Fighting cancer is currently a messy war. Modern chemotherapies attack tumors with the equivalent of a machinegun approach: cover the area widely with deadly fire and hope to destroy the tumor with a minimum of collateral damage. Doctors have long sought a way to precisely target tumors with their chemical therapies. Now researchers may have found it in a nanoparticle laced with a cancer-combating drug.

Omid Farokhzad of Harvard University, Robert Langer of the Massachusetts Institute of Technology and their colleagues created the nanoparticle out of a previously FDA-approved polymer that has been shown to dissolve inside cells. This nanoparticle--one-thousandth the width of a human hair--carries a load of a lethal chemical: docetaxel, which is currently used to treat prostate cancer. In addition, the scientists studded the outside of the particle with so-called aptamers--tiny proteins that link directly to cancer cells while avoiding regular cells. Finally, they equipped the nanoparticles with polyethylene glycol molecules, which allow them to resist the internal defenses of a tumor cell.

In both laboratory dishes and mice with human prostate cancers, the nanoparticles proved extremely effective. "A single injection of our nanoparticles completely eradicated the tumors in five of the seven treated animals and the remaining animals had significant tumor reduction compared to the controls," Farokhzad says.

In fact, the mice that received the complete nanomedicine package had smaller tumors and longer lifespans than their counterparts injected with saline, nanoparticles without the drug, the drug alone, and nanoparticles with the drug but without the targeting aptamers. The research appears online this week in the Proceedings of the National Academies of Science.

Further tests will be needed to ensure that the nanoparticle is safe in animals and, eventually, in humans afflicted with prostate cancer. The technique may even find wider application. "[Researchers] can put different things inside or other things on the outside of the nanoparticles. In fact, this technology could be applied to almost any disease," Farokhzad argues. And that may prove the advent of a little more rifle-like precision in the war on cancer.