Second generation 2-pyridyl biphenyl amide inhibitors of the hedgehog pathway

Article abstract of DOI:10.1016/j.bmcl.2010.08.134

Potent and efficacious inhibitors of the hedgehog pathway for the treatment of cancer have been prepared using the 2-pyridyl biphenyl amide scaffold common to the clinical lead GDC-0449. Analogs with polar groups in the para-position of the aryl amide ring optimized potency, had minimal CYP inhibition, and possessed good exposure in rats. Compounds 9d and 14f potently inhibited hedgehog signaling as measured by Gli1 mRNA and were found to be equivalent or more potent than GDC-0449, respectively, when studied in a Ptch^+/- medulloblastoma allograft model, that is, highly dependent on hedgehog signaling.

Full text of DOI:10.1016/j.bmcl.2010.08.134

Bioorganic & Medicinal Chemistry Letters 20 (2010) 6748–6753
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Second generation 2-pyridyl biphenyl amide inhibitors
of the hedgehog pathway
Georgette M. Castanedo a, , Shumei Wang a, , Kirk D. Robarge a, Elizabeth Blackwood a, Daniel Burdick a,
Christine Chang a, Gerrit J. P. Dijkgraaf a, Stephen Gould a, Janet Gunzner a, Oivin Guichert b, Jason Halladay a,
Cyrus Khojasteh a, Leslie Lee a, James C. Marsters Jr. a, Lesley Murray a, David Peterson a, Emile Plise a,
Laurent Salphati a, Frederic J. de Sauvage a, Susan Wong a, Daniel P. Sutherlin a,
⇑
a Genentech, 1 DNA Way, South San Francisco, CA 94080, United States
b Curis Inc., 45 Moulton Street, Cambridge, MA 02138-1118, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 17 July 2010
Revised 24 August 2010
Accepted 27 August 2010
Available online 15 September 2010
Potent and efficacious inhibitors of the hedgehog pathway for the treatment of cancer have been pre-
pared using the 2-pyridyl biphenyl amide scaffold common to the clinical lead GDC-0449. Analogs with
polar groups in the para-position of the aryl amide ring optimized potency, had minimal CYP inhibition,
and possessed good exposure in rats. Compounds 9d and 14f potently inhibited hedgehog signaling as
measured by Gli1 mRNA and were found to be equivalent or more potent than GDC-0449, respectively,
when studied in a Ptch+/À medulloblastoma allograft model, that is, highly dependent on hedgehog
signaling.
Keyword:
Hedgehog pathway inhibitors
Ó 2010 Elsevier Ltd. All rights reserved.
While the hedgehog pathway plays an important role in embry-
onic tissue development, hedgehog signaling occurs to a lesser ex-
tent in the adult where pathway activation contributes to tissue
maintenance and repair.1,2 In addition to its normal functions,
aberrant activation of this pathway has also been found to contrib-
ute to the growth of certain cancers via mutation of pathway genes
in basal cell carcinoma (BCC) and meduloblastoma.3–8 Aberrant
hedgehog expression in colorectal and pancreatic tumors lead to
the up regulation of pathway genes in the surrounding tumor stro-
ma.9–11
(GDC-0449) was discovered as a potent and efficacious inhibitor
of the pathway that was recently communicated in this journal
(Fig. 1).12 This compound has shown clinical responses in patients
with metastatic and inoperable BCC14 and is currently in clinical
The pathway is activated when a hedgehog ligand (Hh) binds to
the transmembrane protein patched (PTCH), relieving suppression
of smoothened (SMO) by PTCH and allowing SMO to signal. The re-
sult of this pathway initiation is the activation of transcription fac-
tors GLI2 and GLI3, which in turn transcribe a number of proteins
important for differentiation, growth, and survival. One of these
transcribed genes, Gli1 can also be used to specifically monitor
pathway activity either in vitro in cell based assays or in vivo as
a PD marker.12
The first demonstration that a small molecule could effectively
inhibit this pathway came from work done with the natural prod-
uct cyclopamine. This compound and other small molecules were
found to bind SMO, and inhibit pathway activation.13 With the goal
of developing
a potentially novel therapeutic for cancer, 2
⇑
Corresponding author. Tel.: +1 650 225 3171; fax: +1 650 225 2061.
E-mail address: dans@gene.com (D.P. Sutherlin).
These authors contributed equally to this work.
Figure 1. Schematic for the discovery of 2 (GDC-0449) from 1, and the inspiration
for further analogs 3 and 4.
0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2010.08.134

G. M. Castanedo et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6748–6753
6749
trials targeting this and other indications.15 Additionally, a number
of other compounds are being pursued both preclinically and clin-
ically as modulators of the Hh pathway.16,17
During our investigation of 2 (GDC-0449) in xenograft and allo-
graft models, we noted that concentrations in the micromolar
range were necessary to achieve sufficient efficacy. Our backup
strategy then became centered around the development of com-
pounds with greater in vivo potency through the increase of cell
based in vitro potency. Ultimately, compound 2 was able to suc-
cessfully attain high concentrations in patients that were sufficient
to modulate the Hh pathway.
The 2-pyridyl biphenyl amide 2 originated from a lead optimi-
zation program centered around analog 1 (Fig. 1). Modification of
the trifluoro methyl nicotinic amide found in 1 to a 2-chloro-4-
methanesulphonyl benzamide in 2 was effective in improving
the solubility of the molecule while maintaining good potency
and pharmacokinetics in rats and dogs.12 We considered both of
these molecules to be promising starting points to further explore
the SAR around the aryl amide, in that previous SAR demonstrated
that substitutions around this ring were well tolerated. Described
herein is the discovery of potent compounds of the general struc-
tures 3 and 4 that were explored further in PK/PD and efficacy
studies.
Scheme 2. Reagents and conditions: (a) BBr3, CH2Cl2, 0 °C to rt, 2.5 h, 55%; (b)
isobutylene, H2SO4, CH2Cl2, À78 °C, 48 h, 73%; (c) NaBH4, EtOH, 0–40 °C, 0.5 h, 97%;
(d) NBS, PPh3, DCM, 0 °C, 2 h, 87%; (e) NaSO2Me, DMF, 1.5 h, 60 °C, 98%; (f) 4 N HCl,
CH2Cl2, 1.5 h, 45 °C, 93%; (g) HATU, HoAT, DIPEA, 5, DMF, rt, 18 h, 79%.
Starting with the previously described pyridyl biphenyl aniline
5,18–20 6-chloronicotinamides 8 were prepared by amide coupling
with chlorinated nicotinic acids 7,18 prepared from the ester 6
(Scheme 1). This advanced intermediate was then used to generate
a number of N-substituted replacements for the trifluoromethyl
group 9a–f.
The extended sulfone was prepared by selective demethylation
of the bis-methylester 10 with BBr3 to yield 11 (Scheme 2).21 This
acid 11 was then converted to the t-butyl ester prior to reduction
of the remaining methyl ester to a benzyl alcohol which was then
used to prepare benzyl bromide 22. The bromide was then treated
with methyl sulfinate to make the sulfone. Following the removal
of the t-butyl group the acid 13 was coupled to aniline 5 to prepare
compound 14a.
Scheme 3. Reagents and conditions: (a) MeSO2Cl, py, DCM, 0 °C to rt, 18 h, 100%;
(b) LiOH, THF/H2O, 5 h, 50 °C, 80%; (c) HATU, DIPEA, 5, DMF, 18 h, rt (46–48%); (d)
NaNO2, HCl, CuCl2, SO2, AcOH, H2O, 2 h, 0 °C, 75%; (e) 2 M NH3 in MeOH, DIPEA,
5 min, rt, 84%.
Sulfonamides 14b and 14c were both made starting from aniline
15, prepared following an iron reduction of 2-chloro-4-nitrobenzoic
acid methyl ester (Scheme 3). Simple manipulations led to 16 that
was then coupled to aniline 5 to make methylsulfonamide 14b.
A Sandmeyer reaction was used to convert the aniline 15 to the aryl
sulfonyl chloride 17.22 Addition of ammonia and then hydrolysis of
the methyl ester prepared the acid 18 that was used to prepare the
primary aryl sulfonamide 14c. Finally, amides 14d–f were made
from the advanced intermediate 19, prepared beginning with the
coupling of aniline 5 and the acid 11 from Scheme 1 (Scheme 4).
Nicotinic amide 1 was considered to be a good starting point for
new analog design in that the compound had good potency, no CYP
inhibition, and low clearance (CL) in vitro and in vivo (Table 1).
Despite these promising properties, this compound failed to show
a strong modulation of downstream Gli1 transcript when dosed at
Scheme 4. Reagents and conditions: (a) HATU, DIPEA, DMF, 2 h, rt; (b) LiOH,
THF/H2O; (c) HATU, DIPEA, amine, DMF (49–82%).
75 mg/kg in a Calu-6 PK/PD model.12 This poor in vivo activity
correlated well with a lower than expected Cmax possibly due to
Scheme 1. Reagents and conditions: (a) LiOH, THF/H2O, 45%; (b) HATU, HOAT, DIPEA, DMF; rt, R2 = H, 5 h, 76%; R2 = CH3, 18 h, 95%; (c) for amines: n-butanol or ethylene
glycol, 175–220 °C, 1 h, microwave, 34–71%; for triazoles: NaH, DMF, 140 °C, 20 h, 68%.

6750
G. M. Castanedo et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6748–6753
Table 1
Compd
R2
R3
Mouse
S12 (nM)
Human
HEPM (nM)
CYP 3A4/
2Cp ( m)
Predicated CL in
rata (mL/min/kg)
In vivo CL ratb
(mL/min/kg)
Vss rat
(L/kg)
Thermodynamic solubility
l
pH 1 mg/mL
pH 6.5 mg/mL
1
CH3
CH3
42
62
15
23
>20/>20
>20/>20
5.9
34
4.5
—
0.95
—
1.0
—
0.002
—
9a
9b
9c
CH3
CH3
53
14
19/0.5
48
48
—
—
—
—
—
—
—
—
160
5.0
>20/>20
9d
9e
9f
CH3
H
22
47
67
5.0
8.0
8.0
>20/16
0.2/0.2
>20/>20
12
0.6
19
2.0
4.0
0.7
0.38
1.4
3.2
4.0
0.9
0.006
0.008
0.006
CH3
0.24
a
Based on rat liver microsomes.
b
Male rats were dosed with the TFA salt as a solution intravenously (1 mg/kg) and orally (5 mg/kg) in a solution of 60–80% PEG.
dose-limited solubility that resulted in lower absorption (this com-
pound had high permeability in MDCK and Caco-2 cell lines with
no evidence of efflux). Additionally, as we have reported previ-
ously, a small library of aryl amides in place of the nicotinic amide
had indicated that polar groups para to the amide bond appeared
to maintain potency relative to 1. Based on these observations,
we sought to replace the lipophilic trifluoromethyl group in 1 with
more polar substituents.
Table 1 describes a subset of representative analogs of 1 that
highlights general structure–activity relationship (SAR) trends
and our strategy for selecting molecules for further study. The nic-
otinic amide tolerated a variety of substitutions at the 6 position
including primary amines, cyclic amines, and N-linked heterocy-
cles which had cell based potencies near 1. Nearly all compounds
prepared were more potent in the reporter gene assay derived
from human cells (HEPM) than in the mouse-derived cell line
(S12) and the majority of compounds had the same rank order in
both assays.
Moving beyond potency we observed that more hydrophobic
substituents began to increase inhibition of CYP 2C9, illustrated
in the comparison of 9a and 9b. Charged groups, exemplified by
methyl piperidine 9c tended to have less CYP inhibition but had
predicted clearances in the moderate range. The acylated pipera-
zine 9d had seemed to strike a good balance with minimal CYP
inhibition and lower predicted hepatic clearance in rat that trans-
lated to lower in vivo CL. This compound was twofold more potent,
more stable, and showed a similar pH dependent solubility to 1.
The triazole 9e was also pursued based on its very low predicted
clearance in rat despite strong CYP inhibition for isoforms 3A4
and 2C9, potentially contributing to the increased stability. Once
low clearance was confirmed in vivo, the introduction of a methyl
group adjacent to the ring nitrogen of the nicotinic amide and the
triazole resulted in 9f and significantly reduced CYP inhibition,
presumably by sterically blocking the heterocyclic nitrogens. Inter-
estingly, a single methyl group on the triazole or the nicotinic
amide alone was sufficient to reduce inhibition of CYPs (analogs
not shown). Like 9d, methyl triazole 9f also had a low in vivo clear-
ance in rats and was considered a promising lead.
Additionally, GDC-0449 (2) served as an excellent starting point
from which to discover new benzamide analogs. Again we focused
our attention on the para substituent and chose to retain the ortho-
chloro group that we had previously determined to be critical to
for acceptable solubility. Table 2 describes some of the SAR that
was discovered and exemplifies many of the molecules that were
pursued further into PK/PD and efficacy studies. As we saw with
the nicotinamides (Table 1) a variety of polar functional groups
are tolerated in the para-position. The extended sulfone 14a had
excellent activity in both mouse and human assays, low Cl in rats,
but a surprisingly >10-fold lower solubility at pH 1 when com-
pared to most analogs. Sulfonamide 14b was favored over analog
14c due to better potency. Simple amides (Me, Et, etc.) lost potency
relative to 2 and additional functionality had to be incorporated to
recover better than average potencies, resulting in 14d–f. Similar
trends observed in ADME and PK for the nicotinic amide series
were also seen in the benzamide series including CYP inhibition
with more hydrophobic groups, exemplified by 14e, and high
in vitro and in vivo clearance for charged substituents. Encouraged
by the potency of benzyl amide 14e we prepared three pyridyl ana-
logs, in hopes to add some additional solubility to the molecule and
to reduce the CYP inhibition. Compound 14f was by far the most
potent of the three pyridyl regioisomers and had acceptable solu-
bility, a slight improvement in CYP inhibition, and improved
microsomal stability relative to 14e. Although this compound
had microsomal clearance that was higher than most analogs,
the improved potency relative to 2 prompted us to move forward
into rat PK where the clearance was found to be low.
To further differentiate the most promising compounds from
Tables 1 and 2 we studied their ability to reduce Gli1 expression
in a PK/PD xenograft model derived from the Calu-6 non-small cell
lung carcinoma (NSCLC) cell line that recruits a large stromal com-
ponent when grown as xenografts in nude mice. Evidence strongly
suggests that in colon and pancreatic cancers where the Hh path-

G. M. Castanedo et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6748–6753
6751
Table 2
Compd
R
Mouse
S12 (nM)
human
HEPM (nM)
CYP 3A4/
2Cp ( m)
Predicated CL in
rata (mL/min/kg)
In vivo CL ratb
(mL/min/kg)
Thermodynamic solubility
l
pH 1 mg/mL
pH 6.5 mg/mL
2
13
3.0
1.0
>20/>20
>20/16
3.7
10
3.7
5.5
3.5
0.010
14a
3.0
0.11
0.003
14b
14c
17
35
2.0
5.0
>20/8.0
>20/>20
13
18
2.4
—
0.91
—
0.001
—
14d
14e
14f
33
5.0
1.0
0.4
>20/9.0
>20/1.2
>20/4.5
18
42
32
35
—
4.3
—
0.060
—
7.0
4.0
6.7
4.3
0.003
a
Based on rat liver microsomes.
b
Male rats were dosed with the TFA salt as a solution intravenously (1 mg/kg) in either 80% PEG or a solution of 5% DMSO/5% cremophor and orally (5 mg/kg) as a solution
in 60–80% PEG.
way is active, the tumor produces Hh ligand that then activates
PTCH on the surrounding stromal cells.9 Once the pathway is acti-
vated, the stromal respond by producing proteins that promote tu-
mor growth and survival. We felt that this model, governed by this
paracrine signaling pathway, would best mimic expectations in the
clinic3 and provide a convenient way to assess the ability of these
compounds to block hedgehog signaling in vivo.
allograft model. The model uses medulloblastoma tumors devel-
oped spontaneously in mice with activating mutations in the Hh
pathway (Ptch+/À) passaged subcutaneously in nude mice. Mice
with established subcutaneous tumors were treated twice daily
(BID) with inhibitors for 20 days. Previously, we had determined
that 5 mg/kg BID of 2 significantly inhibited the growth of the
medulloblastoma tumors but that higher doses of compound were
required for tumor regressions. In order to compare the in vivo po-
tency of the new inhibitors to 2 this sub-maximal efficacious dose
of 5 mg/kg BID was selected. Compound 9d performed as well as 2
when dosed at 5 mg/kg BID (Fig. 2A) and only led to partial efficacy
at that dose. In a separate experiment, 14f showed superior
potency compared to 2 when both were dosed at 5 mg/kg BID
and resulted in complete regressions (Fig. 2B). Additionally, we
tested the ability of these two potent SMO antagonists to inhibit
pathway signaling using a cell line transiently transfected with
SMO-D473H, a point mutant which was recently identified from
a medulloblastoma patient who had become resistant to treatment
with GDC-0449.25 Neither 9d nor 14f showed significant activity in
this assay, resulting in 20% and 2% inhibition, respectively, when
Once Calu-6 tumors were established, mice were dosed by oral
gavage at 75 mg/kg twice a day (BID) for five doses and tumors
harvested 4 h after the last dose for analysis of stromal (murine)
Gli1 mRNA levels and plotted relative to vehicle treated tumors.
We also determined plasma concentrations at this same time point
to establish a PK/PD relationship (Table 3). For the nicotinic amide
series, the acylated piperazine 9d showed twofold improvement in
Gli1 suppression relative to 1, due to more exposure and increased
potency for the target. Triazole 9f did not perform well despite
high plasma concentrations, an observation that was ultimately
attributed to a very low volume of distribution in mouse of
0.15 L/kg, close to the total blood volume of that animal
(ꢀ0.08 L/kg)23 combined with a lack of potency in the mouse S12
assay. In contrast most analogs had volumes closer to 1 L/kg. In
the benzamide series, the potent extended sulfone 14a had very
low plasma concentrations and thus did not lead to target modula-
tion. The low exposure for 14a was thought to occur from solubil-
ity-limited absorption, supported by the solubility measurements
described in Table 2. Sulfonamide 14b also had poor exposure
which resulted in less impressive PD responses. Finally, the very
potent pyridyl amide 14f demonstrated equivalent Gli1 suppres-
sion to 2 at doses as low as 25 mg/kg.24
tested at 1 lM.
In conclusion, two Hh inhibitors were discovered that demon-
strated equal to improved potency relative to 2 (GDC-0449) when
compared at a similar dose. These compounds were prepared by
modifying the trifluoro nicotinic amide found in 1 or the benzam-
ide ring found in 2. From both starting points ADME properties
(mainly but not limited to in vitro metabolic stability and inhibi-
tion of major CYP isoforms) were used as an important selection
criteria for further evaluation and a focus for medicinal chemistry
optimization. The Calu-6 PK/PD assay was useful in prioritizing
compounds for efficacy studies. Compounds that failed in this
Based on their activity in the PK/PD model we determined the
efficacy of 9d and 14f compared to 2 in a mouse medulloblastoma

6752
G. M. Castanedo et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6748–6753
Table 3
PK/PD data for advanced Hh pathway inhibitors
Compd
R
Mouse S12 (nM)
42
4 h plasmaa concn (
15
lM)
Mouse PPb
95%
Gli sup. versus cont.% at 4 h
40%
1
9d
9f
22
67
22
87%
89%
80%
50%
150
2
13
23
91%
90%
90%
0%
14a
3.0
0.3
14b
14f
17
2.2
—
25%
90%
4.0
25 mg/kg 1.7 (6 h)
98%
a
Mice were dosed with the free base or HCl salt as a suspension in a methylcellulose/Tween or Labrafil based formulation.
Figure 2. Medulloblastoma allograft models comparing compound two dosed BID in tumor volume over time with BID dosing of compounds 9d (A) and 14f (B).
assay were those that lacked sufficient target exposure relative to
their potency, likely due to poor solubility exemplified by 9f, 14a,
and 14b. Compounds 9d and 14f had good potency and high expo-
sure in mice, which translated into excellent in vivo activity in an
allograft model that was either similar to or better than 2, respec-
tively. The improved activity of 14f in the model was attributed to
increased potency of the compound in its ability to inhibit the Hh
pathway. Both of these compounds could be considered as poten-
tial backups to GDC-0449.
References and notes
1. Taipale, J.; Varjosalo, M. Genes Dev. 2008, 22, 2454.
2. Jaing, J.; Hui, C. C. Dev. Cell 2008, 15, 801.
3. Scales, S. J.; de Sauvage, F. J. Trends Pharmacol. Sci. 2009, 30, 303.
4. Hahn, H.; Christiansen, J.; Wicking, C.; Zaphiropoulos, P. G.; Chiambarami, A.;
Gerrard, B.; Vorechovski, I.; Bale, A. E.; Toftgard, R.; Dean, M.; Wainwright, B. J.
Biol. Chem. 1996, 271, 12125.
5. Johnson, R. L.; Rothman, A. L.; Xie, J.; Goodrich, L. V.; Bare, J. W.; Bonifas, J. M.;
Quin, A. G.; Myers, R. M.; Cox, D. R.; Epstein, E. H. Science 1996, 272, 1668.
6. Pietsch, T.; Waha, A.; Koch, A.; Kraus, J.; Albrecht, S.; Tonn, J.; Sorensen, N.;
Berthold, F.; Henk, B.; Schmandt, N.; Eolf, H. K.; Deimling, A.; Wainwright, B.;
Chenevix-Trench, G.; Wiestler, O. D.; Wicking, C. Cancer Res. 1997, 57, 2085.
7. Raffel, C.; Jenkens, R. B.; Frederick, L., et al Cancer Res. 1997, 57, 842.
8. Vorechovsky, I.; Tingby, O.; Hartman, M.; Stromburg, B.; Nister, N.; Collins, V.
P.; Toftgard, R. Oncogene 1997, 15, 361.
Acknowledgment
The authors thank Martin Struble and Mengling Wong for puri-
fication of compounds, and Mike Reich and the in vivo group for
their support of PK studies.
9. Yauch, R. L.; Gould, S. E.; Scales, S. J.; Tang, T.; Tian, H.; Ahn, C. P.; Marshall, D.;
Fu, L.; Januario, T.; Kallop, D.; Nannini-Pepe, M.; Kotkow, K.; Marsters, J. C.;
Rubin, L. L.; de Sauvage, F. J. Nature 2008, 455, 406.

G. M. Castanedo et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6748–6753
6753
10. Fan, L.; Pepicelli, C. V.; Dibble, C. C.; Catbagan, W.; Zarycki, J. L.; Laciak, R.; Gipp,
J.; Shaw, A.; Lamm, M. L. G.; Munoz, A.; Lipinski, R.; Thrasher, B.; Bushman, W.
Endocrinology 2004, 145, 3961.
19. Anghelide, N.; Draghici, C.; Raileanu, D. Tetrahedron 1974, 30, 623.
20. Andrews, A.; Finlay, M. R.; Green, C.; Jones, C.; Oza, V. World Patent
2,006,095,159, 2006.
11. Dierks, C.; Grbic, J.; Zirlik, K.; Beigi, R.; Englund, N. P.; Guo, G.-R.; Veelken, H.;
Engelhrdt, M.; Mertelsmann, R.; Kelleher, J. F.; Schultz, P.; Warmuth, M. Nat.
Med. 2007, 13, 944.
12. Robarge, K. D.; Brunton, S. A.; Castanedo, G. M.; Cui, Y.; Dina, M.; Goldsmith, R.;
Gould, S. E.; Guichert, O.; Gunzner, J. L.; Halladay, J.; Jia, W.; Khojasteh, C.;
Koehler, M. F. T.; Kotkow, K.; La, H.; Lalonde, R. L.; Lau, K.; Lee, L.; Marshall, D.;
Marsters, J. C.; Murray, L. J.; Qian, C.; Rubin, L. L.; Salphati, L.; Stanley, M. S.;
Stibbard, J. H. A.; Sutherlin, D. P.; Ubhayaker, S.; Wang, S.; Wong, S.; Xie, M.
Bioorg. Med. Chem. Lett. 2009, 19, 557.
13. Chen, J. K.; Taipale, J.; Cooper, M. K.; Beachy, P. A. Genes Dev. 2002, 16, 2743.
14. Von Hoff, D. D.; LoRusso, P. M.; Rudin, C. M.; Reddy, J. C.; Yauch, R. L.; Tibes, R.;
Weiss, G. J.; Borad, M. J.; Hann, C. L.; Brahmer, J. R.; Mackey, H. M.; Lum, B. L.;
Darbonne, W. C.; Marsters, J. C.; de Sauvage, F. J.; Low, J. A. N. Engl. J. Med. 2009,
361, 1164.
15. Rudin, C. M.; Hann, C. L.; Laterra, J.; Yauch, R. L.; Callahan, C. A.; Fu, L.; Holcomb,
T.; Stinson, J.; Gould, S. E.; Coleman, B.; LoRusso, P. M.; Von Hoff, D. D.; de
Sauvage, F. J.; Low, J. A. N. Engl. J. Med. 2009, 361, 1173.
21. Burdick, D. J.; Gadek, T. R.; Marsters, J. C.; Oare, D.; Reynolds, M. E.; Stanley, M.
S. World Patent 2,002,059,114, 2002.
22. Mitsumori, S.; Tsuri, T.; Honma, T.; Hiramatsu, Y.; Okada, T.; Hashizume, H.;
Inagaki, M.; Arimura, A.; Yasui, K.; Asanuma, F.; Kishino, J.; Ohtani, M. J. Med.
Chem. 2003, 46, 2436.
23. Harkness, J. E.; Wagner, J. E. Biology and Husbandry. In The Biology and Medicine
of Rabbits and Rodents; Harkness, J. E., Wagner, J. E., Eds., 3rd ed.; Lea & Febiger:
Philadelphia, 1989; p 372.
24. Spectral data for lead compounds 9d 1H NMR (400 MHz, DMSO) d 10.25 (s, 1H),
8.70 (d, J = 4.8 Hz, 1H), 8.01 (d, J = 2.6 Hz, 1H), 7.91 (td, J = 7.7, 1.8 Hz, 1H), 7.75
(m, 2H), 7.68 (s, 1H), 7.52 (d, J = 8.7 Hz, 1H), 7.44 (m, 1H), 6.74 (d, J = 8.8 Hz,
1H), 3.68–3.61 (m, 2H), 3.55 (t, J = 4.8 Hz, 6H), 2.48 (s, 3H), 2.05 (s, 3H). MS: m/z
450 [M+H]+ and 14f 1H NMR (400 MHz, CD3OD) d 8.96 (ddd, J = 5.8, 1.5, 0.7 Hz,
1H), 8.79 (ddd, J = 5.9, 1.5, 0.7 Hz, 1H), 8.72 (td, J = 8.0, 1.6 Hz, 1H), 8.61 (td,
J = 7.9, 1.6 Hz, 1H), 8.29–8.23 (m, 2H), 8.16–8.08 (m, 3H), 8.00 (m, 2H), 7.85
(dd, J = 8.8, 2.6 Hz, 1H), 7.73 (d, J = 8.0 Hz, 1H), 7.71 (d, J = 8.8 Hz, 1H), 4.93 (s,
2H). MS: m/z 477 [M+H]+.
16. Tremblay, M. R.; Nesler, M.; Weatherhead, R.; Castro, A. C. Expert Opin. Ther.
Patents 2009, 19, 1.
17. Mahindroo, N.; Punchihewa, C.; Fujii, N. J. Med. Chem. 2009, 52, 3829.
18. Gunzner, J.; Sutherlin, D.; Stanley, M.; Bao, L.; Castanedo, G.; Lalonde, R.; Wang,
S.; Reynolds, M.; Savage, S.; Malesky, K.; Dina, M. World Patent 2,006,028,956,
2006.
25. Yauch, R. L.; Dijkraaf, G. J. P.; Alike, B.; Januario, T.; Ahn, C. P.; Holcomb, T.;
Pujara, K.; Stinson, J.; Callahan, C. A.; Tang, T.; Bazan, J. F.; Kan, Z.; Seshagiri, S.;
Hann, C. L.; Gould, S. E.; Low, J. A.; Rudin, C. M.; de Sauvage, F. J. Science 2009,
326, 572.