A major breakthrough in cancer research may soon make chemotherapy more effective and much safer.
Scientists at Northwestern University have redesigned an old chemotherapy drug to dissolve better, attack cancer cells more powerfully, and cause far fewer side effects.
The research team achieved this by rebuilding the drug at the molecular level using special nanostructures called spherical nucleic acids, or SNAs. These are tiny, round particles coated with strands of DNA.
The scientists managed to embed the chemotherapy drug directly into these DNA strands, turning a weak and toxic medicine into a highly targeted and efficient cancer fighter. Their results were published in the journal ACS Nano on October 29.
The researchers tested this new drug design in animals with acute myeloid leukemia (AML), a fast-growing and aggressive blood cancer that is often difficult to treat.
Compared to the standard chemotherapy version, the SNA-based version of the drug entered leukemia cells 12.5 times more easily, destroyed them up to 20,000 times more effectively, and slowed cancer growth 59 times more. Even more impressively, the treatment caused no detectable side effects in the animals.
Dr. Chad Mirkin, the senior scientist leading the project, said, “In animal models, we demonstrated that we can stop tumors in their tracks. If this translates to human patients, it could mean more effective chemotherapy, better response rates, and fewer side effects.”
Mirkin is a leading expert in nanomedicine and serves as the George B. Rathmann Professor at Northwestern University.
He also directs the International Institute for Nanotechnology. His team’s work focuses on creating new ways to deliver medicine more precisely and safely through the use of nanotechnology—science on a microscopic scale measured in billionths of a meter.
For this study, Mirkin’s team focused on improving a classic chemotherapy drug called 5-fluorouracil (5-Fu). Although 5-Fu has been used for decades to fight cancer, it is known for causing severe side effects such as nausea, fatigue, and heart problems.
This happens because the drug attacks both cancerous and healthy cells. Another problem is that it does not dissolve well in the body, which means only a small portion actually reaches the cancer cells.
Mirkin explained that this poor solubility was a key challenge. “A lot of chemotherapy drugs are not only toxic but also poorly soluble. That means the body can’t use most of it,” he said. His team’s solution was to rebuild the drug in a new, more water-friendly form using spherical nucleic acids.
SNAs are tiny globes surrounded by dense layers of DNA or RNA. Cells recognize these structures and pull them inside naturally.
Mirkin’s team took advantage of this property by chemically attaching the chemotherapy molecules to the DNA shell, which helps the drug enter cancer cells more efficiently. Once inside the cells, enzymes break down the DNA strands and release the active drug exactly where it’s needed.
In mice, this new SNA-based drug nearly wiped out leukemia cells in the blood and spleen and greatly extended survival. Because the treatment specifically targeted leukemia cells, healthy cells remained unharmed.
“Today’s chemotherapy drugs kill everything they encounter,” Mirkin said. “Our nanomedicine focuses on the right cells and delivers a higher, more precise dose where it’s needed most.”
The next step for the researchers is to test this therapy in larger animal models before moving to human trials. They hope this approach will be supported by the National Cancer Institute and other medical research organizations to bring the treatment closer to real-world use.
In reviewing this study, experts say it represents a major leap in cancer therapy. By redesigning an old drug at the nanoscale, scientists have shown how chemistry and engineering can work together to make medicine smarter and safer.
The SNA design solves two key problems—poor solubility and non-specific toxicity—that have long limited chemotherapy’s effectiveness. If the same results are achieved in human patients, this innovation could change how cancer is treated, offering stronger results with fewer painful side effects.
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The study is published in ACS Nano.
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