Treatment of Cusn/ng’s disease
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`223:2
`
`R1 9—R39
`
`This material may be protected by Copyright law [Title 17 US. Code]
`
`Treatment of Cushing’s disease:
`
`a mechanistic update
`
`Danlel Cuevas-Ramos"2 and Marla Fleserlu3
`
`1Department of Medicine, Pituitary Center, Cedars-Sinai Medical Center, Los Angeles, California, USA
`2Neuroendocrinology Clinic, Department of Endocrinology and Metabolism, Instituto Nacional de Ciencias
`Médicas y Nutricion Salvador Zubiran, Mexico City, Mexico
`5Departments of Medicine and Neurological Surgery, and Northwest Pituitary Center. Oregon Health & Science
`University, 3181 SW Sam Jackson Park Road (BTE 472), Portland, Oregon 97239, USA
`
`Correspondence
`should be addressed
`to M Fleseriu
`Email
`
`fleseriuGohsuedu
`
`Abstract
`
`JournalofEndocrinology
`
`Cushing's disease (CD) is characterized by an ACTH-producing anterior corticotrope pituitary
`adenoma. If hypothalamus—pituitary—adrenal (HPA) axis physiology is disrupted, ACTH
`secretion increases, which in turn stimulates adrenocortical steroidogenesis and cortisol
`production. Medical treatment plays an important role for patients with persistent disease
`after surgery, for those in whom surgery is not feasible, or while awaiting effects of
`
`radiation. Multiple drugs, with different mechanisms of action and variable efficacy and
`tolerability for controlling the deleterious effects of chronic glucocorticoid excess, are
`available. The molecular basis and clinical data for centrally acting drugs, adrenal
`steroidogenesis inhibitors, and glucocorticoid receptor antagonists are reviewed, as are
`potential novel molecules and future possible targets for CD treatment. Although progress
`has been made in the understanding of specific corticotrope adenoma receptor physiology
`and recent clinical studies have detected improved effects with a combined medical therapy
`approach, there is a clear need for a more efficacious and better-tolerated medical therapy
`for patients with CD. A better understanding of the molecular mechanisms in CD and of HPA
`axis physiology should advance the development of new drugs in the future.
`
`Key Words
`cortisol
`
`Cushing’s disease
`ACTH
`
`pasireotide
`mifepristone
`ketoconazole
`LCl699
`
`cabergoline
`
`VVVVVVVV
`
`Journal of Endocrinology
`
`(2014) 223. R19—R39
`
`Introduction
`
`is caused by an adrenocortico-
`(Zushing's disease ((21))
`tropin (ACTH)-secreting pituitary tumor that stimulates
`cortisol production by the adrenal glands. Morbidity and
`mortality are significantly increased if hypercortisolemia
`is left untreated. Transsphenoidal surgery, performed by
`an experienced neurosurgeon, is currently considered the
`first-line treatment. Medical treatment is commonly used
`to control the deleterious effects of persistent chronic
`glucocorticoid excess and 24-h urinary free cortisol (UFC)
`normalization still represents the gold standard to
`evaluate the efficacy of most medical treatments.
`Glucocorticoid exerts effects through the glucocorti-
`coid receptor (GR) and as the GR is expressed in almost
`
`
`http:/fioerendocrinology-iournals.org
`DOI: 10.1530/10E-14-0300
`
`© 2014 Society for Endocrinology
`Printed in Great Britain
`
`every human tissue, conditions of glucocorticoid excess,
`such as CD,
`result
`in deleterious effects on cell
`
`metabolism. Pharmacological agents can be classified as
`adrenal steroidogenesis blockers, centrally acting drugs,
`and GR antagonists. Recent
`research has evaluated
`
`chimeric compounds that work synergistically through
`membrane interaction or dimerization of both somato-
`
`statin receptors (SSTRs) and dopamine D2 receptors in
`corticotrope cells. Although no available medical agents
`surpass the efficacy of surgical therapy, new treatments
`acting directly at
`the pituitary adenoma have been
`approved for use and highlight
`the importance of
`targeting the pituitary corticotrope. A review of the
`
`‘ Published by Bioscientifica Ltd.
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`Teva Pharmaceuticals USA, Inc. v. Corcept Therapeutics, Inc.
`PGR2019-00048
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`

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`L‘- cutva: ammo: and 24 ittsr nu
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` 223 :2
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`Treatment of Cushing’s d/sease
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`R20
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`)ournalofEndocrinology
`
`mechanisms of current and future medical
`
`treatment
`
`modalities for CD is provided.
`
`Overvlew of CD therapy
`
`is characterized by chronic
`Cushing’s syndrome (CS)
`overproduction of cortisol resulting in significant morbidity
`and, when left untreated, increased mortality (Newell-Price
`et al. 2006, Dekkers et a1. 2007). CS is classified as ACTH-
`
`dependent and -independent. The most common etiology
`(70—80%) of CS is CD, caused by an ACTH-secreting
`pituitary adenoma or, more rarely, by ectopic ACTH or
`corticottopin-releasing hormone (CRl-i) production that
`may result in corticotrope hyperplasia (Newell-Price et a].
`2006, Biller et ul. 2008). Chronic cortisol excess leads to a
`
`typical clinical phenotype (Table 1). Although epidemio-
`logical data on CD are limited, population-based studies
`indicate an incidence of 1.2—2.4 per million (Arnardottir &
`Sigurjonsdottir 2011, Holland et al. 2011) with a preva-
`lence of approximately 39 per million population
`(Feelders et a1. 2012). Compared with the general
`population or patients with other pituitary adenomas,
`patients with hypercortisolism have a four times higher
`
`mortality risk if untreated and cardiovascular disease
`remains the leading cause of death (Newell-Price et al.
`2006, Dekkers er a1. 2007, Feelders & Hofland 2013).
`
`line therapy
`Transsphenoidal surgery is the first
`achieving 65—90% disease remission for microadenomas
`(tumors <1 cm; Billeretal. 2008,1‘ritosetal. 201 l, Fleseriu
`2012), and lower remission rates (<65%) for macroade-
`
`nomas (tumors >1cm) (Aghi 2008). The risk of CD
`recurrence can reach 25%, 3 years after surgery (Patil
`et al. 2008). Second and third line therapies such as a
`second pituitary surgery (Patil et a1. 2008, Fleseriu 2012),
`pituitary irradiation (conventional and/or stereotactic)
`(Estrada et al. 1997, Tritos et a1. 2011) and bilateral
`
`adrenalectomy (Young 81 Thompson 2005, Assie et al.
`2007, Chow et ul. 2008, Rilzel et ul. 2013) have been
`
`utilized with variable results and specific complications.
`
`Targets for medlcal treatment of CD
`
`The hypothalamus—pituitary—adrenal (HPA) axis is orga-
`nized into three regions:
`the hypothalamus, pituitary
`gland, and adrenal glands (Fig. 1). CD is caused by a
`pituitary tumor; therefore, medical therapy should ideally
`
`'l'able 1 Clinical features and associated morbidity observed in Cushing's syndrome
`Clinical feattl'es
`
`
`
`Frequency (96)
`
`Increased weight (centripetal obesity, supraclavicular region, and upper back)
`Skin changes (round face, facial plethora, and skin atrophy)
`Decreased libido
`Menstrual irregularity
`Muscle proximal weakness
`Hirsutism
`Violaceous striae
`Easy bruising
`Associated morbidity
`Obesity
`Hypertension
`Glucose intolerance or diabetes mellitus
`Osteoporosis
`Psychiatric symptoms
`Dyslipidemia
`Increased infections and decreased wound healing
`Renal calculi
`Venous thromboembolism
`Avascular necrosis in femoral head
`Specific for Cushing's disease
`Headaches
`Visual problems (bitemporal hemianopsia)
`Other anterior pituitary hormone deficiencies
`Alterations with severe hypercortisolism
`Weight reduction (with ectopic ACTH secretion by malignancy)
`Hypoalbuminemia
`Skin hyperpigmentation
`Hypokalemia and metabolic alkalosis
`
`80-95
`80—90
`25—90
`75—80
`60—80
`70—75
`55—65
`45—65
`
`40-95
`60—80
`50—80
`40—75
`50—70
`40—70
`1 5—30
`1 5—20
`10—20
`5—1 0
`
`0—37
`0—33
`0—25
`
`10-50
`15—35
`10—15
`4—10
`
`Boscaro et al. (2001), NeweII-Price et al. (2006), Biller er al. (2008), Bertagna (2006), and Greenman (2010).
`
`
`http:/fjoeendocrinology-ioumals.org
`DOI: 10.1530'106-14‘0300
`
`© 2014 Society for Endocrinology
`Printed in Great Britain
`
`‘ Published byBioscientifica Ltd.
`
`Teva Pharmaceuticals USA, Inc. v. Corcept Therapeutics, Inc.
`PGR2019-00048
`
`Corcept Ex. 2034, Page 2
`
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`Treatment of Cush/ng’s dlsease
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`223 :2
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`R21
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`Centrally actlng urugs
`
`
`
`
`t
`
`Corticotrope
`adenoma
`
`Serotonlnerglc antagonlsts
`Cyproheptadine
`
`GABA agonlsta
`““9”": 3"“
`
` Temozolomlde
`. Etomidate
`
`Dopamlne agonlsts
`. Cabergoline
`Chlmerlc compounds
`
`Retlnolc acid
`
`Sicrondogcncsis blocks rs
`Imldazoles
`Ketoconazole
`Fluconazole
`
`L
`
`Mlteprlstone (nuns)
`7
`7 7
`
`kMifepriStone
`
`Cell membrane
`mm of peripheral
`tissue
`k
`‘
`
`Nuclear
`membrane
`WM DNA
`
`Inhibition of cell
`transcription
`
`Figure ‘l
`The hypothaIamus—pituitary—adrenal (HPA) axis and targets of drugs used
`for treating Cushing‘s disease. Under physiological conditions, cortisol
`synthesis and production are tightly regulated by the HPA axis.
`Adrenocortlcotropln (ACTH)-producing cells in the anterior pituitary
`respond to hypothalamic corticotropin-releasing hormone (CRH) and
`arglnine vasopressln (AVP). After binding to melanocortin type 2 receptor
`(MCZR), ACTH induces the steroidogenic enzymes to increase the
`biosynthesis of cortisol and will decrease ACTH and CRH secretion. Pituitary
`corticotrope ACTH-secreting adenomas, however, function autonomously
`
`JournalofEndocrinology
`
`and overstimulate cortisol production at the adrenal cortex. The
`pharmacotherapies for ACTH-secreting pituitary corticotrope adenomas
`are categorized by the site of action into three groups: i) centrally acting
`agents or neuromodulators, which inhibit ACTH release from pituitary
`adenomas, ii) adrenal steroidogenic inhibitors, which black one or several
`steps in cortisol blosynthesls and Ill) the glucocortlcold receptor-blocking
`agent mifepris'tone. Green arrows indicate activation and red arrows/lines
`indicate inhibition.
`
`target the corticotrope cell adenoma. However, as gluco-
`corticoids represent the end hormone of the HPA axis and
`hypercortisolism induces comorbidities, steroidogenic
`inhibition was the first
`therapy used. Indications for
`medical therapy in patients with CD are summarized
`in Table 2.
`
`Adrenal steroidogenesis blockers
`
`Adrenal cortical atrophy was first documented in dogs
`treated with the insecticide dichlorodiphenyldichloro-
`ethane (DDD; Nelson 8t Woodard 1949). This observation
`
`led to the development of the use of o,p’-DDD or
`mitotane, initially for adrenal cancer and CS (Cueto «St
`Brown 1958, Southren et a1. 1961). Subsequently, ampho-
`nenone B (Hertz et al. 1956, Thorn et al. 1956),
`
`aminoglutethimide (Camacho er al. 1967), metyrapone
`(Gower 1974), trilostane (Potts et a1. 1978), and ketocona-
`
`zole (Pont et al. 1982) were identified as steroidogenic
`inhibitors (Fig. 2 and Table 3).
`
`
`http:/Iioe.endocrinology-ioumals.org
`DOI: 10.1530lJOE-14-0300
`
`© 2014 Society for Endocrinology
`Printed in Great Britain
`
`Ketoconazole
`
`Introduced as an antifungal agent, ketoconazole exerts
`endocrine side effects indicating its possible therapeutic
`efficacy in lowering cholesterol
`levels.
`Indeed,
`the
`imidazole derivative ketoconazole was noted to cause
`
`gynecomastia associated with lower plasma testosterone
`and cortisol values (Table 3; Font et at. 1982). Ketocona-
`
`zole was first used in the treatment of a patient with a
`cortisol-producing adrenal adenoma in 1983 (Engelhardt
`et al. 1983), and has been used off-label since then.
`
`Ketoconazole inhibits the side-chain cleavage complex
`(P4SOscc, CYP11A1, or 20,22 desmolase),
`llfi-hydroxyl-
`ase, and 17a—hydroxylase (Table 4) (Feldman 1986, Loli etal.
`1986). As a result of effective inhibition of cholesterol side-
`
`chain cleavage and 17-hydroxylase/17,20 lyase activity,
`ketoconazole may reduce androgen synthesis; therefore,
`effects on hirsutism are favorable (Fig. 2). There are
`inhibitory effects on several cytochrome P450 enzymes,
`mainly CYP3A4, CYP2C9, and CYP1A2 (Feldman 1986,
`Feelders et al. 2010a, Fleseriu 8r Petersenn 2012),
`
`‘ Published byBioscientifica Ltd.
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`Treatment of Cushmg’s (1159558
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`R22
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`)ournalofEndocrinology
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`Table 2 Use of medical
`indications and needs
`
`
`therapy in Cushing's disease —
`
`Before or after pituitary surgery
`Preparation for surgery
`Patients with contraindications for surgery
`High operation risk
`Patients unwilling to undergo surgery
`After unsuccessful surgery
`Amelioration or control of the metabolic effects of
`hypercortisolemia
`Potentially life-threatening complications
`Patients awaiting effects of pituitary radiation
`Whenever a definitive treatment is delayed
`Primary medical therapy
`Low probability of surgical cure
`Unfavorable localization
`Invisible adenomas
`Adenoma without optic chiasm compression
`
`Fleseriu et al. (2007), Biller et al. (2008), Castinetti et al. (2008), Godbout
`er al. (2010), Fleseriu (2012), and Feeiders 81 Hofland (2013).
`
`but minimal effect on aromatase enzyme (Miller &
`
`Crapo 1993).
`The first clinical reports on patients with CD described
`
`normalization of urinary or plasma cortisol values with
`ketoconazole doses of 600—1200 mg/day (Loli er al. 1986,
`
`Tabarin et al. 1991, Miller 8r Crapo 1993). Ketoconazole
`treatment is usually started at 200 mg twice a day, and
`
`is achieved at 600—1200 mg/day
`biochemical effect
`(Fable 3; Nieman 2002, Fleseriu et al. 2012). It has been
`
`suggested that ketoconazole may also have inhibitory
`effects on ACTH secretion by corticotrope tumor cells as
`AC1"H shows no significant increase despite confirmed
`reduction in cortisol levels (Loose et al. 1983, Loli et al.
`1986, Jimenez-Rema et al. 1989, Tabarin et al. 1991).
`
`Escape from pharmacological control has been reported
`(Sonino et al. 1991). Administered as a monotherapy,
`ketoconazole decreases cortisol
`levels in 30-80% of
`
`patients (Sonino et ul. 1991, Sonino & Boscaro 1999,
`Castinetti et al. 2008). Results from a recent large multi-
`
`center retrospective study (n=200) revealed normaliza-
`tion of UFC levels measured at the last follow-up in 49% of
`
`patients (Castinetti et al. 2014). Ketoconazole also blocks
`the GR at high concentrations in cultured hepatoma cells
`(Loose et al. 1983). Reportedly, hepatotoxicity (Sonino
`1987, Sugar etal. 1987, Tabarin et a1. 1991) was mild in the
`study and resolved after drug withdrawal (Castinetti et al.
`
`2014). Ketoconazole has also been used in older patients
`(> 75 years of age) with good tolerance and disease control
`(Berwaerts et al. 1998).
`
`The use of ketoconazole has been questioned after
`warnings from the European Medicine Agencies and the
`
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`
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`Printed in Great Britain
`
`US Food and Drug Administration (FDA) of potential
`hepatotoxicity (Castinetti et al. 2014). Long-term safety
`remains to be prospectively studied.
`In contrast
`to
`mitotane (which causes hypercholesterolemia), ketocona-
`zole interferes with the conversion of lanosterol
`to
`
`leading to low cholesterol concentrations.
`cholesterol,
`Ketoconazole absorption requires an acidic environment,
`precluding the use of proton pump inhibitors or H2
`receptor blockers. Currently, drug availability is limited
`in many countries.
`
`Fluconazole
`
`Fluconazole appears to have similar effects to ketoco-
`nazole; however, data are limited. Fluconazole inhibits
`
`llB-hydroxylase and 17-hydroxylase activities (Fig. 2) and
`blocks cortisol production in primary cultures of human
`adrenocortical cells (van der Pas etal. 2012). Fluconazole has
`
`been shown to decrease 11-deoxycortisol production in
`H295R cells and reduce cortisol secretion in HACIS cells and
`
`primary cultures (van der Pas et al. 2012). In cultures of
`normal adrenals, fluconazole suppressed corticosterone,
`17-hydroxypregnenolone, and androstenedione levels,
`whereas concentrations of progesterone, deoxycorti-
`costerone, and 11-deoxycortisol were increased (Fig. 2).
`Fluconazole slightly increased StAR protein mRNA
`expression (van der Pas at al. 2012). Results from clinical
`studies indicated that fluconazole at adose of 100 mgtwice a
`day successfully controlled UFC levels in two patients (Riedl
`et al. 2006). Together, the results of these in vitro and in vivo
`studies indicate that fluconazole can be used to control
`
`cortisol hypersecretion in patients with CD (Table 3).
`Neither ketoconazole nor fluconazole were shown
`
`to affect the mRNA levels of steroidogenic enzymes or
`cell number: therefore; a single dose is unlikely to have a
`long-term effect (van der Pas et al. 2012).
`
`Metyrapone
`
`Metyrapone (SU-4885 : Metopirone) inhibits IIB-hydroxyl-
`ase (Fig. 2) (Liddle et al. 1959) and 17a-, 18-, and 19-
`hydroxylase (Table 4)
`(Gower 1974). Cortisol
`levels
`decrease after 2 h of the first dose (Verhelst et a1. 1991).
`
`Doses range from 500 mg to 4.5 g/day, or 6 g/day in divided
`doses (usually starting with 250 mg four times daily,
`Table 3; Nieman 2002, Fleseriu 2012). Notably, and similar
`to ketoconazole, rapid uptitration of metyrapone is
`essential to achieve a full effect (Kamenicky et al. 2011,
`Castinetti et al. 2014). The strong cortisol-lowering effect of
`metyrapone can be accompanied by the loss of negative
`
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`lam-.10: and xi vim w
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`Treatment of Cushmg’s dlsease
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`D (div-L“:
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`223 :2
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`R23
`
`2.
`
`22
`
`24
`
`as
`
` Cholesterol
`
`CYP1 7A1
`
`Zona tasciculata
`Glucocorticoids
`
`CYP17A1
`
`Zona reticularis
`Androgens
`
`HSD332
`
`Pregnenolone
`
`—t-
`
`Progesterone
`
`CYP11BI
`
`CYP21 A2 —t-
`
`Deoxycortioostorone
`
`cvpnaz -t :-
`
`Ooniooslerone
`
`CYP1132 - t .
`
`Aldosterone
`
`17-OH-pregnenoione
`
`- t a
`
`1 7-OH-progesterone
`
`
`
`1 1-Deoxycortisoi
`
`Zona glomerulosa
`Mineralooortlcolds
`
`JournalofEndocrinology
`
`Figure 2
`Adrenocortical steroidogenic pathways. A simplified diagram of adrenal
`steroidogenesis is depicted. Cushing's disease is almost always caused by
`a pituitary corticotrope adenoma that oversecretes corticotropin (ACI'H).
`ACTH stimulates the adrenal gland to start steroid synthesis. After
`activation of MCZR by ACTH, the StAR protein is phosphoryiated. Then,
`StAR facilitates cholesterol transport across the mitochondrial inner
`membrane. Cholesterol is the common precursor of the steroid molecules
`and, after several enzymatic reactions, is ultimately converted into
`
`biologically active aldosterone. cortisol, or androstenedione that is further
`processed to testosterone in testicles. The zona glomerulosa, fasciculata,
`and reticularis are the three adrenal cortex histological zones. which
`synthesize steroid hormones with mineraloconlcold, glucocortlcoid, or
`androgenic properties respectively. Enzyme nomenclature is given in detail
`in Table 1. CYP11A1, CYPHB1, and CYP1’lBZ are located in the
`mitochondria, and the remaining enzymes are located in the smooth
`endoplasmic reticulum.
`
`feedback and ACTH inhibition (Fig. 1). Increments in
`ACTH secretion may override steroidogenic blockade that
`may occur during the first month following initiation of
`treatment. Nevertheless, prolonged metyrapone activity
`in patients with (ID has been shown, despite a rise in
`plasma ACTH levels (Verhelst et al. 1991). ACTH also
`overstimulates production of adrenal androgen and miner-
`alocorticoid precursors (e.g. desoxycorticosterone). More-
`over, aldosterone biosynthesis is more severely affected
`than that of cortisol (Gower 1974). Therefore, several side
`
`effects related to metyrapone treatment limit its clinical use
`in patients with CD (Table 3). However, combination
`
`therapy has been proposed to improve tolerance and
`increase efficacy (Table 5; Verhelst et a1. 1991, Kamenicky
`er al. 2011). Despite safety concerns about the use of this
`drug in pregnant women, metyrapone has been used
`sporadically during pregnancy (Lindsay er al. 2005, Karaca
`et al. 2010). Additional long-term studies with metyrapone
`
`
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`DOI: 10.1530106'14‘0300
`
`© 2014 Society for Endocrinology
`Printed in Great Britain
`
`in patients with CD are warranted. Currently, metyrapone
`has limited availability in most countries.
`
`Mitotane
`
`1 -(o-Chlorophenyi)-1-(p-chiorophenyi)-2,2—dichloroethane
`
`(o,p’-DDD) (Lysodren; mitotane), an insecticide analog of
`dichlorodiphenyltrichloroethane has been extensively used
`
`to treat all forms of hypercortisoiism (Boscaro et al. 2001).
`Mitotane’s mechanism of action was initially described in
`animal studies as lipid accumulation and atrophy of
`fasciculate and reticularis regions of the adrenal cortex. Effects
`
`on the zona glomerulosa were only observed after prolonged
`therapy (Cueto St Brown 1958). Within 12 h of treatment in
`dogs, electron microscopy revealed rupture of mitochondrial
`cristae, followed by mitochondrial swelling, lysis, and cell
`death (Miller St Crapo 1993). Conversion of cholesterol to
`pregnenolone was markedly impaired indicating that
`
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`Teva Pharmaceuticals USA, Inc. v. Corcept Therapeutics, Inc.
`PGR2019-00048
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`lournalofEndocrinology
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`0 (Java: ammo: and 24 (LUL nu 223 :2
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`Treatment of Cushmg’s d/sease
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`R24
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`Table 3 Doses and relevant side effects of drugs used in the medical treatment for Cushing's disease
`
`
`
`
`Steroidogenesis inhibitors
`Ketoconazole
`Fluconazole
`
`Metyrapone
`
`Mitotane
`
`Etomidate
`
`LCI699
`
`Centrally acting drugs
`Cabergoline
`Bromocriptine
`Pasireotide
`
`Retinoic acid
`
`400—1200 mg/day
`200 mg/day
`
`0.5—4.5 g/day
`
`2—5 g/day
`
`Bolus 0.03 mg/kg i.v.;
`followed by
`0.1-0.3 mg/kg per h
`4—100 mg/day
`(investigational drug)
`
`0.5-7 mg/week
`1—30 mg/day
`750—2400 pig/day
`
`10-80 mg/day
`(research drug)
`
`Glucocorticoid receptor antagonist
`Mifepristone
`300—1200 mg/day
`
`
`
`
`
`Hepatitis. cholestasis, gynecomastia, gastrointestinal upset.
`edema, skin rash. Hypogonadism in men. Fluconazole may be
`better tolerated
`
`Acne, hirsutism, lethargy, dizziness, ataxia, nausea, hypertensive
`crisis, hypokalemia, edema, and adrenal insufficiency
`Gastrointestinal distress, impaired concentration and dizziness,
`gynecomastia, hepatitis, cholestasis, hyperlipidemia,
`prolongation of bleeding time, and adrenal insufficiency.
`Effect antagonized by spironolactone
`Nephrotoxicity, sedation, pain at the infusion site. anaphylactic
`reactions. coughing, hiccups, nausea, vomiting, and
`myoclonus
`Fatigue, nausea, headache, and hypokalemia
`
`Nasal congestion, nausea, postural hypotension, and headache.
`Gradual increase minimizes side effects
`
`Gastrointestinal-related conditions, hyperglycemia, cholel'rtiasis,
`nausea, abdominal pain, fatigue, headache, hypotension, and
`adrenal insufficiency
`Xerophthalmia and arthralgias
`
`Hypokalemia, worsening of hypertension, adrenal insufficiency,
`endometrial hyperplasia, fetal loss, gastrointestinal
`complaints, fatigue, nausea, headache, arthralgia, vomiting,
`and edema. Contraindicated in women planning pregnancy
`
`leffcoate et al. (1977), Robinson et al. (1987). Verhelst et al. (1991), Castinetti et al. (2009), Fleseriu et al. (2012), Heyn et al. (2012), Nieman (2002). and
`Feelders 8r Hofland (2013).
`
`side—chain cleavage of cholesterol was the major enzymatic
`
`increment from 0.5 to 1 g/day (Table 3; Luton er a1. 1979).
`
`step affected inhibiting the cytochrome P450 enzymes
`CYPllAl
`(mitochondrial side-chain cleavage enzyme),
`IIB-hydroxylation (CYPllBI), and 18-hydroxylation
`
`Results from a recent retrospective study revealed remission in
`48 (72%) out of 67 patients treated for long-term CD after a
`median of 6.7 (5.2—8.2) months (Baudry et a1. 2012) at lower
`
`(CYPllBZ), and non-P450 enzymes (SB-hydroxysteroid
`dehydrogenase) (Fig. 2; Miller & Crapo 1993). Mitotane also
`
`doses compared with adrenal cancer.
`Despite its effectiveness, mitotane therapy is compli-
`
`stimulates CYP3A4 expression, reducing cortisol bioavail-
`ability (Kroiss et al. 2011). Therefore, mitotane has three
`effects:
`i) adrenocorticolytic,
`ii) modification of steroid
`metabolism, and iii) direct inhibition of steroid biosynthesis.
`Although used to treat adrenocortical carcinoma, mitotane
`has proven effective in patients with CD (Bledsoe et al. 1964,
`Baudry er al. 2012). Mitotane displays a relatively slow onset
`
`of action compared with other steroidogenesis inhibitors
`and saturation can be expected 2—3 months after initiation
`of therapy (Luton et al. 1979, Fleseriu 8r Petersenn 2012).
`Overall, 80% of patients achieve normalization of urinary
`markers; however, 60% relapsed after therapy withdrawal
`indicating a low level of adrenolytic action (Luton eta]. 1979,
`Schteingart et a1. 1980). Sustained remission after mitotane
`
`discontinuation has been reported in 30% of patients
`measured at a mean follow-up of 37 months (Miller 6t
`Crapo 1993). Doses are approximately 4 g/day, with a gradual
`
`
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`Printed in Great Britain
`
`cated by several side effects (Table 3). Owing to an
`accelerated metabolism of exogenous steroids, especially
`hydrocortisone, replacement doses must be increased to
`avoid adrenal crises (Robinson et a1. 1987). Mitotane may
`
`lead to restoration of gonadal function and fertility:
`therefore, effective contraception is advisable for female
`patients (Miller 8r Crapo 1993). Mitotane is stored in
`
`adipose tissue for 2 years after administration ends and
`should not be used in women considering pregnancy
`within 5 years of discontinuation (Leiba eta]. 1989). Owing
`to the stimulatory effect of mitotane on cortisol-binding
`globulin levels (Nader er al. 2006), serum cortisol measure-
`ments are not useful and monitoring of urinary or serum
`free cortisol is the best index of response (Alexandraki et ul.
`
`2010). Replacement therapy requirements are higher than
`normal, due to interference of hormone-binding proteins
`as well. Mitotane combined with pituitary irradiation was
`
`‘ Published byBioscientifica Ltd.
`
`Teva Pharmaceuticals USA, Inc. v. Corcept Therapeutics, Inc.
`PGR2019-00048
`
`Corcept Ex. 2034, Page 6
`
`

`

`L‘- ccntvc‘: ammo: and 24 titer nu
`
`Treatment of Cushmg’s dlsease 223 :2
`
`R25
`
`
`Table 4 Enzymes that catalyze the initial reaction in the pathways of steroid hormone biosynthesis
`Nomenclature“
`
`Localization and common name
`
`Previous
`
`Current
`
`Inhibitors
`
`References
`
`Mitochondrial
`StAR protein
`Side-chain cleavage (scc)
`enzyme or 20,22 desmolase
`
`StAR
`P450scc
`
`StAR
`CYP11A1
`
`11B-hydroxylase
`
`P450 C11
`
`CYP11B1
`
`Aldosterone synthase,
`18-hydroxylase
`
`P450 C11AS
`
`CYP11BZ
`
`Imidazolesb
`Imidazoles
`Etomidate
`Mitotane
`
`Aminoglutethimide
`Imidazoles
`Mitotane
`Aminoglutethimide
`Metyrapone
`Mitotane
`LCI699
`Aminoglutethimide
`Metyrapone
`
`3B-HSD
`
`33-HSD
`
`Trilostane
`
`Walsh et al. (2000)
`Ca macho et al. (1967), Schulte et al.
`(1990), and Miller & Crapo (1993)
`
`Camacho et al. (1967), Gower (1974),
`Feldman (1986), Loli et al. (1986),
`and Miller & Crapo (1993)
`
`Camacho et al. (1967), Gower (1974),
`Miller & Crapo (1993), and Calhoun
`et al. (2011)
`
`Potts et al. (1978), Dewis et al. (1983),
`and Engelhardt & Weber (1994)
`
`Smooth endoplasmic reticulum
`17B-hydroxysteroid dehydro-
`genase, 35-hydroxysteroid
`dehydrogenase
`17a-hydroxylase/17,20 lyase
`
`Camacho et al. (1967), Gower (1974),
`Imidazoles
`Feldman (1986), Loli et al. (1986),
`Aminoglutethimide
`and Miller 8: Crapo (1993)
`Metyrapone
`Ca macho et al. (1967)
`Aminoglutethimide
`CYP21A2
`P450 C21
`21-Hydroxylase
`
`
`
`P450 aroAromatase CYP19
`Ca macho et al. (1967)
`Aminoglutethimide
`
`P450 C17
`
`CYP17
`
`)ournalofEndocrinology
`
`“P4505cc or CYP11A1, i.e. gene family 11, subfamily A, polypeptide 1.
`hImidazoles:ketoconazole, fluconazole, econzale. and/or miconazole.
`
`shown to be efficacious in non-controlled clinical trials
`
`(Luton et al. 1979, Schteingart et al. 1980).
`
`disturbance, sepsis, severe psychosis, and in preoperative
`instability (Heyn et a1. 2012, Preda et al. 2012).
`
`Etomidate
`
`LCI699
`
`The imidazole anesthetic agent etomidate (Amidate or
`Hypnomidate) was observed to decrease postoperative
`cortisol values in patients during anesthesia (Feldman
`1986). Subsequently,
`it was discovered that etomidate
`inhibits
`the
`llB-hydmxylase
`enzyme
`((ZVPl 1 Bl),
`17a—hydroxylase (CYP17A1), and the cholesterol side-chain
`cleavage complex (P4505cc, or CYP11A1, or 20,22 desmo-
`lase), thus blocking multiple steps ofsteroidogenesis (Fig. 2).
`It is the only parenteral steroidogenesis inhibitor available
`and provides rapid hypercortisolemia control (Allolio et al.
`1988, Schulte etal. 1 990). An iv. bolus injection of etomidate
`at a low non-hypnotic dose (0.03 mg/kg) followed by
`constant infusion of 0.3 mg/kg per h for 24 h (Table 3)
`decreases serum cortisol in a dose-dependent manner with
`significant suppression after the first 5 h with a maximum
`effect after 11 h (Allolio et al. 1988, Schulte er al. 1990).
`
`Glucocorticoid replacement to prevent adrenal insufficiency
`is warranted after 24 h of etomidate infusion. Clinical use of
`
`etomidate in CS has been limited by sedative side efi‘ects, but
`could be safe and effective in significant biochemical
`
`
`httpzlfjoeendocrinology-iournalsorg
`DOI: 10.153MOE-14‘0300
`
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`Printed in Great Britain
`
`First characterized as an aldosterone biosynthesis inhibitor
`for primary aldosteronism and essential hypertension,
`LC1699 is an iS-hydroxylase (aldosterone synthase)
`inhibitor blocking the conversion of hydroxycortico-
`stemne tn aldosterone. It also inhibits llB-hydroxylase
`(CYPIIBI) in a similar manner to the R-enantiomer of
`
`that blocks the hydroxylation of
`fadrozole (FAD286)
`deoxycortisol
`to cortisol as well as CYPllBZ blocking
`the conversion of deoxycorticosterone to corticosterone
`(Fig. 2) (Calhoun et al. 2011). LC1699 is currently under
`investigation as a treatment for CD (Tritos et a1. 2011,
`Feelders 8t Hoflancl 2013). In a phase II proof of concept
`study of LC1699, rapid UFC normalization in 11 out of
`12 patients with CD, all achieving >50% reduction in
`baseline UFC, was observed. Doses ranged from 4 to
`100 mg/day for 10 weeks (Bertagna et al. 2014). As
`expected, ACTH increased; 45% of cases had ACTH more
`than twice that of baseline. Most adverse events were mild
`
`or moderate (Table 3). Based on these promising results,
`a larger phase II] trial is awaited.
`
`‘ Published byBioscientifica Ltd.
`
`Teva Pharmaceuticals USA, Inc. v. Corcept Therapeutics, Inc.
`PGR2019-00048
`
`Corcept Ex. 2034, Page 7
`
`

`

`L‘- cutva: Minus and 24 (List an 223 :2
`
`Treatment of Cushmg’s d/sease
`
`R26
`
`Table 5 Overview of agents that have been tested as combination drug therapy for Cushing's disease. Doses: cabergoline from 0.5
`to 3 mg/week, ketoconazole 200 to 1200 mglday, pasireotide 300 to 750 pig/day, mitotane 3 to 5 g/day, metyrapone 3 to 4.5 g/day,
`and octreotide 300 to 1500 rig/day. The studies are described in the text
`
`
`
`
`UFC normalization (%)
`
`References
`
`Compounds
`
`Patients (n)
`
`Monotherapy
`
`Combination
`
`Barbot er a]. (2014)
`Feelders et al. (2010b,c)
`
`Ketoconazole +cabergoline
`Pasireotide + cabergoline + ketoconazole
`
`14
`17
`
`Cabergoline+ketoconazole
`Vilar er al. (2010)
`—
`Total/average
`Severe hypercortisolism/aggressive tumor
`4
`Vignati & Loli (1996)
`Ketoconazole +octreotide
`1
`Bode er al. (2010)
`Temozolomide+ pasireotide
`11 CS (4 CD)
`Kamenicky et a]. (2011)
`Mitotane + metyrapone+ ketoconazole
`
`
`Total/average
`—
`16
`
`12
`43
`
`20—30
`30
`
`25
`27
`
`0
`0
`0
`0
`
`80
`50 P+C
`90 P + C + K
`70
`73
`
`0
`100
`100
`66
`
`)ournalofEndocrinology
`
`UFC, urinary free cortisol.
`
`Trilostane (Vetoryl), an inhibitor of 30-hydroxy-
`steroid, was withdrawn from human use in the USA in
`
`1994 (Potts et a]. 1978, Dewis et a]. 1983, Engelhardt 8r
`Weber 1994). Aminoglutethimide (Cytadren; Camacho
`eta]. 1967, Misbin eta]. 1976) is rarely used in the treatment
`of patients with CD. The mechanisms of action, common
`doses, and main adverse effects of aminoglutethimide are
`listed in Tables 2 and 3.
`
`Centrally acting drug treatments
`
`Human corticotrope adenomas display responsiveness to
`neurohumoral influences such as dexamethasone suppres-
`sion, lysine vasopressin, thyrotropin-releasing hormone,
`and metyrapone administration. Dexamethasone is a
`synthetic glucocorticoid extensively used to demonstrate
`the sensitivity of HPA axis negative feedback to gluco-
`corticoids for differential diagnosis of (ES. if the HPA axis
`
`is normal, any supraphysiologicai dose of dexamethasone
`is sufficient to suppress pituitary ACTH secretion. ACTH
`secretion can also be suppressed in most patients with CD
`as pituitary corticotrope adenomas are only relatively
`resistant to inhibition of glucocorticoid negative feedback.
`Hypophyseal ACTH secretion can be influenced by
`serotonin antagonists, dopamine or gamma-amino buty-
`ric acid (GABA) agonists, somatostatin receptor ligands
`(SRLs), retinoic acid, and temozolomide (Fig. 1). In
`addition to biochemical effects, CD has been associated
`with periodic hormonogenesis (cyclical CD) or spon-
`taneous remission, indicating that some cases of CD may
`be due to altered neuroregulatory influences (Van Cauter
`8r Refetoff 1985, Dickstein et a]. 1991, Colao et a]. 1997,
`Nieman 2002).
`
`
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