Mount Sinai study finds childhood leukemia aggressiveness depends on timing of genetic mutation

New York, NY (December 8, 2025) – A team of researchers at the Icahn School of Medicine at Mount Sinai has uncovered why children with the same leukemia-causing gene mutation can have dramatically different outcomes: it depends on when in development the mutation first occurs.

The study, led by Elvin Wagenblast, PhD, Assistant Professor of Oncological Sciences, and Pediatrics, at the Icahn School of Medicine at Mount Sinai, was published this week in Cancer Discovery, a journal of the American Association for Cancer Research. It shows that leukemia beginning before birth is often more aggressive, grows faster, and is harder to treat. This adds a missing dimension to precision medicine for childhood leukemia.

Dr. Wagenblast and his team at the Wagenblast Lab set out to answer a central question about how a normal blood stem cell can become cancerous. They applied cutting-edge CRISPR/Cas9 genome-editing approaches in human primary blood stem cells to model different developmental stages of acute myeloid leukemia, one of the most aggressive types of blood cancer.

Using CRISPR technology, the team induced the NUP98::NSD1 fusion oncoprotein, a cancer-promoting protein created when two genes abnormally fuse, into human blood stem cells from multiple developmental stages, ranging from prenatal to postnatal, adolescence, and adulthood. This approach created the first humanized experimental model that tracks how the same mutation behaves differently depending on when in life it arises.

The results were striking: stem cells produced during prenatal development transformed easily into leukemia, creating a highly aggressive and more primitive form of leukemia. Stem cells produced postnatally became increasingly resistant to transformation and required additional mutations to become cancerous. Prenatal-origin leukemia stem cells, which are abnormal blood stem cells that arise before birth and can cause certain childhood leukemias, were more dormant (quiescent) and relied heavily on certain energy sources specific to the cancer state, which were not seen in the leukemias that originated later in life. Although these prenatal leukemia stem cells were more dormant, this quiescent state makes them harder to eliminate with standard treatments, helping explain why prenatal-origin leukemias behave more aggressively, despite identical genetics.

By analyzing single-cell gene expression data from their models, the investigators identified a prenatal gene signature that predicts whether a child’s leukemia likely began before birth. In patients, this signature strongly correlated with significantly worse clinical outcomes.

“This work tells us that age matters at the cellular level,” said Dr. Wagenblast. “The same mutation behaves very differently depending on when it happens. Understanding this gives us a new way to identify the highest-risk patients and to tailor therapies that go beyond standard genetic classifications.”

The team tested therapies against the most aggressive leukemia stem cells and discovered that these cells were especially vulnerable to venetoclax, a Food and Drug Administration-approved drug already used in the clinic. Venetoclax-based combinations, including with standard chemotherapy, significantly reduced aggressiveness in the experimental models.

“These findings give clinicians mechanistic support to use venetoclax combinations in NUP98-rearranged acute myeloid leukemia, particularly in younger patients whose disease likely started before birth,” said Dr. Wagenblast.

Understanding when leukemia begins may help doctors choose more effective therapies earlier, reducing trial-and-error approaches and preventing resistance and relapse later on.

Conceptually, the study shifts how scientists understand childhood cancer. The developmental timing of the first mutation is not a minor detail. It fundamentally shapes disease biology, treatment resistance, and relapse risk.

The research opens the door to new diagnostic tools that can identify prenatal-origin leukemias, venetoclax-based combination therapies that more precisely target vulnerable leukemia stem cells, and clinical trials that incorporate developmental timing into risk assessment.

Next, the team plans to develop therapies that more directly target the metabolic program unique to prenatal-origin leukemias, with the goal of selectively eliminating leukemia stem cells while sparing healthy blood stem cells.

The study was conducted in collaboration with Fred Hutchinson Cancer Center, Children's Hospital of Philadelphia, and Cincinnati Children’s Hospital. With funding from the National Institutes of Health and private foundations.

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About the Icahn School of Medicine at Mount Sinai
 

The Icahn School of Medicine at Mount Sinai is internationally renowned for its outstanding research, educational, and clinical care programs. It is the sole academic partner for the seven member hospitals* of the Mount Sinai Health System, one of the largest academic health systems in the United States, providing care to New York City’s large and diverse patient population.
 

The Icahn School of Medicine at Mount Sinai offers highly competitive MD, PhD, MD-PhD, and master’s degree programs, with enrollment of more than 1,200 students. It has the largest graduate medical education program in the country, with more than 2,700 clinical residents and fellows training throughout the Health System. Its Graduate School of Biomedical Sciences offers 13 degree-granting programs, conducts innovative basic and translational research, and trains more than 560 postdoctoral research fellows.
 

Ranked 11th nationwide in National Institutes of Health (NIH) funding, the Icahn School of Medicine at Mount Sinai is among the 99th percentile in research dollars per investigator according to the Association of American Medical Colleges. More than 4,500 scientists, educators, and clinicians work within and across dozens of academic departments and multidisciplinary institutes with an emphasis on translational research and therapeutics. Through Mount Sinai Innovation Partners (MSIP), the Health System facilitates the real-world application and commercialization of medical breakthroughs made at Mount Sinai.

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* Mount Sinai Health System member hospitals: The Mount Sinai Hospital; Mount Sinai Brooklyn; Mount Sinai Morningside; Mount Sinai Queens; Mount Sinai South Nassau; Mount Sinai West; and New York Eye and Ear Infirmary of Mount Sinai.