Shares of Ascendis Pharma (ASND) were up about 3.6% on Friday after the company released some impressive five-year data from its Phase 2 trial for TransCon PTH, a drug for hypoparathyroidism.

The trial, called PaTH Forward, enrolled 59 adults with the condition, and 56 of them stuck around for the full five years. That's a pretty good retention rate for a long-term study, and it suggests patients were seeing enough benefit to keep coming back.

TransCon PTH is already approved as YORVIPATH in the U.S., European Union, and other markets for adults with hypoparathyroidism. But this data gives a longer-term view of how the drug holds up over time.

Most Patients Maintained Treatment Goals at Five Years

The company said the therapy continued to replicate the effects of natural parathyroid hormone (PTH), which is exactly what you want it to do. That translated into stable calcium control, healthy kidneys and bones, and a better quality of life for patients. Most were even able to ditch their conventional treatments.

At Week 266 — that's roughly five years — 82% of patients hit a composite endpoint that included maintaining normal serum calcium levels, avoiding active vitamin D, and keeping calcium supplementation under 600 mg per day. That's a pretty high bar, and most cleared it.

Broken down further: 88% of patients maintained normal albumin-adjusted serum calcium levels, 96% were independent of active vitamin D therapy, and 95% didn't need therapeutic doses of calcium supplements anymore.

Kidney Function and Quality of Life Improvements Sustained

The kidney benefits were particularly striking. Mean estimated glomerular filtration rate (eGFR) — a key measure of kidney function — increased by 9.4 mL/min/1.73 m² from baseline and stayed elevated through five years. That's a meaningful improvement for patients whose kidneys are often under stress from the disease.

Urine calcium levels also dropped substantially, normalized within 26 weeks, and stayed in the normal range for the rest of the study. That's important because high urine calcium can lead to kidney stones and other problems.

Patients also reported lasting improvements in symptoms, daily functioning, and cognitive well-being. So it's not just lab values looking good — people actually felt better.

Safety Profile Remained Consistent

On the safety front, TransCon PTH was generally well tolerated. Most side effects were mild to moderate, and no new safety signals popped up over the five-year follow-up. Importantly, no patient stopped taking the drug because of it.

That's a reassuring sign for a drug that patients may need to take for many years.

As of Friday's publication, Ascendis Pharma shares were trading at $223.37, up 3.60% on the day.