Randomized clinical trial of the iron-based phosphate binder PA21 in hemodialysis patients

Abstract

Background and objectives: A dose-finding study was undertaken to investigate the efficacy of PA21, a novel polynuclear iron(III)-oxyhydroxide phosphate binder.

Design, setting, participants, & measurements: In a randomized, active-controlled, multicenter, open-label study at 50 clinical sites in Europe and the United States, hemodialysis patients were randomized to PA21 at dosages of 1.25, 5.0, 7.5, 10.0, or 12.5 g/d or sevelamer-HCl 4.8 g/d for 6 weeks. The primary efficacy endpoint was the change in serum phosphorus concentration from baseline.

Results: There were 154 participants who were randomized and received the study drug. All groups except PA21 1.25 g/d showed a significant decrease in serum phosphorus. Mean decreases in serum phosphorus in PA21 10 g/d and 12.5 g/d were -2.00±1.71 mg/dl and -1.69±1.81 mg/dl, respectively. A similar decrease to sevelamer-HCl (-1.06±1.35 mg/dl) was seen with PA21 5.0 g/d (-1.08±2.12 mg/dl) and 7.5 g/d (-1.25±1.21 mg/d). Overall, 60.9% of participants randomized to PA21 and 57.7% randomized to sevelamer-HCl reported ≥1 adverse event. The most frequent adverse events were hypophosphatemia (18.0%) and discolored feces (11.7%) for the pooled PA21 dose groups, and diarrhea, hypophosphatemia, and hypotension (each 11.5%) for sevelamer-HCl. Discontinuation due to adverse events occurred at a similar rate in PA21-treated (21.1%) and sevelamer-HCl-treated (23.1%) participants.

Conclusions: PA21 5-12.5 g/d significantly reduces serum phosphorus in hemodialysis patients. The 5 g/d and 7.5 g/d dosages showed similar efficacy to 4.8 g/d of sevelamer-HCl. The adverse events rate was similar for PA21 and sevelamer-HCl.

Figure 1.

Patient disposition.

Figure 2.

Change in serum phosphorus from baseline (week 1) according to treatment group. Data are shown as mean (SEM) change from baseline to end of treatment (primary endpoint) according to treatment group (efficacy and per protocol populations) (last observation carried forward, LOCF). *P=0.02, **P=0.003, ***P<0.001 (all versus baseline).