{"id":135,"date":"2011-08-31T17:43:37","date_gmt":"2011-08-31T17:43:37","guid":{"rendered":"https:\/\/blogs.nature.com\/spoonful\/2011\/08\/cancer-killing-viruses-zero-in-on-tumor-cells.html"},"modified":"2011-08-31T17:43:37","modified_gmt":"2011-08-31T17:43:37","slug":"cancerkilling_viruses_zero_in","status":"publish","type":"post","link":"https:\/\/blogs.nature.com\/spoonful\/2011\/08\/cancerkilling_viruses_zero_in.html","title":{"rendered":"Cancer-killing viruses zero in on tumor cells"},"content":{"rendered":"

Doctors have known for nearly a century that when cancer patients catch a virus the infection can help to beat back their tumors. But developing therapies hinged upon this idea has not been easy. Researchers first have to engineer the viruses to discriminately attack only the cancer cells. Then the virus has to actually reach those tumor cells and kill them. Despite these barriers, research has plunged forward, with several viruses in late-stage clinical development (see \u2018Recent deal highlights hopes for cancer-killing viruses<\/a>\u2019).<\/p>\n

Clinicians typically inject these so-called \u2018oncolytic viruses<\/a>\u2019 into the tumors themselves using a syringe. But this delivery approach lacks precision. Thus, researchers have long sought cancer-killing viruses that can home in on cancerous cells on their own while leaving healthy tissue intact. (Scientists are similarly trying to develop bacteria that serve the same purpose, as we reported<\/a> in March.) Now, for the first time, researchers have engineered a virus that, when injected into people\u2019s bloodstreams, preferentially attacks only cancer cells.<\/p>\n

\u201cThis data set really puts oncolytic virotherapy on the map as a very, very promising experimental approach to the systemic treatment of metastatic cancer,\u201d Stephen Russell<\/a>, director of the molecular medicine program at the Mayo Clinic in Rochester, Minnesota who was not involved with the research, wrote in an email.<\/p>\n


\nIn the new study, a team led by John Bell<\/a>, a cancer researcher at Ottawa Hospital Research Institute in Canada, and David Kirn<\/a>, president and CEO of San Francisco-based Jennerex Pharmaceuticals, engineered a poxvirus to target cancer cells and, once inside the tumor, activate the immune system as well as express a reporter gene. Their poxvirus, dubbed JX-594, can only replicate in the presence of thymidine kinase, an enzyme downstream of a growth signaling pathway often activated in tumors, so it leaves normal cells alone while proliferating inside cancer cells.<\/p>\n

In a phase 1, proof-of-concept study<\/a>, the researchers injected the modified virus into the bloodstreams of 23 people with a variety of metastatic cancers \u2014 lung, colon, skin, thyroid and ovarian, to name a few \u2014 and performed biopsies on cancerous and noncancerous tissue eight days later. Reporting today<\/a> in Nature<\/em>, the researchers found that those study subjects given lower doses of the treatment had no virus in their tumors. But seven of the eight participants given higher doses had viral particles in just the cancerous tissue, providing evidence that the virus gets to the tissue and only infects the cancer.<\/p>\n

For their safety trial, Bell and his colleagues used fairly benign genes to prove that the virus made its way into the tumors. But in the future, the researchers plan to load up the vector with drug converting enzymes, immune stimulants or bacterial toxins to help kill off tumor cells. (Beyond its intravenous use, Jennerex is running randomized clinical trials testing tumor-injected JX-594 in people with liver cancer<\/a>, too.)<\/p>\n

\u201cThe exciting piece about it is that you can get a virus to go in there and to replicate and to produce as a gene-delivery vehicle,\u201d says Timothy Cripe<\/a>, co-medical director of clinical and translational research at Cincinnati\u2019s Children\u2019s Hospital, who was not involved in the study.<\/p>\n

The seven patients that reacted to the virus did see their cancer stabilize \u2014 although it\u2019s a little early to make any sweeping conclusions about its efficacy. \u201cIt\u2019s a small trial with a small number of patients so I wouldn\u2019t want to sell the bank on that data,\u201d says Bell. \u201cBut it\u2019s a hint that we\u2019re seeing real biologic activity.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

Doctors have known for nearly a century that when cancer patients catch a virus the infection can help to beat back their tumors. But developing therapies hinged upon this idea has not been easy. Researchers first have to engineer the viruses to discriminately attack only the cancer cells. Then the virus has to actually reach those tumor cells and kill them. Despite these barriers, research has plunged forward, with several viruses in late-stage clinical development (see \u2018Recent deal highlights hopes for cancer-killing viruses\u2019).  Read more<\/a> Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":128,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"class_list":["post-135","post","type-post","status-publish","format-standard","hentry","category-cancer"],"_links":{"self":[{"href":"https:\/\/blogs.nature.com\/spoonful\/wp-json\/wp\/v2\/posts\/135","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.nature.com\/spoonful\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.nature.com\/spoonful\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.nature.com\/spoonful\/wp-json\/wp\/v2\/users\/128"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.nature.com\/spoonful\/wp-json\/wp\/v2\/comments?post=135"}],"version-history":[{"count":0,"href":"https:\/\/blogs.nature.com\/spoonful\/wp-json\/wp\/v2\/posts\/135\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.nature.com\/spoonful\/wp-json\/wp\/v2\/media?parent=135"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.nature.com\/spoonful\/wp-json\/wp\/v2\/categories?post=135"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.nature.com\/spoonful\/wp-json\/wp\/v2\/tags?post=135"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}