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Study: Virus eliminates mesothelioma tumors in lab mice


Mice infected with pleural mesothelioma showed no sign of the disease two weeks after being treated with a genetically engineered virus, according to a new study by an international team of cancer researchers.


Oncolytic viruses are genetically programmed to replicate within cancer cells and kill them, either by inducing a process called cell lysis or by delivering anticancer compounds directly to tumors. Previous studies have shown that oncolytic viruses are safe and can be effective against tumors that are resistant to chemotherapy or radiotherapy.


In the October issue of Molecular Cancer Therapeutics, researchers at three centers — Memorial Sloan-Kettering Cancer Center, Mount Sinai School of Medicine and the Medical University Vienna — describe testing for the first time a recombinant Newcastle disease virus, NDV, on several mesothelioma cell lines injected into lab mice.


Three of five mice who received a single treatment one day after being infected with the cancer survived the four-month follow-up period, with no signs of tumor found in a post-mortem analysis of tissue. Using bioluminescent imaging, the researchers observed that tumors in this group of mice were eradicated within 13 days of treatment.


Mice who received multiple treatments — four injections of NDV every other day — fared even better. The bioluminescent tumor signal was gone in all animals within 12 days, with no histologic evidence of tumors found in the post-mortem; 80 percent of the mice in this group survived 90 days of follow-up.


Even mice whose treatment was delayed 10 days after being injected with mesothelioma cells showed improvement. Two mice showed a significant decrease of tumor signal within 10 days; no tumor was evident in one animal 30 days after the start of treatment.


Meanwhile, 10 mice in the control group all showed signs of heavy tumor burden and were sacrificed after 24 days.


“Overall, multiple-dose treatment with [NDV] showed significant survival benefit when compared with single treatment,” the researchers report “Interestingly, comparing the different treatment groups according to treatment start time showed no significant difference in survival.”


The study could hold promise for the safe treatment of pleural mesothelioma in humans, the researchers say. The deadly disease, caused by asbestos exposure, is often diagnosed too late for surgery, and it has proven resistant to the conventional drugs and radiation therapy.


About 2,000 deaths are caused by mesothelioma in the United States every year. Asbestos use has been restricted in the U.S. since the 1970s, but because the disease is usually not diagnosed until 30-50 years after asbestos exposure, experts expect the annual incidence will continue to increase through the next decade.