Leukemias

Acute Lymphocytic Leukemia

Acute lymphocytic leukemia (ALL), also called acute lymphoblastic leukemia, starts in the cells that become lymphocytes, a type of white blood cell that normally helps protect people from infections. In ALL, the abnormal cells grow quickly and, if untreated, can spread rapidly from the blood and bone to other parts of the body and be life-threatening.

Classifying ALL

To classify ALL, your doctor may use the World Health Organization (WHO) classification system, which considers the results of morphology (shape and size of the cancer cells), flow cytometry (the process of identifying markers/proteins on a cell), cytogenetic tests (a process that looks at the number and structure of chromosomes that make up the cancer cells), and other molecular lab tests that provide detailed information about the subtype of ALL.

These tests help divide ALL into groups to take into account the type of lymphocyte (B-cell or T-cell, which are the two main types of lymphocytes) the leukemia comes from and how mature these leukemia cells are. The subtypes of ALL include the following:

  • Acute precursor B-cell (pre-B-cell) lymphoblastic leukemia
  • Acute T-cell (lymphoblastic) leukemia (T-cell ALL)
  • Burkitt acute lymphoblastic leukemia (B-ALL)
  • Ph-positive (Philadelphia positive) ALL

In about 4 of every 10 cases of B-cell ALL (B-ALL), a genetic change takes place when chromosomes, which are long strands of DNA, break off and swap places. This process is called a translocation. The resulting abnormal chromosome, known as the Philadelphia chromosome, is in the ALL cells. The swap causes the formation of an abnormal fusion of two genes, BCR and ABL. The BCR-ABL gene fusion produces the BCR-ABL protein. This protein, a tyrosine kinase (an enzyme), helps B-ALL cells grow and multiply at a much faster rate than normal white blood cells. It is important to test for the Philadelphia chromosome or the BCR-ABL gene fusion, as some treatments are more likely to be effective for this type of ALL.

ALL is classified into general categories of untreated (usually people who are newly diagnosed), in remission, refractory or recurrent.

Treating ALL

Because ALL progresses quickly, treatment is recommended soon after diagnosis and consultation with a leukemia expert physician. The following types of treatment may be used alone or in combination.

Chemotherapy is typically the main treatment for ALL. Many different chemotherapy drugs are commonly given in a specific regimen for a certain amount of time. Chemotherapy for ALL spans approximately three years and is given in three phases: induction, consolidation and maintenance.

The goal of induction is to eliminate as many ALL cells as possible. The consolidation phase aims to destroy any remaining leukemia cells. During the maintenance phase, lower-dose treatments are given to prevent new leukemia cells from growing. Your doctor may also prescribe a corticosteroid to reduce inflammation and to offer additional benefits.

Targeted therapy is a type of treatment that includes tyrosine kinase inhibitors (TKIs). TKIs are used primarily to treat ALL that is Philadelphia chromosome-positive. Targeted therapy drugs are often given in combination with chemotherapy. Resistance to targeted therapy is common in B-ALL, but more targeted therapies are being developed to target the BCR-ABL gene fusion in B-ALL.

Immunotherapy is approved to treat ALL in these forms:

  • Chimeric antigen receptor (CAR) T-cell therapy is the first gene therapy approved in the U.S. to treat children and young adults with B-ALL. A patient’s T-cells are collected, and a CAR that is specific for B-cells is added to the patient’s T-cells to aid it in recognizing normal and malignant B-cells. These engineered T-cells are called CAR T-cells. They are multiplied in a laboratory and infused back into the patient. The goal is for the infused T-cells to multiply then seek and destroy the cancer cells that carry those specific antigens. Serious side effects can occur from CAR T-cell therapy, but it can induce a complete remission when other treatments have failed.
  • Monoclonal antibodies (mAbs, pronounced "mabs") are artificial antibodies (proteins) designed to attack specific targets, such as proteins found on cancer cells. The type of mAb approved for ALL functions as a bridge. One end of the antibody engages a normal T-cell and the other end binds to a protein on the surface of B-ALL, allowing the T-cell to come in close proximity and kill the B-ALL.

Stem cell transplantation in the form of an allogeneic transplant may be an option to treat poor-prognosis, relapsed or refractory ALL.

Radiation therapy may be used to treat leukemia cells that have spread to other areas of the body, such as to the fluid surrounding the brain and spine or to the testicles. When it is given to the brain or spinal cord, it is known as central nervous system (CNS) sanctuary therapy or CNS prophylaxis.

Clinical trials may be a valuable treatment option to consider.

Refractory Or Recurrent ALL

Treatment may not always result in complete remission. In that case, the ALL is considered refractory. Immunotherapy, such as CAR T-cell therapy, targeted therapy, chemotherapy and stem cell transplantation, may be treatment options. If ALL returns after going into remission, it is considered recurrent. Your doctor will re-evaluate your diagnosis and may choose a different therapy.

 

Drug Therapies for ALL as of 10/16/20
asparaginase (Elspar)
asparaginase Erwinia chrysanthemi (Erwinaze)
blinatumomab (Blincyto)
calaspargase pegol – mknl (Asparlas)
clofarabine (Clolar)
cyclosphosphamide
cytarabine
dasatinib (Sprycel)
daunorubicin
dexamethasone
doxorubicin hydrochloride (Adriamycin)
imatinib mesylate (Gleevec)
inotuzumab ozogamicin (Besponsa)
mercaptopurine (Purinethol, Purixan)
methotrexate
nelarabine (Arranon)
pegaspargase (Oncaspar)
ponatinib (Iclusig)
prednisone
tisagenlecleucel (Kymriah)
vincristine (Oncovin)

 

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