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Biotech / Medical : Alnylam Pharmaceuticals, Inc. (ALNY) -- Ignore unavailable to you. Want to Upgrade?

To: tom pope who wrote (93)	9/7/2006 2:08:26 PM
From: dr.praveen	Read Replies (1) \| Respond to of 166

Gene genius: Are scientists closing in on the holy grail? Scientists claim they are near to finding a therapy that could cure Aids and cancer. So how real is this new medical dawn? By Steve Connor Published: 06 September 2006 Imagine a treatment for cancer, a cure for infectious diseases such as Aids, or maybe an effective therapy for blindness or a lethal brain disease. Now imagine that one breakthrough is responsible for all this medical hope. The breakthrough is RNA interference (RNAi), which some scientists believe could be the biggest advance in healthcare since the development of antibiotics. There is barely an area of medicine that may not be touched by future advances in RNAi - a technique for switching off genes selectively and precisely. RNAi was only formally recognised in 1998 but over the past few years it has emerged as one of the hottest developments in the field of medical science. Yet another international conference on RNAi (titled RNAi Europe) is planned at the end of September in Prague. The sheer range of illnesses and disorders that RNAi might address is unprecedented. RNAi promises to become a radically new form of treatment for an entire spectrum of illnesses, whether they result from an infectious attack from the outside environment or an inner malfunction of the body's vital genes. In 2002, the journal Science voted RNAi its top breakthrough of the year and biotechnology companies are pumping millions into its development. But sceptics have warned that medical science is littered with false dawns. RNAi, they warn, might fails the ultimate clinical tests of safety and efficacy. RNA stands for ribonucleic acid, the less well known cousin of deoxyribonucleic acid (DNA), the molecule of inheritance. RNAi works by interfering with the normal activity of genes. Scientists - to their amazement - discovered that short molecules of RNA can block or "silence" the activity of a particular gene, working like the dimmer switch of an electric light. RNAi lowers or halts the production of the proteins produced from the genes on the DNA of a chromosome. Scientists were surprised to discover that RNAi seems to be a universal mechanism used by all living organisms for controlling gene activity. Everything from petunia plants and fungi to fruit flies, nematode worms and mice use RNAi to switch off their genes. Four years ago, scientists found that human cells also use RNAi. It may have evolved as a protection against viruses by targeting and switching off vital viral genes - a sort of micro immune system. Discovering that RNAi works inside human cells led to the idea of exploiting the phenomenon therapeutically. Could potentially harmful genes - either the body's own mutations or viral invaders - be switched off using RNAi itself? If so, virologists could design a new type of anti-viral drug that cripples the ability of an infectious agent to attack human cells. Cancer specialists could develop RNAi as a therapy to switch off the genes of a cancer cell, forcing it to commit suicide while leaving healthy, cells unaffected. Meanwhile, geneticists believed they might be able to rid the body of the harmful mutations behind many inherited disorders. Many scientists were ecstatic about the prospect for treating human diseases. "The broader science of RNAi is spectacular," Professor Phillip Sharp, a Nobel laureate at the Massachusetts Institute of Technology, said in 2003. Three years later, Professor Sharp remains in ebullient mood. "The advances in the field have exceeded expectations," he says.The most advanced clinical trials of RNAi are being carried out in America by two biotechnology companies, Acuity and Sirna. Both involve patients suffering from macular degeneration, when the abnormal growth of blood vessels in the eye causes visual impairment and, eventually, blindness. Both companies have developed RNAi therapies that target the human gene that makes a protein called vascular endothelial growth factor. This growth factor stimulates the growth of the blood vessels that cause the disorder. The aim of the RNAi therapy is to silence this gene, curbing the further invasion of blood vessels. Scientists believe that macular degeneration is a good disorder to test RNAi because the eye is a relatively closed system easily treated with direct injections. Acuity has already completed phase I clinical trials, which test for toxicity and general tolerance, and is preparing for larger, phase-II clinical trials. A spokesman for Acuity said that results of the phase-II trial are expected soon. But it is only after the much larger phase-III clinical trials - involving hundreds or possibly thousands of patients - that doctors will be able to say whether RNAi is any good for macular degeneration. One of the beauties of the RNAi approach is that it is comparatively easy for scientists to make RNAi drugs. Effectively they are just small strands of the RNA molecule, which can be synthesised by machine. Each strand is about 22 units long - tiny compared with the 3 billion units that make up the entire DNA molecule of the human genome. Each of these "short-interfering" strands of RNA can be targeted to work against a particular gene, which is one of the reasons why the technique is so attractive. There is less chance of cross-reactions or unintended side effects. However, one of the biggest problems with RNAi is "delivery": how do you make sure that the synthetic RNA molecules get inside the cells that matter?