MEMPHIS, Tenn. — A new gene therapy which scientists believe will suppress prostate cancers will be tested on humans for the first time Monday, a University of Tennessee-Memphis researcher announced Friday.
A genetically altered virus carrying a normal human gene known as BRCA1 will be injected into the cancerous prostates of two patients, said Dr. Mitchell S. Steiner, director of urologic oncology research at UT-Memphis.
Once in the prostate tumor, BRCA1 begins replacing defective genes with normal genes, Steiner said.
The new therapy dramatically reduced the size of human prostate tumors growing in laboratory mice, Steiner said.
“We found that nine of 16 tumors (in the mice) disappeared after one injection of the gene therapy material. The other seven were smaller,” Steiner said.
The therapy, developed by Steiner and his colleagues at Vanderbilt University, will be tested for safety on humans in a phase one study, authorized by the Food and Drug Administration.
Phase one patients will be aged 35-75 with advanced prostate cancer and a life expectancy of 6-18 months. UT-Memphis and Vanderbilt will test 10 patients each.
“We should know within the next four months whether it’s safe (for use in humans),” Steiner said. “Once we’ve determined it’s safe, then we can move to phase two to test the efficacy, to see if it really does work.”
The patients receiving the therapy will remain in the UT-Memphis Bowld Hospital four days. They will return one week later for a blood test and 2-4 weeks later for a biopsy. The tumors will be measured before and after injection to determine if they have changed in size.
Prostate cancer is the second-leading cause of cancer death in men and the most frequently diagnosed. An estimated 317,000 new cases of prostate cancer will be diagnosed and more than 45,000 cancer deaths will occur this year in the United States.
The BRCA1 gene, being used in the UT tests, was first identified with breast cancer.
“Women with that gene have an 80 percent chance of breast cancer,” Steiner said. “Families that have a large amount of breast cancer also have a large amount of prostate cancer.”
Steiner, Dr. Jeff Holt of Vanderbilt and Dr. Mary Claire King of the University of Washington concluded that a broken or altered BRCA1 gene may lead to both breast and prostate cancer. King led the team that recently discovered the BRCA1 gene.
“The same therapy is being used by Holt and his colleagues at Vanderbilt University to treat advanced breast cancer,” Steiner said.
To get the normal BRCA1 gene into the prostate tumor, the researchers chose as a delivery mechanism a virus which injects disease-causing material into human cells.
“We’ve tinkered with it genetically so that it can no longer produce disease. We’ve tricked it into delivering our therapeutic gene (BRCA1) to the tumor,” Steiner said.
The virus has become “a molecular hypodermic needle,” binding itself to the cell and “squirting” the BRCA1 gene into the tumor, he said.
The genetic engineering for the therapy for use on humans is done at the Francis William Preston Laboratory at Vanderbilt, Steiner said.
Steiner, formerly at Vanderbilt, joined UT-Memphis in 1995.
Contact: Dr. Mitchell Steiner (901-448-5868)