FDA Grants Orphan Drug Designation to Treatment for Rare Endocrine Disorder

The US Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) to Ascendis Pharma’s long-acting prodrug for parathyroid hormone (PTH) TransCon PTH currently in development for the treatment of hypoparathyroidism, a rare endocrine disorder.

“We are pleased about the ODD for TransCon PTH, which reflects the need for a true PTH replacement therapy that more fully addresses all aspects of hypoparathyroidism,” Ascendis Pharma’s chief medical officer Jonathan Leff, MD, said in a recent statement.

Characterized by insufficient levels of PTH, hypoparathyroidism results in low calcium levels and increased phosphate levels within the blood. The rare disorder is estimated to affect around 80,000 individuals in the United States alone. Most individuals develop this condition after having experienced damage to, or accidental removal of, the parathyroid glands during thyroid surgery.

Many of these patients experience weakness, muscle cramps, abnormal sensations including tinging, burning, and paresthesias, along with memory loss, impaired judgment, and headaches. Furthermore, patients are also known to experience a decreased quality of life. More long-term symptoms associated with the disorder include extraskeletal calcium depositions which can result in diminished renal function.

Conventional therapy to treat hypoparathyroidism consists of active vitamin D analogs and calcium supplementation, but this approach does not successfully control the disease fully and it could potentially result in renal disease, according to Ascendis Pharma. In fact, because of this, these patients at 4 times the risk of renal disease than their healthy counterparts are.

TransCon PTH was developed to restore PTH to physiologic levels, which would result in normal blood and urinary calcium levels, serum phosphate levels, as well as bone turnover.

“We have recently completed a phase 1 trial in healthy adults, which reinforced the potential of TransCon PTH to restore PTH to physiological levels for 24 hours per day. We are committed to developing innovative new therapies that improve patients’ lives and look forward to advancing Transcon PTH,” Dr Leff said.

After speaking with regulatory agencies, Ascendis Pharma has plans to launch a phase 3 program to further explore TransCon PTH for the first quarter of 2019.