New targeted therapies promise to improve the outlook for patients with advanced kidney cancer, according to researchers at the annual meeting of the American Society of Clinical Oncology, held in Atlanta.

Kidney cancer is expected to strike nearly 39,000 Americans this year, and kill nearly 13,000. The disease is difficult to detect because it frequently shows no symptoms until it is very advanced. It is also highly resistant to treatment, said researcher Robert Motzer, MD, of Memorial Sloan-Kettering Cancer Center in New York.

"Until recently there was literally no drug that showed an advantage in this disease," Motzer told reporters at the conference. "Now there are several different drugs that are clearly having an impact."

Motzer presented findings from a study of sunitinib (Sutent), which was approved by the FDA in January as a second-line treatment for advanced renal cell carcinoma. His research involved 750 people with metastatic disease who had had surgery, but no chemotherapy or immunotherapy. Half were randomly assigned to take Sutent, while the rest were given interferon-alpha, the current standard treatment.

Patients on interferon typically see their cancers start to grow again after about 5 months of treatment, Motzer explained. That was the case in this study, too; patients on interferon went an average of 25 weeks until progression.

But the patients on Sutent did much better. On average, it took about 47 weeks (11 months) for their cancers to start growing again. And, about 25% of people on Sutent had their tumors shrink, while just 5% of those on interferon-alpha did. The study did not look at whether Sutent helped patients live longer.

People on Sutent experienced more diarrhea, high blood pressure, and hand-foot syndrome, but patients on interferon had more fatigue.

"As a result of this trial, we believe sunitinib will become the new standard of care for advanced renal cell cancer, Motzer said.

The drug is made by Pfizer. Aside from delaying cancer progression longer, Sutent is easier for patients to take -- a pill they can take at home. Interferon, on the other hand, must be injected several times a week.

But Sutent isn't the only drug making inroads against kidney cancer. Sorafenib (Nexavar), which was also recently approved by the FDA, has been shown to extend the time it takes for kidney cancer to progress. Two investigational drugs that have not yet been approved by the FDA also appear effective.

One is temsirolimus, made by Wyeth. Doctors from Fox Chase Cancer Center in Philadelphia presented research at the ASCO conference showing that it actually helped patients live longer compared to interferon-alpha or a combination of temsirolimus and interferon-alpha. What's more, the benefits were seen in patients with advanced disease and poor performance status, a group with an especially bleak outlook.

The study involved 626 patients. Those given temsirolimus lived an average of 11 months, compared to 7 months for the group on interferon-alpha alone and 8 months in the group on the combination regimen.

"There were similar numbers of deaths across groups," said lead researcher Gary Hudes, MD, director of the genitourinary malignancy program at Fox Chase. "It's when these people died that's the unique finding."

Patients in this situation typically survive only about 6 months, he explained.

Side effects of temsirolimus included rashes, high blood sugar, anemia, and mouth sores, but Hudes said these were easy to manage. Weakness and fatigue were less common than in patients taking interferon.

The third drug showing promise for kidney cancer patients is lapatinib (Tykerb), made by GlaxoSmithKline. A study of 416 patients showed that the drug is better than hormone therapy -- at least for some patients. Those whose tumor cells had the most EGFR lived longer and had longer times to cancer progression. EGFR is epidermal growth factor receptor, a protein on cell surfaces that plays a key role in cell growth and division. It is one of the targets of Tykerb.

The new findings represent real progress against an intractable form of cancer, said Len Lichtenfeld, MD, deputy chief medical officer for the American Cancer Society.

"Here you have a disease where a couple of years ago, there wasn't much to offer," he said. "Therapies were extremely toxic or of limited value."

Indeed, only about 10%-20% of patients who take interferon-alpha, or a similar drug, interleukin-2, actually respond to treatment. Side effects can be very serious and include extreme fatigue, fluid accumulation in the lungs, heart attacks, and intestinal bleeding.

Although the new drugs don't cure kidney cancer, they do open a whole new set of opportunities for treating this disease, Lichtenfeld said. Studies are planned to test the drugs in patients with earlier-stage cancer, and to try combining the drugs or giving them in sequence in hopes of improving outcomes even more.

Citations: "Phase III randomized trial of sunitinib malate (SU11248) versus interferon-alfa (IFN-á) as first-line systemic therapy for patients with metastatic renal cell carcinoma (mRCC)." Abstract #LBA3, presented June 4, 2006, at the annual meeting of ASCO. First author: Robert J. Motzer, MD, Memorial Sloan-Kettering Cancer Center, New York.

"A phase III, randomized, 3-arm study of temsirolimus (TEMSR) of interferon-alpha (IFN) or the combination of TEMSR+IFN in the treatment of first-line, poor-prognosis patients with advqnced renal cell carcinoma (adv. RCC)." Abstract #LBA4, presented June 4, 2006, at the annual meeting of ASCO. First author: Gary R. Hudes, MD, Fox Chase Cancer Center, Philadelphia.

"Efficacy of lapatinib in patients with high tumor EGFR expression: results of a phase III trial in advanced renal cell carcinoma (RCC)." Abstract #4502 presented June 4, 2006, at the annual meeting of ASCO. First author: Alain Ravaud, MD, PhD, University Victor Segalen, Bordeaux, France.