CHICAGO May 14 An experimental cancer drug
being developed by Plexxikon, a unit of Daiichi Sankyo,
appears to ease pain and swelling in patients with a rare joint
disease caused by a genetic mutation, researchers said on
The finding, borne out of recent advances in understanding
the genetic underpinnings of cancer, shows how greater knowledge
of individual mutations can lead to more specific treatments.
The disease, called recurrent pigmented villonodular
synovitis, or PVNS, is caused by a glitch in a single gene that
instructs cells to overproduce a molecule called colony
stimulating factor 1. It causes immune cells to collect in the
soft tissue of joints, gradually destroying them.
Plexxikon's drug, PLX3397, is a new cancer drug that acts on
this same pathway, blocking the abnormality that drives PVNS.
Researchers at Memorial Sloan-Kettering Cancer Center in New
York tested the drug in people with this rare disease, which
affects about 600 people in the United States.
Like cancer, the disorder is marked by the overgrowth of
abnormal cells, but it does not spread to other parts of the
Results of an early-stage trial of the treatment, released
on Wednesday, look promising. Eleven of 14 patients had a
partial response to the drug, meaning the tumor shrank at least
by half, and three patients had stable disease. On average,
tumors among this sample of 14 patients shrank by 61 percent.
"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 Dr
William Tap of Memorial Sloan-Kettering, who led the study.
Tap said patients often reported a marked decrease in
swelling and pain "even very early in their treatment course."
More testing is needed to determine whether the treatment
works in a larger population of patients. A late-stage study of
the treatment is planned.
Dr Clifford Hudis, president of American Society of Clinical
Oncology, said the study "offers an exciting glimpse" at future
treatments that will become possible as a result of efforts to
better match patients' tumors with targeted drugs.
"The research shows what's possible when we unravel the
molecular drivers of a disease and identify a drug that directly
targets these defects."
Full results of the study will be presented at the ASCO
meeting in Chicago starting on May 30 and running through June
(Reporting by Julie Steenhuysen; Editing by Dan Grebler)