Extended Treatment With Recombinant Human Parathyroid Hormone (1-84) in Adult Patients With Chronic Hypoparathyroidism

Objective: Recombinant human parathyroid hormone (1-84) (rhPTH[1-84]) is efficacious in patients with hypoparathyroidism but additional data supporting its prolonged use are needed. We evaluated whether efficacy, safety, and tolerability are maintained during long-term rhPTH(1-84) treatment of patients with chronic hypoparathyroidism. Methods: This was a phase 4, single -center, open-label, single -arm, 3 -year extension (NCT02910466) of the phase 3 Hypo Extended (HEXT) study (NCT01199614). Patients self-administered rhPTH(1-84) once daily by subcutaneous injection, with doses individualized based on clinical parameters. Albumin-adjusted serum calcium levels (primary outcome measure), other disease biomarkers, healthrelated quality of life, and safety of rhPTH(1-84) were assessed using descriptive statistics. Results: All patients (n 1/4 39) had been exposed to rhPTH(1-84) (mean exposure [SD] 8.5 [3.5] years) before the start of the study, resulting in a mean exposure of 10.8 years including the present study. Mean patient age was 51.9 years, 79.5% were female, and 97.4% were White. Mean albumin-adjusted serum calcium concentrations were within the target range, and mean serum phosphate, serum calciumphosphate product, and 24 -hour urinary calcium excretion levels were within reference ranges at end of treatment. Mean doses of supplemental calcium and active vitamin D were maintained throughout the study. Bone turnover marker levels were maintained from baseline to end of treatment. No clinically relevant changes in bone mineral density were observed. Patient-reported health-related quality-of-life scores were generally maintained throughout the study. Four adverse events were considered treatment related and no new safety signals were identified. Conclusion: The effects of rhPTH(1-84) on biochemical, skeletal, and health-related quality-of-life parameters did not wane with extended use. (c) 2023 AACE. Published by Elsevier Inc. This is an open access article under the CC BY -NC -ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).