A group of Australian scientists has come up with an innovative treatment technique for acute myeloid leukemia (AML), a rare yet deadly disease affecting blood and bone marrow cells. One of the most aggressive types of cancer, known for its relatively rapid progression, the malady accounts for 1.2-percent of total cancer deaths in the United States, and has a five-year survival rate of only 24-percent. By comparison, bladder cancer has a five-year survival rate of around 78-percent, while that of breast cancer is about 89-percent.
Developed by researchers from Melbourne-based Walter and Eliza Hall Insitute of Medical Research, the new technique works by targeting a specific protein, called Hhex, that is essential to the growth cancerous cells. According to the team, blocking the production of the protein has been shown to stop the spread of leukemia. While it has not yet been tested on humans, the new method vastly differs from the AML treatments currently available to sufferers. Most of them are associated with an array of side effects, with over three quarters of the patients relapsing after only a short period.
AML is characterized by rapid growth of malignant cells, often appearing suddenly without much warning. For the very first time, the scientists have successfully identified a crucial factor facilitating the growth and spread of leukemia-afflicted cells: the protein Hhex. During laboratory testing, cutting of the supply of Hhex was found to stop the cancer from spreading uncontrollably. Speaking about the breakthrough, recently published in the Genes & Development journal, Dr. Matt McCormack of the institute’s Cancer and Hematology department said:
There is an urgent need for new therapies to treat AML. We showed blocking the Hhex protein could put the brakes on leukaemia growth and completely eliminate AML in preclinical models. This could be targeted by new drugs to treat AML in humans.
Produced in greater quantities in people with leukemia, the protein Hhex is surprisingly not required by healthy blood cells. As the researchers point out, this could pave the way for effective treatment techniques, focused on halting the protein’s production. Unlike existing AML treatments, which are not cancer cell-specific, the new method could do its job without attacking health cells, and would likely cause fewer side effects. Dr. McCormack added:
Hhex is only essential for the leukaemic cells, meaning we could target and treat leukaemia without toxic effects on normal cells, avoiding many of the serious side-effects that come with standard cancer treatments. We also know that most people with AML have increased levels of Hhex, often associated with adverse outcomes, further indicating it is an important target for new AML drugs.
Every cell in the human body contains specific control genes, whose function is to encourage and manage normal cell growth and division when faced with threatening conditions, such as the start of cancer. These genes are also responsible for preventing the damaged cells from proliferating. In AML patients, however, the body’s self-defence mechanism gets “switched off”, via a complicated process known as epigenetic modification. Dr. Ben Shields, a member of the research team, explained:
Hhex works by recruiting epigenetic factors to growth control genes, effectively silencing them. This allows the leukaemia cells to reproduce and accumulate more damage, contributing to the speed of AML progression.
Up until now, cancer drugs have focused on inhibiting epigenetic modification, often killing healthy blood cells in the process. The new treatment technique is much safer and more effective as it works by stopping the production of Hhex, a protein that is not needed by normal cells, but is essential to the leukemic ones. Dr. McCormack said:
Unlike the epigenetic factors targeted previously, Hhex only regulates a small number of genes and is dispensable for normal blood cells. This gives us a rare opportunity to kill AML cells without causing many side effects. We now hope to identify the critical regions of the Hhex protein that enable it to function, which will allow us to design much-needed new drugs to treat AML.