Original Full Length ArticleEvaluation of the efficacy, safety and pharmacokinetic profile of oral recombinant human parathyroid hormone [rhPTH(1-31)NH2] in postmenopausal women with osteoporosis

ContextTreatment of osteoporosis with subcutaneous (SC) injections of rhPTH(1-34) or rhPTH(1-84) is associated with significant improvements in BMD and reductions in osteoporotic fractures. However, subcutaneous injections can be associated with discomfort and thus deteriorating compliance.ObjectiveThe UGL-OR1001 trial aimed to establish the efficacy and safety parameters of a novel oral tablet formulation of rhPTH(1-31)NH2 and matching placebo tablets and open-label teriparatide positive control in postmenopausal women with osteoporosis.Design24 weeks of randomized, double-blind treatment with once daily doses of 5 mg oral treatment or corresponding placebo, or open-label subcutaneous teriparatide.Patients or other participantsWomen diagnosed with postmenopausal osteoporosis as detected by lumbar spine DXA, with an exclusion of those with prior treatment with bone active agents.Intervention(s)Orally formulated recombinant human PTH(1-31)NH2 and placebo, or open-label subcutaneous teriparatide as a positive control.Main outcome measure(s)The primary endpoint was to characterize the percent change from baseline in bone mineral density (BMD) at L1-L4 axial lumbar spine after 24 weeks in the rhPTH(1-31)NH2 arm. Secondary and exploratory endpoints included safety and tolerability of the oral formulation, measurement of biochemical markers of bone turnover, and evaluation of the PK profile at first and last dose. The study was registered at ClinicalTrials.gov with the identifier: NCT01321723.ResultsThe oral tablet formulation of rhPTH(1-31)NH2 resulted in similar PK profiles at both timepoints with mean Cmax values similar to subcutaneous administration. In the rhPTH(1-31)NH2 arm, a 2.2% increase in lumbar spine BMD was observed compared to baseline (p < 0.001), while no change was observed in the placebo arm. Open-label teriparatide resulted in a 5.1% increase in LS BMD (p < 0.001). In the oral PTH study arm, the bone formation marker osteocalcin was increased by 32%, 21% and 23% at Weeks 4, 12 and 24, respectively. There was no significant increase in the level of the bone resorption marker CTx-1.ConclusionsIn summary, these data demonstrate that enteric-coated oral tablet formulation technology consistently generated robust levels of exposure of rhPTH(1-31)NH2 leading to induction of bone formation without inducing bone resorption resulting in significantly increased levels of LS BMD. Few adverse events were observed, recommending this orally delivered drug candidate for further development.

► Oral rhPTH(1-31)NH2 shows a PK profile compatible with the anabolic effect of PTH ► Oral rhPTH(1-31)NH2 induces a 2.2% increase in LS BMD over 6 months ► Oral rhPTH(1-31)NH2 induces a modest increase in bone formation markers ► Oral rhPTH(1-31)NH2 does not cause an increase in bone resorption markers ► Further clinical studies of this oral formulation of rhPTH(1-31)NH2 are warranted