Nov. 14, 2014
By Medical Discovery News
Today, the words measles, mumps, and rubella (MMR) sound foreign to children. But before a vaccine prevented these three viruses, three to four million American children contracted measles, a possibly serious respiratory disease that can lead to pneumonia, and 40 percent of them required hospitalization each year. The vaccine is 95 percent effective, and in 2012 only 55 cases of measles were reported in the U.S., mostly due to traveling abroad.
Now, a study has demonstrated that the measles virus might actually be a useful treatment, for cancer. It sounds strange – using one serious disease to fight off another – but scientists have found a way to direct the cell-killing powers of viruses to cancer cells. The use of viruses to destroy cancer cells, called oncolytic virotherapy, has been investigated since the 1950s. Other viruses such as herpes and pox have also been used as treatments for other diseases, but the measles virus’s potential to fight cancer is very promising.
The Mayo Clinic in Rochester, Minn., utilized a modified measles virus called MV-NIS. To create this version of the virus, scientists inserted a gene for the protein sodium iodide symporter. This protein helps concentrate iodine in the human thyroid. Therefore, when this genetically engineered measles virus infects tumor cells and replicates, it produces this protein that binds to and concentrates iodine.
This is important because researchers can then inject a patient with radioactive iodine, which shows up on a 3-D imaging technique called SPECT-CT. Using the images, they can observe where cancer cells are at any site in the body. The engineered virus attacks and kills tumor cells but leaves normal cells alone. This works because the virus detects a protein called CD46 on the surface of a cancer cell, then enters the cell and replicates itself, killing the cancer cell.
The first clinical trial consisted of only two myeloma patients who had exhausted all other treatment options. Each patient was injected with one ultra-high dose (the equivalent of 100 million doses of the vaccine) of MV-NIS intravenously.
The results were astounding. The number of myeloma cells in both patients dramatically declined. One patient became cancer free and has remained so, while the other patient’s life was prolonged during this late-stage cancer. Advanced myeloma affects plasma cells, a type of white blood cell that produces antibodies, and is difficult to treat so this result is unprecedented.
MV-NIS is not yet ready for widespread use, but scientists will continue to build off this newfound virotherapy. Already, they plan to experiment with using another radioactive iodine molecules to additionally attack the tumor cells, uniting virotherapy with localized radiation treatment for myeloma. Stay tuned for updates on this promising discovery.
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Pamela K. Bond 