Cancer requires support from immune system to develop, UT Southwestern research...( DALLAS Oct. 30 2008 Tumors that gr...),Health

DALLAS Oct. 30, 2008 Tumors that grow around nerves in a rare genetic disease need cooperation from cells from the immune system in order to grow, reports a team of scientists, including researchers from UT Southwestern Medical Center.

Treating mice with a drug that attacks the immune cells not the tumor greatly reduced the size and metabolism of the tumors, the scientists reported. A clinical trial of the treatment in humans has begun.

"It was not the tumor being treated, but its environment," said Dr. Luis Parada, chairman of developmental biology at UT Southwestern and co-senior author of the study, which appears in the Oct. 31 issue of the journal Cell. "This insight has led to a very promising therapy of a previously untreatable tumor.

"This is the first time a mouse model has been used to gain insight into a cancer that could not be derived from patient studies," said Dr. Parada, director of the Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration.

The researchers were studying tumors called plexiform neurofibromas, which occur around peripheral nerves. In humans, they occur as part of a genetic disease called neurofibromatosis-1. About 25 percent to 40 percent of people with the disease develop the tumors, which are generally benign but can grow large enough to cause disfigurement or disability and can sometimes become malignant.

These tumors are complex structures that include many different types of cells, particularly Schwann cells, which provide a fatty coating that makes nerve cells electrically efficient, and mast cells.

Because of their complexity, plexiform neurofibromas are difficult to remove surgically, and there is currently no cure for them.

Neurofibromatosis-1 is caused by a mutation in a single gene called Nf1. About 250,000 people in the U.S., Europe and Japan have this mutation. The mutation is dominant, meaning that people with one normal
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