From Foe to Friend

A chemical called thapsigargin is a deadly poison derived from a plant botanists call Thapsia garganica. The weed is native to the area around the Mediterranean Sea. It killed enough camels in caravans that it acquired the name “death carrot” in the Middle East. Thapsigargin destroys cells by blocking the action of a protein that keeps them alive. This protein is found in almost all animal cells and is necessary to sustain them.

Now scientists have been able to modify the chemical into a drug called G202, which affects only cancer cells. Tumors have a biochemical signature that distinguishes them from healthy tissue. This signature is the focus of much oncologic research, providing a target for tumor fighters.

G202 is engineered to respond to those signals, allowing it to attack tumors while moving harmlessly through the bloodstream and sparing healthy cells. In tests, G202 shrunk prostate tumors by an average of 50 percent within 30 days. That’s far better than docetaxel, the first-line drug used against prostate cancer. G202 was also an effective fighter of breast, kidney and bladder cancer tumors.

“Our goal was to try to re-engineer this very toxic natural plant product into a drug we might use to treat human cancer,” study author Samuel Denmeade, M.D., said in a release. “We achieved this by creating a format that requires modification by cells to release the active drug.”

Because the modified toxin is triggered by the cancer cells themselves, they are unlikely to develop resistance to it, a common obstacle to long-term cancer treatment.

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