Acute Myeloid Leukemia Induction
The treatment of acute myeloid leukemia (AML) has improved dramatically over the past 30 years. Because of the development of more dose intensive chemotherapy and improvements in supportive care, many patients with AML are now cured. In order to have the best chance of being cured, it is important to understand the treatments available and what is necessary to achieve the best results.
A variety of factors ultimately influence a patient’s decision to receive treatment of cancer. The purpose of receiving cancer treatment may be to improve symptoms through local control of the cancer, increase a patient’s chance of cure, or prolong a patient’s survival. The potential benefits of receiving cancer treatment must be carefully balanced with the potential risks of receiving cancer treatment.
The following is a general overview of the treatment of acute myeloid leukemia. Circumstances unique to your situation and prognostic factors of your cancer may ultimately influence how these general treatment principles are applied. The information on this Web site is intended to help educate you about your treatment options and to facilitate a mutual or shared decision-making process with your treating cancer physician.
Most new treatments are developed in clinical trials. Clinical trials are studies that evaluate the effectiveness of new drugs or treatment strategies. The development of more effective cancer treatments requires that new and innovative therapies be evaluated with cancer patients. Participation in a clinical trial may offer access to better treatments and advance the existing knowledge about treatment of this cancer. Clinical trials are available for most stages of cancer. Patients who are interested in participating in a clinical trial should discuss the risks and benefits of clinical trials with their physician. To ensure that you are receiving the optimal treatment of your cancer, it is important to stay informed and follow the cancer news in order to learn about new treatments and the results of clinical trials.
Researchers have learned that the best way to cure patients with AML is to administer large doses of chemotherapeutic agents in a short period of time. The concept is to kill leukemia cells within 6 months before resistance to the drugs occurs. Therapy is divided into two phases: remission induction and post-remission consolidation/maintenance. Induction chemotherapy is administered to produce a complete remission in the bone marrow, which is defined as less than 5% “blasts” in the bone marrow sample and a return to normal blood counts.
Remission Induction Therapy
During remission induction therapy, patients are given large doses of chemotherapy over a period of 5-7 days. These chemotherapy drugs kill leukemia cells and normal bone marrow cells. The major side effects of these drugs are related to toxicities of rapidly growing cells in the body, i.e., normal bone marrow, skin and the gastrointestinal tract. Each drug also has specific side effects for other organs.
Standard remission induction therapy currently consists of 3 days of an anthracycline and 7 days of cytarabine. Following induction, patients typically require 2-3 weeks for bone marrow blood cell production to recover. During this time, patients often require blood and platelet transfusions to maintain red blood cell and platelet levels. In order to reduce the risk of infection, antibiotics and blood cell growth factors that stimulate the bone marrow to produce normal white blood cells are often given during this period of time. Neupogen® and Leukine® are white blood cell growth factors currently approved by the Food and Drug Administration to facilitate white blood cell production. After 2-3 weeks, blood counts will begin to recover and often return to normal. A bone marrow examination is repeated to see if a remission has been achieved. For patients in remission, the consolidation therapy will begin. If patients have not achieved a remission, another induction course of treatment will be given immediately. However, for patients with an HLA-compatible marrow donor, consideration should be given to having an immediate allogeneic stem cell transplant without receiving a second course of induction therapy. This will depend on chances of achieving a remission with a second cycle of chemotherapy. However, even if a remission is achieved with a second cycle of chemotherapy, remission duration is often very short despite consolidation.
For patients with acute promyelocytic leukemia (M3), all-trans-retinoic acid, Vesanoid®, may be included in the remission induction regimen. Patients with acute promyelocytic leukemia typically receive Vesanoid® at some time during their treatment course. There are ongoing clinical trials to determine the optimal time to administer this drug.
If a complete remission is achieved and no further therapy given, over 90% of patients will have a recurrence of disease in weeks to months. To prevent recurrence of leukemia, consolidation therapy is initiated immediately after recovery from induction therapy. These treatments are given as close together as possible. The more intensive the chemotherapy and the closer together the courses of therapy are given, the less chance the leukemia has of returning. It is very important for patients to understand that lower doses of drugs do not work as well as higher doses of drugs.
Strategies to Improve Remission Induction
New Drug Development: All new drugs for the treatment of patients with AML are tested first in patients with relapsed or refractory disease. When they are found to be effective, they are then evaluated in remission induction regimens.
Multiple Drug Resistance Inhibitors: Patients with AML fail to achieve a remission or relapse because of chemotherapy drug resistance genes that can be present at the time of diagnosis or are induced by treatment. Several drugs are being tested to determine if they will overcome or prevent the development of multiple drug resistance in AML as part of remission induction strategies.