Reduction in lipophilicity improved the solubility, plasma-protein binding, and permeability of tertiary sulfonamide RORc inverse agonists

Article abstract of DOI:10.1016/j.bmcl.2014.06.048

Using structure-based drug design principles, we identified opportunities to reduce the lipophilicity of our tertiary sulfonamide RORc inverse agonists. The new analogs possessed improved RORc cellular potencies with >77-fold selectivity for RORc over oth

Full text of DOI:10.1016/j.bmcl.2014.06.048

Bioorganic & Medicinal Chemistry Letters 24 (2014) 3891–3897
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Reduction in lipophilicity improved the solubility, plasma–protein
binding, and permeability of tertiary sulfonamide RORc inverse
agonists
a
a
b
a
Benjamin P. Fauber a, , Olivier René , Gladys de Leon Boenig , Brenda Burton , Yuzhong Deng ,
Céline Eidenschenk a, Christine Everett a, Alberto Gobbi a, Sarah G. Hymowitz a, Adam R. Johnson a,
Hank La a, Marya Liimatta a, Peter Lockey b, Maxine Norman b, Wenjun Ouyang a,
Weiru Wang a, Harvey Wong a
⇑
a Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
b Argenta, Units 7-9 Spire Green Centre, Flex Meadow, Harlow, Essex CM19 5TR, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Using structure-based drug design principles, we identified opportunities to reduce the lipophilicity of
our tertiary sulfonamide RORc inverse agonists. The new analogs possessed improved RORc cellular
potencies with >77-fold selectivity for RORc over other nuclear receptors in our cell assay suite. The
reduction in lipophilicity also led to an increased plasma–protein unbound fraction and improvements
in cellular permeability and aqueous solubility.
Received 22 May 2014
Revised 16 June 2014
Accepted 18 June 2014
Available online 25 June 2014
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
RORc
ROR
c
IL-17
X-ray structure
Permeability
Solubility
The cytokine interleukin (IL)-17 plays a central role in the path-
for MS.14–17 This preclinical in vivo efficacy data has further vali-
dated RORc as a suitable target for the treatment of inflammatory
disease.
A biochemical screening campaign at Genentech identified a
series of tertiary sulfonamides as RORc inverse agonists (Fig. 1,
Compounds 1 and 2), which we disclosed in a previous publica-
tion.18 In order to assist in the optimization of these tertiary sul-
fonamide lead molecules, we co-crystallized compound 1 with
the human RORc ligand-binding domain (LBD) and obtained a
2.2 Å resolution X-ray structure.19 The helices of the RORc-LBD
ogenesis of many inflammatory diseases including rheumatoid
arthritis (RA),1 multiple sclerosis (MS),2 psoriasis,3 and inflamma-
tory bowel disease (IBD).4 It has been demonstrated that the
expression of IL-17 from T helper (TH)-17 cells requires the expres-
sion of the nuclear receptor (NR) retinoic acid receptor-related
orphan receptor gamma (ROR
c
or RORc, also known as NR1F3).5
RORc is also indispensable for the production of IL-17 by innate
lymphoid cells (ILCs)6 and
c
d T cells,7 in addition to playing a role
in the production of the proinflammatory cytokines IL-228 and
granulocyte macrophage colony-stimulating factor (GM-CSF).9
Based on RORc’s influence over multiple inflammatory pathways,
it has been suggested that small molecule regulators of this NR
co-structure adopted the canonical three-layered
a-helical fold
observed with previously reported RORc X-ray structures,20 with
1 bound in the ligand binding pocket. The RORc-LBD crystallized
with two protein molecules in the asymmetric unit, which were
identical in conformation except for the relative order and place-
ment of their C-termini (Supplementary data, Fig. S1a). In one
monomer, only helix 12 was visualized at the interface of the
asymmetric unit (Fig. S1b).21 In the other monomer, the full
C-terminus was packed against a neighboring protein molecule at
the dimer interface (Fig. S1c). RORc inverse agonists can destabilize
helices 11–12.22,23 However, in the RORc-LBD co-structure with 1,
could potentially lead to anti-inflammatory therapeutics.10,11
A
recent series of publications illustrated that small molecule RORc
inverse agonists were efficacious in a murine model of psoriasis,12
a collagen-induced arthritis (CIA) mouse model for RA,13,14 and the
experimental autoimmune encephalomyelitis (EAE) mouse model
⇑
Corresponding author. Tel.: +1 650 467 5773.
E-mail address: Fauber.Benjamin@gene.com (B.P. Fauber).
http://dx.doi.org/10.1016/j.bmcl.2014.06.048
0960-894X/Ó 2014 Elsevier Ltd. All rights reserved.

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B. P. Fauber et al. / Bioorg. Med. Chem. Lett. 24 (2014) 3891–3897
Figure 1. Tertiary sulfonamide RORc inverse agonist ligands reported by
Genentech.
the C-terminal region was ordered and there were no direct inter-
actions between 1 and the protein. Therefore, we assumed that
crystal packing led to the ordering of the C-terminal residues.
The RORc-LDB environment and protein’s interactions with 1
were identical in both monomers of the aforementioned asymmet-
ric unit. The benzylic ring on the tertiary sulfonamide of 1 formed
edge-to-face
p–p
interactions24 with Trp317 (3.7 Å) and Phe486
(3.8 Å) (Fig. 2a). It was notable that His479 on helix 11 of the
RORc-LBD did not adopt the same orientation that was observed
in a previously reported RORc agonist ligand co-structure [PDB:
3L0L], in which His479 formed a hydrogen bond (3.0 Å) with
Tyr502.25 In the RORc-LBD co-structure with 1, His479 engaged
the benzylic ring of 1 in an edge-to-face
p–p interaction (3.3 Å)
(Fig. 2a), and prohibited it from forming the aforementioned hydro-
gen bond with Tyr502 on helix 12. The ligand-induced movement of
His479 may account for the RORc inverse agonist profile of 1 and the
disorder and/or loss of secondary structure for helices 110–12 in the
RORc-LBD co-structure. The orientation and interactions of His479
have been previously postulated by our group23 and others22 as an
important regulator of RORc function. The N-isobutyl group of 1
resided in a shallow lipophilic pocket lined with Val376, Phe388,
Ile400, and Phe401. The central thiophene ring of 1 hovered over
Met365 and participated in a sulfur–arene interaction26 (4.6 Å).
The thiophene ring of 1 also participated in an edge-to-face
p–p
interaction with Phe378 (4.2 Å). The interactions of the thiophene
ring on 1 with the RORc ligand binding pocket account for the tight
SAR observed with the thiophene ring replacements we described in
a previous publication.18 The para-methanesulfonyl group of 1
resided in the hydrophilic region of the RORc ligand binding pocket
and 1 formed a weak hydrogen bond26 with Arg367 (3.5 Å) and a
water-mediated hydrogen bond (3.1 Å) to Tyr281 (2.7 Å) and the
backbone carbonyl of Cys285 (2.8 Å) (Fig. 2b). It was also noted that
1 resided in the RORc ligand binding pocket in a very different ori-
entation than the previously described co-structure of T0901713
(N-(4-(1,1,1,3,3,3-hexafluoro-2-hydroxypropan-2-yl)phenyl)-N-(2,
2,2-trifluoroethyl)benzenesulfonamide) with the RORc-LBD [PDB:
4NB6],23 and there were limited opportunities to bridge the SAR
between these two distinct classes of RORc inverse agonist ligands.
An evaluation of 1 in a panel of in vitro assays revealed that it
Figure 2. A 2.2 Å resolution co-crystal structure of compound
complex with the RORc-LDB (grey) [PDB: 4QM0]. Water molecules are spheres (red)
and hydrogen bonds are dashed lines (black). Side chain residues have been omitted
1 (yellow) in
had low aqueous solubility (61 lM at pH 7.4), high plasma–
for clarity. (a) The benzylic ring of the tertiary sulfonamide formed edge-to-face
p–
p
interactions with His479 (grey, 3.3 Å), Phe486 (grey, 3.8 Å), and Trp317 (grey,
protein binding (PPB) (99% bound in both human and rodent
3.7 Å). (b) The para-methanesulfonyl moiety of 1 made a direct hydrogen bond
(3.5 Å) with Arg367 (grey) and a water-mediated hydrogen bond (3.1 Å) to Tyr281
(grey, 2.7 Å) and the backbone carbonyl of Cys285 (grey, 2.8 Å).
serum), and low apparent permeability (Papp) as assessed by the
Madin-Darby canine kidney (MDCK)27 cell assay (Papp(A
?
B) = 2 ꢀ
10ꢁ6 cm/s).28 In our evaluation of the X-ray co-structure of 1 with
the RORc-LBD, it was evident that several features on 1 were
interacting with the RORc ligand binding pocket. Yet the terminal
arene ring in the biaryl motif of 1 only served as a spacer to orient
the para-methanesulfonyl moiety toward the aforementioned
hydrogen bonding interaction partners in the protein. Therefore,
we sought to replace the terminal arene in the biaryl motif of 2
with a suitable non-aromatic heterocycle.29 Such a change would

B. P. Fauber et al. / Bioorg. Med. Chem. Lett. 24 (2014) 3891–3897
3893
decrease the aromatic ring count (#Ar) and could increase the
solubility while lowering the PPB.30 It would also lower the
lipophilicity31 of our chemical series and increase the fraction of
sp3-hydridized carbons (Fsp3), which could potentially improve
the solubility.32 A reduction in lipophilicity, as assessed by the
measured logP or calculated logP (clogP) values, can lead to
improvements in cellular permeability and aqueous solubility33,34
while also decreasing PPB35 and minimizing any potential second-
ary pharmacology associated with our molecules.36,37
Aryl-piperazines and aryl-piperidines are proven biaryl isoster-
es.38 With this consideration in mind, we initiated a campaign to
replace the terminal arene of 2 with a range of substituted pipera-
zines and piperidines. The analogs were synthesized via the Buch-
wald–Hartwig amination reaction39 and an aryl-bromide tertiary
sulfonamide advanced intermediate.40 The analogs were tested in
a time-resolved fluorescence biochemical assay that monitored
the ability of the human RORc-LBD to bind to a co-activator pep-
tide derived from steroid receptor co-activator-1 (SRC1).41 Com-
pounds that disrupted the recruitment of the SRC1 co-activator
peptide were RORc inverse agonists.20
piperazine group (14) led to a molecule with additional RORc
potency (EC50 = 57 nM) and an equivalent clogP value to 12. The
methyl carbamate analog (15) was a less potent RORc inverse ago-
nist than 14, and homologation of the amide functional group out-
side of the ring (16) also resulted in a loss of potency. In summary,
the exploration of the heterocyclic aliphatic N-linked rings identi-
fied the amide functionality in 14 as an optimal combination of
RORc inverse agonist potency and decreased lipophilicity relative
to the starting molecule (2). The notable drawback in this endeavor
was the lack of improvement in aqueous solubility values for most
analogs. Thus, we turned our attention to the N-alkyl substituent in
an effort to make further reductions in lipophilicity and potential
improvements in aqueous solubility.
As discussed earlier in the analysis of the X-ray co-structure of 1
with the RORc-LBD, the N-isobutyl group of the ligand resided in a
shallow lipophilic pocket but did not appear to make any specific
interactions with the protein. With this consideration in mind,
we sought to explore a variety of N-alkyl groups that could main-
tain or increase the potency of analogs, relative to 14, while also
lowering the lipophilicity. The N-alkyl analogs were synthesized
by either (1) alkylation of a secondary sulfonamide advanced inter-
mediate or (2) introduction of the bulkier N-alkyl groups early in
the synthesis then carrying the molecules through several standard
transformations to reveal the final compounds.40 Introduction of
the N-cyclobutyl group (Table 2, Compound 17) led to an approx-
imate two-fold improvement in the RORc inverse agonist potency
(EC50 = 30 nM) while also decreasing the clogP value 0.2 log units
Replacement of the terminal arene on 2 with an N-methanesul-
fonyl-piperazine (3) demonstrated that the change was tolerated,
with only a 10-fold loss in RORc inverse agonist potency while also
reducing the clogP42 value by 1.6 log units (Table 1). Homologation
of the sulfonamide functional group one atom outside of the ring
(4) provided
a molecule that was equipotent (RORc SRC1
EC50 = 20 nM) to 2 and less lipophilic. Removal of the sulfonamide
nitrogen in 4 provided sulfone analog 5 which was of similar
potency (RORc SRC1 EC50 = 42 nM). The collective results of ana-
logs 3–5 demonstrated that the orientation and distance of the sul-
fone moiety in relation to Arg367 could be important for potency,
but the sulfonamide N–H was not making any essential hydrogen
bonding interactions with the hydrophilic region of the ligand
binding pocket. To further explore the position of the sulfone moi-
ety, a 1,1-dioxothiomorpholine analog (6) was synthesized because
it had an improved clogP value versus the exocyclic sulfone analog
(5) (clogP = 2.3 and 3.7, respectively). Compound 6 was approxi-
mately 20-fold less potent than 5, further illustrating the impor-
tance of the appropriately positioned sulfonyl group to interact
with the RORc ligand binding pocket. It was also noted that com-
pounds 2–6 all contained multiple sulfonamide/sulfone functional
groups, and all of the compounds had low aqueous solubility val-
and increasing the aqueous solubility (37
tert-butyl isomer (18) resulted in a compound that was equipotent
to 17, yet less soluble (61 M) and more lipophilic. Replacement of
the iso-butyl group with a 3-oxetane ring (19) led to a substantial
loss of RORc potency (EC50 = 4.9 M) with improvements in solu-
bility (189 M) and lipophilicity. Introduction of the n-propyl,
lM). Synthesis of the
l
l
l
i-propyl, and c-propyl N-alkyl groups (compounds 20–22) were
all well tolerated (EC50 = 70, 37, 100 nM, respectively), and most
also provided notable improvements in lipophilicity and aqueous
solubility. The ethyl (23) and 2,2,2-trifluoroethyl (24) analogs also
possessed favorable RORc inverse agonist potencies (EC50 = 94 and
13 nM, respectively) while also displaying improved solubility and
lipophilicity profiles over 14. Polar functional groups such as
methoxyethyl (25) and N,N-dimethylaminoethyl (26) were poorly
tolerated in the lipophilic pocket of the RORc protein as were the
methyl (27) and methylenecyano (28) moieties. The results of
compounds 19 and 25–28 illustrated the tight SAR in the shallow
lipophilic pocket of the protein occupied by the isobutyl group
on 1 (ergo 14), as aliphatic or halogenated aliphatic moieties of a
certain size were the only tolerated N-alkyl substituents. The SAR
of the benzylic sulfonamide group on the right-hand side of the
molecule was also explored with a variety of aliphatic and hetero-
aromatic sulfonamide replacements. Ultimately, there were no
notable improvements over the parent benzylic sulfonamide group
(data not shown).
We analyzed the potent RORc inverse agonist compounds iden-
tified with the SRC1 co-activator recruitment assay in a panel of
HEK293 cell Gal4-ROR construct reporter assays. We profiled three
known isoforms of human ROR (RORc, RORb, and RORa) by moni-
toring the suppression of their basal transcriptional activity in the
absence of any exogenous agonist.41 In order to assess the NR cel-
lular selectivity of the potent RORc inverse agonists, we also tested
these compounds in cellular reporter assays of human farnesoid X
ues (61 l
M at pH 7.4).43 To explore the relationship of sulfones/
sulfonamides and solubility, we focused on other functional groups
in an effort to maintain the potency of 2 while improving the aque-
ous solubility of subsequent analogs. The morpholine analog (7)
was modestly potent in the RORc SRC1 co-activator peptide
recruitment assay (EC50 = 0.21 lM), and it was also more potent
than the corresponding 1,1-dioxothiomorpholine analog (6). This
result indicated that the sulfone or sulfonamide group might not
be the optimal functional group on the aliphatic heterocyclic ring
in the hydrophilic region of the RORc ligand binding pocket. Conse-
quently, we also explored a variety of functional groups. Com-
pound 8 was less potent in the SRC1 co-activator assay, relative
to 7, whereas
9 demonstrated improvements in potency
(EC50 = 0.10 M) and aqueous solubility. Methylation of the hydro-
l
xyl group on 9 resulted in the retention of RORc inverse agonist
potency and a reduction in aqueous solubility (Compound 10,
EC50 = 0.16 lM). Introduction of a nitrile moiety at the 4-position
of the piperidine (11) provided a further improvement in RORc
inverse agonist potency, as did the introduction of a primary amide
(12). Compound 12 was quite promising since it was less lipophilic
than 2, yet it had similar activity in the RORc SRC1 co-activator
peptide recruitment assay (EC50 = 70 nM). We explored other vari-
ants of this functional group such as the tertiary amide analog (13),
which was approximately 10-fold less active than 12. The N-acyl
receptor (FXR), liver X receptor (LXR)-a, LXRb, and pregnane X
receptor (PXR) in both agonist mode (no agonist ligand added)
and antagonist mode (using T0901317 as an exogenous ligand).41
In our NR cellular assays, we found 2 was a modestly potent
RORc inverse agonist (RORc cell EC50 = 0.45
lM) with only four-
fold selectivity over the other NRs in our assay panel (Table 3,

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B. P. Fauber et al. / Bioorg. Med. Chem. Lett. 24 (2014) 3891–3897
Table 1
Structure–activity relationships of the 4-benzylic substituents
clogPb
RORc LLEc
3.0
Solubilityd
(lM)
a
Compd
R-group
RORc SRC1 EC50
(l
M) [%eff.]
2
0.025 [ꢁ94%]
4.5
61
3
4
0.21 [ꢁ92%]
2.9
4.1
4.0
3.2
61
61
0.020 [ꢁ96%]
5
6
0.042 [ꢁ93%]
0.70 [ꢁ89%]
3.7
2.3
3.3
4.2
61
61
7
8
0.21 [ꢁ90%]
2.3 [ꢁ75%]
3.8
4.0
2.6
2.3
61
60
9
0.10 [ꢁ97%]
0.16 [ꢁ92%]
0.074 [ꢁ96%]
4.2
4.7
4.2
2.4
2.1
2.8
7
10
11
61
61
12
13
14
15
0.070 [ꢁ95%]
0.86 [ꢁ90%]
0.057 [ꢁ96%]
0.31 [ꢁ92%]
3.5
4.2
3.5
4.2
3.4
1.7
3.8
2.3
61
61
61
61

B. P. Fauber et al. / Bioorg. Med. Chem. Lett. 24 (2014) 3891–3897
3895
M)
Table 1 (continued)
a
Compd
R-group
RORc SRC1 EC50
(
lM) [%eff.]
clogPb
RORc LLEc
2.3
Solubilityd
(l
16
0.92 [ꢁ84%]
3.9
61
All assay results are reported as the geometric mean of at least two separate runs.41
a
Inhibition of RORc LBD recruitment of a peptide derived from the SRC1 co-activator protein; negative percent efficacy ‘%eff.’ denotes inverse agonism relative to the basal
activity of apo-RORc LBD in this assay format.
b
Calculated logP (clogP) value.42
c
Ligand-Lipophilicity Efficiency (LLE)46 was calculated using the RORc SRC1 EC50 and the clogP.
d
Aqueous kinetic solubility at pH 7.4.
Table 2
Structure–activity relationships of the N-alkyl R-groups
clogPb
RORc LLEc
Solubilityd
(lM)
a
Compd
R-group
RORc SRC1 EC50
(
lM) [%eff.]
17
18
19
20
21
22
23
24
25
26
27
28
c-Bu
t-Bu
3-Oxetane
n-Pr
i-Pr
c-Pr
Et
CH2CF3
(CH2)2OMe
(CH2)2NMe2
Me
0.030 [ꢁ97%]
0.029 [ꢁ97%]
4.9 [ꢁ73%]
0.070 [ꢁ95%]
0.037 [ꢁ98%]
0.10 [ꢁ97%]
0.094 [ꢁ98%]
0.013 [ꢁ98%]
0.68 [ꢁ87%]
>10
3.2
3.4
1.8
3.2
3.0
2.8
2.7
3.0
2.1
2.2
2.2
1.8
4.3
3.8
3.4
3.6
4.0
4.1
4.2
4.5
4.1
—
37
61
189
40
61
71
31
5
87
221
7
5.1
6.5
3.2
3.5
CH2CN
125
All assay results are reported as the geometric mean of at least two separate runs.41
a
Inhibition of RORc LBD recruitment of a peptide derived from the SRC1 co-activator protein; negative percent efficacy ‘%eff.’ denotes inverse agonism relative to the basal
activity of apo-RORc LBD in this assay format.
b
Calculated logP (clogP) value.42
c
Ligand-Lipophilicity Efficiency (LLE)46 was calculated using the RORc SRC1 EC50 and the clogP.
d
Aqueous kinetic solubility at pH 7.4.
Table 3
RORc potency and selectivity profiles in Gal4 human transcription assaysa
Compd RORc Cell EC50
(l
M) RORb Cell EC50
(
lM) RORa Cell EC50
(
lM) FXR Cell EC50
(l
M) LXR
a
Cell EC50
(l
M) LXRb Cell EC50
(lM) PXR Cell EC50 (lM)
2
0.45
0.12
0.13
0.41
0.27
2.5
2.4
2.4
2.3
2.5
3.0
14
17
21
24
>10
>10
1.2
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
All assay results are reported as the geometric mean of at least two separate runs.
a
All assays were conducted in HEK293-Gal4 cellular constructs. All NR assays monitored the suppression of their respective basal transcriptional activities, an outcome
consistent with inverse agonist activity of ligands with these receptors.41
EC50 values = 2.4–3.0
biochemical potency observed with compounds 14 and 17 trans-
l
M). We were pleased to see that the RORc
panel. None of the compounds exhibited agonist activity in the
FXR, LXR, and PXR activation cell assays (data not shown). Only
lated to favorable RORc cellular potencies (EC50 values = 0.12 and
compound 14 exhibited PXR agonist activity (EC50 = 0.50 lM,
0.13
l
M, respectively). Additionally, these compounds were more
25-fold activation versus the T0901317 control).
selective for RORc versus the other NRs in our selectivity panel,
exhibiting a >77-fold selectivity for RORc. Compound 21 was less
potent and selective for RORc than 17 in the ROR cellular assays,
Additionally, we progressed compounds 14, 17, and 24 into
human peripheral blood mononuclear cell (PBMC) cytokine pro-
duction assays to assess their abilities to inhibit the production
of IL-17 (Table 4).41 Compounds 14 and 17 displayed modest inhi-
bition of IL-17 production in the human PBMC assay (EC50 = 0.77
and it harbored some affinity for RORb (RORc cell EC50 = 0.41
RORb cell EC50 = 1.2 M). Compound 24 also exhibited a favorable
RORc potency (RORc cell EC50 = 0.27 M) and selectivity profile,
with >37-fold selectivity for RORc over the other NRs in our assay
lM,
l
l
and 0.80
l
M, respectively), while compound 24 was slightly less
M). The differences in IL-17 inhibition values
potent (EC50 = 0.97
l

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B. P. Fauber et al. / Bioorg. Med. Chem. Lett. 24 (2014) 3891–3897
Table 4
Potency in human IL-17 and INFc
production assaysa
Compd
IL-17 PBMC EC50
(l
M)
IL-17 PBMC%max. inhibition (%)
IFN
c
EC50
(lM)
CTG EC50 (lM)
14
17
24
0.77
0.80
0.97
80
95
81
>10
>10
>10
>10
>10
>10
All assay results are reported as the geometric mean of at least two separate runs.
a
All assays were conducted using peripheral blood mononuclear cells (PBMCs) isolated from human whole blood.41 Interferon gamma (INF ) and CellTiter-GloÒ (CTG) cell
c
culture assays were used as positive controls to monitor for non-TH17 cell cytokine activity and adverse off-target effects on cell physiology, respectively.41
Table 5
In vitro ADME properties of compounds 2 and 17
Compd
Human PPBa (%unbound)
Rat PPBa (%unbound)
MDCKb Papp A ? B (10ꢁ6 cm/s)
MDCKb Papp B ? A (10ꢁ6 cm/s)
2
17
1
6
1
6
3
24
2
24
See the Supplementary data for experimental details associated with each assessment.
a
Plasma–protein binding (PPB).
Apparent membrane permeability (Papp) in a Madin-Darby canine kidney (MDCK) cell permeability assay.
b
between the three compounds exhibited roughly the same trend in
potency observed in the RORc Gal4 cellular assay. It was also note-
worthy that none of the compounds showed any activity in the
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improvements in the in vitro ADME properties.44 Compound 17
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Acknowledgments
We thank Drs. Krista Bowman and Jiansheng Wu, and their
respective Genentech research groups, for performing all required
protein expression and purification activities. In addition, we thank
Crystallographic Consulting, LLC for diffraction data collection. Use
of the Advanced Photon Source was supported by the U. S. Depart-
ment of Energy, Office of Science, Office of Basic Energy Sciences,
under Contract No. DE-AC02-06CH11357.
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