Science Translational Medicine: reovirus for oncolytic viral therapy

里奧病毒 (reovirus) 療法治癌有望 !!   鉅亨網新聞中心　(來源：中廣新聞網)　2012-06-14科學家研究發現，一種常見的無害病毒，可以有效殺死癌症幹細胞，還會刺激人體的免疫系統，達到對抗癌症的效果。這一發現被認為是癌症治療法的一大進步。這種里奧病毒（reovirus），常會存在呼吸道跟腸道之中，加拿大的研究人員發現，這種病毒在正常細胞中並不會複製，但是在癌細胞中卻會快速複製，造成細胞破裂並壞死，病毒並能蔓延道其他癌細胞。而這種病毒能黏著在紅血球上，躲過人體自然的免疫系統。 目前癌症化療可以殺死癌細胞，但是卻無法殺死癌症幹細胞，這也是為什麼有些癌症容易復發的原因。研究人員認為，應該可以利用這一種病毒，把病毒注射到血液中，使病毒有治療多種癌症的潛力。

Hitchhiking Virus Escapes Immune System to Fight Cancer  Jun 19, 2012 A new study published in the Science Translational Medicine journal reveals the discovery of how the reovirus, the virus associated with the common cold, may one day be used as treatment against certain cancers. The reovirus is an oncolytic virus: a virus that attacks cancer cells while leaving healthy cells unscathed. Prior studies have well documented the reovirus’ anti-cancer effects. The virus attacks cancer cells in two ways; it directly infects cancerous cells, killing them the way other viruses destroy healthy cells, and it stimulates the immune system to kill off remaining cancer cells—almost like a vaccine. Oncolytic viral therapy has been researched for some time now and shows promise in treating certain cancers in early-phase clinical trials. However, getting the oncolytic viruses to the cancer cells has proven challenging. One problem is that the viruses are attacked by our immune systems as soon as they enter the bloodstream, so they need to be directly injected into the tumors. When tumors are deep within the body, direct delivery of the viruses may not be possible. This limits its therapeutic use to a specific subset of cancers. The reovirus, as researchers from Leeds University and the Institute of Cancer Research found, surpasses these barriers. The researchers discovered that the reovirus is able to avoid the body’s immune system by “hitching” rides within blood cells, essentially hiding from antibodies that would normally destroy them, until they reach cancer cells. This discovery of the reovirus’ ability to evade antibodies makes its use in cancer therapies potentially effective for a wider range of cancers.? The study included ten patients with advanced cancers that had spread to their livers. Study participants were given doses of the reovirus treatment in the weeks leading up to a surgery intended to remove the cancerous tissues. In post- surgery examinations of the removed tissues, the researchers found active reoviruses in cancer tissues, but not in normal liver tissue. This finding confirmed that the reovirus had survived the bodies immune response long enough to reach the cancer cells. More importantly, the reovirus was able to reach the cancer cells deep in the liver despite being injected into the blood stream. The outcome of the study suggests that the reovirus may be able to reach and treat a wider range of cancers than originally thought. It also shows that the reovirus’ preference for attacking cancer cells may result in fewer side effects for patients. The study team hopes the discovery will encourage the use of oncolytic viral therapies in cancer trials and treatment.   Written by David Bui