the spread of ALL to the CNS. If a person already has CNS involvement, treatment can destroy the ALL cells there.

CNS prophylaxis can include:

• intrathecal chemotherapy, which is where healthcare professionals inject chemotherapy drugs into the fluid between CNS tissues
• high doses of other chemotherapy drugs
• radiation therapy of the brain and spinal cord

Learn about the difference between chemotherapy and radiation therapy here.

Chimeric antigen receptor (CAR) T cell therapy

CAR T cell therapy is a form of immunotherapy. Immunotherapy is a cancer treatment that uses a person’s immune system to fight ALL cells.

CAR T cell therapy involves removing a person’s T cells, modifying them, and reinserting them into a person’s blood. T cells are a type of lymphocyte that can attack invading organisms or boost other white blood cells. CAR T cells are modified to attack specific proteins on ALL cells, which helps destroy them.

Currently, CAR T cell therapy is not used for initial treatment and is only used to treat relapsed disease.

Once a person’s ALL is in remission, they can move to consolidation treatment. Doctors use consolidation treatment to further reduce ALL cell numbers.

A person will usually have consolidation therapy for a few months following induction therapy. Doctors typically continue to prescribe CNS prophylaxis during this phase. During consolidation, a person will usually receive the same chemotherapy drugs they had during induction.

Certain types of ALL have high chances of returning. If a person is at risk of their ALL returning, their healthcare team may recommend a stem cell transplant (SCT).

Stem cells are cells that can develop into other types of cells. A person who has ALL can have an SCT to replace cancerous stem cells with healthy ones.

If a person has a sibling, a doctor may recommend using the sibling’s stem cells because they will be a close genetic match. Alternatively, a person can receive stem cells from an unrelated matching donor.

Maintenance treatment follows consolidation. Doctors use these treatments to help ensure that ALL cells do not return.

A person receives maintenance treatment for around 2 years. It usually involves chemotherapy, but targeted therapy and CNS prophylaxis may also continue during this phase.

According to the American Cancer Society, 80–90% of adults will experience remission during ALL treatment. However, about 50% of people in remission will have a relapse. This means that the actual cure rate of ALL is around 40%.

The outlook for a person with ALL can vary based on certain factors, such as:

• a person’s age
• the subtype of ALL
• the specific gene or chromosome abnormalities within a person’s ALL cells
• a person’s white blood cell count at the time of diagnosis

People who go into remission within 4–5 weeks of starting treatment have a better outlook than those who go into remission later. People who do not go into remission at all have a poorer outlook.

The National Cancer Institute notes that around 98% of children with ALL achieve remission following treatment.

Although treatment can cure ALL, it often returns. This is known as relapsed or recurrent ALL.

Relapsed ALL can occur when some of the leukemia cells survive induction, consolidation, and maintenance. These surviving cells then replicate and return as before. If ALL relapses within 3 years of treatment, doctors classify it as early relapse. If it occurs after 3 years, they classify it as late relapse.

Treatment for relapsed ALL is similar to the treatment for initial ALL. These treatments include:

• combination chemotherapy, which uses a variety of chemotherapy drugs
• targeted therapy
• SCT
• CAR T cell therapy
• CNS prophylaxis
• radiation therapy

Survival rates for people with ALL can depend on certain factors, such as age. Following treatment, the 5-year survival rate for children and adolescents up to 19 years old is around 80–90%. The 5-year survival for an adult following ALL treatment is 68.6%.

However, these survival rates are lower for people who have relapsed ALL. A 2020 article states that the 5-year survival rate for children with relapsed ALL is around 50%.

A study from 2020 noted that the 5-year survival rate for an adult with relapsed ALL is 5.8% if they relapse shortly after initial remission. The 5-year survival rate for an adult with relapsed ALL that develops later is 20%.

ALL is a form of blood and bone marrow cancer. If a person has ALL, various treatment options are available to them. A person can speak with their healthcare team about treatments that are most appropriate for them.

Treatment follows three phases:

• induction, which focuses on remission
• consolidation, which aims to remove any remaining ALL cells
• maintenance, which helps prevent ALL from returning

Response rates to ALL treatments are high. However, there is also a chance that ALL can return. The outlook for those with relapsed ALL is poorer than for those with initial ALL.