New Renal Cancer Drug's Activity Long-Lasting

An investigational drug for kidney cancer appears to have long-lasting activity, a British researcher said here.

In a phase II study of patients with advanced renal cell carcinoma, the compound BAY 73-4506 -- being developed by Bayer Schering Pharma -- was associated with long-lasting partial responses, according to Tom Eisen, Ph.D., of Addenbrooke's Hospital in Cambridge, England.

While only 27% of the 49 patients had a partial response, 88% of those are still responding and only two have progressed, Dr. Eisen said at the annual meeting of the American Society of Clinical Oncology.

"If you got a partial response," he said, "the investigators' feeling is that it seems to be well maintained."

Overall, Dr. Eisen said, the clinical activity of the drug is "in the same ballpark as the other leading agents."

The compound is an oral multi-kinase inhibitor that targets such receptor tyrosine kinases as vascular endothelial growth factor (VEGF) receptor, platelet derived growth factor (PDGF) receptor, and TIE2.

The study enrolled patients with metastatic or unresectable cancer and measurable disease according to the international RECIST (Response Evaluation Criteria In Solid Tumors) criteria.

They were given 160 milligrams of the drug daily on a schedule of 21 days on and seven off.

Of the original 49 patients, 25 remain on treatment, he said, with a partial response in 13 and an unconfirmed partial response in another four. Twenty-four patients have stopped -- including because of disease progression, five owing to adverse events, and three because of death.

The most common adverse event was hand-foot syndrome -- formally palmar-plantar erythrodysesthesia -- with 63.3% reporting it, Dr. Eisen said. But he said the syndrome was not as "explosive" as it sometimes is with other agents in the class.

Dr. Eisen said that if the apparent length of response holds up as the study continues and in future trials, the drug might have potential as first-line therapy in kidney cancer.

The drug's "clinical activity is right up there with other agents," said Brian Rini, M.D., of the Cleveland Clinic Taussig Cancer Institute, who was not part of the study.

But because it is less specific than some others, he said, "there is a higher incidence of all-grade and grade 3 toxicity," with the main issue being hand-foot syndrome.

Dr. Rini argued that the important step in learning how to use the new agents is understanding the "diverse spectrum of biochemical, clinical, and toxic effects."

For the Bayer drug, he said, it will be important to define the risk-benefit ratio. "We may be willing to tolerate more side effects of an agent if we know patients are going to benefit," he said.

Source : www.medpagetoday.com