Maybe in Animals But Not in Humans

Kidney cancer tumors do not grow after sunitinib treatment ends

(RxWiki News) Cancer research usually begins by performing tests on cells. The next step involves animals, and finally humans. A recent controversy involving one medicine’s effect in animals has been refuted in human studies.

Kidney tumors did not start growing faster after stopping treatment with Sutent (sunitinib), according to data from a phase lll clinical trial.

"Talk to your doctor before stopping any medication."

The review was conducted by senior author Tito Fojo, MD, PhD, of the National Cancer Institute at the National Institutes of Health, and colleagues.

In addition to kidney cancer, sunitinib is used to treat a soft tissue cancer known as gastrointestinal stromal tumors (GIST) after another medication – imatinib (Gleevec) – fails. Sunitinib also treats a form of pancreatic cancer.

Sunitinib works by attacking blood vessels that feed cancer tumors. Animal studies have hinted that the medicine promotes changes in these vessels or within the tumor itself, resulting in tumor growth and spread. What was true in animals did not hold up in humans.

"We were able to demonstrate that this applied across all patients and that those who had the greatest benefit from the drug [sunitinib] while it was administered retained this benefit," Dr. Fojo said in a statement.

Dr. Fogo and his team found this to be the case after analyzing data from the phase lll clinical trial that led to the US Food and Drug Administration approving sunitinib for advanced kidney cancer in 2007.

That trial, which involved 750 people, showed the medication was safe no matter how long it was taken. The study also found that sunitinib slowed tumor growth during treatment, extended patient lives and did not affect survival after treatment ended.

First author Dr. Krastan Blagoev of the National Science Foundation, said that "other drugs also approved worldwide for a variety of cancers—including sorafenib [Nexavar], pazopanib [Votrient], and axitinib [Inlyta] —are similar to sunitinib, and this will give some reassurances that one need not expect things to get worse after such drugs are discontinued."

This study, which was funded by the National Science Foundation, was published February 7 in the Cell Press journal Cell Reports.

Review Date: 
February 6, 2013