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Therapy of hypoparathyroidism with PTH(1-84): a prospective four-year investigation of efficacy and safety.

ABSTRACT: PTH may be an effective treatment option for hypoparathyroidism, but long-term data are not available.We studied the effect of 4 yr of PTH(1-84) treatment in hypoparathyroidism.Twenty-seven subjects were treated with PTH(1-84) for 4 yr, with prospective monitoring of calcium and vitamin D requirements, serum and urinary calcium, serum phosphorus, bone turnover markers, and bone mineral density (BMD).Treatment with PTH(1-84) reduced supplemental calcium requirements by 37% (P = 0.006) and 1,25-dihydroxyvitamin D requirements by 45% (P = 0.008). Seven subjects (26%) were able to stop 1,25-dihydroxyvitamin D completely. Serum calcium concentration remained stable, and urinary calcium and phosphorus excretion fell. Lumbar spine BMD increased by 5.5 ± 9% at 4 yr (P < 0.0001). Femoral neck and total hip BMD remained stable. At 4 yr, distal radius BMD was not different from baseline. Bone turnover markers increased significantly, reaching a 3-fold peak from baseline values at 6-12 months (P < 0.05 for all), subsequently declining to steady-state levels at 30 months. Hypercalcemia was uncommon (11 episodes in eight subjects over 4 yr; 1.9% of all values), with most episodes occurring within the first 6 months and resolving with adjustment of supplemental calcium and vitamin D.PTH(1-84) treatment of hypoparathyroidism for up to 4 yr maintains the serum calcium concentration, while significantly reducing supplemental calcium and 1,25-dihydroxyvitamin D requirements. Lumbar spine BMD increases without significant changes at other sites. These data provide support for the safety and efficacy of PTH(1-84) therapy in hypoparathyroidism for up to 4 yr.

SUBMITTER: Cusano NE

PROVIDER: S-EPMC3537109 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Therapy of hypoparathyroidism with PTH(1-84): a prospective four-year investigation of efficacy and safety.

Cusano Natalie E NE Rubin Mishaela R MR McMahon Donald J DJ Zhang Chiyuan C Ives Rebecca R Tulley Amanda A Sliney James J Cremers Serge C SC Bilezikian John P JP

The Journal of clinical endocrinology and metabolism 20121115 1

<h4>Context</h4>PTH may be an effective treatment option for hypoparathyroidism, but long-term data are not available.<h4>Objective</h4>We studied the effect of 4 yr of PTH(1-84) treatment in hypoparathyroidism.<h4>Design</h4>Twenty-seven subjects were treated with PTH(1-84) for 4 yr, with prospective monitoring of calcium and vitamin D requirements, serum and urinary calcium, serum phosphorus, bone turnover markers, and bone mineral density (BMD).<h4>Results</h4>Treatment with PTH(1-84) reduced ...[more]

PMID: 23162103

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Project description:Human recombinant (rh)PTH(1-84) was recently approved for the treatment of refractory hypoparathyroidism, based upon a short-term phase 3 clinical trial. Long-term data are needed, because no time limit was placed on the treatment period.We studied the effect of long-term rhPTH(1-84) treatment in hypoparathyroidism for up to 6 years.Prospective open-label study.Referral center.A total of 33 subjects with hypoparathyroidism.rhPTH(1-84) treatment was initiated at a starting dose of 100 ?g every other day for 6 years. Due to the availability of new dosages during the 6-year time period of the study, the dose could be and was adjusted for most patients to a daily dosing regimen.Supplemental calcium and vitamin D requirements, serum and urinary calcium (monthly for 6 mo and then biannually), serum phosphorus, bone turnover markers, and bone mineral density (BMD) biannually.Treatment with rhPTH(1-84) progressively reduced supplemental calcium requirements over 6 years by 53% (P < .0001) and 1,25-dihydroxyvitamin D requirements by 67% (P < .0001). Sixteen subjects (48%) were able to eliminate 1,25-dihydroxyvitamin D supplementation completely. Serum calcium concentration remained stable, and urinary calcium excretion fell. Lumbar spine BMD increased (3.8 ± 1%, P = .004) as did total hip BMD (2.4 ± 1%, P = .02), whereas femoral neck BMD remained stable and the distal one third radius decreased (-4.4 ±1%, P < .0001). Bone turnover markers increased significantly, reaching a 3-fold peak above baseline values at 1 year and subsequently declining but remaining higher than pretreatment values. Hypercalcemia was uncommon (12 episodes over 6 y; 2.5% of all values).Long-term, continuous therapy of hypoparathyroidism for 6 years with rhPTH(1-84) is associated with reductions in supplemental calcium and calcitriol requirements, stable serum calcium concentration, and reduced urinary calcium excretion. The safety profile remains good. These data represent the longest experience with the therapeutic use of PTH for any condition and demonstrate its long-term efficacy and safety in hypoparathyroidism.

Project description:Hypocalcemia and hyperphosphatemia are encountered in idiopathic hypoparathyroidism (IHP) and pseudohypoparathyroidism type Ib (PHP1B). In contrast to PHP1B, which is caused by resistance toward parathyroid hormone (PTH), the genetic defects leading to IHP impair production of this important regulator of mineral ion homeostasis. So far, only five PTH mutations were shown to cause IHP, each of which is located in the hormone's pre-pro leader segment and thus impair hormone secretion. In three siblings affected by IHP, we now identified a homozygous arginine-to-cysteine mutation at position 25 (R25C) of the mature PTH(1-84) polypeptide; heterozygous family members are healthy. Depending on the assay used for evaluating these patients, plasma PTH levels were either low or profoundly elevated, thus leading to ambiguities regarding the underlying diagnosis, namely IHP or PHP1B. Consistent with increased PTH levels, recombinant [Cys25]PTH(1-84) and wild-type PTH(1-84) were secreted equally well by transfected COS-7 cells. However, synthetic [Cys25]PTH(1-34) was found to have a lower binding affinity for the PTH receptor type-1 (PTH1R) than PTH(1-34) and consequently a lower efficiency for stimulating cAMP formation in cells expressing this receptor. Consistent with these in vitro findings, long-term infusion of [Cys25]PTH(1-34) resulted only in minimal calcemic and phosphaturic responses, despite readily detectable levels of [Cys25]PTH(1-34) in plasma. The mineral ion abnormalities observed in the three IHP patients are thus most likely caused by the inherited homozygous missense PTH mutation, which reduces bioactivity of the secreted hormone. Based on these findings, screening for PTH(1-84) mutations should be considered when clinical and laboratory findings are consistent with PHP1B, but GNAS methylation changes have been excluded. Differentiating between IHP and PHP1B has considerable implications for genetic counseling, therapy, and long-term outcome because treatment of IHP patients with inappropriately high doses of active vitamin D and calcium can contribute to development of nephrocalcinosis and chronic kidney disease.

Project description:Abstract RACE is an open-label study that assessed the long-term safety and efficacy of recombinant human parathyroid hormone 1-84 (rhPTH[1-84]) for the treatment of hypoparathyroidism in adults (ClinicalTrials.gov identifier NCT01297309). Patients initially received 25 or 50 µg/day of rhPTH(1-84) subcutaneously, once daily, with stepwise dose adjustments of 25 µg (up or down) to a maximum of 100 µg/day. rhPTH(1-84) could be titrated and oral calcium (Ca) and calcitriol doses adjusted at any time during the study to maintain albumin-corrected serum Ca levels in the target range of 8.0-9.0 mg/dL. A composite efficacy endpoint was the proportion of patients who achieved at least a 50% reduction from baseline (BL) in oral Ca dose (or Ca ≤500 mg/day) and at least a 50% reduction from BL in calcitriol dose (or calcitriol ≤0.25 µg/day), while normalizing or maintaining albumin-corrected serum Ca compared with BL value and not exceeding the upper limit of normal for the central laboratory. Here, we present 6-year safety and efficacy data with descriptive summary statistics (mean ± SD). The study cohort consisted of 49 patients enrolled at 12 US centers (mean age, 48.1±9.78 years; 81.6% female); data from 34 patients (69.4%) who completed 72 months (M72) of treatment with rhPTH(1-84) as of July 17, 2018 are presented here. Oral Ca and calcitriol doses were reduced by 40.4% and 72.2% at M72, respectively, and albumin-corrected serum Ca levels were maintained within the target range (BL, 8.4±0.70 mg/dL; M72, 8.4±0.68 mg/dL). At M72, 22 of 34 patients (64.7%) achieved the composite efficacy endpoint. Urinary Ca excretion declined from above-normal at BL to within the normal range (BL, 356.7±200.37 mg/24 h; M72, 213.2±128.82 mg/24 h). Mean serum creatinine levels remained stable (BL, 1.0±0.21 mg/dL; M72, 0.9±0.21 mg/dL), as did estimated glomerular filtration rate (eGFR; BL, 77.7±17.67 mL/min/1.73 m2; M72, 79.4±18.39 mL/min/1.73 m2). Serum phosphorus levels declined from above-normal at BL to within normal range (BL, 4.8±0.58 mg/dL; M72, 4.0±0.62 mg/dL); calcium-phosphorus product levels also declined (BL, 42.1±6.35 mg2/dL2; M72, 33.7±5.01 mg2/dL2). Treatment-emergent adverse events and treatment-emergent serious adverse events were reported in 98.0% and 26.5% of patients, respectively; no new safety concerns were identified. Continuous use of rhPTH(1-84) over 6 years resulted in a favorable safety profile, was effective, and improved key measurements of mineral homeostasis, notably normalization of urinary calcium. Disclosures: All of the authors disclose a relationship with Shire: advisory board member, JPB, MAL, MM, DMS, TJV; consultant, JPB, BLC, MAL, MM, DMS, TJV; grant recipient, JPB, DD, MM, MP, DMS, MLW; employee, H-ML, NS; research investigator, JPB, HB, JR, DMS, TJV, MLW, NBW; speaker, JPB, HB, MLW, NBW. Funding: Shire

Dataset Information

Therapy of hypoparathyroidism with PTH(1-84): a prospective four-year investigation of efficacy and safety.

Publications

Therapy of hypoparathyroidism with PTH(1-84): a prospective four-year investigation of efficacy and safety.

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