Millendo Therapeutics announces Positive Topline Phase 2 Results of ATR-101 in Classic CAH

Millendo Therapeutics announced positive topline results from a Phase 2 proof-of-concept study of ATR-101 in classic congenital adrenal hyperplasia (CAH), a rare inherited endocrine disease characterized by abnormal hormone levels and overgrowth of the adrenal glands.

In the Phase 2 study, 7 of the first 10 patients demonstrated a clear biological effect as measured by reductions in 17-hydroxyprogesterone (17-OHP), a key measure of disease control. Based on the trial results, Millendo ended the trial early and the U.S. Food and Drug Administration (FDA) has granted orphan drug status to ATR-101 in this indication.

“The encouraging topline results announced today support the further clinical development of ATR-101 in classic congenital adrenal hyperplasia, a disease for which current treatment options are limited and are associated with significant side effects,” said Julia Owens, Ph.D., President and Chief Executive Officer, Millendo Therapeutics. “In this clinical trial, ATR-101 added to existing treatment with glucocorticoids was well-tolerated and demonstrated promising reductions in 17-OHP. ATR-101 also exhibited rapid onset of action with reductions in key steroids and steroid precursors. Significant reductions in steroidogenesis were seen even in patients with unusually high 17-OHP levels at baseline.”

Enrollment in the trial was stopped at 10 patients due to the demonstration of a clear biological effect in 7 patients with marked reductions in 17-OHP. Mean reductions in 17-OHP were observed at all ATR-101 doses while mean increases were observed during all placebo treatments. Two patients experienced a reduction in 17-OHP levels to ≤2x ULN, the primary endpoint, a result consistent with the short duration of treatment (2 weeks/dose level) and high baseline levels. ATR-101 was well-tolerated at all dose levels. Millendo will present full results at an upcoming medical meeting.

“Treatment of patients with classic congenital adrenal hyperplasia is a difficult balance between the morbidities of androgen excess resulting from undertreatment with glucocorticoids and the morbidities of excess glucocorticoids due to overtreatment,” said Richard Auchus, M.D., Ph.D., Professor of Internal Medicine and Professor of Pharmacology, University of Michigan. “While additional studies will need to be carried out, the results of this Phase 2 trial of ATR-101 give promise to patients in need of improvement with hormonal imbalances seen in CAH.”

The U.S. FDA granted orphan drug status to ATR-101 based on the demonstrated activity of the drug in this trial as well as the size of the patient population living with CAH. The prevalence of CAH is estimated at approximately 1 in 10,000 to 1 in 15,000 births in North American and European populations.

Separately, Millendo has decided to discontinue development of MLE4901 after assessment of the clinical risks and benefits of the program.