Oncologist-approved cancer information from the American Society of Clinical Oncology
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In the Future, Patients with a Rare Neoplastic Joint Disease May Have a New Treatment Option

ASCO Annual Meeting
May 14, 2014

Early-stage research suggests that a new targeted drug, PLX3397, could become a treatment option for people with a neoplastic joint disorder called pigmented villonodular synovitis (PVNS). PVNS is a rare joint condition that usually affects the hip or knee, causing tumors to form in these joints that destroy joint tissue and cause severe, life-changing symptoms. PVNS is a type of uncontrollable cell growth, similar to a cancer, but it is not considered a cancer because it usually does not spread to other parts of the body.

PVNS is usually well-managed with surgery, but the disease comes back in some patients. When the disease recurs, more surgery is needed, often including a joint replacement, and the disease will eventually worsen so much that surgery can no longer control it. PLX3397 is a targeted therapy that could be an option for patients who have the disease worsen. A targeted therapy is a treatment that targets the specific genes, proteins, or the tissue environment that contributes to uncontrolled cell growth. Specifically, this treatment can target the change that controls PVNS, which causes some cells to make too much of a protein called colony stimulating factor 1 receptor. Blocking the overproduction of this protein with PLX3397 slows the damage to the joint and reduces swelling from the disease.

The 23 patients who received PLX3397 as part of this early study had PVNS that had worsened despite other treatment. Most had already had more than one surgery for the disease, as well as radiation therapy and other types of targeted therapy. Eleven out of 14 (79%) of the patients in the study had the tumors shrink, and the other three patients had the disease stop worsening.

What this means for patients

“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 lead author William D. Tap, MD, Chief of the Sarcoma Medical Oncology Service at Memorial Sloan Kettering Cancer Center in New York. “PLX3397 seemed to have a tremendous impact on the disease process that is destroying the joint as patients often reported a marked decrease in swelling and pain, even very early in their treatment.” Because this study is very early, research on this treatment is ongoing, and it is only available through clinical trials. If you have PVNS, talk with your doctor about clinical trials as a treatment option.

Questions to Ask Your Doctor

  • What are my treatment options for PVNS?
  • How likely is the disease to return and worsen after surgery?
  • In this situation, what treatment options are available?
  • What clinical trials are open to me?
  • How can I manage the symptoms of PVNS?

More Information

Targeted Treatments

Clinical Trials

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