What’s new in acute myeloid leukemia research and treatment?
Researchers are now studying the causes, diagnosis, supportive care, and treatment of acute myeloid leukemia (AML) at many medical centers, university hospitals, and other institutions.
Genetics of leukemia
Scientists are making great progress in understanding how changes in a person’s DNA can cause normal bone marrow cells to develop into leukemia cells. A greater understanding of the genes (regions of the DNA) involved in certain translocations or other chromosomal changes that often occur in AML is providing insight into why these cells become abnormal. Doctors are now learning how to use these changes to help them determine a person’s outlook and whether they should receive more or less intensive treatment.
In the future, this information may also be used to help develop newer targeted therapies against AML (see below).
Gene expression profiling
This new lab technique is being studied to help identify and classify different cancers. Instead of looking at single genes, this test is able to look at the patterns of many different genes in the cancer cells at the same time. This may add to the information that comes from the currently used lab tests.
Detecting minimal residual disease
Progress in understanding DNA changes in AML has already provided a highly sensitive test for detecting the smallest amount of leukemia left after treatment (minimal residual disease), even when so few leukemia cells are present that they cannot be found by routine bone marrow tests.
The polymerase chain reaction (PCR) test can identify AML cells based on their gene translocations or rearrangements. This test can find one leukemia cell among a million normal cells. A PCR test can be useful in determining how completely the treatment has destroyed the AML cells.
Doctors are now trying to determine what effect minimal residual disease has on a patient’s outlook, and how this might affect the need for further or more intensive treatment.
Studies are being done to find the most effective combination of chemotherapy (chemo) drugs while still avoiding unwanted side effects. This is especially important in older patients, who are less likely to benefit from current treatments.
Sapacitabine, which is a type of drug known as a nucleoside analog, has shown promise as a treatment option for older patients with AML.
Laromustine, a type of chemo drug known as an alkylating agent, is also being tested as an option for in older adults with AML.
Tipifarnib, a newer type of drug known as a farnesyl transferase inhibitor, has also shown promise in early studies. Farnesyl transferase inhibitors are drugs that keep a protein that is very active in cancer from functioning. These drugs are now being tested in larger clinical trials.
Bortezomib (Velcade®) is a type of drug known as a proteasome inhibitor. It is helpful in the treatment of multiple myeloma and certain types of lymphoma. A recent study looked at adding this drug to chemo for AML with promising results.
The effectiveness of chemo may be limited in some cases because the leukemia cells become resistant to it. Researchers are now looking at ways to prevent or reverse this resistance by using other drugs along with chemo.
Treating acute promyelocytic leukemia
Most patients with acute promyelocytic leukemia are treated with ATRA combined with chemo. A recent study has shown that combining ATRA with arsenic trioxide was at least as good for many patients. This combination had been used before, but often only for patients who couldn’t get the standard chemo drugs. With the results of this study, ATRA plus arsenic may be used more often.
Stem cell transplants
Researchers continue to refine stem cell transplants to try to increase their effectiveness, reduce complications and determine which patients are likely to be helped by this treatment. Many studies are under way to try to help determine exactly when autologous, allogeneic, and mini-transplants might best be used.
New targeted drugs that specifically attack some of the genetic changes seen in AML are now being developed.
About 1 person out of 3 with AML has a mutation in the FLT3 gene. Several new drugs, called FLT3 inhibitors, target this gene. They have shown activity against AML in early studies, especially when combined with chemotherapy. So far, they are only available in clinical trials.
Other gene mutations, such as changes in the c-KIT gene, also appear to be important in some cases of AML, and may become important targets for new therapies. Drugs that target this gene, such as imatinib (Gleevec®) and dasatinib (Sprycel®) are already used against other types of leukemia, and are now being studied against AML.
Monoclonal antibodies are man-made versions of immune system proteins (antibodies) that are designed to attach to specific targets, such as substances on the surface of cancer cells. Some work by boosting the body’s immune response against the cancer cells. Other monoclonal antibodies have radioactive chemicals or cell poisons attached to them. When they are injected into the patient, the antibodies act like a homing device, bringing the radioactivity or poison directly to the cancer cells, which kills them. Monoclonal antibodies are often used to treat lymphoma, but their use in leukemia has been more limited.
Gemtuzumab ozogamicin (Mylotarg®) is a monoclonal antibody with a cell poison attached that at one time was approved by the FDA to treat AML in older patients. Although it was taken off the market because it didn’t seem very helpful, it is showing promise in certain patients in clinical trials.
Vaccine therapy: A study of an experimental vaccine had promising results. For this vaccine, white blood cells (cells of the immune system) are removed from the patient’s blood and exposed to a protein found on many AML cells called Wilms’ tumor 1 protein (WT1). These cells are then given back to the patient by infusion into a vein (IV). In the body, the cells induce other immune system cells to attack the patient’s leukemia.
Last Medical Review: 07/24/2013
Last Revised: 09/20/2013