Keryx Biopharmaceuticals reports the final dataset from the phase III short-term clinical trial of Zerenex (ferric citrate) for the treatment of hyperphosphatemia in 151-end-stage renal disease patients on dialysis. 

This phase III study was a multicenter, randomized, open-label trial with a two-week washout period, following which patients were randomized 1:1:1 to receive a fixed dose of Zerenex of either 1 gram, 6 grams or 8 grams per day for a treatment period of 28 days. Zerenex was administered using a 1 gram oral caplet formulation, hence, the fixed-dose arms of 1 gram, 6 grams and 8 grams per day represent 1, 6 and 8 pills per day, respectively.

The intent-to-treat (ITT) group included 146 patients, representing all patients who took at least one dose of Zerenex and provided a baseline (at the end of washout) and at least one post-baseline efficacy assessment.  Efficacy assessments were taken weekly starting at baseline and subsequently at days 7, 14, 21 and 28.

The primary endpoint of the study was to determination of a dose response in the change in serum phosphorus from baseline to day 28 in the ITT group, using a regression analysis to evaluate this objective. The study met the primary endpoint, with the regression analysis indicating a highly statistically significant dose response (p