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A Randomized, Double-Blind, Multicenter, Placebo-Controlled Study to Evaluate the Safety and Efficacy of Atumelnant in Adult Participants with Classic Congenital Adrenal Hyperplasia

A Study to Evaluate Atumelnant in Adults with Congenital Adrenal Hyperplasia

Alejandro Ayala

Crinetics Pharmaceuticals, Inc.

6055 Lusk Blvd, San Diego, California 92121, USA

clinicaltrials@crinetics.com

Tsukada Kenji

CMIC Co., Ltd.

1-1-1, Shibaura, Minato-ku, Tokyo

+81-3-6779-8000

ClinicalTrialInformation@cmic.co.jp

Pending

Aug. 14, 2026

Interventional

randomized controlled trial

double blind

placebo control

parallel assignment

treatment purpose

1. Male or female, between >=18 to <75 years of age at the time of signing the ICF.
2. Willing and able to understand and adhere to the study procedures as specified in the protocol and comply with the study treatment.
3. Have classic CAH due to 21-OHD confirmed by the Investigator.
4. Participants Visit2 levels of morning serum A4 as follows:
- A4 >ULN and treated with <11 mg/m2/day (physiologic) GC doses
OR
- normal A4 (>=0.5 x ULN to 1 x ULN) and treated with >=14 mg/m2/day GC doses
OR
- A4 >ULN and treated with >=11 mg/m2/day GC doses.
5. On a stable (defined as no dose change of >5 mg/day hydrocortisone equivalent within 3 months prior to Screening) regimen of GC replacement (e.g., hydrocortisone, prednisolone, prednisone, methylprednisolone, meprednisone, dexamethasone, cortisone acetate) at the time of informed consent.
6. If treated with mineralocorticoids (fludrocortisone), the dose should be stable for at least 1 month prior to Screening with a plasma renin concentration during Screening that is not greater than the ULN on the participant's usual sodium intake. If plasma renin concentration is greater than the ULN, the participant must have systolic blood pressure >100 mm Hg, without orthostatic hypotension and with serum sodium and potassium in the normal range.
7. If on estrogen therapy (any route), the dose must be stable for at least 3 months prior to Screening.

1. Diagnosis of any form of CAH other than classic 21-OHD.
2. History of bilateral adrenalectomy, hypopituitarism, or other conditions requiring chronic GC therapy.
3. Clinically significant medical condition or abnormal laboratory tests, as judged by the Investigator, other than CAH.
4. Concomitant mental condition rendering him/her unable to understand the nature, scope, and possible consequences of the study, and/or evidence of poor compliance with medical instructions.
5. Active malignant disease within the 5 years prior to Screening excluding dermal squamous or basal cell carcinoma of the skin with complete local excision or resected cervical carcinoma in situ.
6. Women who are pregnant or lactating or, if of childbearing potential, who are unwilling to use highly effective contraception as described in this study. Male participants who are unwilling to use highly effective contraception as described in this study.
7. Known history of, or concern for, risk of hypersensitivity reaction to atumelnant or any of its excipients.
8. Participants with an increased risk of developing adrenal insufficiency as judged by the Investigator.
9. Severe erythrocytosis as judged by the Investigator.
10. Use of atumelnant prior to screening.

Both

Classic Congenital Adrenal Hyperplasia

Atumelnant 80 mg tablet or placebo will be administered orally once daily in the evening. From Week 20 onwards, if dose escalation is deemed necessary, the dose will be increased to 120 mg tablet, administered orally once daily in the evening. The treatment duration will be up to a maximum of 32 weeks.

Proportion of participants with morning post GC A4<=ULN who are on physiologic GC replacement at Week 32

- Percent change from baseline of morning A4 at Week 2
- Percent change from baseline of morning 17 OHP at Week 32
- Proportion of participants with morning pre GC A4<=ULN who are on physiologic GC replacement at Week 32
- Percent change from baseline in GC daily dose when morning post-GC A4<=ULN at Week 32

+81-3-3202-7181

May. 27, 2026

No

US/Argentina/Australia/Brazil/France/Germany/Poland/Austria/Italy/Sweden/The Netherlands/Turkey/UK/Saudi Arabia