Hypoparathyroidism is characterized by insufficient levels of parathyroid hormone (PTH), resulting in hypocalcemia, hyperphosphatemia, hypercalciuria, and a reduced quality of life (QoL). PTH replacement therapy should restore physiologic levels of PTH and restore downstream physiologic levels of calcitriol, promoting independence from Ca and active vitamin D supplements and normalization of QoL. TransCon PTH is an investigational long-acting prodrug of PTH(1–34) for the treatment of hypoparathyroidism. Week 26 results from the PaTH Forward open-label extension (OLE) Trial in adult patients with hypoparathyroidism are reported.
Subjects received fixed doses of TransCon PTH 15, 18, or 21 µg PTH(1–34)/day or placebo for 4 weeks, followed by an OLE period during which TransCon PTH dose was titrated (630 µg PTH[1–34]/day) with the goal to maintain normocalcemia. Safety and efficacy endpoints were evaluated at predefined timepoints over the OLE. Efficacy end points evaluated at Week 26 included intake of active vitamin D and calcium supplements, 24-hour uCa, sCa, sP, and CaxP. QoL was assessed by the SF-36 and the Hypoparathyroidism Patient Experience Scales (HPES).
All 59 subjects completed the initial 4-week period and continued in the OLE; 58 subjects continue in the OLE beyond 6 months (1 withdrew unrelated to safety or efficacy). By Week 26, TransCon PTH enabled 91% of subjects to achieve independence from SoC (active vitamin D = 0 mg/day and calcium ≤ 500 mg/day) and 76% of subjects to achieve complete independence from SoC (active vitamin D = 0 mg/day and calcium = 0 mg/day). Mean 24-hour uCa decreased from a baseline mean of 415 mg/24 h to 178 mg/24 h by Week 26 (n = 44) while maintaining sCa and reducing sP and CaxP to fall within the normal range. By Week 26, the mean scores for all SF-36 summary and domains increased from below normal at baseline to within the normal range. The HPES Symptom and Impact scores decreased through 26 weeks for TransCon PTH and placebo subjects switching to TransCon PTH (lower scores are associated with less symptoms/impact). TransCon PTH continued to be well-tolerated with no treatment-related serious or severe adverse events.
Through Week 26 of the PaTH Forward OLE Trial, TransCon PTH enabled independence from active vitamin D and calcium supplements for most subjects while maintaining normal sCa, sP, uCa, CaxP, and demonstrating enhanced QoL. These results support TransCon PTH as a potential hormone replacement therapy for adults with hypoparathyroidism.
22 May 2021 - 26 May 2021