Two U.S. Food and Drug Administration (FDA)-approved drugs for treating prostate cancer may also be effective against acute myeloid leukemia (AML), according to a new study by researchers at Penn State. AML, a cancer of blood and bone marrow, can affect people of all ages but is the most common type of leukemia in adults.
The research, recently published in the journal Blood Advances, tested the ability of the two drugs - apalutamide and finasteride - to treat leukemia in experimental models. They found that the drugs were effective in treating mice with AML as well as patient-derived AML cells.
K. Sandeep Prabhu, head, department of veterinary and biomedical sciences, and professor of immunology and molecular toxicology in the College of Agricultural Sciences and a lead author on the paper, said the drugs work by inhibiting the pathway that is activated by dihydrotestosterone - an androgen hormone more potent than testosterone.
"Although androgen signaling is well-studied in prostate cancer and has successfully guided molecular-targeted therapies, its role in AML has been under-explored," Prabhu said. "In our study, these two drugs effectively suppressed AML progression in both male and female mice, highlighting its potential for new uses for the drugs."
Robert Paulson, professor of veterinary and biomedical sciences at Penn State and co-author on the paper, said the findings offer a promising new direction for AML treatment.
"AML is a tough disease," Paulson said. "Many patients relapse and the treatments haven't really changed. It is exciting to identify a new target, the androgen receptor, where there are already FDA approved drugs. The next steps will be using these drugs in clinical trial. We are excited to see what happens in patients."
Before the current study, the connection between leukemia and androgen receptors was previously unknown, according to the researchers, who have also registered a patent for using the androgen receptor inhibitors to treat AML.
Fenghua Qian, a senior scientist at Regeneron who led the study as a graduate assistant at Penn State, where he earned his doctorate in pathobiology, said the discovery came about when he was working on establishing a method to develop an AML mouse model. This is a common approach for studying various disease progressions and potential therapeutic targets, Qian said. While developing the AML model, Qian found that some of the female mice failed to develop AML, but the disease was unusually aggressive in some of the male mice.
His first idea was that estrogen might be protecting the female mice against AML, Qian said, but found that mice without ovaries - and therefore no estrogen - still had a lower chance of developing AML.
"This was when I switched gears to analyzing the potential role of androgen," Qian said. "I started to analyze female and male donor leukemic cells, as well as female and male recipients, and was able to demonstrate that androgen receptors are highly expressed in female donor leukemic cells. And the interaction of androgen and androgen receptors could potentially be a target for the treatment of leukemia."
In the current study, the researchers found that in male mice, high dihydrotestosterone promoted the development of AML despite low androgen receptors in their leukemia cells. Meanwhile, even though female mice had low dihydrotestosterone, this was offset by high levels of androgen receptors in their leukemia cells. The team found this held true for AML cells transplanted from human patients into the mouse model, as well.
Finasteride slowed AML progression by inhibiting dihydrotestosterone, the researchers said, while apalutamide worked by targeting a slightly different pathway in androgen receptor activity.
Qian said that currently, treatments for leukemia include chemotherapy, radiotherapy and stem cell transplantation along with emerging immunotherapies. However, androgen receptors have never been considered as a target.
"This study provides a novel targetable pathway for leukemia patients," he said. "Not only can androgen receptors be the direct target, but also its upstream and downstream interactors. It could also potentially benefit those patients who are resistant to traditional treatments."
The researchers added that while the study was promising, the drugs will still need additional testing, including in humans. Qian said he expects to test both drugs in clinical trials on leukemia patients with strict inclusion criteria such as increased androgen receptor expression in leukemic cells.
Prabhu said the study is a good example of how attention to detail can lead to new, important scientific discoveries.
"Qian was so vigilant, and he was the one who saw that there was a problem here," Prabhu said. "He had the presence of mind as well as a close observation of what he was seeing, and he managed to catch this. And that is what changed everything."
Deborpita Sarkar, graduate assistant at Penn State; Brooke Arner, undergraduate student at Penn State; Vanessa Peduzzi, Temple University; Yuting Bai, research technician at Penn State; Baiye Ruan, Regeneron Pharmaceuticals; Bei Jia, assistant research professor at Penn State; and Hong Zheng, professor and staff physician at Penn State Hershey, also co-authored the paper.
The American Institute for Cancer Research, National Institutes of Health, and U.S. Department of Agriculture's National Institute of Food and Agriculture helped support this research.
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