'These are win-win reports. They show that these new drugs can extend life and extend progression-free life while being less toxic than previous treatments.'

However, in studies presented at the American Society of Clinical Oncology in Atlanta, cancer doctors say they can extend survival for the sickest of people with kidney cancer and can offer nearly a year of progression-free survival -- an average of 11 months in which disease doesn't grow -- to another group of patients.

The drugs target the molecular growth patterns of kidney cancer and offer renewed hope to the 38,800 people who will find out they have the disease this year. According to the American Cancer Society, more than 12,800 people will die of kidney cancer this year.

Superior to Interferon

These are revolutionary studies, said Dean Bajorin, attending physician and professor of medicine at Memorial Sloan-Kettering Cancer Center in New York, that absolutely are going to change the physician's daily practice.

Bajorin, who moderated a news briefing at which the new studies were discussed, told United Press International, "These are win-win reports. They show that these new drugs can extend life and extend progression-free life while being less toxic than previous treatments."

In one study, Robert Motzer, also an attending physician at Memorial Sloan-Kettering, said that sunitinib -- Pfizer's Sutent -- was able to keep cancer at a standstill for at least 11 months in patients with kidney cancer that had already spread from the kidney to other areas of the body.

Motzer and colleagues enrolled patients in the study and assigned them to sunitinib -- a drug that inhibits the ability of the cancer cell to recruit a blood supply and to replicate -- or to the previous standard of care, interferon.

In the Phase 3 study, the 335 patients who received sunitinib achieved progression-free survival for an average of 11 months while those on interferon saw the disease begin to progress after five months of therapy.

About 31 percent of patients on sunitinib showed an initial objective response -- tumors actually regressed in size -- compared with just 6 percent of the patients on interferon. Those differences were highly statistically significant, Motzer said.

"Sunitinib is superior to interferon in first-line treatment of metastatic renal cell cancer. As a result of this trial, we believe sunitinib will become the new standard of care for advanced renal cell cancer," he said.

Attack on mTOR Protein Validated

In the other study involving patients with advanced kidney cancer who were considered to have a poor prognosis, doctors tried an experimental drug, temsirolimus -- an agent that attacks mTOR, a protein that controls the molecular cascade required for cells to proliferate.

Although mTOR exists in all cells, it is overexpressed in cancer cells. Doctors believe that by attacking this target in cancer cells the damage will be limited to the malignancy rather than healthy cells.

"This is the first trial that really validates mTOR as a target for treatment of cancer," said Gary Hudes, director of genitourinary oncology at Fox Chase Cancer Center in Philadelphia, in presenting his study at the meeting that drew more than 25,000 health professionals to Atlanta.

Importantly, Hudes showed that by giving patients temsirolimus, being developed by Wyeth Pharmaceuticals of Madison, NJ, the overall survival of these patients was nearly 50 percent greater than people treated with interferon.

The 209 patients getting interferon lived an average of 7.3 months after starting treatment while the 207 patients on temsirolimus survived 10.3 months, Hudes said. Another 210 patients received both agents in a combination therapy, but they only fared slightly better than those getting interferon alone.

"The ability to improve survival for these patients with advanced renal cell carcinoma and poor-risk features by three and a half months is quite an achievement," Hudes said.

He said the difference between temsirolimus and the single agent interferon reached statistical significance.

Wyeth is expected to seek Food and Drug Administration approval for temsirolimus later this year.