WEDNESDAY, March 30, 2005 (HealthDay News) -- Combining agents that damage DNA with a drug that sensitizes cancer cells to those agents may prove an effective way to fight tumors, according to a new study.
Researchers examined the effects of combining a DNA-damaging agent called cisplatin with RAD001, a derivative of the immunosuppressive drug rapamycin, which is used in organ transplant patients. In Phase I and Phase II clinical trials, rapamycin has shown promising anti-tumor activity.
The use of RAD001 lowers the amount of DNA-damaging agent that's needed to kill malignant cells. That's because RAD001 blocks the ability of a protein called p53 to repair DNA.
The result: Cancer cells have no protection against DNA-damaging agents such as cisplatin.
"These findings provide the rationale for combining DNA-damaging agents with sensitizing agents like RAD001," research leader George Thomas, a professor at the University of Cincinnati's Genome Research Institute, said in a prepared statement.
"Since about 50 percent of all solid tumors contain p53, such a drug combination could dramatically improve the treatment of solid tumors," Thomas said. "The use of DNA-damaging agents has revolutionized chemotherapy against a wide variety of cancers."
However, side effects have limited the use of these agents, he added.
High doses of DNA-damaging agents can be toxic, but doses that are too low enable cancer cells to repair their DNA and continue to grow, he explained.
What's needed are drugs like RAD001, which sensitize cells to doses of DNA-damaging agents strong enough to guarantee the death of cancer cells, but without the toxic side effects, he said.
The research, published in the March 25 issue of Cell, was funded in part by the drug company Novartis.
More information
The American Academy of Family Physicians has more about cancer treatments.
