Plexxikon's Experimental Cancer Drug Eases Pain From PVNS

An experimental cancer drug developed by Plexxikon, a unit of Daiichi Sankyo, has been shown to relieve pain caused by pigmented villonodular synovitis (PVNS). The drug is called PLX3397.

PVNS is a rare joint disease that is caused by a genetic mutation. The disease causes cells to overproduce a molecule named colony stimulating factor 1. The overproduction of that molecule causes immune cells to build up in the soft tissue of a patient’s joints, which destroys the tissues over long periods of time. The disease is similar to cancer in that there is an overproduction of cells, but unlike many cancers, it does not spread to other parts of the body. The experimental drug PLX3397 works by blocking the gene glitch that causes the colony stimulating factor 1 overproduction.

Researchers at the Memorial Sloan-Kettering Cancer Center in New York treated 14 patients with PVNS with the Plexxikon drug. The disease is reported to afflict 600 patients in the United States. The results of the study have been called “promising,” as 11 of the 14 patients had at least a partial response to the drug. Those patients saw their tumor shrink by 61 percent. The other three patients had a stable disease. Dr. William Tap, who led the study, says, “These results are a shining example of how patients can experience a meaningful clinical benefit when we are able to match the right treatment with the right target,” said Tap. Tap went on to say that patients enrolled in the study described a decrease in pain and swelling as the study wore on.

The researchers have planned a late-stage study of PLX3397 in order to determine if the drug would be successful treating larger populations.

The president of the American Society of Clinical Oncology, Clifford Hudis, says that the study, which aims to better match patients’ tumors with targeted drugs, is a window into the future of medicine.