Efficacy and Safety of SBR759, a Novel Calcium-free, Iron (III)-based Phosphate Binder, Versus Placebo in Chronic Kidney Disease Stage V Japanese Patients on Maintenance Renal Replacement Therapy

Background: SBR759, an iron (III)-based oral phosphate binder, was developed for the treatment of hyperphosphataemia in chronic kidney disease stage V patients receiving maintenance renal replacement therapy (RRT). Serum phosphate-lowering efficacy and dose response of SBR759 (3-, 6-, 9- and 12-g/day doses) were compared with placebo.

Methods: Japanese patients with hyperphosphataemia (P ≥ 5.5 mg/dL [≥ 1.78 mmol/L]) receiving maintenance RRT (N = 63) were randomised to receive either SBR759 (3-, 6-, 9-, 12-g/day dose) or placebo (12-g/day dose) for 4 weeks. The primary endpoint was change from baseline in 72-h post-dialysis serum phosphate levels at week 4 for different doses of SBR759 versus placebo. Secondary endpoints were change from baseline in serum phosphate levels and dose-dependent efficacy of SBR759 during the 4-week treatment period.

Results: SBR759 showed significant reduction in serum phosphate levels compared with placebo at week 4, demonstrating a significant linear dose response (P < 0.001). Incidence of adverse events was comparable between the SBR759 treatment groups (7/13 and 5/12 in the 3- and 12-g/day groups, respectively, and 8/13 in the 6- and 9-g/day groups) and was 6/12 in the placebo group. Discoloured faeces and diarrhoea were the most frequently reported adverse events. Two serious adverse events were reported--one in the SBR759 3-g/day group (1/13, skin ulcer) and one in the SBR759 12-g/day group (1/12, arthralgia).

Conclusions: SBR759 showed significant phosphate-lowering efficacy and dose-dependent response compared with placebo in patients with chronic kidney disease receiving RRT.