FDA delays decision on TransCon PTH for hypoparathyroidism

Hormone replacement therapy is approved in Europe, Great Britain

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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The U.S. Food and Drug Administration (FDA) is delaying by three months its decision to approve Ascendis Pharma’s TransCon PTH (palopegteriparatide) as a hormone replacement therapy for adults with hypoparathyroidism.

The FDA decided not to approve the investigational therapy in April 2023 over concerns about its manufacturing control strategy rather than the clinical data, leading the company to resubmit its new drug application (NDA). The response counts as a major update, according to the FDA, which pushed back the timeline to review it. A decision is now expected by mid-August, three months later than the previous May 14 deadline.

“We have responded to all requests received to date from FDA and will work with the agency as they continue their review of our NDA,” Jan Mikkelsen, Ascendis’ president and CEO, said in a company news release.

Despite first being rejected, the therapy received the green light in November to enter the market under the name Yorvipath in the European Union, where it was made available to patients in Germany and Austria. And just last month, the U.K.’s regulatory agency approved Yorvipath in Great Britain and also granted it orphan drug status, which allows for 10 years of market exclusivity over similar products for chronic hypoparathyroidism in adults.

Hypoparathyroidism occurs when the parathyroid glands in the neck produce too little of the calcium-regulating parathyroid hormone (PTH). Without enough PTH in the bloodstream, calcium levels drop, causing a range of symptoms. Hypoparathyroidism is considered chronic if it persists for more than six months.

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Hypoparathyroidism due to surgery controlled with TransCon PTH

What is TransCon PTH?

TransCon PTH contains palopegteriparatide, a “prodrug” that’s modified in the body over time into teriparatide, a shortened version of PTH that works not unlike the naturally occurring full-length hormone.

Given once daily as an injection under the skin using a pre-filled pen, TransCon PTH provides a round-the-clock supply of PTH, which should restore calcium and reduce the need for it and vitamin D supplements.

Its approval in Europe was based on the results of the placebo-controlled portion of PaTHway (NCT04701203), a Phase 3 clinical trial that’s testing how safe and well tolerated Yorvipath is, and how well it works in 84 adults with hypoparathyroidism.

In the first six months, a greater proportion of patients treated with Yorvipath achieved normal levels of calcium in the blood and no longer needed conventional therapy with calcium and vitamin D compared with those on a placebo (78.7% vs. 4.8%). Yorvipath continued to show benefits for up to at least a year.

In the U.S., TransCon PTH has been available only through clinical trials and an expanded access program (EAP) that lets doctors make an online request so their patients can obtain the therapy, provided they have previous PTH-treatment experience.

“The EAP remains open for enrollment for eligible patients,” Mikkelsen said. “We remain committed to bringing TransCon PTH to adults with hypoparathyroidism in the United States, who face an urgent need for new treatments.”