Zerenex ferric citrate: Phase III data

Top-line data from an open-label, U.S. Phase III trial in 146 evaluable dialysis patients with ESRD showed that once-daily Zerenex met the primary endpoint by demonstrating a significant dose response in the change in mean serum phosphorus from baseline to day 28. Specifically, 6 and 8 g/day Zerenex significantly reduced mean serum phosphorus from baseline to day 28 by 1.9 and 2.2 mg/dL, respectively, vs. a gain of 0.1 mg/dL from baseline for the 1 g/day Zerenex dose (p<0.0001 for both compared to baseline and p<0.0001 for both compared to the 1 g/day dose).

On secondary endpoints, Zerenex led to a significant dose response increase in serum bicarbonate and a significant dose response reduction in calcium-phosphorous product. Furthermore, there was no clinically meaningful change in serum calcium levels observed. Keryx said high levels of serum calcium and calcium-phosphorus product are believed to be drawbacks of some of the currently marketed phosphate binders. Additionally, upward trends in ferritin and transferrin saturation levels were observed for the 6 and 8 g/day Zerenex doses, which Keryx said supports the potential to reduce the need for IV iron supplements and/or erythropoiesis stimulating agents (ESAs) in dialysis patients. Zerenex was well tolerated. ...