The three phosphate binders currently on the market for reduction of elevated serum phosphate in CKD patients are "really marginal treatments," according to Dr. Block. He was first author on a study in which 148 patients with moderate CKD were randomized to 9 months of calcium acetate, sevelamer carbonate, lanthanum carbonate, or placebo. Serum phosphorus inched lower over the 9 months from a baseline of 4.2 mg/dL to 3.9 mg/dL with active therapy, which was only 0.2 mg/dL better than with placebo. In contrast, serum phosphate fell by an average of 0.6 mg/dL during 3 months on FCCC in the phase II study. Moreover, active therapy with the commercially available phosphate binders had no effect upon FGF23 levels, and it significantly increased coronary artery and abdominal aorta calcification by a median of 18% and 15%, respectively (J. Am. Soc. Nephrol. 2012;23:1407-15).
• Iron-deficiency anemia: The Kidney Dialysis International Guideline Organization defines iron deficiency warranting iron supplementation in CKD patients as a transferrin saturation of 30% or less and a serum ferritin of 50 ng/mL or less. By those criteria, it is estimated that nearly 70% of CKD patients are iron deficient. So there is a large unmet need for iron repletion therapies that avoid the use of erythropoietin-stimulating agents and intravenous iron, Dr. Block noted.
The FCCC trial was sponsored by Keryx Biopharmaceuticals. Dr. Block serves as a consultant to the company and was principal investigator in the study.