A Multicenter, Phase 2/3, Dose Range Finding Study to Evaluate the Efficacy and Safety of Atumelnant in Adults with ACTH-Dependent Cushing’s syndrome (ADCS) Including an Open-Label Extension for Long-Term Assessment (EQUILIBRIUM ADCS) - Part A
Crinetics Pharmaceuticals, Inc.
57 participants
Feb 23, 2026
Interventional
Conditions
Summary
The purpose of this study is to evaluate the efficacy, safety, and PK of atumelnant in participants with ADCS. This study will consist of 3 parts: Part A, Part B (not described in this registration), and Part C (not described in this registration). Part A has 4 groups: -Part A Arm 1: Open-label part: All participants will receive atumelnant by mouth for up to 12 weeks with oral GC therapy as needed. - Part A Arms 2, 3 and 4: Double-blind, randomized, placebo-controlled part: Participants receive study drug (atumelnant or placebo) by mouth in a 1:1:1 ratio. Whether a participant receives atumelnant or placebo will be determined by chance (like drawing straws). A placebo looks like medication but contains no active ingredient. All participants also receive steroid medication or steroid placebo. After participation in Part A of the study, participants might be able to stay in the study in Part C (open-label extension where all participants will receive atumelnant and steroid replacement therapy) if, in the Investigator’s opinion, they would benefit from it.
Eligibility
Inclusion Criteria4
- Male or female, between 18 up to and including 74 years of age at the time of signing the ICF. Participants from 16 years of age may be included at sites located in the US.
- Participants must have confirmed ADCS.
- Morning plasma ACTH greater than 10 pg/mL during screening confirmed by the central laboratory and available prior to randomization on Day 1.
- Participants with de novo Cushing’s disease (pituitary Cushing’s syndrome), ectopic ACTH syndrome (EAS), or ADCS of uncertain etiology who are not eligible for surgery (eg, poor surgical candidates, surgically unapproachable tumors, who refuse to have surgical treatment, or surgical treatment is not available) and could benefit from chronic treatment with study drug for at least 4 months.
Exclusion Criteria8
- Use of some medications could lead participants to enter the Washout Period.
- History of bilateral adrenalectomy.
- History of major surgery within 1 month prior to screening.
- Pituitary surgery within 3 months of Day 1.
- Participants who received pituitary irradiation within 2 years (stereotactic radio surgery) or 3 years (conventional radiation) before enrolment (Day 1).
- Participants who have previously taken atumelnant.
- Participants who will not benefit from chronic treatment with study drug or have a life expectancy of less than 6 months.
- Clinically significant concomitant disease considered by the Investigator likely to affect safe participation in the study.
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Interventions
Intervention: Atumelnant (CRN04894) A potent and selective orally administered nonpeptide small molecule melanocortin 2 receptor (MC2R) competitive antagonist under development for the treatment of ACTH-Dependent Cushing’s syndrome and congenital adrenal hyperplasia. Atumelnant is provided as a film coated tablet for oral use. Participant IP compliance will be monitored through an electronic clinical outcome assessment (eCOA system) requiring real-time documentation of dosing and administration, with ongoing review to assess adherence. Participants will also bring the study drugs on their visits so the study doctor can monitor the intake. Intervention Model: Part A Arms 1, 2, 3, and 4 will be run in parallel: -Part A Arm 1: Open-label, single arm -Part A Arms 2, 3, and 4: Randomized, double-blind, parallel arms Dosage and frequency: - Part A Arm 1: open-label where participants will receive 20mg oral atumelnant with oral glucocorticoid (GC) therapy initiated as needed for up to 12 weeks. - Part A Arms 2, 3, and 4: randomized, double-blind, placebo-controlled design where participants will be randomized 1:1:1 to oral atumelnant dose of 40mg or 80mg or placebo for up to 12 weeks. Participants who take part in Arms 2, 3, and 4, will be treated using a concomitant Block & Replace (B&R) treatment strategy receiving simultaneous initiation of atumelnant/GC or placebo/placebo administration. The standard B&R strategy in the treatment of ADCS involves inhibiting cortisol synthesis until the point of hypoadrenalism and replacing it with physiological dose of GC replacement therapy.
Locations(18)
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ACTRN12626000211369