Switzerland's Vifor Pharma has posted promising late-stage data on PA21, its new phosphate binder for treating hyperphosphatemia in patients with chronic kidney disease.

The Phase III trial showed that PA21 (iron(III)-oxyhydroxide) successfully controls hyperphosphatemia, ie the accumulation of phosphorus in the blood, in patients with CKD on dialysis. Results of the six-month study which involved more than 1,000 patients established the superiority of maintenance doses of PA21 versus a PA21 inactive low-dose in sustaining the phosphate-lowering effect in dialysis patients.

In addition, Vifor notes that PA21 was shown to be as good as Sanofi's Genzyme unit's Renvela (sevelamer carbonate), a current standard of therapy, in lowering serum phosphorus levels after 12 weeks of treatment, using an average of three-four tablets of PA21 per day (compared to eight-nine of Renvela).

Vifor, the pharma unit of Galenica, noted that PA21, a chewable, iron-based phosphate binder, appears to be generally well-tolerated and efficacious with the advantage of a lower pill burden. On the basis of the data, the firm intends regulatory filings in the USA, Europe and Switzerland, with the first submission planned for the fourth quarter.

PA21 is being developed with Fresenius Medical Care and it is also currently undergoing Phase II trials in Japan by Kissei Pharmaceuticals Co. Vifor notes that while all dialysis patients are treated with phosphate binders, less than 50% achieve and maintain their target serum phosphorus levels.