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Study of Crinecerfont in Adults with Classic Congenital Adrenal Hyperplasia to Reduce Androgen Levels

Verified siteInvestigationalNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study involves adults who have Classic Congenital Adrenal Hyperplasia (CAH), a rare inherited condition in which the adrenal glands produce too much androgen, a type of male hormone. Participants are already taking a stable dose of a glucocorticoid medication, which replaces missing hormones. The investigational drug being tested is an oral capsule called crinecerfont, which works by blocking signals that lead to excess androgen production. The purpose of the study is to evaluate the effect of crinecerfont on elevated androstenedione levels in adults with classic CAH who are already on a stable glucocorticoid dose.

During the trial, participants will take the study medication once daily for about 24 weeks. They will attend regular clinic visits where blood samples are drawn to measure hormone levels and safety checks are performed. The study follows a straightforward schedule of visits and tests, allowing researchers to observe changes in hormone levels over time without requiring any invasive procedures.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Screening and enrollment

    You will be checked to confirm that you have classic congenital adrenal hyperplasia and that you have been taking a glucocorticoid medication at a stable dose for at least six months. the study team will verify that you meet all other eligibility requirements before you are allowed to join the trial.

  2. Step 2

    Baseline visit

    Before starting the study drug, you will have a blood draw to measure your pre‑glucocorticoid serum androstenedione level. this measurement serves as the baseline for later comparison. any additional routine checks required by the study will also be performed at this visit.

  3. Step 3

    Start of study medication

    You will begin taking crinecerfont as an oral capsule. the prescribed dose is 00 mg, taken once daily. the medication will be taken for a total of twenty‑four weeks.

  4. Step 4

    Daily medication routine

    Each day you will take the crinecerfont capsule at the same time, following any instructions about food or water. maintaining the same schedule helps ensure consistent drug exposure.

  5. Step 5

    Follow‑up visits

    You will return to the study site at scheduled intervals. a key visit occurs at week 24, when another blood sample will be drawn to measure your androstenedione level and assess the effect of the medication. any additional assessments required by the protocol will be performed at these visits.

  6. Step 6

    End of study

    After the week 24 assessments are completed, the study medication will be stopped. a final evaluation will be performed to document your overall experience and any outcomes measured during the trial.

Who can join the trial?

15 criteria

  • You have signed a written informed consent form agreeing to take part in the study.
  • You are at least 18 years old. If you are female, you must be 45 years of age or younger.
  • If you are female, blood tests must show an anti‑Müllerian hormone (AMH) level of 1 ng/mL or higher and a follicle‑stimulating hormone (FSH) level below 25 mIU/mL. AMH helps indicate ovarian function, and FSH is a hormone that controls the menstrual cycle.
  • You have a confirmed diagnosis of classic 21‑hydroxylase deficiency congenital adrenal hyperplasia (CAH). This means doctors have identified the condition using accepted tests such as a high 17‑hydroxyprogesterone level, genetic testing for the CYP21A2 gene, newborn screening results, or a special hormone‑stimulating test.
  • A blood test done before your morning steroid dose must show a measurable level of androstenedione, a hormone that can be high in CAH.
  • You are taking a stable dose of a glucocorticoid (GC) medication (such as hydrocortisone, prednisone, prednisolone, or methylprednisolone) for at least one month before the screening visit, and you take at least one dose in the morning.
  • If you also take fludrocortisone (a medication that helps control salt balance), your dose must have been stable for at least one month, and a test called plasma renin activity (PRA) must not be higher than the normal upper limit while you are on your usual salt intake. If PRA is higher, you must have a systolic blood pressure above 100 mm Hg, no drop in blood pressure when standing (no orthostatic hypotension), and normal blood levels of sodium and potassium.
  • If you have ovaries and could become pregnant, you must use an effective form of contraception from the time of screening until 30 days after your last study dose. Acceptable methods include:
    • Surgical sterilization of the fallopian tubes (bilateral salpingectomy or tubal occlusion)
    • Intrauterine device (IUD) or hormonal IUD
    • Combined hormonal birth control (estrogen + progestogen) that stops ovulation, started at least 3 months before screening
    • Progestogen‑only hormonal methods (pill, injection, or implant) started at least 3 months before screening
    • Complete abstinence from sexual intercourse (periodic abstinence is not allowed)
    • A partner who has had a successful vasectomy performed at least 3 months earlier
    • Male or female condoms, with or without spermicide
    • Cap, diaphragm, or sponge used with spermicide

Who cannot join the trial?

21 criteria

  • Being pregnant, breastfeeding, or planning to become pregnant during the study.
  • Having a high CCI score, which means other serious health problems that could affect safety.
  • Having had a hysterectomy (removal of the uterus) or oophorectomy (removal of the ovaries).
  • Having chronic kidney or liver disease, shown by any of the following lab results:
    • eGFR (a measure of kidney function) less than 45 ml/min/1.73 m².
    • AST or ALT (liver enzymes) more than three times the normal upper limit.
    • Total bilirubin more than 1.5 times the normal upper limit, unless caused by a known condition called Gilbert’s syndrome.
    • Having a low absolute neutrophil count (< 1,000 cells per mm³), which means a reduced type of white blood cell.
    • Using any experimental drug in a clinical trial within the past 30 days (or longer, depending on the drug’s half‑life) or planning to use another experimental drug during the study.
    • Having taken a CRF1 antagonist (including crinecerfont) within the past year.
    • Taking prohibited medicines that cannot be stopped for the entire duration of the study.
    • Having current substance or alcohol dependence or abuse (nicotine and caffeine dependence are not excluded).
    • Having another form of classic CAH, such as 11‑β‑hydroxylase deficiency, 17‑α‑hydroxylase deficiency, 3‑β‑hydroxysteroid dehydrogenase deficiency, P450 side‑chain cleavage deficiency, or P450 oxidoreductase deficiency.
    • Having a significant risk of suicidal or violent behavior, including recent active suicidal thoughts with intent or a plan, or any suicidal behavior in the past year.
    • Having lost a large amount of blood (≥ 550 mL) or donated blood within 8 weeks before the first day of the study.
    • Being judged by the investigator as unable to follow the study procedures and visits.
    • Having a history of bilateral adrenalectomy (removal of both adrenal glands), hypopituitarism, or needing long‑term oral or inhaled glucocorticoid therapy that could affect the study results.
    • Having used dexamethasone regularly for chronic treatment in the 6 months before screening.
    • Being at high risk for an adrenal crisis (a sudden, dangerous drop in hormone levels) based on the investigator’s opinion.
    • Having any other serious medical condition (such as neurological, liver, kidney, heart, gastrointestinal, blood, lung, psychiatric, or endocrine disease other than CAH) that could interfere with participation or the interpretation of study results.
    • Having a history of cancer, unless it was completely treated with curative intent and is considered cured.
    • Being allergic or hypersensitive to any corticotropin‑releasing hormone (CRH) receptor antagonist or any component of the study medication.
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Investigated drugs

NBI-74788 (crinecerfont) is an oral capsule taken by mouth. It is being studied as a new treatment for adults who have classic congenital adrenal hyperplasia (CAH) and are already taking a stable dose of glucocorticoid medication. In this trial, the drug’s goal is to lower the high levels of androstenedione, a male hormone that can be too high in people with CAH. By reducing this hormone, the study hopes to improve related health outcomes and better control the symptoms of the condition. The medication is classified as an orphan drug, meaning it is intended for a rare disease.

What is already known about the treatment

Crinecerfont - Crinecerfont is taken orally as a capsule that the patient swallows whole. It is an orphan drug currently being studied in a Phase 3b trial for classic congenital adrenal hyperplasia, so it is not yet approved for general medical use. The medication is intended to lower the high levels of androgens that cause symptoms in this condition. It works by blocking the body’s CRF‑1 receptors, which reduces the hormone ACTH and therefore decreases the production of adrenal steroids; it is classified as a CRF‑1 receptor antagonist.

Investigated diseases

Classic Congenital Adrenal Hyperplasia - Classic Congenital Adrenal Hyperplasia is a genetic disorder that reduces the activity of an enzyme needed to make cortisol in the adrenal glands. Because cortisol is low, the body makes more of other hormones, especially androgens, which can cause early signs of puberty and growth changes. The condition is present from birth and may become more noticeable as a child grows. Hormone levels can fluctuate, leading to periods of increased skin darkening, rapid growth, or changes in body shape. Over time, the excess androgens can affect bone development and menstrual patterns in females. The disease usually follows a steady pattern unless hormone levels are altered.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-524282-24-00Protocol codeNBI-74788-CAH3033Estimated enrolment100 patientsSponsorNeurocrine Biosciences Inc.

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