Bacterial Enzyme Helps Deliver Cancer Drugs to Tumors
Injection of bacterial spores, liposome-coated doxorubicin causes complete tumor regression in all mice in study
FRIDAY, Nov. 24 (HealthDay News) -- An enzyme found in the anaerobic bacterium Clostridium novyi-NT might help deliver liposome-coated cancer drugs specifically to tumors and enhance tumor shrinkage, according to a report in the Nov. 24 issue of Science.
Because C. novyi-NT has hemolytic activity and tends to grow in hypoxic areas of tumors, Bert Vogelstein, M.D., of Johns Hopkins Kimmel Comprehensive Cancer Center in Baltimore, and colleagues asked whether the bacterium could enhance the activity of liposome-encapsulated drugs by disrupting tumor-cell membranes.
The researchers gave mice with a large tumor burden an intravenous injection of C. novyi-NT spores, followed by an injection of liposome-coated doxorubicin about 16 hours later. The combination had potent anti-tumor activity with minimal accumulation in normal tissues. There was a complete tumor regression in 100 percent of the mice, and 65 percent were alive at 90 days. The bacterial factor responsible for drug release from liposomes was found to be a previously unidentified enzyme, liposomase.
"Because virtually any therapeutic agent can be packaged in liposomes and can thereby act as a 'prodrug,' liposomase offers a number of possibilities for the specific delivery of drugs to tumors," the authors conclude.