For the first time in decades there are new treatments available for kidney cancer, and as more data emerges about their efficacy, the competition looks set to heat up.
Data presented on Sunday at the annual meeting of the American Society of Clinical Oncology confirmed the potency of Sutent, a drug marketed by Pfizer Inc. that was approved by U.S. regulators in January.
For the first time, too, data was released from a late-stage, or phase III, clinical trial of an experimental new drug from Wyeth called temsirolimus that showed it improved overall survival by 49 percent in patients with the poorest outlook.
Nexavar, a drug made by Onyx Pharmaceuticals Inc. and Bayer AG, was approved in December and has already shown that it doubled the time before the disease progressed to 24 weeks from 12 weeks for patients in the placebo group.
On Monday, investigators will release updated survival data for Nexavar. This time last year, interim results of a phase III trial showed that Nexavar improved survival by 39 percent, but the results were not statistically significant.
While trial investigators for Sutent and temsirolimus each claimed superiority for their drug, they conceded that direct comparisons were impossible as each trial was designed differently. The Sutent trial, for example, tested patients with a wide range of disease severity, from those whose prognosis was favorable to those whose prognosis was poor. About 40 percent were in the middle.
The late-stage confirmatory trial of Sutent showed the median time before which a patient’s disease progressed was 11 months in the Sutent group compared to five months in the group taking standard interferon therapy. The response rate, a measure of tumor shrinkage, was 31 percent in the Sutent group compared to 6 percent in the interferon group.
The results did not show whether patients who took Sutent lived longer than those who took the standard therapy.
Wyeth, by contrast, only tested patients with the poorest prognosis. Its trial found patients who were treated with temsirolimus alone had a median survival time of 10.9 months, compared with 7.3 months in the interferon group.
“In general, in oncology, drugs that work in patients with the worst prognosis will work at least as well if not better in those with a better prognosis,” said Gary Hudes, director of the genitourinary malignancies program at Fox Chase Cancer Center in Philadelphia.
The Wyeth drug, which has not yet been approved, is important because it is the first to fully validate the potential of a new target for cancer therapy called mTOR, Hudes said. mTOR is a signaling protein that regulates cell and blood vessel growth.
Revision date: June 11, 2011
Last revised: by Jorge P. Ribeiro, MD