Trials for Best Ways to Treat Non-Dialysis–Dependent CKD

The search for effective treatments for non-dialysis–dependent chronic kidney disease (NDD-CKD) is gaining renewed interest. In the United States, more than one and a half million people suffering from stages 3 to 5 non-dialysis dependent NDD-CKD have iron deficiency anemia, but no oral iron supplements have yet been approved by the FDA for use for the condition. Likewise, no FDA-approved phosphate binders exist for use in NDD-CKD.

The federal government issued a request for application (RFA) for CKD clinical trials that closed on Nov. 21. That RFA sought pilot studies that optimize critical elements of a full-scale, randomized controlled trial design in return for U01 grant funding. The National Institute of Diabetes and Digestive and Kidney Diseases noted in its RFA that studies to date have looked at treatments and effects in small groups of patients, and that many questions remain regarding optimal dosing and drugs’ ability to reach appropriate patient outcomes.

One new NDD-CKD study that builds on earlier work was announced in early November. Keryx Biopharmaceuticals said that it had started a phase 2 study of its drug Zerenex (ferric citrate) for the treatment of patients with stage 3 to stage 5 non-dialysis dependent chronic kidney disease.

Zerenex is a ferric iron–based phosphate binder drug candidate for managing serum phosphorus and iron deficiency in anemic patients with NDD-CKD.

Several studies have shown that higher serum phosphorus concentrations may be associated with increased mortality and morbidity in CKD.

The phase 2 study will be a multicenter, randomized, safety and efficacy clinical trial designed to compare the ability of Zerenex to manage serum phosphorus and iron deficiency versus placebo in anemic patients. Eligible patients will be randomized in similar groups to receive either Zerenex or placebo for a 12-week treatment period.

The primary endpoints of the study are designed to demonstrate changes in ferritin, transferrin saturation (the ratio of serum iron and total iron-binding capacity), and serum phosphorus levels over the 12-week treatment period.

The study plans to randomize about 150 patients from about 15 sites in the United States. Patient enrollment should take about six months, and Keryx expects the study to wrap up in mid-2013.

December 2012 (Vol. 4, Number 12)