TUESDAY, July 31 (HealthDay News) -- Kidney cancer might have met its match in a new combination of cancer drugs, a new study shows.

Used together, interferon alpha, a drug that boosts the body's ability to fight off tumors and infections, and sorafenib, a drug that cuts off a tumor's blood supply, led to significant tumor shrinkage in 33 percent of patients in a U.S. pilot study.

"We found that by combining a drug that enlists the immune system's help in combating cancer with one that cuts off a tumor's blood supply, we could substantially increase patients' response rates to treatment," lead investigator Dr. Jared Gollob, of the Duke Comprehensive Cancer Center in Durham, N.C., said in a prepared statement.

Used alone, each drug is only successful in fighting 5 percent to 10 percent of tumors. But the new study finds that the combination works much better. Sorafenib is sold under the brand name Nexavar.

The drugs had an additional benefit, the researchers said, in that the combo therapy doubled the time before tumors began to grow again. According to Gollob, most tumors begin growing again after about five or six months when treated by either drug alone.

Reporting in the Aug. 1 issue of the Journal of Clinical Oncology, Gollob and his research team gave 40 study patients sorafenib in pill form twice daily and interferon alpha injections three time a week for eight weeks. If the patient's tumor had not grown or had shrunk after eight weeks, they repeated the cycle after a two-week break until the tumors disappeared or the cancer got worse. The researchers monitored the tumors using computerized-tomography (CT) scans.

The approach completely destroyed tumors in two of the 40 patients.

Researchers plan to begin a multi-site clinical trial that will analyze the impact of giving patients increasing doses of sorafenib alone after their tumors have shrunk as much as possible on the combination treatment.

According to the U.S. National Cancer Institute, about 51,000 people suffer from kidney cancer every year, and almost 13,000 will die from the disease. The majority of patients are men over the age of 45. The cancer is especially deadly, because it very rarely causes symptoms until it has reached an advanced stage. By the time kidney cancer rates stage IV status, it has spread to other organs such as lungs, liver and bones. People are given six months to two years to live once they reach stage IV, and only about 10 percent are alive five years after diagnosis.

The Duke team noted that one of the biggest challenges facing doctors and patients with kidney cancer is the cancer's resistance to chemotherapy, radiation and other common cancer-fighting tools.

More information

To learn more about kidney cancer visit the U.S. National Cancer Institute.

-- Madeline Vann

SOURCE: Duke University, news release, July 30, 2007

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