Induction

Treatment for AML uses combinations of drugs that are different from those used for ALL. The drugs most often used are daunorubicin (daunomycin) and cytarabine (ara-C), which are each given for several days in a row. The schedule of treatment may be repeated in 10 days or 2 weeks, depending on how intense the doctor wants the treatment to be. A shorter interval between treatments causes more severe side effects, but may be more effective in killing leukemia cells.

If the doctors think that the leukemia may not respond to just 2 drugs alone, they may add etoposide and/or 6-thioguanine. Children with very high numbers of white blood cells or whose leukemia has certain chromosome abnormalities may fall into this class.

Treatment with these drugs is repeated until the bone marrow shows no more leukemia. This usually occurs after 2 or 3 treatments.

Preventing relapse in the central nervous system: In most cases, intrathecal chemotherapy (given directly into the cerebrospinal fluid, or CSF) is also given to help prevent leukemia from relapsing in the brain or CSF. Radiation therapy to the brain is used less often. The risk for recurrence in the brain or CSF is lower in children with AML than in children with ALL.

Consolidation (Intensification)

This begins after the induction phase, when the bone marrow has no more visible leukemia cells.

About 1 out of 5 children has a brother or sister who would be a good stem cell donor. For these children, an allogeneic stem cell transplant is often recommended. Most studies have found this improves the chance for long-term survival over chemotherapy alone, although it is also more likely to cause serious complications. For children with good prognostic factors, some doctors may recommend just giving high-dose chemotherapy, and reserving the stem cell transplant in case the AML relapses.

For most other children, consolidation consists of giving the chemotherapy drug cytarabine (ara-C) in high doses. Daunorubicin may also be added. It is usually given for at least several months.

Intrathecal chemotherapy (into the cerebrospinal fluid) is usually given initially and every 1 to 2 months for as long as intensification continues.

Maintenance chemotherapy is not needed for children with AML (other than those with APL - see below).

An important part of treatment for AML is the supportive care (proper nursing care, nutrition supplement, antibiotic use, and blood transfusions). Without antibiotic treatment of infections or transfusion support, children with AML could not expect the current 75% to 85% remission rate at the end of induction.

Refractory or Recurrent AML

Less than 15% to 20% of children have refractory AML (leukemia that does not respond to initial treatment). The outlook for the child who doesn't go into remission is often poor, and doctors may recommend some type of stem cell transplant if it can be done.

In a recent clinical trial, children who were not in complete remission after induction chemotherapy were given a drug called gemtuzumab ozogamicin (Mylotarg) as part of their intensification. Mylotarg is a chemotherapy drug attached to a manmade antibody. The antibody is designed to bring the chemotherapy directly to the AML cells. Early results suggest this treatment may help improve survival rates for some children with AML.

Generally, the outlook for a child whose AML relapses (comes back) after treatment is slightly better, but this depends on how long the initial remission was. In more than half of cases of relapse, a second remission can be achieved with more chemotherapy. The chance of getting a second remission is better if the first remission lasted for at least a year, but long-term second remissions are rare without a stem cell transplant.

Many different combinations of standard chemotherapy drugs have been used in these situations, but the results have been mixed.

Most children will be offered a clinical trial that is testing a new treatment regimen. The hope is that some sort of a remission can be attained so that an allogeneic stem cell transplant can be done. If remission is achieved, a stem cell transplant should be considered. Some doctors may advise an allogeneic stem cell transplant even when there is no remission. This can sometimes be successful.

Cure Rates for AML

The cure rate for AML (with standard chemotherapy) is 40% to 50%. Treatment of AML with a stem cell transplant from a brother or sister with the same tissue type results in a higher cure rate of 55% to 60%.