JPET #112326
1
Rapid suppression of plasma testosterone levels and tumour growth in the
Dunning rat model treated with degarelix, a new GnRH antagonist
Marc Princivalle, Pierre Broqua, Richard White, Jessica Meyer, Gaell Mayer, Lucy
Elliott, Ketil Bjarnason, Robert Haigh and Christopher Yea
Ferring Research Ltd, Southampton, UK (M.P., P.B., J.M., G.M., L.E., R.H., C.H.)
Ferring Inc, San Diego, USA (R.W.)
Ferring International Center, Copenhagen, Denmark (K.B.)
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Copyright 2006 by the American Society for Pharmacology and Experimental Therapeutics.
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Running Title: Tumour suppression with degarelix, a new GnRH antagonist
Corresponding author: Marc Princivalle, Ph.D., Ferring Research Ltd, Chilworth
Science Park, 1 Venture Road, SO16 7NP Southampton, UK. Phone: +4423 8076
3480, Fax: +4423 8076 6253, [email protected]
Number of text pages: 22
Number of tables: 2
Number of figures: 4
Number of references: 40
Number of words in the abstract: 230
Number of words in the introduction: 806
Number of words in the discussion: 704
Abbreviations: GnRH, gonadotropin-releasing hormone; LH, luteinizing hormone;
FSH, follicle stimulating hormone; LHRH, Luteinizing hormone releasing hormone;
SPF, Specific pathogen free; MW, Molecular weight; LPL, Leuprolide; RIA,
radioimmunoassay; ANOVA, analysis of variance
Section assignment: Endocrine and Diabetes
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Abstract
Degarelix (FE 200486) is a member of a new class of water-soluble (>50 mg/ml)
GnRH antagonists in clinical development for prostate cancer. Upon subcutaneous
administration degarelix forms a gel resulting in a sustained release of the compound
into the circulation immediately blocking GnRH receptors in the pituitary inducing a
fast and sustained suppression of gonadotrophin secretion in rats and primates. One of
the few animal models of prostate adenocarcinoma is the Dunning R3327H rat
carcinoma transplanted into Copenhagen rats. The growth of the Dunning tumour can
be inhibited by various treatments reported to be effective in the clinic such as GnRH
superagonists, antiandrogens, 5-alphareductase inhibitors, tyrosine kinase inhibitors
and surgical castration. We report in this study that degarelix produces a fast and
sustained suppression of the pituitary gonadal axis in rats and a similar inhibition of
tumour growth compared to surgical castration in the Dunning R3327H rat carcinoma
model. Firstly, degarelix as been compared with D-Trp6-LHRH and surgical
castration on a short-term study (2 months) and secondly, degarelix has been
compared with Leuprolide and surgical castration on a long-term study (12 months).
In both studies, degarelix demonstrated a sustained inhibition of tumour growth at
least comparable to surgical castration. These data provide a convincing profile of
degarelix as a potential candidate for the clinical management of sex steroid-
dependent pathologies, such as prostate cancer, where long-term reversible chemical
castration is required.
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Prostate cancer is a leading cause of mortality and morbidity of men in the
industrialised world, second only to lung cancer. In these countries, where the
incidence is highest, a man has a 10% chance of developing prostate cancer, and a 3-
4% chance of dying from the disease (Cook and Sheridan, 2000). In the European
Community and in the US, where both the prevalence and incidence of prostate
cancer are increasing, more than 500’000 new cases are diagnosed each year, with an
estimated 50’000 deaths (Jemal et al., 2004; Kirkels and Rietbergen, 1997). The
number of patients with prostate cancer is expected to increase steadily over the next
decade because the average age of men is increasing and the incidence of prostate
cancer increases more rapidly with age than the incidence of other cancers (Jemal et
al., 2004).
A widely recognised feature of prostate cancer is its high sensitivity to testosterone
deprivation. The current medical approach in the treatment of androgen-dependent
prostate tumours is to suppress testosterone production using agonist analogues of the
hypothalamic gonadotrophin-releasing hormone (GnRH, also known as LHRH) that
control the secretion of luteinizing hormone (LH) and follicle-stimulating hormone
(FSH) from the anterior pituitary gland. Chronic administration of GnRH
superagonists, eventually leads to a desensitisation of pituitary GnRH receptors and a
corresponding inhibition of gonadotrophin and testosterone secretion (Heber et al.,
1982; Nett et al., 1981; Rivier et al., 1978). However, a major drawback of agonist
therapy is that it initially stimulates gonadotrophin and testosterone secretion,
resulting in a surge in LH and testosterone levels for 2-3 weeks before castration is
completed and a subsequent delay in therapeutic benefit. This temporary increase in
testosterone levels can exacerbate the hormone-sensitive cancer, as well as patient
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symptoms such as sudden paraplegia due to spinal cord compression by epidural
metastases, exacerbation of bone pain and urinary retention (Kahan et al., 1984).
Therefore anti-androgens are often co-administered in the initial phase of GnRH
receptor agonist treatment to minimise the stimulatory effects of the testosterone surge
on the prostate cancer cells (Dupont et al., 1988). Furthermore, “depot” injections
may result in small bursts of androgens (acute on chronic phenomenon), which may
over-stimulate growth of tumours that have adapted (through gene mutations) to low
levels of androgens by over-activity of androgen receptors and associated
transcription factors (Suzuki et al., 2003; Langeler et al., 1993; Montgomery et al.,
2001).
In the search for alternatives to superagonist therapy, researchers have been
developing GnRH antagonists that suppress the release of gonadotrophins by binding
competitively to pituitary GnRH receptors. GnRH antagonists do not induce the LH
and testosterone surge, but instead work directly to reduce the release of
gonadotrophin and testosterone within hours. Despite the advantages of GnRH
antagonists over agonists in suppressing serum gonadal steroids, many of the peptide
GnRH antagonists investigated so far show histamine–releasing properties and/or
solubility limitations that affect their clinical usefulness or even preclude their
development as drugs (Bagatell et al., 1993; Bagatell et al., 1995; Hocart et al., 1987;
Flouret et al., 1992).
Degarelix (FE 200486) is a member of a new class of water-soluble (>50 mg/ml)
GnRH antagonists forming a subcutaneous gel, that has only very weak histamine-
releasing potential compared to other GnRH antagonists (Broqua et al., 2002; Tornoe
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et al., 2004; Schwach et al., 2003; Schwach et al., 2004). When administered
subcutaneously in rats and primates, degarelix immediately blocks GnRH receptors in
the pituitary resulting in fast and sustained suppression of gonadotrophin secretion
with the absence of initial stimulation of the gonadotrophic axis (Broqua et al., 2002).
The present study compares the pharmacological activity of a new GnRH antagonist,
degarelix to two widely and currently used GnRH superagonists (D-Trp6-LHRH and
Leuprolide) in an experimental model of prostate adenocarcinoma in both short and
long-term studies. The Dunning R3327H rat carcinoma transplanted into Copenhagen
rats (Redding and Schally, 1981; Block et al., 1977; Claflin et al., 1977) is of
dorsolateral prostatic origin, developed spontaneously in an aged animal, has
histological and biochemical similarities to the human prostatic carcinoma and is
androgen-dependent (Hierowski et al., 1983; Daehlin et al., 1986; Daehlin and
Damber, 1987). The growth of the Dunning tumour can be inhibited by various
treatments reported to be effective in the clinic such as GnRH superagonists,
antiandrogens, 5-alphareductase inhibitors, tyrosine kinase inhibitors and surgical
castration (Ichikawa et al., 1988; Pinski et al., 1994; George et al., 1999; Presnell et
al., 1998; Tennant et al., 2000).
Blockage of the GnRH receptor by GnRH antagonists produces a fast, profound and
sustained suppression of gonadotrophin release and therefore testosterone secretion in
human males (Jockenhovel et al., 1988; Salameh et al., 1991; Bagatell et al., 1993;
Bagatell et al., 1995; Klingmuller et al., 1993; Pinski et al., 1994). Consequently,
antagonists such as degarelix, have been recognized as potential drugs for the
management of sex steroid-dependent pathologies, such as prostate cancer.
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Material and methods
Animals
In vivo studies were performed by Oncodesign, l’Arbesle, France. Male
Copenhagen/Hsd rats, 7-8 weeks old and weighing 100-125g, were obtained from
Harlan Breeding Center (Indianapolis, USA). Animals were observed for 7 days in a
specific-pathogen-free (SPF) animal care unit before tumour implantation. The animal
care unit (INRA, Dijon, France) is authorized by the French Ministry of Agriculture
and Research (Agreement No. A21100). All animal experiments were performed
according to ethical guidelines of animal experimentation. Animals were maintained
in rooms under controlled conditions of temperature (25°C ± 1°C, humidity (55 ±-
1%), photoperiod (12h light/12h dark) and air exchange. The experimentation room is
maintained at a positive pressure to prevent outside contamination into the rat colony.
Animals were housed in polycarbonate cages (UAR, Epinay sur Orge, France) with
sterile wood shavings (UAR) as bedding, which was replaced twice a week. Diet
(controlled and sterilised granules, AO4) was purchased from UAR. Food and water
were provided ad libitum. Water bottles were cleaned, sterilised and replaced once a
week. The water was sterilised by filtration using 0.2 µm absolute filters (Millipore,
USA)
Tumour preparation
Cryopreserved R-3327H tumour trocar pieces were obtained from John Hopkins
Oncology Centre (Dr J.T. Isaacs, Baltimore, MD) and kept in liquid nitrogen. Before
implantation, the trocar pieces were thawed by immersing the vial in a 37°C water
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bath and tumours washed in RPMI medium. Surgical operations were performed
under isofluran anaesthesia. The hairs from the flank region of rats were shaved and a
skin incision was made. Fresh tumour trocar pieces of R-3327H tumour were serially
implanted subcutaneously into the right flank of the rats (1 tumour/rat). Before
implantation, the mean weight of 10 tumour fragments was 48.5 ± 2.6 mg.
Test substance
Degarelix (N-acetyl-3-(naphtalen-2-yl)-D-alanyl-4-chloro-D-phenylalanyl-3-(pyridin-
3-yl)-D-alanyl-L-seryl-4-[[[(4S)-2,6-dioxohexahydropyrimidin-4-yl]carbonyl]amino]-
L-phenylalanyl-4-(carbamoylamino)-D-phenylalanyl-L-leucyl-N6-(1-methylethyl)-L-
lysyl-L-prolyl-D-alaninamide), FE 200486 acetate salt (Batch No 2010-042-01, MW:
1632.3, peptide content: 88.2%, purity:98.8%) was supplied by Ferring Research
Institute (San Diego, USA) as a white powder. It was stored at -20°C. The
manipulation of compound was performed under laminar flow conditions. The vehicle
of degarelix was 5% Mannitol diluted in sterile distilled water. The degarelix
solutions were prepared just before administration to animals.
D-Trp6-LHRH acetate, (Triptorelin, Batch No 0537085, MW: 1311.5, purity: 89.9%)
was obtained from Bachem (Zurich, Switzerland) as a white powder. It was stored at -
20°C. The manipulation of compound was performed under laminar flow conditions.
Leuprolide-depot (LPL, Enantone, Batch No S306) was supplied by Oncodesign from
Takeda (Puteaux, France). The vehicle for Leuprolide was composed of cellulose and
D-mannitol diluted in distilled water just before administration to rats.
Treatment doses and regimens
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Treatments started at D0 when the tumour size reached approximately 300 mm3.
Before treatment, the mean tumour size of each group at randomisation was not
statistically different. For the short-term study, D-Trp6-LHRH was administered
subcutaneously at 0.5 mg base/kg daily for 62 days (n=10). At this dose, D-Trp6-
LHRH induced a complete suppression of testosterone after the flare-up period to
levels published in the literature (Redding and Schally, 1981; Redding and Schally,
1990; Schally et al., 1986). Degarelix was administered subcutaneously at 1.0 mg
base/kg monthly (n=10). Pharmacological profile of degarelix has been described
recently (Broqua et al., 2002; Agerso et al., 2003). At this dose, degarelix induced
complete and rapid suppression of testosterone. One control group received a monthly
subcutaneous injection of 5% mannitol (n=10) and another control group was
castrated and injected subcutaneously with 5% mannitol once a month (n=10). The
blood samples were collected at D-1, D0, D1, D2, D3, D4, D5, D6, D7, D10, D14,
D21, D28, D,35, D42, D49 and D62. For the group treated with D-Trp6-LHRH, blood
samples were also taken 2 hours after treatment. For the long-term study, Leuprolide-
Depot was administered subcutaneously at 1.5 mg base/kg every 3 weeks until day
288 (n=11). At this dose, Leuprolide-depot induced a complete suppression of
testosterone after the flare-up period to levels published in the literature (Okada et al.,
1991). Degarelix was administered subcutaneously at 1.0 mg base/kg monthly (n=11)
(Broqua et al., 2002; Agerso et al., 2003). One control group received a monthly
subcutaneous injection of 5% mannitol (n=11) and another control group was
castrated and injected subcutaneously with 5% mannitol once a month (n=11). Blood
samples were collected at D0, D2 and every month thereafter until the end of the
study D343.
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Blood sample collection and testosterone assay
Blood samples (approximately 500µl) were taken 2 hours after treatment from the
caudal vein into tubes containing lithium heparin and immediately centrifuged at
1000xg for 10 min at 4°C to obtain plasma samples. The samples were collected in
propylene tubes and stored at -80°C. Plasma testosterone was assayed by
radioimmunosay following the manufacturer’s instructions (Diagnostic System
Laboratories).
Castration
A 0.8 cm incision was made transversally in the abdomen, just above the pubis. The
anterior abdominal muscles and skin were incised and the testes were delivered into
the surgical field, and removed from animals. The incisions were closed separately
using Dexon needle and suture thread (Ref. 58419, Sherwood, Bondoufle, France).
Sacrifice of animals
The animals were sacrificed under anaesthesia with isofluran by cervical dislocation.
The R-3327H tumours, seminal vesicles, prostates, testis of each rat were removed,
cleaned and weighed. Animal reaching the maximal tumour size defined by the
welfare of the animal were sacrificed.
Tumour volume determination
The length and width of the tumour were measured once a week with callipers and the
volume of the tumour was estimated by the formula: (length x width2)/2
Statistical analysis
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The statistical tests were performed using StatView Software (Abacus Concept,
Berkeley, USA). The following parameters were compared: the plasma testosterone
level at each sampling time, the mean body weight change, the weight of tumours,
seminal vesicles, testes and prostates at the end of the experiment, the tumour
volumes on each day of measurement. Statistical analysis of the treatment was
performed using an ANOVA followed by Bonferroni/Dunn multiple comparison
procedures or by unpaired t-tests. A p value < 0.05 was considered significant.
Results
Short-term effects of degarelix, D-Trp6-LHRH and surgical castration on the growth
of the Dunning R-3327H
Effects of degarelix and D-Trp6-LHRH on plasma testosterone levels.
In rats treated with D-Trp6-LHRH 0.5 mg base/kg daily (Figure 1), testosterone levels
were initially raised to more than 20 ng/ml (flare-up effect). Testosterone levels then
decreased to a low level at D5 (80 pg/ml) and thereon slowly to castrate levels, at
D28. Thereafter castration levels (below detection limit (<25 pg/ml)) were maintained
to the end of the study (D62). In rats treated with degarelix 1 mg/kg monthly, the
initial flare-up is not observed; moreover plasma testosterone quickly reached
castrated levels at D3 (below detection limit (<25 pg/ml)) and remained at this level
throughout the time course of the experiment with a pattern similar to castration. In
control animals, testosterone level is within normal range (Figure 1).
Effects of degarelix and D-Trp6-LHRH on tissues weights
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Testes weights at the end of the study (D62) represent an integrated measure of the
pituitary-gonadal axis activity over time. Testes weights was significantly lower
(p<0.01) in rats treated with degarelix (410 ± 40 mg) compared to rats treated with D-
Trp6-LHRH (900 ± 120 mg). Control animals showed normal testes weights (2650 ±
250 mg) compared with the two treated groups (Table 1). However, no statistically
relevant differences were observed for the weight of the seminal vesicles and
prostates of the animals treated with D-Trp6-LHRH or degarelix (40 ± 10 mg and 30 ±
20 mg respectively) (Table 1). Prostates from castrated animals were too small to be
weighted accurately.
Effects of degarelix, D-Trp6-LHRH and surgical castration on tumour volume
Degarelix and surgical castration produced an immediate suppression of tumour
growth that lasted throughout the study period (Figure 2). Tumour volumes in rats
treated with degarelix were significantly smaller than control rats at D21. This
difference lasted until the end of the study at D62. For the D-Trp6-LHRH group, there
is no apparent suppression of the tumour growth until D38 compared to control
animals. A significant difference (p<0.01) between D-Trp6-LHRH treated rats and
controls occurred at D49 and last until the end of the study at D62 (Figure 2, Table 1).
Effects of degarelix, D-Trp6-LHRH and surgical castration on tumour weight
At the end of the study (D62), tumours were excised and weighed. Tumours in the
degarelix treated and surgically castrated groups had similar weight (310 ± 150 mg
and 370 ± 120 mg respectively). Tumours in the degarelix treated group were
significantly smaller (p<0.01) than tumours in the D-Trp6-LHRH treated group (370 ±
120 versus 1340 ± 750 mg) (Table 1).
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Long-term effects of degarelix, leuprolide-depot and surgical castration on the
growth of the Dunning R-3327H
Effects of degarelix, surgical castration and leuprolide-depot on plasma testosterone
levels.
Degarelix suppressed testosterone to castration levels within 2 days of treatment
initiation and maintained castration levels throughout the course of the study. Onset of
testosterone suppression by leuprolide-depot was delayed after the flare-up period,
castration levels being achieved within a month. Thereafter testosterone remained
suppressed until treatment was stopped. Control animals stayed within normal range
(about 2 ng/ml) throughout the study (Figure 3). Data from animals of the control and
leuprolide-depot groups have been discarded after 223 days because of the smaller
group size (animals reaching the maximal size of the tumour have been sacrificed).
However, data from castrated and degarelix-treated groups were continued until the
end of the study (D343).
Effects of degarelix, surgical castration and leuprolide-depot on tumour volume
Degarelix profoundly suppressed tumour growth immediately after administration and
with an efficacy similar to surgical castration. In contrast, similar to the short-term
study, during the first month there is no obvious suppression of tumour growth for the
leuprolide-depot compared to the control group (Figure 4). Moreover, escape from
androgen deprivation occurred sooner in rats treated with leuprolide-depot. Data from
control groups or treated with leuprolide-depot were discarded after D223 due to low
animal numbers remaining (animals reaching the maximal size of the tumour have
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been sacrificed, Table 2). At D223, the mean tumour volume for the leuprolide-depot
group (2489 ± 1063 mm3) was higher than degarelix and castration groups (666 ± 291
mm3 and 820 ± 552 mm3 respectively). Degarelix treatment inhibited tumour growth
throughout the experiment with efficacy at least identical to surgical castration until
D343 (2140 ± 1165 mm3 and 1897 ± 1391 mm3 respectively, Figure 4, Table 2).
Discussion
Our interest in developing a GnRH antagonist was stimulated by the need for
improved therapeutics for the management of sex steroid-dependent pathologies
including uterine leiomyoma, endometriosis, and sex-steroid dependent cancer, such
as prostate cancer. Prostate cancer is currently managed with long-acting (1 or 3
months) formulations of GnRH superagonists that initially stimulate pituitary LH and
FSH release as well as gonadal steroids, and then, after 2 to 4 weeks, desensitise the
gonadotrophe cells, leading to suppression of gonadotrophin and sex steroid secretion.
An alternative pharmacological approach is the use a GnRH antagonist which
immediately blocks GnRH receptors in the pituitary resulting in fast and sustained
suppression of gonadotrophin secretion together with a tight control over the
testosterone level (below castration level) which could translate into significant
clinical advantages. In the first study we investigated the short-term effects of
degarelix on tumour growth over a 2 month period; we have demonstrated that
suppression of the pituitary-gonadal axis occurred sooner in rats treated with degarelix
than in rats treated with D-Trp6-LHRH as evidenced by the shorter time to castration
levels of testosterone. Differences in the mechanisms of pituitary-gonadal suppression
produced by GnRH superagonists and GnRH antagonists can explain this different
onset of action. D-Trp6-LHRH will first stimulate LH release (flare-up effect) from
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the pituitary and then testosterone secretion from the testes before suppressing the
pituitary-gonadal axis by a “down-regulation” mechanism. In contrast, degarelix will
immediately bind to the pituitary GnRH receptor, block it and preclude substantial
occupation and stimulation by endogenous GnRH and therefore release of LH/FSH
from the pituitary. The flare of testosterone initially produced by D-Trp6-LHRH
translates into a significant delay in onset of tumour inhibition compared to degarelix
and surgical castration. The data are consistent with a correlation between the time to
castrate and the time to suppress the tumour growth. Over a 2 month period, this delay
has significant consequences on the overall anti-tumour efficacy as indicated by the
measurement of tumour weight. More importantly, in the second study (long-term
effect) tumour growth started to escape androgen-deprivation after about 5 months of
treatment with leuprolide-depot. In contrast, degarelix induced a rapid suppression of
plasma testosterone levels and sustained inhibition of tumour growth over the whole
study period. Two hypotheses can be proposed to explain the premature tumour
growth from androgen deprivation in rats treated with leuprolide-depot. Firstly, there
are reports suggesting that low concentrations of GnRH superagonists can stimulate
the proliferation of human prostate cancer cell lines by acting through tumour GnRH
receptors (Limonta et al., 1999; Bahk et al., 1998; Qayum et al., 1990). The Dunning
tumour expresses GnRH receptors, it is therefore possible that long-term exposure to
leuprolide may stimulate proliferative pathways or promote adaptation to androgen-
deprivation. Secondly, it has been suggested that escape from androgen deprivation
occurs when the tumour has adapted to low levels of androgens. In tumours escaping
from androgen deprivation, androgen receptors and downstream pathways for control
of androgen-dependent gene expression are still functional. Escape from androgen
deprivation could result from mutation of androgen receptors leading to ligand-
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independent activation, or from super sensitivity of the androgen receptors and/or
activation of alternative transcription factors. In that situation even very low levels of
androgens will be sufficient to maintain tumour survival and expansion.
In conclusion, degarelix is a new GnRH antagonist blocking immediately GnRH
receptors in the pituitary resulting in a fast and sustained suppression of
gonadotrophin secretion and inducing a sustained inhibition of tumour growth at least
comparable to surgical castration. The fast cessation of testosterone production by
degarelix is clearly advantageous, allowing an immediate inhibition of tumour growth
and avoiding other side effects of the flare. Such a rapid anti-tumour response cannot
be achieved by a GnRH superagonist. In the long-term studies, superiority of
degarelix over a GnRH agonist is demonstrated; escape to androgen independence
occurred sooner in animals treated with the GnRH superagonist leuprolide. These data
provide a convincing profile of degarelix (GnRH antagonist) as a more effective
GnRH blocker than the superagonists to inhibit the growth of the Dunning tumour
possibly due a better short-term and long-term testosterone control and provide a
convincing profile of degarelix as a potential candidate for the clinical management of
sex steroid-dependent pathologies where long-term chemical castration is required.
Acknowledgments
The authors thank Dr Wolfgang Koechling for his attentive reading and advice
regarding preparation of this manuscript. The authors also thank Dr David Smart, Dr
Andy Sheppard and Dr Dominic Corkill for helpful discussions and technical
assistance.
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Legends for Figures
Figure 1: Effects of degarelix (1 mg/kg subcutaneous, monthly), D-Trp6-LHRH (0.5
mg/kg subcutaneous, daily) and surgical castration on plasma testosterone levels (D0-
D63) in rats bearing a Dunning R3327H prostate tumour. Results are the mean ± SEM
of 10 rats.
Figure 2: Effects of degarelix (1 mg/kg subcutaneous, monthly), D-Trp6-LHRH (0.5
mg/kg subcutaneous, daily) and surgical castration on tumour weight at the end of the
study (D62) in rats bearing a Dunning R-3327H prostate tumour. Results are the mean
± SEM of 10 rats.
Figure 3: Effects of degarelix (1 mg/kg subcutaneous, monthly), leuprolide-depot (1.5
mg/kg subcutaneous, every 3 weeks) and surgical castration on plasma testosterone
levels (D0-D343) in rats bearing a Dunning R-3327H prostate tumour. Results are the
mean ± SEM of 10-11 rats. # Data from animals of the control and leuprolide-depot
groups have been discarded after 223 days (animals reaching the maximal size of the
tumour have been sacrificed).
Figure 4: Effects of degarelix (1 mg/kg subcutaneous, monthly), leuprolide-depot (1.5
mg/kg subcutaneous, every 3 weeks) and surgical castration on tumour volume (D0-
D343) in rats bearing a Dunning R-3327H prostate tumour. Results are the mean ±
SEM of 10-11 rats. # Data from animals of the control and leuprolide-depot groups
have been discarded after 223 days (animals reaching the maximal size of the tumour
have been sacrificed).
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Tables
Table 1: Short-term study. Effects of degarelix (1 mg/kg subcutaneous, monthly), D-Trp6-LHRH (0.5 mg/kg subcutaneous, daily) and surgical
castration on tumour volume, tumour weight, testis weight, prostate weight and seminal vesicles weights at the end of the short-term study (D62)
in rats bearing a Dunning R-3327H prostate tumour. Results are the mean ± SD of 10 rats.
Treatment Nb of animal D62
Tumour volume D62 [mm3]
Tumour weight D62 [mg]
Testis weight D62 [mg]
Prostate weight D62 [mg]
Seminal vesicles D62 [mg]
5% Mannitol 10 2295 ± 1035 2930 ± 162 2650 ± 260 370 ± 120 960 ± 230
Castration 10 351 ± 174**, †† 310 ± 150**, †† a 80 ± 20**
D-Trp6-LHRH
10 818 ± 413** 1340 ± 750** 900 ± 120** 40 ± 10** 100 ± 20**
Degarelix 10 326 ± 87**, †† 370 ± 120**, †† 410 ± 40**, †† 30 ± 20** 100 ± 30**
a Prostate weight not determined. ** p<0.01 versus 5% Mannitol, †† p<0.01 versus D-Trp6-LHRH
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Table 2: Long-term study. Effects of degarelix (1 mg/kg subcutaneous, monthly), Leuprolide-depot (1.5 mg/kg subcutaneous, every 3 weeks)
and surgical castration on tumour volume in rats bearing a Dunning R-3327H prostate tumour. Results are the mean ± SD of 10-11 rats.
Day 0 Day 223 Day 343 Treatment
No. of animals
Tumour volume [mm3]
No. of animals
Tumour volume [mm3]
No. of animals
Tumour volume [mm3]
5% Mannitol 11 247 ± 61 5b 6262 ± 1696 0 -
Castration 11 260 ± 71 11 666 ± 291** 11 2140 ± 1165
Leuprolide 11 277 ± 87 7b 2489 ± 1063** 0 -
Degarelix 10a 257 ± 76 10 820 ± 552**, †† 9c 1897 ± 1391
a 1 animal died before the start of the treatment. b animals reaching the maximal size of the tumour were sacrificed. c 1 animal has been
sacrificed before the end of the study. ** p<0.01 versus 5% Mannitol, †† p<0.01 versus D-Trp6-LHRH
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