Researchers at UCSF are working on a potential new treatment for childhood leukemia. The senior author of a paper published in March in the Science Transactional Medicine details a new drug that although has not been shown to be a cure, did have a signicifant impact in lessoning the symptoms in the mouse studies currently being conducted.
The experimental drug offers insight into the cellular development of the disease, according to findings from a new UCSF study.
“Although this drug did not produce a cure, it alleviated the symptoms of leukemia as long as the treatment was continued and delayed the development of a more aggressive disease,” said senior author Benjamin Braun, MD, PhD, a pediatric cancer specialist at UCSF Benioff Children’s Hospital in a press release by the University. “Maintaining a clinical remission for as long as we can may help patients who don’t have other options, and perhaps will allow us to approach this disease as a chronic, but manageable, condition.”
The study focused on a type of leukemia called juvenile myelomonocytic leukemia, or JMML. An aggressive blood cancer usually found in very young children under the ago of 5. JMML accounts for 1 to 2 percent of all childhood leukemia cases.
The disease which develops in the bone marrow, leads to an elevated white blood cell count that interferes with bone marrow’s ability to produce healthy red blood cells. The abnormal increase in white blood cells occurs when genetic changes, or mutations, arise in the genes that encode proteins in a cellular signaling network called the Ras pathway. This network, controlled by the Ras protein, is a critical regulator of cell growth and a frequent target of cancerous mutations.
Currently, JMML is curable only through bone marrow transplantation, in which healthy blood stem cells are extracted from a matched donor and intravenously transplanted into the patient. Still, nearly half of patients relapse after undergoing a transplant, and others are not candidates for transplantation because of advanced illness or the lack of a suitable donor, Braun said.
The researchers treated mice genetically engineered to have JMML with a drug that inhibits a signaling protein called MEK. The drug, known as a MEK inhibitor, blocks just one of the many chemical pathways controlled by Ras. Although several pharmaceutical companies already are developing these drugs, this is the first time a MEK inhibitor has been piloted as a treatment for JMML.
Remarkably, within one week of starting treatment, leukemia symptoms in nearly all of the afflicted mice reversed. Specifically, mice that were treated with the MEK inhibitor produced more red blood cells and fewer white blood cells than untreated mice, and the anemia commonly associated with JMML also disappeared.
Additional co-authors include Matthew Gorman, MD, Jennifer Lauchle, MD, Wan Xing Hong, Jon Akutagawa and Kevin Shannon, MD, all with the UCSF Department of Pediatrics.
The research was supported by grants from the National Institutes of Health, the Aplastic Anemia and Myelodysplastic Syndrome Foundation, the MPD Foundation, the V Foundation for Cancer Research, the Ronald McDonald House Charities of Southern California/Couples Against Leukemia, the Jeffrey and Karen Peterson Family Foundation and the Frank A. Campini Foundation.
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