The the Technology Review: "A specialized nanoparticle filled with an RNA-based cancer therapy can successfully target human cancer cells and silence the target gene, according to results from an early clinical trial. The research [is] the first to demonstrate this type of tissue targeting and gene-silencing in humans. ... Since the discovery 12 years ago that double-stranded RNA can silence genes in a targeted manner, researchers have hailed the technique, known as RNA interference (RNAi), as a powerful approach to creating new and potent medicines. ... The trouble is, getting the therapeutic RNA to the right cells has proven to be a sticky challenge. When injected on their own, so-called small interfering RNAs (siRNAs) are quickly filtered out by the kidneys, and researchers have struggled to design particles that carry their contents to target cells with enough specificity, or that don't cause toxicity or elicit an immune reaction from the body. ... The new trial [is] the first to administer the RNA therapy systemically into the body, using specialized particles that protect the RNA while in the bloodstream and target it directly to cancer cells. ... 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."