Citations

Abstract Hypoparathyroidism is an endocrine disease caused by insufficient levels of PTH, which acts directly on bone and kidney and indirectly on the intestine to regulate calcium and phosphate balance. In clinical trials, palopegteriparatide (TransCon PTH) treatment enabled independence from conventional therapy (no active vitamin D, ≤600 mg/d calcium) and maintained serum biochemistries within normal ranges. The current analyses describe patterns of change in BMD, serum bone turnover markers, and serum and urine calcium in adults with chronic hypoparathyroidism treated with palopegteriparatide through 3 years of the PaTH Forward trial. Baseline BMD Z-scores for the LS, TH, FN, and 1/3 distal radius were above zero, indicating bone mass exceeding age-adjusted normative values. BMD decreased from these elevated baseline levels with palopegteriparatide treatment, with larger reductions during the first 26 weeks and modest declines thereafter. Mean BMD Z-scores at week 162 remained above zero for all 4 sites. Participants with lower baseline BMD (Z-scores below −1 and T-scores below −2.5) generally exhibited lesser declines in BMD versus those with higher baseline BMD. Palopegteriparatide treatment was associated with early increases in bone resorption (serum C-terminal telopeptide of type I collagen, CTx) and bone formation (serum procollagen type 1 N-terminal propeptide, P1NP) that peaked at weeks 12 and 26, respectively, followed by declines to levels moderately higher than baseline at week 162. Mean CTx and P1NP in the overall population and the subgroup of postmenopausal women were below their upper limits of normal from weeks 58-162. At week 162, mean serum and median urine calcium remained within normal ranges and 91% of participants were independent from conventional therapy. These results suggest that long-term palopegteriparatide therapy in adults with chronic hypoparathyroidism gradually returns the skeleton toward its natural state thereby enhancing the skeleton’s contribution to calcium homeostasis.

Abstract Disclosure: A.A. Khan: Alexion Pharmaceuticals, Inc., Amgen Inc, Amolyt Pharma, Ascendis Pharma. B.L. Clarke: Amolyt Pharma, Ascendis Pharma, EnteraBio, Extend Bio, Takeda. M.R. Rubin: Ascendis Pharma, MBX Biosciences. P.E. Schwarz: Aventis Pharmaceuticals, Genmab, Novo Nordisk. D.M. Shoback: Ascendis Pharma. C. Gagnon: Amgen Inc, Ascendis Pharma, Novo Nordisk, Shire, Takeda. A. Palermo: None. L.G. Abbott: Abbott Laboratories, Ascendis Pharma, Clarus, Shire, Takeda. L. Kohlmeier: Amgen Inc, Ascendis Pharma, Radius Health, Inc. E. Tsourdi: Alexion Pharmaceuticals, Inc., Ascendis Pharma, Kyowa Kirin, Takeda, UCB. F. Cetani: None. R. Jain: Amgen Inc, Ascendis Pharma. C. Zhao: Ascendis Pharma. B. Lai: Ascendis Pharma. M.A. Makara: Ascendis Pharma. J. Ukena: Ascendis Pharma. C.T. Sibley: Ascendis Pharma. A.D. Shu: Ascendis Pharma. L. Rejnmark: Amolyt Pharma, Ascendis Pharma, BridgeBio, Kyowa Kirin, Takeda. Background: Hypoparathyroidism is an endocrine disease caused by insufficient levels of parathyroid hormone (PTH) and is associated with reduced quality of life and a high comorbidity burden. Conventional therapy for hypoparathyroidism (active vitamin D and elemental calcium) aims to alleviate hypocalcemia but does not address insufficient PTH and may increase the risk of renal complications. Palopegteriparatide is a prodrug of PTH(1-34), administered subcutaneously once daily, designed to provide active PTH within the physiological range for 24 hours/day. It is approved by the Food and Drug Administration, European Commission, and Medicines and Healthcare products Regulatory Agency. This analysis evaluated the long-term efficacy and safety of palopegteriparatide in adults with chronic hypoparathyroidism through week 156 of the PaTHway trial. Methods: PaTHway is a phase 3 trial with a 26-week randomized, double-blind, placebo-controlled period followed by an ongoing open-label extension period. Serum biochemistries were assessed at baseline and regular intervals. Renal function was assessed by estimated glomerular filtration rate (eGFR). Safety assessments included 24-hour urine calcium and treatment-emergent adverse events (TEAEs). Results: At week 156, 89% (73/82) of participants remained in the trial; of those, 96% were independent from conventional therapy (no active vitamin D and ≤600 mg/day elemental calcium) and 88% had normal albumin-adjusted serum calcium levels (8.3-10.6 mg/dL) with a mean (SD) of 8.9 (0.6) mg/dL. Mean (SD) serum phosphate (3.4 [0.6] mg/dL) and calcium x phosphate product (30.6 [5.4] mg2/dL2) levels remained within normal ranges through week 156. Mean (SD) eGFR at week 156 was 78.0 (14.5) mL/min/1.73 m2, reflecting a mean (SD) increase of 8.8 (11.9) mL/min/1.73 m2 from baseline (P<0.0001); 59% and 43% of participants had an increase in eGFR of ≥5 mL/min/1.73 m2 and ≥10 mL/min/1.73 m2, respectively. Among participants with baseline eGFR <60 mL/min/1.73 m2 (n=23), the mean (SD) increase in eGFR was 14.0 (8.9) mL/min/1.73 m2 from baseline to week 156. Mean (SD) 24-hour urine calcium levels normalized with palopegteriparatide treatment, remaining below the upper limit of normal (≤250 mg/day) through week 156 (162.1 [117.8] mg/day). TEAEs were mostly grade 1 or 2, with no new safety signals identified. Conclusion: Through year 3 of the PaTHway trial, retention rate was high and palopegteriparatide demonstrated consistent longer-term safety and efficacy, which included the maintenance of serum and urine biochemistries within normal levels and sustained improvement in renal function. Presentation: Saturday, July 12, 2025

Abstract Context Conventional therapy for hypoparathyroidism aims to alleviate symptoms of hypocalcemia but does not address insufficient parathyroid hormone (PTH) levels. Objective Assess the long-term efficacy and safety of TransCon PTH (palopegteriparatide) for hypoparathyroidism. Design Phase 3 trial with a 26-week, double-blind, placebo-controlled period followed by a 156-week, open-label extension (OLE). Setting Twenty-one sites across North America and Europe. Participants A total of 82 adults with hypoparathyroidism were randomized and received study drug and 78 completed week 52. Intervention(s) All OLE participants received TransCon PTH administered once daily. Main Outcome Measure(s) Multicomponent efficacy endpoint: proportion of participants at week 52 who achieved normal serum calcium (8.3-10.6 mg/dL) and independence from conventional therapy (≤600 mg/day of elemental calcium and no active vitamin D). Other efficacy endpoints included patient-reported outcomes and bone mineral density. Safety was assessed by 24-hour urine calcium and treatment-emergent adverse events. Results At week 52, 81% (63/78) met the multicomponent efficacy endpoint, 95% (74/78) achieved independence from conventional therapy, and none required active vitamin D. Patient-reported outcomes showed sustained improvements in quality of life, physical functioning, and well-being. Mean bone mineral density Z-scores decreased toward age- and sex-matched norms from baseline to week 52. Mean (SD) 24-hour urine calcium excretion decreased from 376 (168) mg/day at baseline to 195 (114) mg/day at week 52. Most treatment-emergent adverse events were mild or moderate and none led to trial discontinuation during the OLE. Conclusion At week 52 of the PaTHway trial, TransCon PTH showed sustained efficacy, safety, and tolerability in adults with hypoparathyroidism.

Abstract Disclosure: S.W. Ing: Advisory Board Member; Self; Ultragenyx, Amolyt. Grant Recipient; Self; Alexion Pharmaceuticals, Inc.. Research Investigator; Self; BridgeBio Pharma, Takeda, Amolyt, Radius Health, Inc, Ultragenyx. P. Harmatz: Research Investigator; Self; BridgeBio Pharma. S. Mora: Research Investigator; Self; BridgeBio Pharma. E.A. Imel: Research Investigator; Self; BridgeBio Pharma. P.J. Tebben: Research Investigator; Self; BridgeBio Pharma. M.L. Warren: Research Investigator; Self; BridgeBio Pharma, Ascendis, Amolyt. Speaker; Self; Ascendis. N. Ma: Research Investigator; Self; Calcilytix Therapeutics, Ultragenyx, Inozyme. Other; Self; Up To Date. A.A. Khan: Research Investigator; Self; BridgeBio Pharma, Ascendis. A. Palermo: Research Investigator; Self; BridgeBio Pharma. B. Decallonne: Research Investigator; Self; BridgeBio Pharma. S. Lemoine: Research Investigator; Self; BridgeBio Pharma, Kyowa Kirin. G. Mantovani: Research Investigator; Self; BridgeBio Pharma. A. Linglart: Consulting Fee; Self; Alexion, Novo Nordisk, Merck, Pfizer, Inc.. Research Investigator; Self; BridgeBio Pharma, Kyowa Kirin. H. Wasserman: Research Investigator; Self; BridgeBio Pharma. A.P. Barbosa: Research Investigator; Self; BridgeBio Pharma. C. Cardot-bauters: Research Investigator; Self; BridgeBio Pharma. M. Roberts: Employee; Self; BridgeBio Pharma. A. Mathew: Employee; Self; BridgeBio Pharma. S. Adler: Employee; Self; BridgeBio Pharma. M.C. Zillikens: Research Investigator; Self; BridgeBio Pharma. R.J. Clifton-Bligh: Consulting Fee; Self; Ipsen, Kyowa Kirin, Amgen Inc, Eisai. Research Investigator; Self; BridgeBio Pharma. L. Rejnmark: Research Investigator; Self; BridgeBio Pharma, Ascendis, Amolyt, Takeda, Kyowa Kirin. Autosomal dominant hypocalcemia type 1 (ADH1), caused by gain-of-function calcium-sensing receptor gene (CASR) variants, is characterized by low parathyroid hormone (PTH) concentrations, hypocalcemia, hypercalciuria, hyperphosphatemia and hypomagnesemia. While a rare disease, ADH1 is one of the more frequently identified causes of genetic hypoparathyroidism. Conventional therapy includes calcium (Ca) and/or active vitamin D, but this regimen incompletely corrects the hypocalcemia and is associated with persistent hypercalciuria, which may result in renal complications including nephrocalcinosis (NC), nephrolithiasis (NL), and chronic kidney disease (CKD). The CLARIFY disease monitoring study [NCT05227287] is a global, multicenter, longitudinal study to understand disease burden, management, and progression in children and adults with ADH1 over a 5-year period. Here we report data on the characteristics of adult participants at study entry. As of November 2023, 45 adults (≥18 years) with ADH1 were enrolled, with a mean±SD age of 42.1±16.5 years (range 18-80). The mean±SD age of a hypocalcemia diagnosis was 19.1±19.1 years, while the mean±SD age for a diagnosis of ADH1 was 28.2±20.6 years. As reported on medical history, in decreasing order of prevalence, 36% (16) had NC, 22% (10) had intracranial calcifications, 11% (5) had history of seizures, 11% (5) had CKD, 9% (4) had cataracts, 7% (3) had NL, and 4% (2) had undergone renal transplant. Treatment data were available for 43 participants and included the following: 74% (32) Ca and active vitamin D, 9% (4) Ca alone, 9% (4) active vitamin D alone, 37% (16) magnesium, 33% (14) thiazide diuretics, 26% (11) potassium, 7% (3) phosphate binder, 7% (3) PTH, and 5% (2) no treatment. Mean±SD fasting values collected prior to conventional therapy dose are presented. PTH concentrations (10.1±8.2 pg/mL [nl 15-65]) and albumin-corrected calcium ([cCa]=7.5±1.0 mg/dL [nl 8.5-10.5]) were low. Despite the low mean cCa, the mean 24-hr urine calcium was elevated (268±183 mg/d, [nl <250 women, <300 men]). Blood phosphate was 4.8±0.8 mg/dL [nl 2.5-4.8] while blood magnesium was 1.8±0.2 mg/dL [nl 1.8-2.4]. 25-OH vitamin D was 35.0±13.5 ng/mL [nl 30-80]. Renal function as assessed by CKD-EPIcr_R showed eGFR of 86±23 mL/min/1.73m² (range 36-123). This study represents the largest cohort of adults with ADH1 described to date. These data highlight variability in therapeutic approaches in a real-world setting with some participants receiving up to 6 different medications/supplements. Despite being followed in expert centers, and treated with available therapies, patients on average have low cCa with relatively high 24-hr urine calcium excretion. The CLARIFY study provides an opportunity to better understand the progression and burden of disease in participants with ADH1. Presentation: 6/3/2024

Abstract Disclosure: B. Clarke: Advisory Board Member; Self; Ascendis Pharma, Takeda, Entera-Bio, Extend-Bio, Amolyt. Consulting Fee; Self; Ascendis Pharma, Takeda, Entera-Bio, Extend-Bio, Amolyt. Grant Recipient; Self; Ascendis Pharma, Takeda. Research Investigator; Self; Ascendis Pharma, Takeda. Other; Self; Ascendis Pharma, Takeda, Entera-Bio, Extend-Bio, Amolyt. A.A. Khan: Advisory Board Member; Self; Amgen Inc, Alexion Pharmaceuticals, Inc., Ascendis Pharma, Takeda, Ultragenyx. Consulting Fee; Self; Amgen Inc, Alexion Pharmaceuticals, Inc., Amolyt, Ascendis Pharma, Ultragenyx. Grant Recipient; Self; Amolyt. Research Investigator; Self; Radius Health, Inc, Takeda, Ultragenyx, Amolyt, Ascendis Pharma, Chugai. Speaker; Self; Amgen Inc. Other; Self; Amgen Inc, Alexion Pharmaceuticals, Inc., Ascendis Pharma, Takeda, Ultragenyx. M.R. Rubin: Research Investigator; Self; Chugai Pharma. P.E. Schwarz: Stock Owner; Self; Novo Nordisk, Genmab. T.J. Vokes: Consulting Fee; Self; Takeda, Ascendis Pharma. Research Investigator; Self; Ascendis Pharma, Radius Health, Inc. D.M. Shoback: Research Investigator; Self; Bone Health Tech. C. Gagnon: Advisory Board Member; Self; Novo Nordisk. Grant Recipient; Self; Shire, Takeda, Ascendis Pharma. Research Investigator; Self; Novo Nordisk. Other; Self; Amgen Inc. A. Palermo: Consulting Fee; Self; Theramex, Bruno, Farmaceutici, Amgen Inc. Grant Recipient; Self; Amgen Inc. Research Investigator; Self; Amgen Inc, Shire, Ascendis Pharma. Speaker; Self; UCB, Amgen Inc. L.G. Abbott: Advisory Board Member; Self; Ascendis. Research Investigator; Self; Takeda, Shire, Ascendis Pharma. Speaker; Self; Abbott Laboratories, Clarus. Other; Self; Ascendis. L.C. Hofbauer: Advisory Board Member; Self; Amgen Inc, UCB. Other; Self; Amgen Inc, UCB. L. Kohlmeier: Advisory Board Member; Self; Alexion Pharmaceuticals, Inc., Ascendis Pharma. Research Investigator; Self; Ascendis Pharma. Speaker; Self; Amgen Inc, Radius Health, Inc, Alexion Pharmaceuticals, Inc., Ascendis Pharma. Other; Self; Amgen Inc, Radius Health, Inc, Alexion Pharmaceuticals, Inc., Ascendis Pharma, MediMaps. F. Cetani: None. S. Phil: Employee; Self; Ascendis Pharma. X. An: Employee; Self; Ascendis Pharma. A.R. Smith: Employee; Self; Ascendis Pharma. B. Lai: Employee; Self; Ascendis Pharma. J. Le: Employee; Self; Ascendis Pharma. J. Ukena: Employee; Self; Ascendis Pharma. C. Sibley: Employee; Self; Ascendis Pharma. A. Shu: Employee; Self; Ascendis Pharma. L. Rejnmark: Advisory Board Member; Self; Takeda, Amolyt. Research Investigator; Self; Takeda, Kyowa Kirin International, Ascendis Pharma, Calcilytix Therapeutics. Other; Self; Calcilytix Therapeutics. Objective: Evaluate the long-term efficacy and safety of TransCon PTH as a potential hormone replacement therapy for hypoparathyroidism. Methods: PaTHway is a phase 3 trial of TransCon PTH with a placebo (PBO)-controlled 26-week blinded period and a 156-week open-label extension (OLE) period. Results through Week 52 (26 weeks blinded + 26 weeks OLE) are reported. Three-component efficacy endpoint: normal serum calcium (8.3-10.6 mg/dL) and independence from conventional therapy (≤600 mg/day of elemental calcium and no active vitamin D). Other endpoints: Hypoparathyroidism Patient Experience Scale (HPES); 36-Item Short Form Survey (SF-36); bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA); bone turnover markers (BTM) procollagen type 1 N-terminal propeptide (P1NP) and C-terminal telopeptide of type 1 collagen (CTx). Safety was assessed by 24-hour urine calcium and reported treatment-emergent adverse events (TEAEs). Results: Of the 82 participants given study drug, 79 completed blinded treatment and entered the OLE, and 78 (59 TransCon PTH/TransCon PTH, 19 PBO/TransCon PTH) completed Week 52. Overall at Week 52, 81% (63/78) met the efficacy endpoint, 95% (74/78) achieved independence from conventional therapy, and none required active vitamin D. Mean albumin-adjusted serum calcium was within the normal range at all time points in the OLE (8.9 mg/dL at Week 52). Mean Week 52 HPES scores showed sustained improvement from baseline in disease-related symptoms and the impact of hypoparathyroidism on physical functioning and daily life. Mean Week 52 SF-36 physical functioning scores also remained above baseline. In the TransCon PTH/TransCon PTH group, mean BMD corrected Z-scores trended toward norms from baseline to Weeks 26 and 52:1.5, 0.7, 0.7 at the lumbar spine (L1-L4); 0.8, 0.3, 0.3 at femoral neck; 0.9, 0.5, 0.4 at total hip; and 0.3, 0.3, 0.3 at distal 1/3 radius; P1NP peaked at Week 26 and CTx at Week 12. Smaller incremental changes were seen in BMD and BTM from Weeks 26 to 52 than baseline to Week 26. In the PBO/TransCon PTH group, changes in BMD and BTM from Week 26 to 52 resembled those in the TransCon PTH/TransCon PTH group from baseline to Week 26. Mean 24-hour urine calcium excretion decreased from 376 mg/day at baseline to 195 mg/day at Week 52. Most TEAEs were mild or moderate and none led to discontinuation of the study drug or trial. Conclusions: At Week 52 of the PaTHway trial, TransCon PTH showed a similar sustained efficacy, safety, and tolerability profile to that of Week 26, demonstrating its potential as a hormone replacement therapy for adults with hypoparathyroidism. Indices of skeletal dynamics trended toward age- and sex-matched norms in the TransCon/TransCon PTH group. TransCon PTH treatment in the PBO/TransCon PTH group showed rapid improvement in all outcomes in the first 26 weeks of the OLE consistent with the pattern in the TransCon PTH group during the blinded period. Presentation: Saturday, June 17, 2023

ABSTRACT Conventional therapy for hypoparathyroidism consisting of active vitamin D and calcium aims to alleviate hypocalcemia but fails to restore normal parathyroid hormone (PTH) physiology. PTH replacement therapy is the ideal physiologic treatment for hypoparathyroidism. The double-blind, placebo-controlled, 26-week, phase 3 PaTHway trial assessed the efficacy and safety of PTH replacement therapy for hypoparathyroidism individuals with the investigational drug TransCon PTH (palopegteriparatide). Participants (n = 84) were randomized 3:1 to once-daily TransCon PTH (initially 18 μg/d) or placebo, both co-administered with conventional therapy. The study drug and conventional therapy were titrated according to a dosing algorithm guided by serum calcium. The composite primary efficacy endpoint was the proportion of participants at week 26 who achieved normal albumin-adjusted serum calcium levels (8.3–10.6 mg/dL), independence from conventional therapy (requiring no active vitamin D and ≤600 mg/d of calcium), and no increase in study drug over 4 weeks before week 26. Other outcomes of interest included health-related quality of life measured by the 36-Item Short Form Survey (SF-36), hypoparathyroidism-related symptoms, functioning, and well-being measured by the Hypoparathyroidism Patient Experience Scale (HPES), and urinary calcium excretion. At week 26, 79% (48/61) of participants treated with TransCon PTH versus 5% (1/21) wiplacebo met the composite primary efficacy endpoint (p < 0.0001). TransCon PTH treatment demonstrated a significant improvement in all key secondary endpoint HPES domain scores (all p < 0.01) and the SF-36 Physical Functioning subscale score (p = 0.0347) compared with placebo. Additionally, 93% (57/61) of participants treated with TransCon PTH achieved independence from conventional therapy. TransCon PTH treatment normalized mean 24-hour urine calcium. Overall, 82% (50/61) treated with TransCon PTH and 100% (21/21) wiplacebo experienced adverse events; most were mild (46%) or moderate (46%). No study drug-related withdrawals occurred. In conclusion, TransCon PTH maintained normocalcemia while permitting independence from conventional therapy and was well-tolerated in individuals with hypoparathyroidism. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). Abstract TransCon PTH is an investigational once-daily prodrug providing sustained release of active PTH designed to maintain stable PTH levels in the physiological range for 24 hours/day. The PaTHway trial met all primary and key secondary endpoints with statistically significant differences from placebo. Most adverse events (AEs) were mild/moderate. Injection-site reactions and headaches were the most common treatment-related AEs.

ABSTRACT In this narrative review, we present data gathered over four decades (1980–2020) on the epidemiology, pathophysiology and genetics of primary hyperparathyroidism (PHPT). PHPT is typically a disease of postmenopausal women, but its prevalence and incidence vary globally and depend on a number of factors, the most important being the availability to measure serum calcium and parathyroid hormone levels for screening. In the Western world, the change in presentation to asymptomatic PHPT is likely to occur, over time also, in Eastern regions. The selection of the population to be screened will, of course, affect the epidemiological data (ie, general practice as opposed to tertiary center). Parathyroid hormone has a pivotal role in regulating calcium homeostasis; small changes in extracellular Ca++ concentrations are detected by parathyroid cells, which express calcium-sensing receptors (CaSRs). Clonally dysregulated overgrowth of one or more parathyroid glands together with reduced expression of CaSRs is the most important pathophysiologic basis of PHPT. The spectrum of skeletal disease reflects different degrees of dysregulated bone remodeling. Intestinal calcium hyperabsorption together with increased bone resorption lead to increased filtered load of calcium that, in addition to other metabolic factors, predispose to the appearance of calcium-containing kidney stones. A genetic basis of PHPT can be identified in about 10% of all cases. These may occur as a part of multiple endocrine neoplasia syndromes (MEN1–MEN4), or the hyperparathyroidism jaw-tumor syndrome, or it may be caused by nonsyndromic isolated endocrinopathy, such as familial isolated PHPT and neonatal severe hyperparathyroidism. DNA testing may have value in: confirming the clinical diagnosis in a proband; eg, by distinguishing PHPT from familial hypocalciuric hypercalcemia (FHH). Mutation-specific carrier testing can be performed on a proband's relatives and identify where the proband is a mutation carrier, ruling out phenocopies that may confound the diagnosis; and potentially prevention via prenatal/preimplantation diagnosis. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). Abstract The prevalence and incidence of PHPT vary around the world and depend on a number of factors, the most important being availability of serum calcium (and parathyroid hormone) measurement for screening, which in the Western world has shifted its presentation to an asymptomatic disorder. Clonally dysregulated overgrowth of one or more parathyroid glands together with reduced expression of CaSRs is the most important pathophysiologic basis of PHPT, which may also occur as a part of inherited syndromes or as a nonsyndromic isolated endocrinopathy in 10% of cases. Genetic testing has roles in establishing the clinical diagnosis, although its value requires assessments using GRADE(176) methodology, which is recommended for future consideration.