Study Suggests Cyclosporine
Can Speed Cancer Growth

By William Mccall
Associated Press
PORTLAND, Ore. (AP) - Cyclosporine, a drug given to transplant patients to prevent organ rejection, may turn pre-existing cancer more aggressive, researchers say.
Transplants always carried the risk of cancer because doctors must suppress the immune system with powerful drugs such as cyclosporine to prevent the patient's body from attacking the new organ.
But previously it was believed the cancer risk increased because the weakened immune system failed to destroy defective cells that could turn malignant.
"This study suggests the drug has a direct effect on the tumor cell and enhances it growth,'' said Dr. Gary Nabel, a University of Michigan researcher who specializes in the immune system.
The study was conducted by Cornell University researchers and published in Thursday's issue of the journal Nature.
Doctors were quick to caution that the findings will not affect treatment of transplant patients because it applies only to cancer that has already formed.
In fact, they emphasized the study provides an important clue about blocking cancer growth.
"If anything, it's a reason for hope,'' said Dr. Manikkam Suthanthiran, chief of transplant medicine at Cornell.
Suthanthiran and his colleagues isolated human lung and bladder cancer cells that were treated with cyclosporine. They also injected cancerous cells into specially bred mice that had virtually no immune system.
The findings indicated that cyclosporine promotes the production of a natural protein called transforming growth factor beta, already a suspect in cancer growth.
"Our findings in no way mean this is increasing the incidence of cancer,'' Suthanthiran said. "It more reflects that cancer can be made more aggressive by a certain protein.''
He added that the study reveals a potential mechanism for blocking cancer by inhibiting the production of TGF beta.
Cyclosporine, which is also used to treat arthritis, is made by the Swiss-based pharmaceutical giant Novartis. Geoff Cook, a Novartis spokesman, said the company sees no cause for concern.
Dr. Israel Penn, a transplant pioneer at the University of Cincinnati, said only a small proportion of transplant patients have pre-existing cancer.
"For the tens of thousands of people receiving cyclosporine for years with very beneficial results, the good far, far outweighs the bad,'' he siads.