The glucocorticoid receptor antagonist CORT125134 is safe and has shown preliminary signs of efficacy in healthy volunteers participating in a Phase 1 trial, say researchers in England.
Their study, “Assessment of Safety, Tolerability, Pharmacokinetics, and Pharmacological Effect of Orally Administered CORT125134: An Adaptive, Double-Blind, Randomized, Placebo-Controlled Phase 1 Clinical Study,” appeared in the journal Clinical Pharmacology in Drug Development.”
Cortisol signaling is indirectly controlled by the glucocorticoid receptor (GR). When cortisol binds the GR, the receptor becomes activated and migrates to the nucleus, where it regulates the expression of many genes. This influences a myriad of processes, including inflammation, immune response and brain function.
CORT125134, also known as relacorilant, is being developed by Corcept Therapeutics of Menlo Park, California, for Cushing’s disease patients and others who may benefit from it. The drug is a GR antagonist, blocking the receptor’s activity.
In order to evaluate the safety and tolerability of CORT125134, and learn how it behaves in the body, Corcept researchers conduced a Phase 1 trial in healthy subjects.
The British study, conducted at the Quotient Clinical in Nottingham, included 81 adults who received a single ascending-dose of CORT125134 or placebo, and 48 subjects who received multiple-ascending doses of the drug versus placebo.
Single doses were tested in nine distinct groups. Six tested six different doses of CORT125134, one tested a 150 mg dose in subjects receiving a high-fat meal, and two groups included patients receiving prednisone (a well-known GR activator), prednisone plus Korlym (mifepristone), or prednisone plus CORT125134.
Korlym is a medicine approved for Cushing’s patients with high blood sugar levels due to high cortisol in circulation. But the drug targets the progesterone receptor and is associated with side effects like pregnancy termination and irregular vaginal bleeding.
Multiple doses, given for up to 14 days, were tested in four additional cohorts. Researchers observed that CORT125134 was rapidly absorbed and eliminated, presenting a suitable profile for once-daily dosing.
Efficacy was determined by CORT125134’s ability to counteract the effects of prednisone. In addition, a single dose of 500 mg or multiple dosing with 250 mg had similar effects as those seen with 600 mg of Korlym — the therapeutic dose used for Cushing’s treatments.
Most common treatment-related adverse events reported in the single-ascending dose part of the study were nausea, vomiting and thirst; most were mild. In those given multiple-ascending doses, adverse events included mild musculoskeletal and connective tissue disorders, as well as gastrointestinal system disorders.
Multiple 500 mg doses exceeded the maximum tolerated dose, as it led to musculoskeletal symptoms that forced researchers to stop treatment.
“This first-in-human study has demonstrated that CORT125134 is well tolerated following single doses up to 500 mg and repeated doses up to 250 mg once daily for 14 days,” researchers wrote. “Pharmacological activity was confirmed following the administration of a single 500-mg dose and daily administration of 250 mg.”
Corcept is now enrolling participants into a Phase 2 open-label trial (NCT02804750) to evaluate CORT125134 in patients with Cushing’s syndrome. This trial is being conducted in the United States and Europe and will include 80 participants. Top-line results are expected in the first quarter of 2018.