British Journal of Cancer (2004) 90, 2317 2325
`& 2004 Cancer Research UK All rights reserved 0007 0920/04 $30.00
`
`www.bjcancer.com
`
`Hormonal impact of the 17a-hydroxylase/C17,20-lyase inhibitor
`abiraterone acetate (CB7630) in patients with prostate cancer
`
`Clinical
`
`A O’Donnell1,2, I Judson*,1,2, M Dowsett3, F Raynaud2, D Dearnaley1,8, M Mason4, S Harland5, A Robbins6,
`G Halbert7, B Nutley2 and M Jarman2
`1Royal Marsden NHS Trust, Sutton, Surrey SM2 5PT, UK; 2CR UK Centre for Cancer Therapeutics, Institute of Cancer Research, Sutton, Surrey SM2 5NG,
`UK; 3Academic Department of Biochemistry, Royal Marsden Hospital, Fulham Road, London SW3 6JJ, UK; 4Department of Clinical Oncology, Velindre
`Hospital, Whitchurch, Cardiff CF4 7XL, UK; 5Department of Oncology, University College of London, The Middlesex Hospital Mortimer St, London W1N
`8AA, UK; 6Drug Development Off ice, Cancer Research UK, PO Box 123, London WC2A 3PX, UK; 7Cancer Research UK Formulation Unit, University of
`Strathclyde, Glasgow G1 1XW, UK; 8Institute of Cancer Research, Sutton, Surrey SM2 5NG, UK
`
`A series of three dose escalating studies were conducted to investigate the ability of the 17a hydroxylase/C17,20 lyase inhibitor
`abiraterone acetate, to cause maximum suppression of testosterone synthesis when delivered to castrate and noncastrate males with
`prostate cancer. Study A was a single dose study in castrate males. Study B was a single dose study in noncastrate males and study C
`was a multiple dose study in noncastrate males. The drug was given orally in a once daily dose and blood samples taken to assess
`pharmacokinetic (PK) parameters and hormone levels in all patients. The study drug was well tolerated with some variability in PKs.
`1 was seen in four out of six castrate males treated with a single dose of 500 mg.
`Suppression of testosterone levels to o0.14 nmol l
`At 800 mg given days 1 12 in noncastrate males, target suppression was achieved in three out of three patients, but a two to three
`fold increase of Luteinising Hormone (LH) levels in two out of three patients overcame suppression within 3 days. All patients in the
`multiple dose study developed an abnormal response to a short Synacthen test by day 11, although baseline cortisol levels remained
`normal. This is the first report of the use of a specific 17a hydroxylase/17,20 lyase inhibitor in humans. Repeated treatment of men
`with intact gonadal function with abiraterone acetate at a dose of 800 mg can successfully suppress testosterone levels to the castrate
`range. However, this level of suppression may not be sustained in all patients due to compensatory hypersecretion of LH. The
`enhanced testosterone suppression achieved in castrate men merits further clinical study as a second line hormonal treatment for
`prostate cancer. Adrenocortical suppression may necessitate concomitant administration of replacement glucocorticoid.
`British Journal of Cancer (2004) 90, 2317 2325. doi:10.1038/sj.bjc.6601879 www.bjcancer.com
`Published online 18 May 2004
`& 2004 Cancer Research UK
`
`Keywords: prostate cancer; hormonal therapy; pharmacokinetics; clinical study
`
`

`
`

`
`Prostate cancer continues to present an enormous challenge in the
`UK, where it is the second most common cause of cancer death in
`men, causing over 9000 deaths per year (Cancer Research UK,
`2002).
`The beneficial effect of androgen ablation on metastatic prostate
`cancer was realised in the 1940s, when Huggins and Hodges
`observed an antitumour response, as measured by a reduction in
`serum acid phosphatase, in patients treated by surgical or medical
`castration (Denmeade and Isaacs, 2002). In general, androgen
`deprivation will give a response of varying duration in 80 90% of
`men with advanced disease (Denis and Murphy, 1993). Although
`the multistep pathway of androgen production resulting in
`testosterone (Figure 1) is present only in its entirety within the
`testes, the adrenal gland is also capable of releasing DHEA and
`androstenedione. Enzymes for the subsequent conversion of
`DHEA and androstenedione to testosterone are present
`in a
`
`*Correspondence: Professor I Judson, Clinical Pharmacology, Institute of
`Cancer Research, E Block, 15 Cotswold Road, Sutton, Surrey SM2 5NG,
`UK; E Mail: Ian.Judson@icr.ac.uk
`Received 27 November 2003; revised 18 March 2004; accepted 22
`March 2004; published online 18 May 2004
`
`variety of peripheral tissues as well as the prostate (Griffin and
`Wilson, 1998).
`sources of
`these extratesticular
`Studies have shown that
`testosterone represent an important alternative source of androgen
`stimulation in a significant proportion of patients with prostate
`cancer. As much as 10% of baseline circulating testosterone
`remains in castrated men, due to peripheral conversion of adrenal
`steroids to testosterone (Hellerstedt and Pienta, 2002). First line
`treatment of prostate cancer by androgen deprivation is generally
`achieved by medical or surgical testicular castration. This leaves
`the testosterone derived from adrenal sources intact.
`It is recognised that the development of androgen independent
`prostate cancer is caused, in part, by changes in androgen receptor
`regulation, activation of the androgen receptor being mitogenic in
`this malignancy. The sensitivity of
`the androgen receptor is
`increased by the overexpression of
`two nuclear coactivators:
`transcriptional intermediary factor 2 and steroid receptor coacti
`vator 1. Transactivation of the androgen receptor is thus enhanced
`at lower concentrations of testosterone (Gregory et al, 2001a, b).
`Furthermore, amplification of the number of androgen receptors
`can be shown in hormone refractory tumours, when compared
`to both benign prostatic hyperplasia and primary prostatic
`
`ARGENTUM EX1003
`
`Page 1
`
`

`
`Abiraterone acetate - hormonal and PK study
`A O'Donnell et al
`
`23l8
`
`Cholesterol
`
`L <: Desmolase
`
`Pregnenolone my 1701. OH—pregnenolone jp DHEA
`‘E’
`‘I’
`
`I
`
`170: hydroxylase
`
`c17—20 lyase
`
`Progesterone T, 17a 0H—progesterone my Androstenedione
`
`<: 11B hydroxylase :{>
`
`<2 21
`
`:>
`
`i
`
`oest.-one
`
`i
`
`Testosterone
`
`@Sared
`
`Cortioosterone
`
`Cortisol
`
`oestradior
`
`DHT
`
`M: 18 hydroxylase
`
`Aldosterone
`
`Figure I
`
`Steroid synthesis pathway. DHEA dehydoepiandrosterone; Sared
`
`Sareductase; DHT dihydrotestosterone
`
`malignancy, using both reverse transcription PCR and fluorescence
`in situ hybridisation (Bubendorf et al, 1999; Linja er al, 2001).
`The imidawle derivative ketoconazole and the aromatase
`
`inhibitor aminoglutethimide have been evaluated as possible
`agents with which to achieve decreased production of adrenal
`steroids. Ketoconazole is relatively unselective, inhibiting both
`cholesterol side chain cleavage and 11]} hydroxylation (Loose et al,
`1983). A direct antitumour effect of ketoconazole in vitro has also
`been demonstrated (Eichenbeger and Trachtenberg, 1988). The
`action of aminoglutethimide is primarily to block the formation of
`pregnenolone from cholesterol but it is also recognised to inhibit
`llfl hydroxylase and peripheral aromatase (Schwimme and
`Parker, 1996). In clinical trials, both agents have shown some
`activity as second line agents (measured by clinical benefit as well
`as reduction in PSA), supporting the concept of a more selective
`inhibitor of the 17a: hydroxylaseIC.7_2o lyase enzyme (Oh. 2002).
`The novel 17a hydroxylase/C17,” lyase inhibitor abiraterone
`acetate (Figure 2) was developed as a mechanism based steroidal
`inhibitor following observations that nonsteroidal 3 pyridyl estes
`had improved selectivity for inhibition (Rowlands et al, 1995).
`Abiraterone acetate is the 3 acetate and a prodrug form of CB7598
`(17 (3 pyridyl)androsta 5,16 dien 3]} ol, abiraterone), a potent
`inhibitor of the enzyme with a
`of 0.5nM (Barrie et al, 1997;
`Potter et al, 1995).
`Using a rodent model. following intraperitoneal administration,
`abiraterone acetate showed rapid deacetylation. Levels of deace
`tylated drug reached > 1 [M at 6h, with persistence of relatively
`high levels of compound (approximately 0.3 pm) for at least 24 h.
`Although this finding may be indicative of depot characteristics of
`the mode of administration used, it may also indicate a degree of
`enterohepatic recirculation that could prove favourable in the
`clinical setting. providing sustained target enzyme inhibition.
`In these preclinical studies, there was correlative evidence of
`inhibition of 17a: hydroxylation as shown, for example, by the
`reduced wdght of the ventral prostate (Barrie et al, 1994; Dowsett
`et al, 1988).
`Hee, we describe a series of three phase one trials in which
`abiraterone acetate was tested in humans for the first time. This is
`
`the first report of the eflects of a specific 17a: hydroxylaselC.7,2o
`
`British Journal of Cancer (2004) 90m), 23:7 237.5
`
`R0
`
`Figure 2 Abiraterone structure. R H: abiraterone (CB7598); R Ac
`abiraterone acetate (CB7630).
`
`in humans. The studies wee conducted to
`lyase inhibitor
`determine the dose of abiraterone acetate that will result in
`maximum suppression of testosteone and to obtain safety,
`pharmacolrinetic (PK) and endocrine data. the latter to determine
`the specificity of inhibition. All three studies involved patients with
`advanced, that is, unresectable, prostate cance.
`
`METHODS
`
`Patients wee recruited to one of the following three studies that
`wee conducted in sequence. The study protocols were approved
`by the Research Ethics Committee of all participating institutions,
`and all patients gave written informed consent prior to inclusion.
`All three studies wee conducted under the auspices of the Cancer
`Research UK Phase IIII Committee.
`
`Study A
`
`This was a single dose study in males with castrate levels of
`testosterone (testosterone < 2 nmol 1‘ ') following orchidectomy or
`Gonadotrophin Releasing Hormone agonist (GnRHa) therapy, to
`
`9 2004 Cancer Research UK
`
`Page 2
`
`Page 2
`
`

`
`Clinical
`
`Abiraterone acetate – hormonal and PK study
`A O’Donnell et al
`
`to study entry all patients must have had an orchidectomy or have
`received (and continued to receive) ongoing treatment with a
`GnRH agonist for at least 2 months. A confirmatory testosterone
`1 was also required.
`level of between 0.2 and 2.0 nmol l
`
`2319
`
`Study B
`
`This was a single centre, open label, phase one, single dose study
`in which sequential cohorts of three noncastrate patients were to
`be treated at four dose levels: 200, 500, 650 and 800 mg. The
`starting dose of 200 mg was chosen when the results of study A
`were available. It was envisaged that a dose level would be
`expanded to five patients if
` one patient at any dose level experienced XGrade 3 toxicity
` there was a significant suppression of serum cortisol in one
`patient as defined as a greater than 50% reduction in levels of
`cortisol, or a smaller fall associated with hypotension (systolic
`BP less than 90 mmHg) or persistent electrolyte disturbance.
` if the target suppression of testosterone was achieved in three
`patients at any one dose level.
`
`All patients were required to have a normal testosterone level
`1) as well as normal
`prior to study entry (i.e. X9.0 nmol l
`1).
`gonadotrophin levels (Luteinising Hormone (LH) p13 IU l
`
`Study C
`
`This was a three centre, open label, phase one, multidose study in
`which sequential cohorts of three noncastrate patients were to
`receive treatment with abiraterone daily for 12 days. All patients
`1)
`were required to have a normal testosterone level (X9.0 nmol l
`1) prior to
`as well as normal gonadotrophin levels (LHp13 IU l
`study entry.
`The starting dose of 500 mg was based upon the data from the
`single dose studies. It was planned that a dose level would be
`expanded to six patients if any patient experienced toxicity X
`Grade III or if there was a significant suppression of serum cortisol
`in one patient (defined as per Study B above). All patients were
`followed for 28 days for any sign of toxicity. If any patient
`developed symptoms suggestive of progressive disease, confirmed
`by a rise in PSA during the study period, they would have been
`offered standard treatment with a GnRH agonist.
`In all studies, the capsules were administered in one oral dose at
`0930 following an overnight fast. Free fluids were permitted and
`patients were allowed a light snack 4 h after dosing on the day of
`PK sampling.
`
`PRETREATMENT ASSESSMENT AND FOLLOW-UP
`INVESTIGATIONS
`
`Prior to the first dose of therapy a complete history, physical
`examination and assessment of performance status was performed
`on all patients. Full blood count, electrolytes and creatinine, liver
`function, urinanalysis, electrocardiograph and chest X ray were
`obtained from all patients. The ECG was repeated 6 h after dosing.
`On the day of therapy heart rate, blood pressure and temperature
`were recorded every 4 h and then daily at the time of blood sampling.
`Thereafter,
`full blood count, electrolytes, creatinine and liver
`function were re evaluated on Days 2 and 7. Toxicity was recorded
`using the NCI CTG Expanded Common Toxicity Criteria V1.
`
`ENDOCRINE ASSESSMENT
`
`Study A and B
`
`Serum samples for endocrine analysis were obtained at 0, 2, 4, 8
`and 24 h on a single day in the week prior to treatment
`
`determine the dose of abiraterone acetate that was sufficient to
`cause suppression of testosterone synthesis to undetectable levels
`1). Significant suppression was defined as either
`(o0.14 nmol l
`1 in individual patients with a pretreat
`testosterone o0.14 nmol l
`1 or a X75% reduction in individual
`ment value of o0.6 nmol l
`1.
`patients with a pretreatment value of X0.6 nmol l
`
`Study B
`
`This was a single dose study in noncastrate males (testosterone
`1) to determine the dose of abiraterone acetate
`level X9.0 nmol l
`that was sufficient to cause suppression of testosterone synthesis to
`1).
`castrate levels (p2.0 nmol l
`
`Study C
`
`This was a multidose study (Days 1 12) in noncastrate males to
`determine the dose of abiraterone acetate that was sufficient to
`cause persistent suppression of testosterone synthesis to castrate
`levels. If this level of suppression was achieved, then it was planned
`to escalate the doses still higher to establish whether further
`suppression of testosterone was possible. Complete suppression of
`testosterone
`synthesis
`should result
`in testosterone
`levels
`1, based upon local data, indicating that the mean
`o0.7 nmol l
`value for testosterone in patients on GnRH agonist therapy is in
`1.
`the region of 0.7 nmol l
`In all three studies, the secondary objectives were as follows:
` to determine the safety and tolerability of abiraterone acetate in
`the single and multiple dose setting;
` to study the PKs of this compound; and
` to determine any other endocrine effects especially suppression
`of cortisol synthesis.
`
`INVESTIGATIONAL AGENT
`
`Abiraterone acetate was provided by Boehringer Ingelheim as a
`micronised powder and prepared by the Cancer Research UK
`Formulation Unit (Glasgow) as 10, 50, 100 and 200 mg dry filled
`capsules. The capsules were stored at room temperature.
`
`PATIENT POPULATION
`
`Patients were required to be at least 18 years of age with a WHO
`performance status of p2. No radiotherapy or hormonal therapy
`(with the exception of GnRHa in Study A as described above) was
`allowed within 6 weeks prior to study, although patients were
`allowed to receive concomitant bisphosphonates. Entry was further
`1, WBC
`restricted to patients with haemoglobin X10.0 g dl
`
`1, platelet count X100 109 l1, alkaline phosphatase
`X4.0 109 l
`less than twice the upper limit of normal and a urea, creatinine and
`bilirubin of not more than 25% above the normal range. Patients
`were excluded with coexistent serious nonmalignant disease and
`were not allowed to take concomitant steroids. All patients had
`stable recurrent malignancy. At the time of participation in these
`trials, none of
`the patients was considered to require any
`alternative therapeutic intervention for symptomatic or progres
`sive disease.
`
`DOSAGE AND ADMINISTRATION
`
`Study A
`
`This was a single centre, open label, phase one, single dose study
`in which sequential cohorts of
`three medically or surgically
`castrate patients were to receive treatment at five dose levels:
`starting at 10 mg and increasing to 30, 100, 200 and 500 mg. Prior
`
`& 2004 Cancer Research UK
`
`British Journal of Cancer (2004) 90(12), 2317 2325
`
`Page 3
`
`

`
`also drawn prior to treatment on Days 2, 3, 4, 7, 8, 9, 10, 11 and 14
`with additional samples on Days 21 and 28. Samples (7 ml) were
`collected into vacutainer
`tubes
`(BD, Rutherford, NJ, USA)
`containing EDTA and immediately centrifuged to separate the
`plasma. At least 2 ml of plasma was transferred into polypropylene
`tubes (NUNC) and frozen at 201 until analysis.
`
`RESULTS
`
`Study A
`
`A total of 16 male patients with histologically confirmed advanced
`adenocarcinoma of the prostate were enrolled. All patients had
`received previous antiandrogen therapy (flutamide or cyproterone
`acetate) and at time of enrolment in this study all were receiving
`treatment with a GnRH agonist;
`leuprorelin or goserelin. All
`patients were evaluable for safety, PK and endocrine assessments.
`The group had a median age of 73.5 years (Range 63 77 years) and
`all were performance status 0, 1.
`
`Endocrine
`Sequential cohorts of three patients were treated at 10,
`30 and 100 mg. At these doses no consistent effect on testosterone
`was observed and the plasma concentrations of abiraterone were
`below the level of detection. Patient 4 (30 mg dose level) was
`observed to have noncastrate levels of testosterone during the
`study period despite a satisfactory screening testosterone level of
`1. On further questioning, it was discovered that there
`1.3 nmol l
`had been suboptimal compliance with goserelin therapy and he
`was deemed ineligible.
`A dose escalation to 500 mg was considered necessary as a result
`of the absence of a pharmacodynamic effect at doses up to 100 mg
`after one patient had already consented to and had received therapy
`at 200 mg. A 75% reduction in testosterone was observed in this
`patient within the first 24 h after treatment with abiraterone. In all
`three patients treated at 500 mg, a reduction in testosterone to the
`1 or X75% reduction in
`target level was seen (o0.14 nmol l
`1). The duration of the
`baseline level testosterone X0.6 mmol l
`suppression was variable. In two of the three patients, suppression
`was sustained from Days 2 to 5 post therapy. Three additional
`patients then received treatment at 500 mg. Target testosterone
`suppression was seen in one of these patients. The same level of
`suppression was not observed in the remaining two apparently due
`to incorrect prior dosing with goserelin and therefore escape of
`testosterone levels to noncastrate levels during the study period.
`These results are illustrated in Figure 3. At the 500 mg dose level, a
`reduction in mean androstenedione levels was parallel to the
`reduction in mean testosterone levels, occurring around Day 2. It
`was notable that there was no corresponding reduction in the levels
`of 17 hydroxyprogesterone. A reduction in serum cortisol levels
`1,
`was seen in one patient treated at 500 mg, baseline 409 nmol l
`1 Day 1. However, as this reduction was
`falling to 81 nmol l
`apparent at the first time point on Day 1 it was felt to be
`inconsistent with suppression due to abiraterone. On questioning
`this patient denied the concomitant use of glucocorticoids.
`
`Study B
`
`Four male patients with histologically confirmed advanced
`adenocarcinoma of prostate were recruited. All patients had
`received prior antiandrogen therapy and previous therapy with a
`GnRH agonist but at
`the time of study entry had a serum
`1. All patients were evaluable for safety,
`testosterone of 49 nmol l
`PK and endocrine assessments. The group had a median age of
`71.5 years (range 60 77 years), and had performance status 0.
`
`Endocrine The first patient received treatment with abiraterone
`at 200 mg. No testosterone suppression was observed and three
`further patients were then treated at 500 mg. In all three patients a
`
`Abiraterone acetate – hormonal and PK study
`A O’Donnell et al
`
`commencement and then on Days 1, 2, 3, 4 and 7. As the duration
`of testosterone suppression was longer than originally anticipated,
`additional samples were added on Days 10, 14 and 21. The serum
`samples were analysed for testosterone, cortisol, 17 a hydroxy
`progesterone (17HP), androstenedione, LH and follicle stimulating
`hormone (FSH) using commercially available kits. However, the
`DPC Coat a count kit for testosterone was sensitised using a larger
`volume of sample/standard and extension of the standard curve.
`Prior to study initiation,
`this was demonstrated to have no
`significant effect on the values of testosterone measured but to
`1. All endocrine
`provide sensitivity to a level of 0.05 nmol l
`analyses were conducted by radioimmunoassay except for LH
`and FSH, which were by enzyme immunoassay.
`
`Study C
`
`The schedule sampling differed slightly with samples removed at
`0930 and 1730 on the day of treatment and thereafter in the
`morning on Days 2, 3, 4, 7, 8, 9, 10, 11, 14, 21 and 28. In Study C, a
`short Synacthen test was also performed prior to therapy and again
`around Day 11.
`
`2320
`
`Clinical
`
`PKS – ANALYTIC METHOD, ASSAYS AND SAMPLING
`
`Sample extracts were analysed by a fully validated liquid
`chromatography mass spectrometry method. The instrument
`consisted of Wisp Model 717 autosampler including a Model
`600MS system controller with a quaternary U6K LC pump. A
`Finnigan MAT TSQ 700 triple quadrupole mass spectrometer was
`used as the detection system, together with Finnigan MAT ICIS
`and ICL software for data capture and processing (ThermoQuest
`Ltd, San Jose, CA, USA). The separation of analytes was performed
`on a Supelcosil LC ABZ (5 mm, 250 4.6 mm) analytical column
`protected by a guard column (Supelco, Bellefonte, PA, USA). The
`mobile phase consisted of 570 ml of 20 mM ammonium acetate
`solution, 100 ml tetrahydrofuran and 1330 ml acetonitrile and was
`1 throughout the system.
`delivered at a flow rate of 1 ml min
`Column eluant was subjected to electrospray ionisation and
`monitored by selected ion monitoring (SIM) of protonated
`pseudo molecular ions of authentic standards of abiraterone
`acetate and abiraterone, and GP488 (an analogue of abiraterone
`used as internal standard). For SIM, the scan width was 0.25 and
`the
`total
`scan time was
`2.99 s. Also, heated capillary
`temperature¼ 2501C,
`voltage¼ 4.5 kV,
`spray
`collision
`off
`set¼ 49.9 V and electron multiplier voltage¼ 1200 eV.
`Samples were extracted as follows: 50 ml of acetonitrile and 40 ml
`of 50 mM GP488 internal standard were added to 500 ml of patient
`plasma. After the addition of 3 ml hexane : butanol (98 : 2, v/v) and
`2 min vortexing, 2 ml aliquots of the organic layer were transferred
`for drying in vacuo for 2 h. The dried residue was reconstituted by
`vortexing in 150 ml of acetonitrile and transferred into autosampler
`vials. Aliquots (100 ml) of these samples were injected onto the LC
`column. Calibration curves were obtained by plotting peak area
`ratios for abiraterone acetates or abiraterone to internal standard
`vs the nominal analyte concentrations using linear regression by
`Microsoft Excel version 5.0 (Microsoft, Redmond, WA, USA).
`Calibrations curves were produced at the levels of 500 and 1000 nM
`for abiraterone acetate and 6.25, 12.5, 25, 50, 100 and 500 nM for
`abiraterone. Quality controls were included at the level of 8, 40 and
`400 nM for abiraterone and 500 nM for abiraterone acetate.
`A comprehensive PK profile (Cmax, Tmax, T1/2a T1/2 and Kabs) was
`determined for each patient. Pharmacokinetic parameters were
`evaluated using WinNonLin Softwares and were conducted at
`The Institute of Cancer Research (Sutton).
`Blood was sampled for analysis of abiraterone concentration
`prior to drug administration and at the following times on Day 1:
`30 min, 1, 2, 4, 6, 8 and 12 h. In the multidose study, samples were
`
`British Journal of Cancer (2004) 90(12), 2317 2325
`
`& 2004 Cancer Research UK
`
`Page 4
`
`

`
`Mean testosterone levels
`
`/'\
`
`Testosterone levels
`
`Abiraterone acetate - hormonal and PK study
`A O'Dome|| et al
`
`232 I
`
`
`
`0
`
`1
`
`2
`
`3
`
`4
`
`5
`
`6
`
`7
`
`Days postdose
`
`Mean androstenedione levels
`
`8
`
`_I_.._l
`
`3E50I
`
`: 28I
`
`) 2 E
`
`
`
`O
`
`3
`
`6 912151821
`Days postdose
`
`74 40
`30
`
`3E
`
`50
`§ 202
`8 10
`§1-
`0
`
`A
`'7
`
`Luteinising hormone levels
`
` Lutelnlslng
`hormone(IUL
`
`0
`
`2 4 6 8101214161820
`Dayspostdose
`
`Figure 4 Serial homlone levels in noncastrate patients treated with a
`single oral dose of abiraterone acetate.
`
`While serum cortisol levels remained within normal limits all three
`
`patients had an abnormal response to Synacthen by Day 11. The
`mean chan e
`in cortisol
`in response to Synacthen was
`294.3 nmol 1‘
`(Le + 77%) at baseline in the patients treated with
`500mg falling to only 42 nmoll" (+10%) by Day 11. A further
`cohort of three patients was then treated at 800 mg to investigate
`whether target testosterone suppression ($0.7 nmoll—') could be
`reached. In the first patient. target suppression was obtained on
`Day 1, sustained for 3 days and then reversed in association with
`rising Ll-I
`(three fold increase)
`from Day 3. Despite this
`testosterone levels remained $2.0 nmoll" for the duration of
`treatment. In the second, target suppression was reached on Day 4,
`testosterone rose to 0.77 nmol I‘ l on Day 7 but otherwise remained
`below the target level for the duration of treatment. In the final
`patient, testosterone fell to 1.7 nmol I" by Day 2 but then rose
`again to >20 nmol 1-‘ from Day 4. A concomitant two fold rise in
`LH was seen from Day 3 in this patient.
`The first and third patients treated at 500 mg had higher LH
`levels at baseline than all patients treated at 800 mg. This may have
`contributed to the difliculty in achieving suppression of testoster
`one at the lower dose level. As in those treated at 500mg, the
`cortisol response to the short Synacthen test in all three patients
`treated at 800mg was abnormal on Day 11. The mean change in
`cortisol levels in response to Synacthen was 385 nmol 1" (120%) at
`baseline in this cohort of patients, falling to an increment of
`65.3 nmol 1" (23%) by Day 11. Sennn cortisol
`levels were
`themselves reduced by the evening of Day 1 in three patients but
`all other assessments remained within normal limits. Evening
`cortisol falling by 60, 71 and 69%, respectively, from baseline
`evening cortisol in these three patients.
`
`PHARMACOKINETICS
`
`The PK parameters all show considerable variability between
`patients and are presented in Table l. The plasma concentration of
`abiraterone at the first three dose levels in study A was below the
`level of detection of the assay precluding analysis of the PK
`
`British Journal of Cancer (2004) 42002). 23:7 2375
`
`Page 5
`
`0
`
`7
`2
`6
`2
`E: 5
`§ 3 ‘
`2 g
`3
`'0 .,
`5
`21
`
`2
`
`3
`
`4
`
`5
`
`6
`
`7
`
`Dayspostdose
`
`Mean 17- hydroxyprogesterone levels
`
`17-hydroxyprogesterone
`
`2
`
`3
`
`4
`
`5
`
`6
`
`7
`
`Dayspostdose
`
`Figure 3 Selected mean hormone levels in castrate men receiving a
`single dose of abiraterone acetate.
`
`reduction in testosterone level of more than 50% from baseline was
`
`seen. The testosterone nadir was observed on the second day after
`therapy with recovery to pretreatment levels 6 9 days later. A
`corresponding rise in LH levels was seen (47 75%) maximal on
`Day 3 with recovery to pretreatment levels by Day 10 (Figure 4).
`No change in cortisol level was seen.
`
`Study C
`
`Six male patients with histologically confirmed advanced adeno
`carcinoma of the prostate were accrued. Five of the six had
`received prior antiandrogen therapy and the same five of six had
`received and completed prior therapy with a GnRH agonist. At the
`time of study entry, all patients had a testosterone level of
`>9 nmoll_'. The group had a median age of 68.5 years (Range
`62 80 years) and had performance status 0 or 1.
`
`Endocrine An initial cohort of three patients received treatment
`at 500mg. Although a reduction in testosterone level
`to
`$2.0nmoll" was seen in all three patients, this did not reach
`the target level of $0.7 nmoll—'. The pattern of suppression was
`variable with maximal suppression occurring Days 1 3 and
`substantial suppression sustained for up to 9 days (Figure 5).
`
`©2004CancerResearchU(
`
`Page 5
`
`

`
`Abiraterone acetate - hormonal and PK study
`A O'Donnell et al
`
`2322
`
`Testosterone levels
`
`—x— Pl_1—5o0mg
`—o—Pl.2-6(X)l‘lIg
`—a—PI.3—51X)I'lfl
`- I- PL1-KXNIQ
`- 0- Pl_2-UXIIIQ
`-=
`
`Pt3—tloomg
`
`
`1 2 3 4 5 6 7 8 9101112131415161718192021&232425
`
`Dayspostdose
`
`Lutenising honnone levels
`
`
`
`Testosterone(nmolL")
`
`
`
`
`
`Lutenlelnghormonelevel(IUL4)
`
`12 3 4 5 6 7 8 91011121314151617181920212Z%2425
`
`Figure 5
`
`Serial hormone levels in noncastrate patients treated with multiple oral doses of abiraterone acetate.
`
`Dayspostdose
`
`behaviour. At 100 mg, concentrations were low and the terminal
`half life was unable to be deternnined confidently. Detectable levels
`were obtained at all doses greater than or equal to 200mg. Data are
`not available for one patient treated at 500 mg due to an assay that
`failed quality control.
`The mean Tm, was 2.70 h (is.d. 2.71) with a mean elimination
`half life of 27.6h (is.d. 20.17). A range of up to 10 fold in AUC
`was seen for a given dose.
`Within the patient groups studied, we were unable to identify
`any distinguishing characteristics to explain this further. The level
`of interpatient variability made analysis of dose dependent PK
`relationships diflicult. Combining the data from all three studies,
`while the mean AUC at each dose level increased with dose, it
`a
`eared that the association between AUC and dose is nonlinear
`
`(R = 0.34). There was no evidence of saturation of drug
`absorption at the dose levels studied (Table 2 and Figure 6).
`
`OVERALL TOXICITY
`
`In all three trials, abiraterone acetate was very well tolerated and
`no serious adverse events attributable to treatment were recorded.
`
`No haematologic or biochemical elfects were observed at any dose
`level or schedule evaluated. No alteration in resting heart rate or
`blood pressure was seen. Systemic effects attributable to abirataer
`one were uncommon. Headache, hot flushes, a mild increase in
`abdominal and testicular pain, and a transient depression in mood
`
`British Journal of Cancer (2004) 90(|2), 23:7 237.5
`
`(all grade II) were reported by individual patients but no relation
`to dose or schedule was apparent. There were no grade three or
`four toxic events.
`
`DISCUSSION
`
`These are the first data to describe the systematic assessmernt ofthe
`endocrine effects of a specific 17¢ hydroxylaseIC.7,m lyase in
`hibitor in humans. The endocrine results that will determine the
`
`further developmernt of abiraterone acetate are likely to be
`qualitatively representative of other drugs of this class.
`The single dose study in castrate patients demonstrated that
`treatment with abiraterone acetate results in sustained suppression
`of the testosteronelandrostenedione axis. The protracted duration
`of this suppression is possibly due to the irreversible nature of the
`drug action. In turn, therefore, one may predict that it may be
`possible to increase the effect with continuous dosing. This single
`dose study showed no elfect on 1711 OH progesterone production.
`This indicates that any inhibition of 17a: hydroxylation that may
`occur as a result of treatment with abiraterone acetate is over
`
`ridden by compernsatory mechanisms related to cortisol feedback.
`Despite 17a hydroxylase and Cu,” lyase activities being contained
`in a single enzyme the compensated effect on 17a: hydroxylase
`activity clearly did not prevent an inhibition of Cum lyase (as
`evidernced by androgen suppression). Supportive evidence for this
`is provided by the observation that there was no significant effect
`
`0 2004 Cancer Research UK
`
`Page 6
`
`Page 6
`
`

`
`Abiraterone acetate - hormonal and PK study
`A O'Dome|l et al
`
`2323
`
`Table I
`
`Summary of pharmacokinetic data for abiraterone acetate when given orally in single and multiple dose studies
`
`Patient
`I
`2
`3
`4
`5
`6
`7
`8
`9
`I 0
`I
`I
`I 2
`I 3
`I 4
`I 5
`I6
`I 7
`I 8
`I9
`20
`2 I
`22
`23
`24
`25
`26
`
`Dose (mam ')
`I0
`I0
`I0
`30
`30
`30
`I00
`I00
`I00
`200
`500
`500
`500
`500
`500
`500
`200
`500
`500
`500
`500
`500
`500
`800
`800
`800
`
`')
`
`AUC (III! II
`ND
`ND
`ND
`ND
`ND
`ND
`0.|5
`009
`0. I 2
`0.39
`0.25
`L68
`0.73
`067
`0.42
`|.38
`0.23
`|.23
`|.|0I
`208
`354
`0.34
`NE
`I |.66
`232
`284
`
`C... (I!!!)
`ND
`000i
`00l8
`ND
`0004
`0.006
`00|2
`0.0| I
`00|9
`0.06|
`0063
`0.| 39
`006
`0.066
`0.077
`0.|67
`0.037
`0.054
`0.I83
`030
`0.62
`0.07
`NE
`l.|9
`0.43
`0. I 8
`
`I
`
`T... (h)
`ND
`2
`I
`ND
`4
`I
`I3
`Q I 6
`3.7
`28
`0.8
`3.7
`3.6
`4
`2
`27
`0.69
`l.7
`l.5I
`L4 I
`L70
`230
`NE
`3.02
`L20
`3. I 0
`
`Tm. (II)
`ND
`N)
`ND
`N)
`ND
`ND
`6.5
`0.97
`2.0
`I .59
`0.28
`I .83
`I .73
`I .43
`QB
`0.05
`I .49
`0. I9
`0.7|
`I .59
`I .07
`0.79
`NE
`L32
`0.45
`I .73
`
`Tm; (II)
`ND
`ND
`ND
`ND
`ND
`ND
`ND
`26.5
`28
`25.8
`D
`2|
`74
`I8
`I3.4
`I3.3
`28
`I4.6
`I4
`24
`23.2
`I2.0
`NE
`87
`|9.9
`26.2
`
`K... (II)
`ND
`ND
`ND
`ND
`ND
`ND
`65
`003
`L8
`387
`0.0I
`I.8
`I.7 I
`L4 I
`I.00
`I. I 5
`0.03
`0.3
`0.7
`0 I 2
`0.82
`0.80
`NE
`I.34
`