TransCon PTH Phase 3 Clinical Trial Moving Forward

Joana Carvalho, PhD avatar

by Joana Carvalho, PhD |

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TransCon PTH

Ascendis Pharma anticipates it will announce top-line data from a new Phase 3 clinical trial of TransCon PTH, the company’s investigational hormone replacement therapy for hypoparathyroidism, before the end of the year, according to a recent company update.

The study, called PaTHway (NCT04701203), seeks to assess the safety, tolerability, and effectiveness of the therapy in 76 adults with hypoparathyroidism. Recruitment is expected to start soon at clinical sites in North America and Europe. More information about recruiting sites should become available here.

During the study, participants will be assigned randomly to receive daily under-the-skin (subcutaneous) injections of TransCon PTH, or a placebo, for 26 weeks. TransCon PTH will be given at a fixed starting dose of 18 mcg during the first 10 weeks of treatment, and then adjusted to each patients’ needs for the remaining 16 weeks.

After completing the 26 weeks of treatment, patients will continue to be monitored in the study’s long-term extension, during which all will be treated with TransCon PTH, given at a personalized dose.

“We expect 2021 will mark a number of key clinical and commercial milestones,” Jan Mikkelsen, president and CEO of Ascendis Pharma, said in a press release. “We expect to further advance our late stage endocrinology pipeline … and to obtain phase 3 results for TransCon PTH in adult hypoparathyroidism.”

In addition to top-line data from PaTHway, Ascendis also expects to announce new one-year data from the extension study of PaTH Forward, as well as requesting authorization to launch a new clinical trial of its hypoparathyroidism treatment candidate in Japan later this year.

PaTH Forward is a double-blind, Phase 2 trial (NCT04009291) comparing the safety and effectiveness of three daily doses (15, 18, or 21 mcg) of TransCon PTH to a placebo in 59 adults with hypoparathyroidism.

Previous data from the study showed that after four weeks of treatment, TransCon PTH was able to normalize calcium levels in the blood and urine, as well as eliminate the need for conventional treatments — vitamin D supplements and high doses of calcium supplements — in a higher proportion of patients compared with the placebo (50% vs. 15%).

Six-month data from the study’s long-term extension, where all patients started being treated with TransCon PTH at a daily dose of 6–30 mcg, showed these benefits in calcium normalization were sustained, and accompanied by improvements in quality of life. Analyses performed at the time also demonstrated that most participants stopped taking vitamin D and calcium supplements.

According to Ascendis, as of Jan. 5, 58 patients are still being treated in the long-term extension of PaTH Forward.

TransCon PTH is a long-acting prodrug, or inactive precursor, designed to mimic the activity of the parathyroid hormone (PTH) that is found at low levels in people with hypoparathyroidism. By doing so, the investigational therapy is intended to normalize calcium and phosphate levels.

TransCon PTH was named an orphan drug for the treatment of hypoparathyroidism in the U.S. and Europe.