Acute lymphoblastic leukemia medical therapy
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Chemotherapy is indicated for acute lymphocytic leukemia and can be divided in several phases: induction chemotherapy, consolidation therapy, CNS prophylaxis and maintenance treatments with chemotherapeutic drugs such as Prednisone plus Vincristine plus Cyclophosphamide plus Doxorubicin or Methotrexate plus 6-MP. Radiation therapy is used on painful bony areas in severe disease or as part of the preparations for a bone marrow transplant. Drugs approved for acute lymphoblastic leukemia include: Methotrexate, Nelarabine, Blinatumomab, Cyclophosphamide, Clofarabine, Cytarabine, Dasatinib, Doxorubicin hydrochloride, Mercaptopurine, Nelarabine, Pegaspargase, Prednisone and Mercaptopurine.
The earlier acute lymphocytic leukemia is detected, the more effective the treatment. The aim is to induce a lasting remission, defined as the absence of detectable cancer cells in the body (usually less than 5% blast cells on the bone marrow).
Proper management of acute lymphoblastic leukemia focuses on control of bone marrow and systemic (whole-body) disease as well as prevention of cancer at other sites, particularly the central nervous system (CNS). In general, acute lymphoblastic leukemia treatment is divided into several phases:
Induction chemotherapy to bring about remission - that is, leukemic cells are no longer found in bone marrow samples. For adult acute lymphoblastic leukemia standard induction plans include prednisone, vincristine, and an anthracycline drug; other drug plans may include L-asparaginase or cyclophosphamide. For children with low-risk acute lymphoblastic leukemia, standard therapy usually consists of three drugs (prednisone, L-asparaginase, and vincristine) for the first month of treatment. High-risk children may receive these drugs plus an anthracycline such as daunorubicin.
Consolidation therapy (1-3 months in adults; 4-8 months in children) to eliminate any leukemia cells that are still "hiding" within the body. A combination of chemotherapeutic drugs is used to keep the remaining leukemia cells from developing resistance. Patients with low- to average-risk acute lymphoblastic leukemia receive therapy with antimetabolite drugs such as methotrexate and 6-mercaptopurine (6-MP). High-risk patients receive higher drug doses plus treatment with extra chemotherapeutic agents.
CNS prophylaxis (preventive therapy) to stop the cancer from spreading to the brain and nervous system. Standard prophylaxis may consist of:
- Cranial (head) irradiation plus spinal tap or intrathecal (IT) delivery (into the space around the spinal cord and brain) of the drug methotrexate.
- High-dose systemic and IT methotrexate, without cranial irradiation
- IT chemotherapy.
Only children with T-cell leukemia, a high white blood cell count, or leukemia cells in the cerebrospinal fluid (CSF) need to receive cranial irradiation as well as IT therapy.
Maintenance treatments with chemotherapeutic drugs (e.g., prednisone plus vincristine plus cyclophosphamide plus doxorubicin; methotrexate plus 6-MP) to prevent disease recurrence once remission has been achieved. Maintenance therapy usually involves drug doses that are lower than those administered during the induction phase. In children, an intensive 6-month treatment program is needed after induction, followed by 2 years of maintenance chemotherapy.
Follow-up therapy for acute lymphoblastic leukemia patients usually consists of:
- Supportive care, such as intravenous nutrition and treatment with oral antibiotics (e.g., ofloxacin, rifampin), especially in patients with prolonged granulocytopenia; that is, too few mature granulocytes (neutrophils), the bacteria-destroying white blood cells that contain small particles, or granules (< 100 granulocytes per cubic millimeter for 2 weeks)
- Transfusions with red blood cells and platelets
A laboratory test known as polymerase chain reaction (PCR) is advisable for acute lymphoblastic leukemia patients, since it may help to identify specific genetic abnormalities. Such abnormalities have a large impact upon prognosis and, consequently, treatment plans. PCR testing is especially important for patients whose disease is B-cell in type. B-cell acute lymphoblastic leukemia cyclophosphamide-based regimens that are used for non-hodgkin's lymphoma.
Among acute lymphoblastic leukemia patients, 3-5% children and 25-50% of adults are positive for the Philadelphia chromosome (Ph1). Because these patients have a worse prognosis than other individuals with acute lymphoblastic leukemia, many oncologists recommend allogeneic bone marrow transplantation (alloBMT), since remission may be brief following conventional acute lymphoblastic leukemia chemotherapy.
People who receive bone marrow transplantation will require protective isolation in the hospital, including filtered air, sterile food, and sterilization of the microorganisms in the gut, until their total white blood cell (WBC) count is above 500.
Recurrent acute lymphoblastic leukemia patients usually do not benefit from additional chemotherapy alone. If possible, they should receive re-induction chemotherapy, followed by allogeneic bone marrow transplant (alloBMT).
Alternatively, patients with recurrent acute lymphoblastic leukemia may benefit from participation in new clinical trials of alloBMT, immune system agents, and chemotherapeutic agents, or low-dose radiotherapy, if the cancer recurs throughout the body or CNS.
Chemotherapy is the initial treatment of choice. Most acute lymphoblastic leukemia patients end up receiving a combination of different treatments. There are no surgical options, due to the body-wide distribution of the malignant cells.
As the chemotherapy regimens can be intensive and protracted (often about 2 years in case of the GMALL UKALL, HyperCVAD or CALGB protocols; about 3 years for males on COG protocols), many patients have an intravenous catheter inserted into a large vein (termed a central venous catheter or a Hickman line), or a Portacath (a cone-shaped port with a silicone nose that is surgically planted under the skin, usually near the collar bone, and the most effective product available, due to low infection risks and the long-term viability of a portacath). Since acute lymphoblastic leukemia cells sometimes penetrate the Central Nervous System CNS, most protocols include delivery of chemotherapy into the CNS fluid. More advanced centers deliver the drug through Ommaya reservoir (a device surgically placed under the scalp and used to deliver drugs to the CNS fluid and to extract CNS fluid for various tests). More traditional centers would perform multiple lumbar punctures as needed for testing and treatment delivery.
Radiation therapy is used on painful bony areas in severe disease or as part of the preparations for a bone marrow transplant (total body irradiation). Radiation in the form of whole brain radiation is also used for central nervous system prophylaxis, to prevent recurrence of leukemia in the brain. Whole brain prophylaxis radiation used to be a common method in treatment of children’s acute lymphoblastic leukemia. Recent studies showed that CNS chemotherapy provided results as favorable but with less developmental side effects. As a result, the use of whole brain radiation has been more limited.
Drugs Approved for acute lymphoblastic leukemia
The following pharmaclogic agents have been aproved for the treatment of acute lymphoblastic leukemia:
- Asparaginase Erwinia chrysanthemi
- Doxorubicin Hydrochloride
Late Effects of Treatment for Adult acute lymphocytic leukemia
Long-term follow-up of 30 patients with acute lymphocytic leukemia in remission for at least 10 years has demonstrated ten cases of secondary malignancies. Of 31 long-term female survivors of acute lymphoblastic leukemia or acute myeloid leukemia younger than 40 years, 26 resumed normal menstruation following completion of therapy. Among 36 live offspring of survivors, two congenital problems occurred.
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