NATPARA, a bioengineered replica of human parathyroid hormone 1-84, is being developed as a hormone replacement therapy for the underlying cause of hypoparathyroidism. NPS reported positive findings from a Phase 3 registration study of NATPARA, known as REPLACE, which met the primary efficacy endpoint with a statistically higher responder rate versus placebo. A responder was defined as a 50% or greater reduction in oral calcium supplementation and active vitamin D therapy and a total serum calcium concentration that was maintained compared to baseline.

Because it mimics the action of natural parathyroid hormone, NATPARA has the potential to treat hypoparathyroidism and offer a more physiological treatment outcome than what is available with existing treatments. In 2007, the FDA granted orphan drug status for NPSP558 for the treatment of hypoparathyroidism. Nycomend, the company’s partner, markets PTH (1-84) in Europe as Preotact^® for the treatment of osteoporosis in post-menopausal women at high risk of fractures.