Fifty-six of fifty-nine adults with hypoparathyroidism stayed on a once-daily hormone injection for five straight years. At the end, Ascendis Pharma reported ↗ on June 11, 82 percent had normal blood calcium while taking no active vitamin D and less than 600 milligrams of calcium a day. That is the standard the field has chased for two decades: a drug that lets these patients put down the supplement bottle.

The data landed as ENDO 2026, the Endocrine Society's annual meeting, opened in Chicago, and it arrived next to a younger rival. The result is the cleanest look in years at a small, hard problem.

A condition stuck on a workaround

Hypoparathyroidism is what happens when the parathyroid glands, four rice-sized glands in the neck, stop making enough parathyroid hormone (PTH). Most cases follow thyroid or neck surgery that damages or removes them. PTH is the body's main calcium thermostat. Without it, blood calcium drifts low, which brings muscle cramps, tingling, brain fog, and in bad cases seizures.

For about twenty years the only treatment has been to flood the body with calcium pills and high-dose active vitamin D. That props up blood calcium, but it does not replace the missing hormone, and it pushes calcium into the urine, which strains the kidneys over time. Natpara, a lab-made full-length PTH, was the first real replacement, but Takeda pulled it ↗ for good at the end of 2024 over manufacturing problems, leaving the gap open again.

The daily drug, now with a five-year record

Palopegteriparatide, sold as Yorvipath, was built to fill it. It is a prodrug: a slightly modified version of teriparatide, the PTH fragment already used for osteoporosis, wrapped so that the active hormone peels off slowly and trickles into the blood over a full day from a single injection. Plain teriparatide ↗ spikes and clears too fast to work as a thermostat. The slow-release design is the whole point, and it is why this peptide targets the PTH1R receptor ↗ on kidney and bone the way the body's own hormone does rather than in bursts.

The FDA approved it in 2024 on the strength of the Phase 2 PaTH Forward and Phase 3 PaTHway ↗ trials. The new number is the long tail: at week 266, five years in, 82 percent of the PaTH Forward patients hit the composite target, 96 percent were off active vitamin D entirely, and 95 percent of those who started finished. For a rare disease, holding nearly every patient in a trial for five years is itself a result.

The weekly challenger

The day after Ascendis, MBX Biosciences reported ↗ the first full read on canvuparatide, a PTH peptide engineered for once-weekly dosing instead of daily. In the 64-patient Phase 2 Avail trial, 63 percent of treated patients were responders at 12 weeks versus 31 percent on placebo, a gap that cleared statistical significance (p=0.042). One year into the open-label extension, 57 percent stayed responders and 90 percent of patients were still in the study.

Canvuparatide is not approved. Its pivotal Phase 3 is set to start in the third quarter of 2026, so it sits years behind the drug already on pharmacy shelves.

What the two numbers do and do not say

It is tempting to line up 82 percent against 57 percent and call a winner. That comparison is unfair and not the point. The figures come from different trials, different patients, and different timepoints, with no head-to-head study between them. A five-year responder rate in an approved drug and a one-year rate in a Phase 2 candidate are not the same measurement.

The real axis is burden. Both peptides hit the same receptor; neither is chasing a novel target. The engineering is all in the pharmacokinetics, how fast the hormone arrives and how long it lasts. Palopegteriparatide spreads one daily shot across 24 hours and now has the deepest, longest safety record in the class. Canvuparatide is betting that one injection a week, roughly a seventh of the needles, will matter to patients who expect to take this for life, and that its control will hold up across a pivotal trial. Two precision PTH peptides, one selling proof and one selling convenience, for a condition that spent twenty years with neither.