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significant side effects, only 18 percent of patients on the new drug had their dosages interrupted, compared with 35 percent on the rival drug. And 14 percent of patients on the Aveo drug had their doses reduced because of side effects, compared with 44 percent of the patients in the control group.
Extended dose interruptions, and dose reductions tend to worry physicians, who wonder if they are providing the cancer with an opportunity to worsen. The Aveo drug is designed to minimize that worry, by being administered once a day for three weeks, followed by a one-week “holiday.” Atkins points out that the Aveo drug has a long enough half-life so that it remains in the bloodstream during most of that one-week break, so it should maintain some effectiveness even while giving patients a respite from side effects. That’s different from the market leading treatment, Pfizer’s sunitinib (Sutent), which is given for four weeks, followed by a two-week break.
When patients have to go off the standard dosing regimen with a longer drug holiday, or a extended dose reduction, it creates a situation that the doctor and patient need to manage, Atkins says.
“That can be difficult for the physician and for the patient, as many patients gets sub-optimal therapy as a result,” Atkins says. With other drugs, “you have to manage, or hold therapy, or reduce the therapy. In this case, you give the treatment, and the patients for the most part don’t have major side effects.”
Still, like any study, this one has its limitations. Researchers don’t yet if the Aveo drug can help people live longer–follow-up data will have to wait until 2013. They also don’t have a strong sense of which patients are most likely to benefit from the new drug, Atkins says. The vast majority of patients in the TIVO-1 study enrolled in Eastern Europe and Asia—not in the U.S. or the wealthier countries of western Europe. That means fewer doctors here will have had experience with the drug once it hits the market, if it wins FDA approval.
Plus, there’s emerging competition from Pfizer’s axitinib (Inlyta). That drug won FDA approval earlier this year as a second-round treatment for kidney cancer, and it is likely to be shown effective among patients getting first-round therapy—the patient population Aveo is targeting. And Atkins says the entire class of VEGF inhibitors could face new competition in renal cell carcinoma drug from antibodies against new targets. One to watch, he says is an experimental drug from Bristol-Myers Squibb that’s designed to hit a marker on cells known as PD-1.