TransCon PTH Granted Orphan Drug Designation in Europe

The European Commission (EC) has granted orphan drug designation to Ascendis Pharma’s experimental hormone replacement therapy TransCon PTH, currently in development for the treatment of hypoparathyroidism.

Medicines receiving this designation are intended to treat or prevent a serious rare disease — one affecting up to five in 10,000 people in the European Union — or have expected proceeds from marketing that are not sufficient to cover the costs of development. In addition, the new treatment must be of superior benefit to patients as compared with any existing medications, if available.

Companies obtaining orphan designation receive incentives such as scientific advice and protocol assistance, as well as market exclusivity for 10 years once the medicine is approved.

“This designation from the EC for TransCon PTH acknowledges the need in Europe for a hormone replacement therapy that can improve symptoms, long-term complications and quality of life for people with [hypoparathyroidism],” Dana Pizzuti, MD, senior vice president of development operations at Ascendis, said in a press release.

Hypoparathyroidism is characterized by insufficient levels of the parathyroid hormone (PTH) in the body, which is involved in regulating calcium and phosphate levels. Conventional treatment options for hypoparathyroidism include supplements to help normalize levels of calcium — calcium citrate and calcium carbonate — and vitamin D, which aids in calcium absorption.

TransCon PTH is a prodrug, or an inactive compound that is converted by the body into an active treatment. It is designed to mimic the activity of PTH, thereby normalizing calcium and phosphate levels. The therapy is administered once daily as a subcutaneous (under-the-skin) injection, from a pre-filled, ready-to-use pen injector. 

The ongoing PaTH Forward Phase 2 trial (NCT04009291) found that — given at a dose of 15, 18, or 21 mg — TransCon PTH significantly reduced calcium loss in urine and normalized the amount of calcium in the blood in adults with hypoparathyroidism.

Then, results from a six-month extension period of PaTH Forward showed that these benefits were sustained, along with improvements in the participants’ quality of life. Importantly, 76% of treated patients no longer required the use of vitamin D or calcium supplements, those trial data showed.

Ascendis is currently seeking approval from the U.S. Food and Drug Administration (FDA) for a Phase 3 trial of TransCon PTH, called PaTHway, to further test the safety and efficacy of the treatment. A similar filing in Europe is expected soon. The trial is expected to enroll an estimated 76 participants in the U.S. and Europe.

The FDA granted TransCon PTH orphan drug designation in 2018.