Osilodrostat for Cyclic Cushing’s Disease

Posted on October 24, 2025 by MaryO

Highlights

  • •
    Cyclic Cushing’s syndrome (CCS) is a rare entity with significant comorbidities
  • •
    It is defined by at least 3 peaks of hypercortisolism, 2 troughs of eucortisolism
  • •
    Surgical cure is preferred, and medications are second-line
  • •
    Our case is the first showing successful treatment of native CCS with osilodrostat
  • •
    Osilodrostat showed rapid onset/offset and reversible inhibition of steroidogenesis

Abstract

Background/Objective

Cyclic Cushing’s syndrome is a rare subtype of Cushing’s syndrome with episodes of hypercortisolism, followed by spontaneous remission.

Case Report

Our patient was a 68-year-old male who presented with his third cycle of cyclic Cushing’s disease with facial swelling, buffalo hump, fatigue, proximal muscle weakness, and lower extremity edema. Laboratory tests showed the following: 24-hour urine free cortisol 12030.3 mcg/d (normal <= 60.0 mcg/d), morning adrenocorticotropic hormone (ACTH) 464 pg/mL (normal 6-59 pg/mL), morning serum cortisol 91 mcg/dL (normal 8-25 mcg/dL), and potassium 3.3 mmol/L (normal 3.6-5.3 mmol/L). MRI pituitary without/with contrast showed a partially empty sella. Prior inferior petrosal sinus sampling during the second cycle indicated a potential pituitary source of increased ACTH production, localized or draining to the right side. The patient was treated with osilodrostat with improvement in laboratory values and clinical symptoms by 2-3 weeks. After development of adrenal insufficiency (AI), osilodrostat was rapidly titrated off by 2 months of treatment. Subsequently, labs after 8 days off osilodrostat confirmed clinical remission and reversibility of medication-induced AI.

Discussion

Since hypercortisolism is associated with mortality risk and comorbidities, timely management is a priority. If a surgical cure is not possible, a medication that treats hypercortisolism with rapid onset, reversible inhibition, and minimal side effects would be ideal to address the cyclicity.

Conclusion

Our case is the first to our knowledge demonstrating osilodrostat’s use for native cyclic Cushing’s syndrome treatment and highlighted its reversibility and ability to preserve normal adrenal function.

Keywords

Osilodrostat
cyclic Cushing’s disease
cyclic Cushing’s syndrome

Introduction

Cyclic Cushing’s syndrome is a rare entity that represents a clinical challenge. It is defined by at least 3 peaks of biochemical hypercortisolism, which is clinically symptomatic in the majority though rarely asymptomatic, and 2 troughs with normalized cortisol production that can last from days to years.1 The phenomenon can arise from any potential source of Cushing’s syndrome, including pituitary (54%), ectopic (26%), adrenal (11%), and unclassified (9%) sources.1 Intermittent hypercortisolism can also occur after pituitary surgery for Cushing’s disease.2
The cyclicity interferes with a straightforward diagnosis. It can lead to paradoxical results from biochemical testing and inferior petrosal sinus sampling (IPSS),3 making determination of therapeutic outcomes more complicated.3 The goal of cyclic Cushing’s syndrome management, as in all types of Cushing’s syndrome, is early diagnosis and intervention to reduce the length of hypercortisolism.4 A surgical cure is preferred, as Cushing’s syndrome is associated with a five-fold increased standardized mortality risk.4 Cardiovascular, metabolic, bone, and cognitive comorbidities may persist despite remission and must be aggressively managed.4,5 For patients in whom surgical management is not possible or has not led to remission, medical therapy has a crucial role. We describe the first case to our knowledge of native cyclic Cushing’s syndrome treated successfully with osilodrostat. A case of exogenous cyclic ACTH-independent Cushing’s syndrome from pembrolizumab, with cyclicity attributed to the infusions, also demonstrated successful treatment with osilodrostat.6

Case Report

The patient was a 68-year-old male with hypertension, hyperlipidemia, and rheumatoid arthritis with a history of cyclical episodes of weight gain and facial swelling, occurring spontaneously without steroid treatments. The initial episode occurred at age 62 for 5 months, and returned at age 64 with facial swelling, buffalo hump, fatigue, proximal muscle weakness, sleep disturbances, and lower extremity edema. Laboratory tests showed the following (Table 1): 24-hour urine free cortisol >245 mcg/d (normal 11-84 mcg/d), morning adrenocorticotropic hormone (ACTH) 528.0 pg/mL (normal 7.2-63.3 pg/mL) and morning serum cortisol 91.7 mcg/dL (confirmed on dilution; normal 6.2-19.4 mcg/dL). Laboratory tests were also notable for a mildly low potassium level, low prolactin, low testosterone, and normal thyroid hormone, insulin-like growth factor-1 (IGF-1), and dehydroepiandrosterone sulfate (DHEA-S) levels. MRI pituitary without/with contrast showed no sellar and suprasellar masses. A prior CT abdomen/pelvis with contrast at age 62 noted unremarkable adrenal glands. The patient was referred for inferior petrosal sinus sampling (IPSS) (Table 2), which indicated a potential pituitary source of increased ACTH production, localized or draining to the right side. The central to peripheral gradient was >2 in the first pre-stimulation sample and >3 in all samples after providing 10mcg of desmopressin (DDAVP). There was a >1.4/1 gradient between the right and left sides, suggesting a potential pituitary source draining to the right side (Table 2). The inferior petrosal sinuses were normal and of similar size. Cushing’s symptoms receded spontaneously in 5 months, and the patient did not follow up until recurrence at age 67.

Table 1. Labs at time of onset of cyclical episodes

Empty Cell Labs at age 64 y/o (2nd episode) Labs at age 67 y/o (3rd episode)
24hr urine free cortisol level >245 mcg/24hr (normal 11-85 mcg/24hr) 12030.3 mcg/d (normal <= 60.0 mcg/d)
24hr urine creatinine 1495 mg/24hr (normal 1000-2000mg/24hr) 1868 mg/day (normal 800-2100 mg/day)
Morning ACTH 528.0 pg/mL (normal 7.2-63.3 pg/mL) 464 pg/mL (normal 6-59 pg/mL),
Morning cortisol 91.7 mcg/dL (normal 6.2-19.4 mcg/dL) 91 mcg/dL (normal 8-25 mcg/dL)
Thyroid-stimulating hormone level (TSH) 0.452 mcIU/mL (normal 0.450-4.500 mcIU/mL) 0.08 mcIU/mL (normal 0.3-4.7 mcIU/mL)
Free thyroxine (free T4) 1.34 ng/dL (normal 0.82-1.77 ng/dL) 1.30 ng/dL (normal 0.8-1.7 ng/dL)
Prolactin <1.0 ng/mL (normal 3.0-15.2 ng/mL) 8.05 ng/mL (normal 3.5-19.4 ng/mL)
Insulin-like growth factor-1 (IGF-1) 148 ng/mL (normal 64-240 ng/mL) 128 ng/mL (normal 41-279 ng/mL)_
Testosterone panel Total 66 ng/dL(11AM)
(normal 264-916 ng/dL)
Free 9.6 pg/mL (11AM)
(normal 6.6-18.1 pg/mL)		 Total 107 ng/dL (8:30AM)
(normal 300-720 ng/dL)
Bioavailable 61 ng/mL (8:30AM)
(normal 131-682 ng/mL)
Follicle-Stimulation Hormone (FSH) 3.6 mIU/mL (normal 1.6-9 mIU/mL)
Luteinizing Hormone (LH) 1.6 mIU/mL (normal 2-12 mIU/mL)
Dehydroepiandrosterone sulfate (DHEA-S) 153 mcg/dL (normal 48.9-344.2 mcg/dL)
Potassium level 3.2 mmol/L (normal 3.4-4.8 mmol/L) 3.3 mmol/L (normal 3.6-5.3 mmol/L)
Creatinine level 0.92 mg/dL (normal 0.7-1.2 mg/dL) 0.89 mg/dL (normal 0.6-1.3 mg/dL)

Table 2. Inferior Petrosal Sinus Sampling (IPSS)

Empty Cell Time Right IPS
ACTH level (normal 6-59 pg/mL)		 Left IPS
ACTH level (normal 6-59 pg/mL)		 Inferior Vena Cava ACTH level (normal 6-59 pg/mL) Serum Cortisol (normal 8-25 mcg/dL)
Baseline 1 08:25 AM 32 23 14 7
Baseline 2 08:27 AM 19 16 13 7
Desmopressin (DDAVP) 08:30 AM
Post 2 min 08:32 AM 150 34 15
Post 5 min 08:35 AM 123 32 18
Post 10 min 08:40 AM 49 26 17
Post 15 min 08:45 AM 124 31 17
Post 30 min 09:00 AM 107 28 13
*These results may indicate a pituitary source for increased ACTH production, localized or draining to the right side. There is a Central:Peripheral gradient of >2 (right IPS) in the first pre-stimulation samples and >3 in all post-desmopressin (DDAVP) 10mcg samples. If due to an adenoma, it might drain into the right given the presence of a significant (greater than 1.4/1) gradient between right and left. The inferior petrosal sinuses were of similar size and normal. These results must take into account the patient’s clinical scenario, and there are false positives and possible overlap with normal results.
*Abbreviation: min = minutes
During the third and most recent cycle of Cushing’s syndrome, laboratory tests after 1 month of symptom development showed the following (Table 1): 24-hour urine free cortisol 12030.3 mcg/d (normal <= 60.0 mcg/d), morning ACTH 464 pg/mL (normal 6-59 pg/mL), morning serum cortisol 91 mcg/dL (normal 8-25 mcg/dL), potassium level 3.3 mmol/L (normal 3.6-5.3 mmol/L), and mild leukocytosis and erythrocytosis. Repeat MRI pituitary without/with contrast showed a partially empty sella and no pituitary mass (Figure 1).

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Figure 1. MRI pituitary without/with contrast at the time of the third cyclical episode of Cushing’s disease. The MRI showed a partially empty sella with no evidence of a pituitary mass. Left) Coronal view. Right) Sagittal view.

The patient was started on osilodrostat 2mg twice daily. By week 2 of treatment, the morning cortisol level improved to 9.5 mcg/dL (8-25 mcg/dL) and potassium level normalized, though facial and body swelling persisted. Significant improvement in symptoms and fatigue were noted by week 3 of treatment with the following labs: morning ACTH 145 pg/mL (normal 6-59 pg/mL), morning serum cortisol 5.4 mcg/dL (8-25 mcg/dL), and 24-hour urine free cortisol 7 mcg/d (normal 5-64 mcg/d). The osilodrostat dose was decreased to 1mg twice daily, then 1mg daily, and stopped by 2 months of treatment after development of adrenal insufficiency (AI), which was confirmed on laboratory results (Table 3), along with corresponding symptoms of nausea, abdominal pain, low appetite, and fatigue. By that time, the facial and body swelling had also resolved. Potassium levels remained normal throughout treatment. After eight days off osilodrostat, laboratory tests showed the following: Noon ACTH 67 pg/mL (normal 6-59 pg/mL), noon serum cortisol 7.24 mcg/dL (normal 8-25 mcg/dL), and 24-hour urine free cortisol 26.2 mcg/d (normal <=60.0 mcg/d). Nearly 3 months off osilodrostat, the patient had an 11 AM ACTH of 68.9 pg/mL (normal 7.2-63.3 pg/mL) and 11AM serum cortisol level of 11.0 ug/dL (6.2-19.4 ug/dL). The clinical course is summarized in Table 3 and Figure 2. A DOTATATE-PET scan was discussed, though the patient wished to reconsider in the future given clinical response.

Table 3. Labs during treatment (Tx) with osilodrostat

Empty Cell 1 month before Tx Week 2 on Tx Week 3 on Tx Week 7 on Tx Week 9 on Tx – Tx stopped Week 1 off Tx Month 3 off Tx
Treatment with osilodrostat None On 2mg BID since Week 0 of Tx Advised to decrease to 1mg BID but patient did not decrease dose. Decreased to 1mg BID Decreased to 1mg daily after serum lab resulted. Then discontinued Tx after 24hr UFC resulted in several days. None None
ACTH level (pg/mL) 464 145 126 135 67 68.9
Cortisol level (mcg/dL) 91
8:32AM		 9.5
7:04AM		 5.4
7:11AM		 3.04
11:56AM		 4.9
11:26AM		 7.24
12:14PM		 11
11:08AM
24hr urine free cortisol (UFC) level (mcg/day) 12030.3 7 14 26.2
*Normal reference ranges depending on assays:
ACTH: 6-59 pg/mL or 7.2-63.3 pg/mL
Serum morning cortisol: 8-25 mcg/dL or 6.2-19.4 mcg/dL
24hr urine free cortisol: <=60.0 mcg/day or 5-64 mcg/day
*Acronyms: Tx = treatment; BID = twice daily; UFC = urine free cortisol, ACTH = adrenocorticotropic hormone

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Figure 2. Trends of 24hr urine cortisol levels and serum cortisol levels with osilodrostat treatment (Tx)

Discussion

Cyclic Cushing’s syndrome is a rare subtype of Cushing’s and occurs in both ACTH-dependent and ACTH-independent cases.3,7 Cyclicity has been attributed to hypothalamic dysfunction exaggerating a normal variant of hormonal cyclicity, a dysregulated positive feedback mechanism followed by negative feedback, intra-tumoral bleeding, and ACTH-secretion from neuroendocrine tumors (ex carcinoid tumors, pheochromocytomas).7,8,9,10
Potentially curative pituitary surgery or unilateral adrenalectomy are the treatments of choice.4 For example, cases of cyclic Cushing’s in primary pigmented nodular adrenocortical disease have demonstrated cure in some patients with unilateral adrenalectomy.11 In florid Cushing’s syndrome that is not amenable or responsive to other treatments, bilateral adrenalectomy could be lifesaving, though risks significant comorbidities including Nelson’s syndrome.4,12 Pituitary radiotherapy/radiosurgery are treatment options, though risks progressive anterior pituitary dysfunction.4 Medical therapy can play an important role as a bridge to surgery or radiation, with recurrence, for poor surgical candidates, or when there is no identifiable source as in our patient.13 Cyclic Cushing’s syndrome, moreover, has a higher recurrence rate (63%) and lower remission rate (25%), compared to classic Cushing’s syndrome.8
Medical treatments of cyclic Cushing’s syndrome include steroidogenesis inhibitors (ketoconazole, levoketoconazole, metyrapone, and osilodrostat), adrenolytic agents (mitotane), glucocorticoid receptor blockers (mifepristone), and pituitary tumor-directed agents (pasireotide, cabergoline, and temozolomide).8,14,15 Treatment goal is normalization of 24-hour urine cortisol levels and morning serum cortisol levels, though block-and-replace regimens occasionally are used.13,14 A block-and-replace regimen with osilodrostat and dexamethasone was used in the case of exogenous cyclic Cushing’s from pembrolizumab, given need for the immunotherapy;6 however, this regimen would hinder assessment of remission in native cyclic Cushing’s.
As our patient had cyclic Cushing’s disease, pituitary tumor-directed medications could be used for treatment. Pasireotide and cabergoline, however, are limited by a significant percentage of non-responders, along with risk of hyperglycemia for pasireotide.15 We considered mifepristone, which is a competitive antagonist at the glucocorticoid receptor and progesterone receptor; however, mifepristone is limited by the inability to directly monitor cortisol response on labs, in addition to the risk of AI and mineralocorticoid side effects with overtreatment.16
Steroidogenesis inhibitors block one or more enzymes in the production of cortisol, with potential risk of AI. The new steroidogenesis inhibitor osilodrostat, like metyrapone, selectively inhibits CYP11B1 and CYP11B2, which are involved in the final steps of cortisol and aldosterone synthesis, respectively.13,14 Ketoconazole and levoketoconazole, on the other hand, block most enzymes in the adrenal steroidogenesis pathway, including CYP11B1 and CYP11B2, and are limited by their inhibition of CYP7A (with associated hepatotoxicity) and strong inhibition of cytochrome p450 CYP3A4 (leading to many drug-drug interactions, decreased testosterone production, and QTc prolongation).14
Osilodrostat and metyrapone do not affect CYP7A and less potently inhibit CYP3A4.13 However, they can lead to increased deoxycorticosterone levels, with associated risks of hypokalemia, hypertension, and edema, and increased androgen production (with metyrapone thus being considered second-line in women).13,14,17
Osilodrostat, compared to metyrapone and ketoconazole, has a higher potency in CYP11B1 and CYP11B2 inhibition and a longer half-life, with stronger effects in lowering cortisol levels, allowance of less frequent (twice daily) dosing, and possibly less side effects.13,14,17,18 Compared to metyrapone, studies have suggested osilodrostat leads to a lesser rise in 11-deoxycortisol levels and less hyperandrogenic effects.13,14 Osilodrostat is also rapidly absorbed with sustained efficacy up to 6.7 years.17,18 Though rare cases of prolonged AI following discontinuation exist, osilodrostat (like other steroidogenesis inhibitors) is generally considered a reversible inhibitor.19 Reversible inhibition of cortisol synthesis is particularly appealing to treatment of cyclic Cushing’s syndrome as patients will not suffer from prolonged AI after episodes subside.
We thus considered osilodrostat an attractive treatment of cyclic Cushing’s syndrome. In our patient, osilodrostat was efficacious and well-tolerated, consistent with the literature,17 with clinical effects within 2-3 weeks without significant mineralocorticoid side effects. Differentiation of AI as a side effect of osilodrostat or from remission of the cyclical episode is crucial. Our patient was carefully tapered off osilodrostat after developing AI, and reversal of AI and osilodrostat inhibition were clearly demonstrated after 8 days off osilodrostat. Off treatment, the patient demonstrated neither prolonged AI nor clinical hypercortisolism, confirming remission of cyclic Cushing’s.

Conclusion

We present the first case to our knowledge demonstrating successful treatment of cyclic Cushing’s syndrome with osilodrostat. Osilodrostat showed rapid and safe control of hypercortisolism and importantly exhibited quick reversible inhibition of steroidogenesis upon discontinuation, a virtue in cyclic Cushing’s syndrome management.

References

Cited by (0)

The authors declare the following:
This paper did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
All authors do not have any conflicts of interests regarding the manuscript.
Run Yu, MD, PhD runyu@mednet.ucla.edu
Clinical Relevance
Osilodrostat is a new steroidogenesis inhibitor. Our case demonstrates the first successful treatment of native cyclic Cushing’s syndrome with osilodrostat, which showed rapid onset/offset, clinical safety, and reversible inhibition of steroidogenesis and medication-induced adrenal insufficiency. Osilodrostat’s preservation of underlying adrenal function is key when the cyclic Cushing’s episode spontaneously remits.

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