Novel progesterone receptor modulators: 4-Aryl-phenylsulfonamides

Article abstract of DOI:10.1016/j.bmcl.2012.09.077

We have developed a new series of progesterone receptor modulators based upon the 4-aryl-phenylsulfonamide. Initial work in the series afforded potent compounds with good properties, however an advanced intermediate proved to be genotoxic in a non-GLP Ame

Full text of DOI:10.1016/j.bmcl.2012.09.077

Bioorganic & Medicinal Chemistry Letters 22 (2012) 7119–7122
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Novel progesterone receptor modulators: 4-Aryl-phenylsulfonamides
Casey McComas a, Jeffrey Cohen b, Christine Huselton c, Michael Marella a, Edward Melenski a,
Cheryl Mugford c, Ov Slayden d, Richard Winneker b, Jay Wrobel a, Matthew R. Yudt b, Andrew Fensome a,
⇑
a Chemical Sciences, Drug Safety and Metabolism, Pfizer Global Research and Development, 500 Arcola Road, Collegeville, PA 19426, United States
b Women’s Health Research Institute, Drug Safety and Metabolism, Pfizer Global Research and Development, 500 Arcola Road, Collegeville, PA 19426, United States
c Biotransformation Division, Drug Safety and Metabolism, Pfizer Global Research and Development, 500 Arcola Road, Collegeville, PA 19426, United States
d Division of Reproductive Sciences, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 9700, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 2 July 2012
Revised 17 September 2012
Accepted 21 September 2012
Available online 29 September 2012
We have developed a new series of progesterone receptor modulators based upon the 4-aryl-phenylsulf-
onamide. Initial work in the series afforded potent compounds with good properties, however an
advanced intermediate proved to be genotoxic in a non-GLP Ames assay following metabolic activation.
We subsequently solved this problem and identified advanced leads which demonstrated oral efficacy in
rhesus monkey pharmacodynamic and kinetics models.
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Progesterone modulator
Progesterone antagonist
Endometriosis
Uterine fibroids
The progesterone receptor (PR) is a member of the steroid
receptor sub-family of the nuclear hormone receptor super-family,
a group of ligand-dependent nuclear transcription factors and
plays an important role in the female reproductive system.1 Regu-
lation of the receptor through it’s ligand binding domain and
endogenous hormone progesterone (P4) has proven to be useful
for effecting contraception and for providing hormonal therapy
during the menopause.2 Steroidal antagonists have been studied
in the clinic as novel therapeutics for treating women with endo-
metriosis3–5 and uterine fibroids.6–8 Of particular interest is the
steroid asoprisnil 2 which reduced bleeding and uterine volume
in a fibroid population (Chart 1).9
Previously we have published several series of non-steroidal
progesterone receptor modulators: benzoxazinones, benzimidaz-
olinones and oxindoles, typified by compounds 3, 4 and 5,
Chart 2.10–12
The most advanced of these derivatives was the oxindole PRA-
348 6,13 which was the starting point for the current work,
Scheme 1.
the 5-cyano-pyrrol-2yl functional group as a privileged steroid
A-ring mimetic, and kept this functionality as a constant.
The amide 7 and sulfonamide target molecules 8 were prepared
according to Scheme 2. 1-Methyl pyrrole 9 was reacted with chlo-
rosulfonyl isocyanate followed by a DMF quench to afford the ni-
trile 10 in 69% yield, Scheme 2. Compound 10 was then lithiated
(LDA in THF at À78 °C) and reacted with tri-isopropyl borate to af-
ford, after work-up, the boronic acid 11. Compound 11 was cou-
pled under palladium catalysis (Pd2(dba)3/P(tBu)3, KF, THF) with
appropriately substituted anilines 12 to afford the biaryl deriva-
tives 13. Yields were typically good to excellent (57–98%), except
in the case of 4-bromo-3-fluoroaniline (27%). Reaction of the inter-
mediate anilines 13 with functionalized acid chlorides 14 afforded
the amides 7, while sulfonyl chlorides 15 then provided the target
compounds 8. Yields were generally in the moderate to high range,
except for the iso-propyl sulfoanmide 23, which was very low (2%).
Compounds were assessed for functional antagonism of proges-
terone in the human T47D breast cancer cell line, using alkaline
phosphatase activity as the readout.14 The T47D cell line endoge-
nously expresses both A and B forms of the progesterone receptor.
Selectivity between the isoforms was not determined.
We wanted to explore the consequences of opening the hetero-
cyclic ring to afford the open chain amides 7 and sulfonamides 8,
which are the focus of this report. We had previously established
We initially prepared compounds from both the amide 7 and
sulfonamide 8 classes, Table 1. It was apparent that both function-
alities support progesterone antagonism in the T47D cell line, how-
ever it was clear that the sulfonamides were considerably more
potent. For example, the acetamide 16 was approximately 10-fold
less active than the methane sulfonamide 17 (T47D IC50 = 75 nM
and 8 nM, respectively). This was also true for the ethyl and
⇑
Corresponding author. Address: Worldwide Medicinal Chemistry, Pfizer Global
Research and Development, 200 Cambridge Park Drive, Cambridge, MA 02140,
United States. Tel.: +1 617 665 5723; fax: +1 617 665 5682.
E-mail address: andrew.fensome@pfizer.com (A. Fensome).
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.09.077

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C. McComas et al. / Bioorg. Med. Chem. Lett. 22 (2012) 7119–7122
Me
O
HO
Me
O
NC
Me
N
OMe
N
Me
Me
H
Me
OMe
N
Me
H
H
F
H
6
O
O
progesterone 1
asoprisnil 2
R1
R1
NC
NC
Chart 1. Structures of progesterone 1 and asoprisnil 2.
N
N
O
O O
S
Me
Me
N
H
R
N
H
R2
7
8
Cl
Cl
Cl
Me
Me
O
Me Me
O
Me
Scheme 1. PRA-348 6 and ring opened derivatives 7 and 8.
Me
O
N
N
O
N
H
N
H
H
n-propyl derivatives, where the amides 18 and 20 were again
approximately 8-fold less active than their sulfonamide counter-
parts 19 and 21 (IC50 = 9 and 10 nM, respectively). Interestingly
in the amide series the iso-propyl derivative 22 lost further activity
(IC50 = 167 nM) whilst the sulfonamide 23 was one of the most po-
tent in the series (IC50 = 1.5 nM). Having observed this general
trend, efforts were concentrated on the sulfonamide series, which
were found to be poorly tolerant of substituted alkyl R2 groups, e.g.
the trifluoroethyl derivative 25 (IC50 = 58 nM). Considerable activ-
ity was lost with larger substituents, for example the aryl sulfona-
mides 25 and 26, which showed only modest antagonism of
progesterone induced alkaline phosphatase activity at the highest
4
5
3
Chart 2. Non-steroidal heterocyclic PR modulators 3–5.
a
b
OH
N
N
B
N
N
N
Me
OH
Me
Me
9
10
11
R1
NH2
c
dose tested (3 lM).
d
N
N
R1
NH2
An early concern that we had with compounds from this series
was the presence of the embedded aniline, which could be a poten-
tial mutagen following hydrolysis of the sulfonamide bond. The
sulfonamide 19 was chosen to assess this risk. The pharmacoki-
netic profile of 19, and of its metabolites (Scheme 3) was studied
in male rats, Table 2. Following a single oral administration of
19, significant levels of the aniline 13 (Cmax = 633 ng/mL or
M) and the secondary metabolite 16 (Cmax = 180 ng/mL or
M) were found in circulation. Parent sulfonamide 19 was still
the predominant species (Cmax = 1926 ng/mL or 6.7 lM), however,
O
Br
Me
13
O O
S
or
Cl R2
14
Cl R2
15
12
R1
R1
O
N
N
N
N
O O
or
Me
R2
S
Me
N
R2
N
3.2
0.7
l
l
H
H
7
8
Scheme 2. Synthesis of amides 7 and sulfonamides 8. Reagents and conditions: (a)
Chlorosulfonyl isocyanate, MeCN À78 °C, then DMF; (b) LDA, THF À78 °C, then
B(OiPr)3; (c) KF, Pd2(dba)3, P(tBu)3, THF; (d) pyridine.
Table 1
Functional activity data in the T47D alkaline phosphatase assay for amides 7 and
sulfonamides 8, where R1 = H
the substantial amounts of the aniline and the acetamide war-
ranted further investigation.
In the non-GLP Ames assay compound 19 was found to be non-
reactive in the absence of metabolic activation, but gave a positive
mutagenicity response in the presence of S-9 activation. A discrete
study with the aniline 13 showed the same behavior.
Having established the aniline as the culprit species in the Ames
test, we then sought to resolve the problem. As the mutagenic re-
sult was only positive upon metabolic activation, we decided to
R1
R1
NC
NC
N
N
O
O O
S
Me
Me
8 R1 = H
N
H
R
N
H
R2
7 R1 = H
a
Compound
Template 7 or 8
R2
Alk. phos. IC50 (nM)
2
0.3
75
8
76
9
78
10
167
1.5
58
16
17
18
19
20
21
22
23
24
25
26
7
8
7
8
7
8
7
8
8
8
8
Me
Me
Et
Et
n-Pr
n-Pr
i-Pr
i-Pr
N
N
O O
N
N
S
N
Me
Me
Me
NH2
H
19
13 (R1 = H)
-CH2CF3
4-tolyl
4-C6H4-i-Pr
N
O
N
55% Inhib at 3
54% Inhib at 3
l
l
M
M
Me
N
Me
H
a
50% effective concentration of tested compounds on alkaline phosphatase
activity in the human T47D breast carcinoma cell line. Values represent the average
of at least duplicate determinations.
16
Scheme 3. In vivo metabolic fate of 19 in male rats.

C. McComas et al. / Bioorg. Med. Chem. Lett. 22 (2012) 7119–7122
7121
Table 2
Table 5
Selected pharmacokinetic parameters of compounds 19, 13 and 16 in male rats
following a single oral dose (20 mg/kg) of 19
Steroid receptor selectivitya in vitro for compound 34 and comparator asoprisinil 2
Sulfonamide IC50 (nM)
2
34
Compound
Cmax (ng/mL)
t1/2 (h)
AUC0-inf (ng h/mL)
Agonist Antagonist Agonist
Antagonist
19
13
16
1926
633
180
2.5
2.5
5.0
12267
3084
1640
Progesterone
Androgen
Glucocorticoid
Mineralocorticoid
Estrogen
IA
IA
IA
IA
IA
0.3
9.0
120
1600
2000
ꢀ20%@ 3
l
M
11.7
100
70% @ 1
60% @ 1
IA
IA
>10,000
IA
IA
l
l
M
M
a
Steroid receptor cross-reactivity data from cellular reporter assays.13
Table 3
Functional activity data in the T47D alkaline phosphatase assay for sulfonamides 8
where R1 is an electron withdrawing group
Table 6
3
Pharmacokinetic properties of compound 34
NC
2 O O
N
34
Cyno.
Rat
Me
S
R2
5
N
R1
8
Dose mg/kg (iv)
Cl (ml/min/kg)
Vss (l/kg)
2
2
H
2
2.6
0.5
2.0
12977
2
0.3
2.8
18035
2
t1/2 (h)
AUCinf (ng h/ml)
Dose mg/kg, (p.o.)
Cmax (ng/ml)
T1/2 (h)
AUCinf (ng h/ml)
F (%)
a
5102
2.7
13679
69
2805
2.3
15164
98.5
Compound
R1
R2
Alk. phos. IC50 (nM)
27
28
29
30
31
32
33
34
35
2-F
2-OCF3
2-CN
3-F
3-F
3-CF3
3-CN
3-F, 5-F
2-F, 5-F
Et
Et
Me
Et
Me
Et
Et
30
36
>3000
6
8
12
128
12
30 or methane sulfonamides 31 (IC50 = 6 and 8 nM, respectively).
The trifluoromethyl derivative 32 was only slightly weaker
(IC50 = 12 nM), however the 3-nitrile compound was much less ac-
tive (IC50 = 128 nM). This latter observation would imply that the
nitrile derivatives are too electron deficient with respect to the
parent system or fluoride derivatives. Steric limitations are appar-
ently not the limiting factor in either the 2- or 3-positions due to
the activity of the 2-OCF3 compound 28 and 3-CF3 32. Additional
substitution with fluorine was also tolerated well in the 3,5-posi-
tion (34, IC50 = 12 nM), but not in the 2,5-difluoro system (35,
IC50 = 57 nM) in concordance with the activity of compound 27.
We then assessed the key mutagenicity question of these deriv-
atives, Table 4. Addition of electron withdrawing groups to the par-
ent anilines 13 in the 3 and or 5-positions was sufficient to
mitigate the Ames response of the parent aniline 19, presumably
through inhibiting the metabolic transformation of the aniline to
a reactive nitroso species. Consequently the sulfonamides 31, 32
and 34 were also Ames negative as well.
Having addressed this liability, compound 34 was selected for
further evaluation. The steroid receptor cross-reactivity of com-
pound 34 was assessed in cellular reporter assays, Table 5. The
closest antagonist cross-reactivity noted was against the androgen
receptor (IC50 = 100 nM). Weak high concentration agonist activity
was noted at the progesterone rector, otherwise the compound had
a clean profile. The pharmacokinetic profile was assessed in both
rats and cynomolgus monkeys, Table 6. Following iv administra-
tion of compound 34, in both species, the compound showed low
clearance, low volume of distribution and high exposure (ca. 18
Et
Et
57
a
50% effective concentration of tested compounds on alkaline phosphatase
activity in the human T47D breast carcinoma cell line. Values represent the average
of at least duplicate determinations.
Table 4
Mutagenicity data determined in the non-GLP Ames test for compounds 31, 32 and 34
and their parent anilines
3
3
N
N
O O
N
N
S
N
Me
Me 5
Me
NH2
5
R1
R1
13
H
1
31
32
R = 3-F, 5-H
1
R = 3-CF3, 5-H
34 R1 = 3-F, 5-F
Sulfonamide
31
32
34
Mutagenica
Parent aniline
Mutagenic
NA
ND
NA
13, R1 = 3-F
13, R1 = 3-CF3
13, R1 = 3-F, 5-F
NA
NA
NA
a
NA denotes Not Active, ND denotes not determined.
and 13 lg h/mL in cyno. monkeys and rats, respectively). The half
life was moderate, 2.8 and 2.0 h for cyno. monkey and rat respec-
tively, following a 2 mg iv dose. Following oral dosing, the kinetics
showed high exposure, a moderate half life (t1/2 = 2.7 and 2.3 h in
monkeys and rats, respectively) with good to excellent bioavail-
ability (F = 69 and 98% in cyno. monkeys and rats, respectively).
The kinetic profile is in accord with a molecule that displays high
evaluate the effect of de-activating the aniline nitrogen through
adding electron withdrawing groups to the aryl ring, Table 3.
Substitution of the aryl ring was tolerated but within well de-
fined boundaries, Table 3. For example the 2-fluoro 27 and 2-triflo-
uromethoxy 28 derivatives of compound 19 were reasonably
potent antagonists in the T47D alkaline phosphatase assay
(IC50 = 30 and 36 nM for 27 and 28, respectively), however the ni-
protein binding: at 10 lM, compound 34 has 0.3% free drug in hu-
man plasma protein and 1.9% free drug in rat plasma protein.
The efficacy of sulfonamide 34 was assessed in a rhesus macaque
pharmacodynamic model of menses induction.15 Ovariectomized
trile 29 was very weak (IC50 >3
lM). The potency was regained at
the 3-position using a fluoride substituent, with either the ethane

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C. McComas et al. / Bioorg. Med. Chem. Lett. 22 (2012) 7119–7122
rhesus monkeys were cycled artificially with 28 days of exposure to
estradiol (silastic implant). On day 14 they received a 14 day pro-
gesterone implant to simulate the follicular phase of the menstrual
cycle. In this paradigm an active progesterone receptor antagonist
(e.g. mifepristone) will block the effect of the progesterone implant
and induce early menstruation, usually within 3 days of adminis-
tration. Following oral administration (5 mg/kg/day) sulfonamide
34 induced early menstruation in all of the monkeys tested
(n = 3). In a satellite PK study, ovariectomized female rhesus
monkeys received the same dose of compound 34. The circulating
and Neil Cooch for assistance with cell culture and biological assay
development.
References and notes
1. Mangelsdorf, D. J.; Thummel, C.; Beato, M.; Herrlich, P.; Schuetz, G.; Umesono,
K.; Blumberg, B.; Kastner, P.; Mark, M. Cell 1995, 83, 835.
2. Yuzpe, A. A. J. Reprod. Med. 2002, 47, 967.
3. Fedele, L.; Berlanda, N. Expert Opin. Emerg. Drugs 2004, 9(1), 167.
4. Kettel, L. M.; Murphy, A. A.; Morales, A. J.; Yen, S. S. C. Am. J. Obstet. Gynecol.
1998, 178, 1151.
5. Kettel, L. M. Intl. Congr. Symp Semin. Series 1997, 13, 334 (Endometriosis Today).
6. Chwalisz, K.; DeManno, D.; Garg, R.; Larsen, L.; Mattia-Goldberg, C.; Stickler, T.
Semin. Reprod. Med. 2004, 22, 113.
drug reached a Cmax = 2888 ng/mL (8.8
(AUC0-last = 28485 ng h/mL). The estimated Cav (AUC0-last/24 h) =
1187 ng/mL or 3.6 M. The free drug available at this concentration
lM) with high exposure
7. Chwalisz, K.; Larsen, L.; Mattia-Goldberg, C.; Edmonds, A.; Elger, W.; Winkel
Craig, A. 2007, 87, 1399.
l
would be approximately 11 nM (using the human protein binding
value), consistent with the IC50 observed in T47D cells.
8. Fedele, L.; Berlanda, N. Expert Opin. Emerg. Drugs 2004, 9, 167.
9. Schubert, Gerd.; Elger, Walter.; Kaufmann, Guenter.; Schneider, Birgitt.;
Reddersen, Gudrun.; Chwalisz, Kristof. Semin. Reprod. Med. 2005, 23, 58.
10. Zhang, P.; Terefenko, E. A.; Fensome, A.; Wrobel, J.; Winneker, R.; Lundeen, S.;
Marschke, K. B.; Zhang, Z. J. Med. Chem. 2002, 45, 4379.
11. Terefenko, E. A.; Kern, J.; Fensome, A.; Wrobel, J.; Zhu, Y.; Cohen, J.; Winneker,
R.; Zhang, Z.; Zhang, P. Bioorg. Med. Chem. Lett. 2005, 15, 3600.
12. Fensome, A.; Bender, R.; Cohen, J.; Collins, M. A.; Mackner, V. A.; Miller, L. L.;
Ullrich, J. W.; Winneker, R.; Wrobel, J.; Zhang, P.; Zhang, Z.; Zhu, Y. Bioorg. Med.
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13. Fensome, A.; Adams, W. R.; Adams, A. L.; Berrodin, T. J.; Cohen, J.; Huselton, C.;
Illenberger, A.; Kern, J. C.; Hudak, V. A.; Marella, M. A.; Melenski, E. G.;
McComas, C. C.; Mugford, C. A.; Slayden, O. D.; Yudt, M.; Zhang, Z.; Zhang, P.;
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65, 637.
In summary we have developed a new series of progesterone
receptor modulators, using our older chemical equity as the start-
ing structural motif. Initial examples from the series were muta-
genic in a non GLP Ames test, following metabolic activation.
This finding was circumvented by modulating the electronics of
the aniline moiety which presumably prevented the aniline metab-
olite from oxidizing to the reactive species. Compound 34 was fur-
ther profiled in pharmacokinetic models in rats and non-human
primates, with exposure sufficient to afford efficacy in a non-
human primate model of the menstrual cycle.
15. Slayden, O. D.; Brenner, R. M. Arch. Hist. Cyt. 2004, 67, 393.
Acknowledgements
The authors would like to thank Dr’s Magid Abou Gharbia and
Len Freedman for their support of this work, and Thomas Berrodin