Acute Myeloid Leukemia Treatment

Chemotherapeutic treatment is divided into two phases: induction and postremission therapy. In all FAB subtypes except M3, the usual initial treatment includes cytarabine (ara-C) and an anthracycline (such as daunorubicin or idarubicin). Because of the toxic effects of therapy (from myelosuppression and increased risk of infection), induction chemotherapy is generally not offered to the very elderly.

Complete remission is obtained in about 50%-75% of newly diagnosed adults. The bone marrow is examined for malignant cells following induction chemotherapy. Complete remission does not mean that the disease has been cured; rather, it signifies that no disease can be detected (i.e., <5% leukemic blasts in the bone marrow).

Once complete remission is achieved, more therapy is necessary to eliminate nondetectable disease to prevent relapse of disease and achieve a cure. The specific type of postremission therapy recommended to the patient is based on the patient's risk of relapse, based on the WHO classification (see above). For good-risk leukemias (i.e. inv(16), t(8;21), and t(15;17)), patients will typically undergo an additional 3-5 courses of intensive chemotherapy, known as consolidation chemotherapy. For high-risk of relapse (high-risk cytogenetics, underyling MDS, or therapy-related AML), usually allogeneic stem cell transplantation is recommended. The best postremission therapy for intermediate risk AML (normal cytogenetics or cytogenetic changes not falling into good-risk or high-risk groups) is less clear and depends on the specific situation, such as the age and overall health of the patient, the patient's personal values, whether a suitable stem cell donor is available.

Despite aggressive therapy, however, only 20%-30% of patients enjoy long-term disease-free survival. For patients with relapsed AML, the only proven potentially curative therapy is a stem cell transplant. In 2000, Mylotarg (gemtuzumab zogamicin) was approved in the United States for patients aged more than 60 years with relapsed AML who are not good candidates for high-dose chemotherapy.

The M3 subtype, also known as acute promyelocytic leukemia, is almost universally treated by the drug ATRA (all-trans-retinoic acid) in addition to induction chemotherapy. For relapsed APL, arsenic trioxide has been tested in trials and approved by the Food and Drug Administration. Like ATRA, arsenic trioxide does not work with other subtypes of AML.

For many AML cases with so-called balanced translocations, doctors can now accurately monitor the effect of chemotherapy with molecular assays (PCR [polymerase chain reaction] tests). Often, these quantitative PCR assays have the sensitivity to detect one leukemic cell in 100,000 normal ones. Such data allow the doctors to better evaluate the effect of therapy and to foresee relapses of the disease long before they can be diagnosed by other methods or even felt by the patients.

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