Gems clear drug resistance hurdle

NORTHWESTERN (US) — Nanodiamonds may be the answer to chemotherapy drug resistance which contributes to treatment failure in more than 90 percent of metastatic cancers.

Each surface of a nanodiamond possesses functional groups that allow a wide spectrum of compounds to be attached to it, including chemotherapy agents.

In studies of liver and breast cancer models, a normally lethal amount of a chemotherapy drug when bound to nanodiamonds significantly reduces the size of tumors in mice.

Survival rates also increased and no toxic effects on tissues and organs were observed.

“Our results show the nanodiamond’s enormous translational potential towards significantly improving the efficacy of drug-resistant cancer treatment and simultaneously improving safety,” says Dean Ho, associate professor of biomedical engineering and mechanical engineering at Northwestern University.

“These are critical benefits. We chose to study these chemo-resistant cancers because they remain one of the biggest barriers to treating cancer and improving patient survival.”

The research, the first to demonstrate the significance and translational potential of nanodiamonds in the treatment of chemotherapy-resistant cancers, is published in the journal Science Translational Medicine.

Researchers took nanodiamonds and reversibly bound the common chemotherapy drug doxorubicin to them using a scalable synthesis process, which enhances sustained drug release.

Using used mouse models with liver and breast cancers—where drugs are able to get inside the tumors but are kicked right back out because of an innate response to expel them, Ho and colleagues treated one group of animals with the doxorubicin-nanodiamond complexes and another group with the drug alone.

In those treated with the nanodiamond complexes, the chemotherapeutic remained in circulation up to 10 times longer than those treated with the drug alone.

Also, the drug itself was retained within both types of tumors for a significantly longer period of time.

Such a high retention rate means a smaller amount of the very toxic drug would need to be administered, thus reducing side effects.

The drug-nanodiamond complexes had no negative effect on the white blood cell count, especially important for cancer treatment: if the white blood cell count drops below a certain level, treatment is stopped due to the risk of major complications.

“Nanodiamonds have excellent biocompatibility, and the process of formulating nanodiamond-drug complexes is very inexpensive,” says Edward K. Chow, a postdoctoral fellow at the University of California, San Francisco, and first author of the paper.

Each surface of a nanodiamond allows compounds to be attached, including chemotherapy agents. (Credit: Northwestern U.)

“Nanodiamonds possess numerous hallmarks of an ideal drug delivery system and are promising platforms for advancing cancer therapy.”

The National Institutes of Health, the National Science Foundation, the Wallace H. Coulter Foundation, the V Foundation for Cancer Research, the G.W. Hooper Foundation and the American Cancer Society supported the research.

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