"Death Carrot" Comes to Cancer

Prostate cancer tumors cut in half by drug derived from weed

(RxWiki News) Arab caravans call the weed "death carrot" because it kills camels if they eat it. While it may not be so good for camels, this toxic Mediterranean weed - Thapsia garganica - may prove to be a very useful anticancer therapy.

In laboartory studies, a newly developed drug derived from this weed has shown to cut the size of prostate tumors in half. This drug - G202 - had the same effect on breast, liver, kidney and bladder cancers in mice.

Those results are much better than standard chemotherapy drugs currently in use.

"Develop a cancer screening program just for you; talk to your doctor."

Scientists, at the Johns Hopkins Kimmel Cancer Center, worked with Danish researchers to create this agent using the by-product of the Thapsia garganica weed - thapsigargin.

“Our goal was to try to re-engineer this very toxic natural plant product into a drug we might use to treat human cancer,” says lead study author Samuel Denmeade, MD, professor of oncology, urology, pharmacology and molecular sciences. “We achieved this by creating a format that requires modification by cells to release the active drug.”

They call the result a "molecular grenade."

G202 moves through the bloodstream and is activated by various proteins. It goes on to blow up cancers and the blood supplies they need to grow and all without touching healthy cells or tissues.

Scientists chemically modified the weed's active ingredient to form what Denmeade describes as "a hand grenade with an intact pin."

After injection, the G202 travels in the blood until it comes upon a protein called prostate-specific membrane antigen (PSMA), which is found in prostate and other cancers.

So the PSMA essentially "pulls the pin" on G202 to release its killer agents into the tumor, its blood supply and other nearby cells. The drug also blocks a protein known as the SERCA pump, which all tumor cells must have to live.

Researchers found that this novel agent outperformed the standard chemotherapy drug - docetaxel. G202 decreased the size of seven of nine human prostate tumors in mice by more than 50 percent in 21 days, while docetaxel reduced only one in eight tumors by the same amount over the same timeframe.

G202 also regressed models of human breast cancer, kidney cancer and bladder cancer by at least percent regression.

Following these results, Johns Hopkins physicians conducted a small phase 1 clinical trial to assess safety of the drug. So far, 29 patients with advanced cancer have been treated.

A phase II trial to test the drug in patients with prostate cancer and liver cancer is planned.

“The exciting thing is that the cancer itself is activating its own demise,” said senior study author John Isaacs, PhD, professor of oncology, urology, chemical and biomedical engineering at Johns Hopkins.

Resistance is unlikely since the drug kills a protein cancer cells can't live without.

Results from this study were reported June 27 in the journal Science Translational Medicine.

This research was funded by the Department of Defense Prostate Cancer Research Program, the Prostate Cancer Foundation and David Koch, the Danish Cancer Society, the Danish Research Council for Strategic Research, the Danish National Research Foundation, the Danish Medical Research Council, the Aarhus University Research Foundation and the National Institute of Health’s National Cancer.

Two of the authors disclosed that they are paid consultants for GenSpera, the company that manufactures G202. 

Review Date: 
July 11, 2012