US-based biopharmaceutical firm Millendo Therapeutics has commenced a Phase II clinical trial of ATR-101 for the treatment of patients with endogenous cushing’s syndrome (CS).

ATR-101 is an oral drug candidate being developed as an adrenal-selective small molecule inhibitor of ACAT1 to minimise adrenal steroid production, as well as stimulate apoptosis of cells derived from the adrenal cortex, at high doses.

The multi-centre, international Phase II trial is to be conducted at the US and UK sites and includes a six-week, open-label, intra-subject dose-escalation part and a four week double-blind randomised withdrawal part to evaluate the efficacy and safety of the product.

Millendo president and chief executive officer Julia Owens said: “The initiation of this Phase II clinical trial of ATR-101 in endogenous CS marks an important milestone in the development of this product candidate in endocrine diseases where current therapies are insufficient.

"We are hopeful that the adrenal-selective effects of ATR-101 will provide a new treatment option for patients with endogenous CS, regardless of the underlying causes."

“There are numerous etiologies of CS and, in patients for whom surgical intervention is not successful, current treatment options are limited.

"We are hopeful that the adrenal-selective effects of ATR-101 will provide a new treatment option for patients with endogenous CS, regardless of the underlying causes.”

The trial's primary efficacy endpoint will measure the impact of ATR-101 on urinary free cortisol (UFC) concentration, while the secondary endpoints will assess its impact on adrenal steroids / steroid intermediates and adrenocorticotropic hormone (ACTH).

ATR-101 is being further evaluated in a Phase II trial for treating patients with classic congenital adrenal hyperplasia (CAH) and a Phase I trial in adrenocortical carcinoma (ACC) patients.