By Janet Fang
Posting in Cancer
Cancer drugs studded with tiny diamonds promise multifaceted benefits for drug delivery. They're more effective and safe, and they help overcome resistance to chemotherapy.
By studding a common breast cancer drug with nanodiamonds, researchers can increase the effectiveness of the treatment and reduce harmful side effects – making it easier to up doses without ramping up toxicity. Bada bling!
One of the major challenges in anticancer chemotherapy is when tumor cells develop a way to pump drugs right back out. But when bound to a nanoparticle, the combination would be too large for the pump and tumors would have a hard time evolving resistance, reasoned study coauthor Dean Ho of Northwestern University.
These nanodiamonds (pictured above) are tiny carbon particles with an octahedral structure. Their surface chemistry makes their value to drug delivery multifaceted. ScienceNOW reports:
They're nontoxic, and the body's immune system doesn't attack them. They can bind tightly to a variety of molecules and deliver them right into a tumor. And because they are only 2 to 8 nanometers in diameter, they are easy for the kidneys to clear from the body before they block up blood vessels, a long-standing problem in nanoparticle therapy.
And they combat chemotherapy drug resistance, which causes treatment failure in more than 90% of malignant cancers. This ‘chemoresistance’ emerges when drugs that must be given at high dosages to work are kicked out before they get the chance to do their jobs.
Ho’s team attached nanodiamonds to molecules that make up doxorubicin, a common breast cancer drug. They injected lethal doses of doxorubicin with nanodiamonds into mice with liver and breast cancers. But as ScienceNOW explains, the drug cargo stayed on the diamond until it reached the tumor, so it didn't damage cells elsewhere in the body. The mice survived and didn’t even lose weight.
They found that the nanodiamond-studded drugs were less toxic and worked better than the drugs alone. They shrank the tumors (pictured, nanodiamonds in green, cancer cells in orange), and they stayed in the blood 10 times longer.
That means a smaller amount of the toxic drug is needed, reducing side effects and limiting unnecessary exposure to healthy tissues.
Also, the nanodiamond-decorated drugs had no negative effect on the white blood cell count. That's important because when those counts drop below a certain level, treatment is stopped to prevent complications.
And surprisingly, nanodiamonds are cheap. They’re formed in explosions, such as in coal mining or oil refinery operations, and are even thought to result from meteorite landings [AFP]. "What is neat about it is it is almost like a waste material, it is going to be produced anyways," Ho says. So instead of throwing it out, researchers can use simple processes to refine this byproduct.
"Nanodiamonds possess numerous hallmarks of an ideal drug delivery system and are promising platforms for advancing cancer therapy,” says study author Edward Chow of the University of California, San Francisco. The team plans to try nanodiamond therapy in larger animals like rabbits.
The study was published in Science Translational Medicine yesterday.
Mar 10, 2011