Medical Health Encyclopedia

When this regimen is used together with CNS prophylaxis, remission rates of greater than 95% have been achieved in children. In a 2001 study, researchers reported that the most effective regimen for many children uses dexamethasone after the first month with a longer duration for asparaginase (30 rather than the standard 20 weeks).

Drugs Used for High-Risk Children. A four or five-drug regimen is used for many high-risk children. An example of a four-drug regimen would be vincristine, prednisone/dexamethasone, plus asparaginase, and an anthracycline (such as doxorubicin, daunorubicin, or epirubicin).

Drugs Used for Specific High-Risk Adults. Adult patients have a poorer outlook than children do, and investigators and looking for more effective chemotherapy regimens. For example, cyclophosphamide-based regimens are used in adult patients with certain types of ALL. In a 2005 study, patients treated with an investigational regimen of cytabarine and high-dose mitoxantrone experienced a much higher rate of remission and survival than patients treated with the standard L-20 chemotherapy regimen of vincristine, prednisone, cyclophosphamide, and doxorubicin. Patients with the Philadelphia chromosome also benefited from the investigational treatment.

Preventing Central Nervous System Disease (CNS Prophylaxis)

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CNS prophylaxis is critical for preventing disease that has spread to the brain, spine, and testes (called sanctuary disease sites). Although only 3% of children with ALL have evidence of leukemia in the central nervous system (CNS) at the time of diagnosis, leukemia will spread to this region in between 50 - 70% of children without preventive (prophylactic) treatment. The brain is one of the first sites for relapsing leukemia.

CNS prophylaxis is usually:

• Administered together with induction therapy before moving to consolidation, the next standard treatment phase, particularly if there are any leukemic cells detected in the spinal fluid.
• Given through  intrathecal chemotherapy, in which a drug is injected directly into the spinal fluid. The drugs used are either methotrexate alone or a combination of methotrexate, hydrocortisone, and cytarabine. (Induction chemotherapy does not penetrate the blood-brain barrier sufficiently to destroy leukemic cells in the brain.)
• In some cases, methotrexate, with or without other drugs, is given as systemic (widespread) therapy at the same time as intrathecal chemotherapy. The addition of this treatment is effective in preventing relapse in the central nervous system and can substitute for radiation to the skull.