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Efficacy and safety of osilodrostat with drug combination in patients with hypertension caused by Cushing's syndrome

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What is this trial about?

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

The study looks at people with Cushing's syndrome, a rare condition where the body makes too much cortisol, a hormone that can cause high blood pressure (hypertension) and other problems. The excess cortisol, called hyper­cortisolaemia, is the main reason for the blood‑pressure issues. Participants will receive either the medication osilodrostat, which blocks cortisol production, or an inactive tablet (placebo) that looks the same.

The main goal is to see if the drug can bring the level of cortisol measured in urine back to normal. The trial is double‑blind, meaning neither the participants nor the doctors know who gets the real medicine, and it lasts about 30 weeks. People are randomly assigned to one of the two groups and take a tablet each day.

During the study, participants will provide urine samples to measure urinary‑free cortisol, have their blood pressure checked regularly, and may undergo a sugar‑drink test (OGTT) to look at how their body handles glucose. These checks help researchers understand how well the treatment works and whether any side effects appear. The study involves several clinic visits, simple tests, and daily medication taken at home.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomisation and first dose

    After joining the study you are assigned, in a double‑blind manner, to receive either osilodrostat tablets or matching placebo tablets. the assignment is unknown to you and to the study staff.

    The first tablet is taken on the same day as the randomisation.

  2. Step 2

    Baseline assessments

    A set of measurements is performed before the daily medication starts. these include:

    urinary‑free cortisol collection: two separate 24‑hour urine samples are collected to measure cortisol that is excreted in the urine.

    blood pressure monitoring: an ambulatory blood pressure monitor (abpm) records your blood pressure over a 24‑hour period.

    Body weight measurement.

    Oral glucose tolerance test (ogtt): you drink a solution containing 75 g of glucose and blood samples are taken to see how your body handles sugar.

    Low‑dose dexamethasone suppression test (lddst) is not performed at baseline but will be done later in the study.

  3. Step 3

    Daily study medication

    You take one film‑coated tablet each day by mouth.

    The tablet contains either osilodrostat 60 mg (the active drug) or placebo 60 mg (an inactive substance).

    The tablet is taken once daily for the entire 30‑week treatment period.

  4. Step 4

    Mid‑study visit (week 21)

    At week 21 you return for a study visit that repeats many of the baseline measurements:

    Two 24‑hour urine collections for urinary‑free cortisol.

    Ambulatory blood pressure monitoring to assess blood pressure changes.

    Body weight measurement.

    Oral glucose tolerance test with a 75 g glucose drink.

    Low‑dose dexamethasone suppression test: you take a single 1 mg dexamethasone tablet in the evening and a blood sample is drawn the next morning to measure morning cortisol.

    The daily study tablet continues to be taken as before.

  5. Step 5

    Final visit (week 30)

    At the end of the 30‑week period you attend the final study visit. the same procedures as at week 21 are performed:

    Two 24‑hour urine collections for urinary‑free cortisol.

    Ambulatory blood pressure monitoring.

    Body weight measurement.

    Oral glucose tolerance test with 75 g glucose.

    Low‑dose dexamethasone suppression test with a 1 mg tablet.

    The study medication is stopped after this visit.

Who can join the trial?

8 criteria

  • Be 18 years old or older.
  • Be able to sign a written consent form agreeing to join the study.
  • Have a diagnosis of endogenous Cushing’s syndrome — a condition that starts inside the body.
  • Show urinary free cortisol (UFC) results from two 24‑hour urine collections that are higher than the normal upper limit but not more than twice that limit (the normal upper limit is called ULN).
  • Have high blood pressure (hypertension) that is not fully controlled, be on stable blood‑pressure medicines for at least 4 weeks, and have a 24‑hour blood‑pressure monitor (ABPM) reading with an average systolic pressure (the top number) between 135 and 170 mmHg or a diastolic pressure (the bottom number) between 85 and 110 mmHg.
  • If you are taking glucocorticoid replacement therapy (a type of steroid medication), you must have stopped it for at least seven days or for five drug half‑lives (the time it takes for half the drug to leave your body), whichever is longer.
  • Not be using any medication to treat Cushing’s syndrome. If you have taken any of the following medicines, you must have stopped them for the required time before screening: steroid‑making blockers (e.g., ketoconazole, metyrapone) — 1 week; mifepristone — 3 weeks; subcutaneous pasireotide — 1 week; long‑acting pasireotide (LAR) — 3 months; cabergoline — 4 weeks.
  • Be able to swallow pills and be willing to follow the study’s schedule and procedures.

Who cannot join the trial?

23 criteria

  • You have taken the study medication osilodrostat less than 12 weeks before the screening visit.
  • You are known to be allergic (have a hypersensitivity reaction) to osilodrostat.
  • You have a severe or uncontrolled medical condition that could affect your safety or the study results.
  • You are scheduled to have surgery to treat Cushing’s syndrome within the next 32 weeks.
  • You have both high blood pressure (hypertension) and diabetes that have been present for more than 10 years before your Cushing’s syndrome diagnosis.
  • You have a history of cyclic Cushing’s syndrome, where symptoms come and go.
  • You have “pseudo‑Cushing’s syndrome,” a condition that mimics Cushing’s syndrome but is caused by something else.
  • You have a large pituitary tumor (macroadenoma) that is pressing on the optic chiasm (the part of the brain where the optic nerves cross) or you are at high risk for this compression.
  • You had pituitary or adrenal surgery for Cushing’s syndrome within the last 3 months.
  • You received radiation therapy to the pituitary gland within the past 3 years.
  • You have ectopic ACTH syndrome or adrenocortical carcinoma (a type of adrenal cancer) with a life expectancy of less than 3 years, or you are currently receiving chemotherapy.
  • You have previously been treated with the drug mitotane.
  • You work night shifts or have conditions that could interfere with tests that measure late‑night salivary cortisol (LNSC) or the low‑dose dexamethasone suppression test (LDDST).
  • You have poorly controlled diabetes, shown by a blood test (HbA1c) higher than 10.5%, or your diabetes medicines have not been at a stable dose for at least 4 weeks.
  • You have an underactive thyroid (hypothyroidism) and are not taking enough thyroid hormone replacement.
  • You had major surgery for any reason within the last 4 weeks and have not fully recovered.
  • You have a slow heart rate (bradycardia) or any heart rhythm problems that affect the QT interval (a measure of heart electrical activity).
  • Your blood tests show a total bilirubin level more than 1.5 times the normal upper limit, or liver enzymes ALT or AST more than 3 times the normal upper limit.
  • You have taken part in another clinical study or used an investigational drug within the last 4 weeks (or longer if required by local rules).
  • You have had a serious acute illness within the last 3 weeks before the study start.
  • You are pregnant, planning to become pregnant, breastfeeding, or have a positive pregnancy test (hCG).
  • You are a woman who could become pregnant and are unwilling to use highly effective birth control methods.
  • You are considered unreliable or vulnerable (for example, a person in detention) or the investigator judges you unsuitable for the study.
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Investigated drugs

  • Osilodrostat

    is an oral tablet that works by blocking an enzyme needed for the body to make cortisol, the stress hormone. In this study, it is being tested to see if it can lower the high blood pressure that occurs when too much cortisol is produced in Cushing’s syndrome. Participants take the medicine regularly, and doctors monitor how well it reduces cortisol levels and improves blood pressure.

  • Glucose

    is a simple sugar given by mouth during the trial. It is used as a background substance to help assess how the body processes sugar and to provide a consistent reference point for other measurements in the study.

  • Dexamethasone

    is a low‑dose steroid tablet taken by participants as part of their usual treatment. In this trial, it serves as background therapy to manage inflammation and other symptoms while the researchers focus on the effect of the test medication.

What is already known about the treatment

Placebo - The placebo is a film‑coated tablet taken by mouth, containing no active drug. It is used only as a control in clinical studies and has no therapeutic effect. Because it contains no ingredient, it has no mechanism of action or pharmacological class. Its status is simply an inert comparator. Osilodrostat (Isturisa) - Osilodrostat is supplied as a film‑coated tablet taken orally, typically in 5 mg or 1 mg doses. It is an approved orphan drug for treating Cushing’s syndrome caused by excess cortisol. It works by blocking the enzyme 11β‑hydroxylase, which reduces cortisol production in the adrenal glands. Pharmacologically it is classified as a steroidogenesis inhibitor (anticorticoid). Glucose - Glucose is provided as an oral preparation taken by mouth, delivering 75 g of sugar per dose. It is used in the trial as a background substance to provide a standard energy source, not as a disease treatment. It simply supplies energy and does not have a therapeutic mechanism or drug class. Its status is that of a nutritional supplement. Dexamethasone - Dexamethasone is a film‑coated tablet taken orally, usually 0.5 mg per tablet. It is a synthetic corticosteroid widely used for its anti‑inflammatory and immunosuppressive effects. It works by binding to glucocorticoid receptors and changing gene activity to reduce inflammation. Pharmacologically it belongs to the glucocorticoid class of drugs.

Investigated diseases

Cushing's syndrome - Cushing's syndrome is a condition in which the body is exposed to too much cortisol over a prolonged period. The excess cortisol can come from the adrenal glands themselves or from external sources. Over time, the high hormone levels cause the body to store more fat, especially around the abdomen and face, and to develop thin skin that bruises easily. Muscle strength may decrease and bones can become weaker, leading to aches and fractures. Blood pressure and blood sugar levels often rise as the disease continues. Without treatment, the hormonal imbalance tends to persist and can worsen these changes.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-524649-28-00Protocol codeLCI699-RECAG-CL-0615Estimated enrolment158 patientsSponsorRecordati AG

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