NPS Pharmaceuticals announced positive results from its Phase 3 REPLACE study of NPSP558 for the treatment of hypoparathyroidism in adults. REPLACE was a 28-week, double-blind, placebo-controlled study. The primary efficacy endpoint was defined as a ≥50% reduction in oral calcium supplementation and active vitamin D therapy and a total serum calcium concentration that was normalized or maintained compared to baseline after 24 weeks of treatment. At Week 24, 43% (36/84) of patients treated with NPSP558 were able to achieve independence from active vitamin D therapy and a calcium supplementation dose of ≤500mg/day, as compared to 5% (2/37) for patients treated with placebo (P<0.0001). In an intent-to-treat analysis, 53% (48/90) of NPSP558-treated patients achieved the primary endpoint vs. 2% (1/44) of placebo-treated patients (P<0.0001).

NPSP558 is an orphan drug that is a bioengineered replica of human parathyroid hormone (rhPTH 1-84).

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