DirkDaring writes "It's been promised for years: that nanoparticles offer a treatment to many forms of cancer. Today, an important first step has been announced. In a new human trial, nanoparticles carrying RNA have successfully reached cancer cells and silenced the target gene. 'The researchers developed a nanoparticle carrying a molecular marker that binds to the surface of cancer cells, triggering the cells to absorb it. The siRNA carried within the particle was designed to silence a gene called ribonucleotide reductase M2 (RRM2), which regulates DNA synthesis and repair and is known to be an anticancer target. Because it was the first trial using targeted RNAi delivery for cancer, says Mark Davis, a professor of chemical engineering at Caltech and the study's lead author, "we wanted to choose a gene that was suspected to be hugely upregulated in a broad spectrum of cancers" in order to increase the likelihood of being able to observe the novel therapy's effect. The researchers analyzed biopsy samples from three melanoma patients in the trial who had received different doses of the therapy. They tracked the particles in the different samples, finding that the amounts they could see in the tumor cells correlated with the doses the patients received.'"