Palopegteriparatide Mechanism and Phase 3 Outcomes in Chronic Hypoparathyroidism

Palopegteriparatide represents a new generation of PTH analog therapy designed to overcome the pharmacokinetic limitations of earlier agents. In this portion of the HCPLive Special Report, Sara Lubitz, MD, describes palopegteriparatide as a prodrug of the N-terminal PTH(1–34) analog that is engineered to provide sustained activation of the PTH1 receptor.

The agent uses a TransCon linker to enable slow release of active PTH, resulting in a prolonged half-life of approximately 60 hours for the released hormone. This design allows for once-daily subcutaneous dosing while maintaining physiologic PTH exposure over a full 24-hour period.

Lubitz reviews key findings from the phase 3, double-blind, placebo-controlled PATHWAY trial and its long-term extension. During the initial 26-week blinded phase, approximately 68.9% of patients treated with palopegteriparatide achieved a composite endpoint of normal albumin-adjusted serum calcium without conventional therapy, compared with only 4.8% of those receiving placebo.

With continued treatment and dose titration into the open-label extension, efficacy remained robust, with roughly two-thirds of patients maintaining normal calcium levels and independence from active vitamin D and pharmacologic calcium at 78 weeks.

Longer-term data out to approximately 182 weeks further support the durability of treatment response. Lubitz notes that 96% of patients were independent from conventional therapy and 89% maintained normal albumin-adjusted serum calcium during extended follow-up. Importantly, renal parameters improved, with a clinically meaningful increase in estimated glomerular filtration rate and a sustained reduction of 24-hour urinary calcium from hypercalciuric to normal levels. Patients also reported significant improvements in disease-specific symptoms, vitality, mental clarity, and overall impact on daily life as early as week 12, with benefits persisting over 3 years.