Researchers have discovered that a rabbit virus can deliver a one-two punch, killing some kinds of cancer cells while eliminating a common and dangerous complication of bone marrow transplants. Their findings, from laboratory testing on human cells, were published in Blood (2015; doi:10.1182/blood-2014-07-587329).

For patients with blood cancers such as leukemia and multiple myeloma, a bone marrow transplant can be both curative and perilous. It replenishes marrow lost to disease or chemotherapy but raises the risk that newly transplanted white blood cells will attack the recipient’s body.

Now researchers say the myxoma virus, found in rabbits, can do double duty. It can quell the unwanted side effects of a bone marrow transplant and destroy cancer cells.

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The virus could be especially helpful to patients who have recurring cancer but cannot find a suitable bone marrow donor, said lead investigator Christopher R. Cogle, MD, an associate professor in the University of Florida College of Medicine division of hematology and oncology.

Bone marrow transplants from partially matched donors carry an estimated 80% risk of graft-versus-host disease, and the myxoma treatment would address that, Cogle said.

The myxoma virus also could improve bone marrow transplant options among African Americans and the elderly. Those patients are less likely to find fully matched bone marrow donors, which raises the risk of graft-versus-host disease, according to Cogle.

“Myxoma is one of the best strategies because it is effective but doesn’t affect normal stem cells,” he said.

During laboratory testing on human cells, the process worked this way: The myxoma virus is attached to a T-cell, a type of white blood cell. The virus-laden white blood cells can then be delivered as part of a bone marrow transplant from a donor. That’s when the virus gets activated and goes to work.

The virus blocks graft-versus-host disease, a complication of bone marrow transplants that can cause problems including skin rash, shortness of breath, abdominal pain, jaundice, and muscle weakness. In severe cases, these complications can be fatal. The white blood cells then deliver the myxoma virus to cancer cells, which are killed off by the virus.

After successfully testing the process with human cells, researchers are now studying its effectiveness in a mouse model. This is the first time that a virus has been shown to simultaneously prevent graft-versus-host disease and kill cancer cells in the laboratory.

The research team hopes to begin a clinical trial within a year.