Synta Pharma starts midstage study of cancer drug

Synta Pharmaceuticals Corp. on Wednesday said it started a mid-stage trial of a cancer drug candidate as a treatment for cancers of the digestive tract.

Synta will study the drug, called STA-9090, in patients who have not responded to treatment with two other cancer drugs, Novartis AG's Gleevec and Pfizer Inc.'s Sutent.

It is testing the drug as a treatment for a rare type of cancer called gastrointestinal stromal tumors, which usually occur in the stomach or small intestine but can also be found in the liver, colon, esophagus or rectum.

The company said 4,500 to 6,000 people are diagnosed with the cancers in the U.S. each year.

About 55 subjects with metastatic or inoperable tumors will be enrolled in the trial. The participants will receive one dose of STA-9090 per week, and those who tolerate the drug will be treated until their cancer begins to progress.

Synta said STA-9090 blocks a protein that activates other proteins that cancer cells need to grow. When the protein is blocked, other proteins degrade and the cancer cells die. Synta said the protein, called Hsp90, also aids the growth of proteins that make some tumors resistant to drugs like Gleevec and Sutent.

STA-9090 is also being studied as a treatment for non-small cell lung cancer, solid tumors and blood cancers. Synta said it plans to start other studies in early 2010.

Gleevec also is approved as a treatment for a type of leukemia, while Sutent is also used against advanced kidney cancer.

In afternoon trading, Synta shares rose 26 cents, or 4.7 percent, to $5.75.