Ascendis Seeks FDA Approval of TransCon PTH for Adults

Treatment could become 1st in class for hypoparathyroidism, developer says

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Ascendis Pharma has submitted an application to the U.S. Food and Drug Administration (FDA) seeking approval of its treatment candidate TransCon PTH for adults with hypoparathyroidism, the company announced.

“Our data support that TransCon PTH, if approved, could become the first-in-class therapy to address the underlying cause of disease and address the urgent needs of patients in the U.S., who today have no such treatment options available,” Dana Pizzuti, senior vice president and chief medical officer at Ascendis, said in a press release.

Ascendis is expected to submit a similar application to the European Medicines Agency (EMA) later this year, seeking the therapy’s approval in the EU.

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Hypoparathyroidism is caused by abnormally low levels of the parathyroid hormone (PTH), which regulates levels of calcium and phosphorus in the body. TransCon PTH contains a long-lasting precursor of this hormone designed to be administered once daily via under-the-skin (subcutaneous) injection to normalize PTH levels.

“We believe the best way to treat hypoparathyroidism is to replace the missing endogenous hormone at stable, physiological levels 24 hours a day,” Pizzuti said.

Hypoparathyroidism treatment candidate in trials

The new drug application for the hypoparathyroidism treatment is supported by data from the Phase 3 clinical trial PaTHway (NCT04701203). In this trial, 82 adults with the rare disease were given either TransCon PTH or a placebo daily for six months. The study was double-blind, meaning neither researchers nor participants knew which patients were getting the therapy and which the placebo.

Results, announced earlier this year, showed that significantly more patients on the investigational therapy had normal calcium levels without a need for standard treatments by the study’s end (78.7% vs. 4.8%). The therapy also outperformed the placebo at easing patients’ symptoms and improving their self-reported physical function.

Ascendis’ application also is supported by data from the Phase 2 PaTH Forward trial (NCT04009291). Initial findings showed that TransCon PTH outperformed a placebo at normalizing calcium levels after one month.

Long-term trial data showed most patients continued to have normal calcium levels without a need for conventional treatment after more than 1.5 years on TransCon PTH.

In both trials, the experimental therapy was generally well-tolerated, with no patients stopping treatment due to side effects. The most common adverse events (side effects) associated with TransCon PTH in the Phase 3 PaTHway study were injection site reactions, headache, unusual skin sensations, and fatigue.

“Our Phase 2 and Phase 3 trials were the first ever in which most treated patients (86% and 79%, respectively; at 6 months of treatment) achieved normalization of serum [blood] calcium and independence from conventional therapy,” Pizzuti said.

“Further underscoring the potential benefits of our TransCon PTH product candidate, treated patients reported significant reductions in disease-specific physical and cognitive symptoms and significant improvements in their quality of life,” Pizzuti added.

TransCon PTH is also being tested in adults with hypoparathyroidism in a Phase 3 clinical trial in Japan, the results of which are expected to be announced later this year. Another Phase 3 study (NCT05387070) in China also is ongoing.

The investigational therapy has been granted orphan drug status — designed to incentivize the development of therapies to treat rare conditions — in the U.S. and in Europe.