The drug, known as bardoxolone methyl, works in a new way, says researcher David Warnock, MD, the Hilda B. Anderson professor of medicine at the University of Alabama at Birmingham. He is slated to present the results of the phase II trial of the drug today at the European Renal Association-European Dialysis and Transplant Association Congress in Prague.
"This is a promising new treatment that may change the course, the whole way we approach severe kidney disease in diabetics," Warnock tells WebMD.
The results are also published in The New England Journal of Medicine.
Diabetes is a major cause of kidney disease, which boosts the risk of kidney failure and the need for dialysis.
"There are 26 million Americans who have chronic kidney disease," Warnock says. "There are 500,000 on dialysis."
The hope, Warnock says, is to improve kidney function with the drug enough to delay or prevent the need for dialysis, which costs about $75,000 a year per patient.
Lynda Szczech, MD, president of the National Kidney Foundation, who reviewed the findings for WebMD, said the results look impressive, but she awaits results from the final clinical trial (phase III), now under way.
New Drug for Kidney Disease: Study Details
In the study, Warnock and his colleagues looked at three doses of the drug -- 25, 75, and 150 milligrams daily. They compared the drug treatment to placebo. The patients remained on other medications, such as blood pressure-lowering drugs, with the bardoxolone added on.
The new drug is an antioxidant that reduces inflammation, working in a new way. The reduction in inflammation leads to improved kidney function, Warnock says.
In all, they evaluated 227 patients, average age 67. The patients were equally divided into the placebo group and the three drug groups.
The researchers followed them for 52 weeks, evaluating the effect at 24 weeks and at 52 weeks.
Compared to placebo, people on the drug had an increase in their average GFR, a measure of kidney function.
Normal GFR is about 90 to 120 milliliters per minute; below 15 is considered late-stage kidney disease.
At the start of the study, all four groups had similar average GFRs, ranging from about 31 to 33.
At 24 weeks, those on the drug had increases in their kidney function, but no substantial differences occurred in the placebo group. At the 52-week mark, those on the drug still had improvement, but there was no substantial improvement in those on placebo.
The 75 mg dose was deemed best, as it produced on average about a 30% increase in kidney function at 52 weeks, Warnock says. ''The maximal effect was apparent in the first 12 to 20 weeks," he says. After that, it reached a plateau and stabilized.
Side effects were more common in the drug-treated groups, but most were mild to moderate, the researchers say. Muscle spasms affected 61% in the middle-dose group, but generally went away with time. Other side effects included elevated liver enzymes, nausea, decreased appetite, and low magnesium.
One death occurred in the 75-mg group after the patient had cardiac bypass surgery.
Warnock was an investigator for the phase II study. He is not an investigator for the phase III study, just launched. He is now a consultant for Reata Pharmaceuticals, which supported the phase II study. (Phase II trials focus on effectiveness and provide more safety information. Phase III studies include larger groups and confirm effectiveness, monitor side effects, and collect other information.)
New Drug for Kidney Disease: Perspective
Szczech of the National Kidney Foundation says the results from the current study look impressive but that ''the real safety and efficacy will be found in phase III."
However, she says, based on the way the drug works, it is ''entirely plausible that this will pan out." Part of the reason, she says, is the novel way the medicine works on kidney disease. "This is the first drug that would come at it from the inflammation pathway.''
Patients on dialysis are often financially devastated, she says, even if they have some insurance coverage.
Szczech is also associate professor of medicine at Duke University School of Medicine, Durham, N.C.
She was not involved in the study but has been a consultant for Abbott. Abbott and Reata have a partnership to develop and market the drug outside the U.S. The phase III trial results are expected in 2013.