Design and Optimization of Sulfone Pyrrolidine Sulfonamide

Subscriber access provided by University of Winnipeg Library

Article

Design and Optimization of Sulfone Pyrrolidine Sulfonamide Antagonists of Transient Receptor Potential Vanilloid-4 (TRPV4) with In Vivo Activity in a Pulmonary Edema Model Joseph E. Pero, Jay Matthews, David J Behm, Edward Brnardic, Carl A Brooks, Brian W Budzik, Melissa Costell, Carla Donatelli, Stephen Eisennagel, Karl F Erhard, Michael Fischer, Dennis A. Holt, Larry Jolivette, Huijie Li, Peng Li, John McAtee, Brent W McCleland, Israil Pendrak, Lorraine Posobiec, Katrina Rivera, Ralph A. Rivero, Theresa J Roethke, Matthew Sender, Arthur Shu, Lamont Terrell, Kalindi Vaidya, Xiaoping Xu, and Brian G. Lawhorn J. Med. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jmedchem.8b01344 • Publication Date (Web): 30 Nov 2018 Downloaded from http://pubs.acs.org on December 1, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Journal of Medicinal Chemistry

Design and Optimization of Sulfone Pyrrolidine Sulfonamide Antagonists of Transient Receptor Potential Vanilloid-4 (TRPV4) with In Vivo Activity in a Pulmonary Edema Model Joseph E. Pero*,ɸ, Jay M. Matthews†, David J. Behm†, Edward J. Brnardic†, Carl Brooks†, Brian W. Budzikɸ, Melissa H. Costell†, Carla A. Donatelli†, Stephen H. Eisennagel†, Karl Erhardɸ, Michael C. Fischerǁ, Dennis A. Holt†, Larry J. Jolivette†, Huijie Liɸ, Peng Liɸ, John J. McAtee†, Brent W. McClelandɸ, Israil Pendrakɸ, Lorraine M. Posobiecǁ, Katrina L.K. Rivera†, Ralph A. Riveroɸ, Theresa J. Roethke†, Matthew R. Senderɸ, Arthur Shuɸ, Lamont R. Terrell†, Kalindi Vaidyaǁ, Xiaoping Xu †, Brian G. Lawhorn† ɸFlexible

Discovery Unit, †Heart Failure Discovery Performance Unit and ǁPlatform Technology and Sciences

GlaxoSmithKline, 1250 Collegeville Road, Collegeville, Pennsylvania, 19426, United States

ABSTRACT: Pulmonary edema is a common ailment of heart failure patients and has remained an unmet medical need due to dose-limiting side effects associated with current treatments. Preclinical studies in rodents have suggested that inhibition of TRPV4 cation channels may offer an alternative - and potentially superior therapy. Efforts directed toward small molecule antagonists of the TRPV4 receptor have led to the discovery of a novel sulfone pyrrolidine sulfonamide chemotype exemplified by lead compound 6. Design elements toward the optimization of TRPV4 activity, selectivity and pharmacokinetic properties are

ACS Paragon Plus Environment

Journal of Medicinal Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 37

described. Activity of leading exemplars 19 and 27 in an in vivo model suggestive of therapeutic potential is highlighted herein. ■ INTRODUCTION: Despite numerous medical advancements and increased awareness of risk factors, heart disease remains one of the leading causes of death.1 Specifically, approximately 2% of adults in developed countries have experienced congestive heart failure (HF), with this number rising to 6-10% for those exceeding 65 years of age.2 Over a 12-month period post-diagnosis, the risk of death is approximately 35%, which is comparable to that of severe cancers.3 HF and its related side effects also pose a significant economic burden on society, with total associated costs in the United States alone projected to increase from $31 billion in 2012 to $70 billion in 2030.4 HF is caused by the inability of an impaired left ventricle to pump sufficient blood into peripheral circulation. This results in elevated pulmonary venous pressure (PVP) and disrupts the septal barrier, which separates the circulatory aqueous environment from the alveolar airspaces.5,6 With an increased flow of fluid from pulmonary circulation into the alveolar space, HF patients frequently suffer from pulmonary edema, which significantly compromises their quality of life and can prove fatal if left untreated.7 TRPV4 receptors are members of the Transient Receptor Potential (TRP) superfamily of cation channels.8 These tetrameric voltage-gated channels are highly expressed in lung endothelial cells9,10 and are up-regulated in HF patients.11 Their direct association with pulmonary edema has been implicated by studying the effects of selective TRPV4 antagonist GSK2193874 (Compound 1, Figure 1a) in rodents.11 In both acute and chronic preclinical models, pre-treatment with GSK2193874 inhibited HF-induced pulmonary edema and increased arterial oxygenation.11 In addition, GSK2193874 was effective at reversing HF-induced pulmonary edema in mice subjected to myocardial infarction (MI) for one week prior to treatment.11


Page 3 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Importantly, strong evidence indicates that these effects may be relevant to humans. GSK2193874 was found to be potent in recombinant hTRVP4 channels (IC50 = 50 nM), and prevented agonist-driven cellular contraction in human umbilical vein endothelial cells (HUVEC’s).11 These experimental findings suggest that TRPV4 blockade has the potential to lead to a novel treatment for HF-induced pulmonary edema that could prove more effective than current standards-ofcare (i.e. diuretics, nitroglycerin, angiotensin antagonists), which have been associated with unfortunate side effects including hypotension and deteriorating renal function.12,13 As such, a number of selective TRPV4 antagonists have been disclosed in the recent literature with superior drug-like properties (i.e. reduced molecular weight, lower lipophilicity) to GSK2193874. Examples from GlaxoSmithKline include 1-(4-piperidinyl)-benzimidazoles14 and spirocarbamates (2, Figure 1b),15,16 while Pfizer has disclosed azetidine sulfonamides (3, Figure 1c) derived from a high-throughput screen.17

a)

b) NH

O

O N

Br

N

Me Me Me

O

N

CN

O

N

c)

N

N Me CF3

Compound 1 (GSK2193874) hTRPV4 IC50 = 50 nM MW = 692, cLogP = 8.1 LE = 0.22, LLE = -0.8

N

Compound 2 (GSK) hTRPV4 IC50 = 7.5 nM MW = 448, cLogP = 3.6 LE = 0.34, LLE = 4.5

NC

OH

O N O S O Cl

Cl

Compound 3 (Pfizer) hTRPV4 IC50 = 21 nM MW = 413, cLogP = 3.9 LE = 0.41, LLE = 3.8

Figure 1. Previously-reported TRPV4 antagonists from GSK (a, b) and Pfizer (c).

With its promising ligand efficiency (LE)18 and lipophilic ligand efficiency (LLE)19, 3 was previously utilized as a starting point in efforts directed toward discovering novel TRPV4 antagonists.20 This led to the discovery of pyrrolidine sulfonamide lead 4, which displayed encouraging in vitro activity (IC50 = 32 nM) at recombinant hTRPV4 channels21 with comparable LE (0.40) and LLE (3.9) relative to



Page 4 of 37

3 (Figure 2). Subsequent scaffold optimization20 led to diol 5, which featured excellent LLE (5.3) due to enhanced TRPV4 activity (IC50 = 5.0 nM) in conjunction with reduced lipophilicity (cLogP22 = 3.0).

NC

N O S O Cl

O

scaf f old NC modif ication

OH

O

N O S O Cl

Cl

Compound 3 (Pfizer) hTRPV4 IC50 = 21 nM cLogP = 3.9 LE = 0.41, LLE = 3.8

OH

diol NC incorporation

Cl

Compound 4 (GSK) hTRPV4 IC50 = 32 nM cLogP = 3.6 LE = 0.40, LLE = 3.9

O

OH OH

N O S O Cl

Cl

Compound 5 (GSK) hTRPV4 IC50 = 5.0 nM cLogP = 3.0 LE = 0.41, LLE = 5.3

Figure 2. Scaffold modification of 3 to give pyrrolidines 4 and 5.

The present work describes an analogous structural class exemplified by sulfone 6, which was viewed as a lead compound superior to ether 4 due to reduced lipophilicity (cLogP = 2.7) and improved LLE (4.9) (Figure 3a). Design elements toward an optimal balance of TRPV4 activity, selectivity and pharmacokinetic (PK) properties are detailed. Evaluation of leading compounds in an in vivo rat pulmonary edema assay indicative of therapeutic potential is also provided.

■ RESULTS AND DISCUSSION: At the outset of our optimization efforts, the potency-enhancing diol of the ether structural class20 was incorporated to afford Compound 7, which displayed improvements in both TRPV4 activity (IC50 = 7.9 nM) and LLE (5.2) with only a slight increase in lipophilicity (cLogP = 2.9). Notably, the stereoisomers of 7 were also explored (Figure 3b, Compounds 8-10), with each exhibiting considerably weaker activity in the primary FLIPR21 assay.


Page 5 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Journal of Medicinal Chemistry a)

O

NC

OH 3 4

Sulf one incorporation

N O S O Cl

NC

N O S O Cl

Cl

3 4

N O S O Cl

Cl

3 4

Cl

Compound 8 (3R, 4R) hTRPV4 IC50 = 1585 nM cLogP = 2.9, LLE = 2.9

NC

OH

N O S O Cl

3 4

OH

Cl

Compound 7 (3S, 4R) hTRPV4 IC50 = 7.9 nM cLogP = 2.9 LE = 0.37, LLE = 5.2

O S O OH

NC

OH

O S O OH N O S O Cl

Compound 6 (3S, 4S) hTRPV4 IC50 = 25 nM cLogP = 2.7 LE = 0.37, LLE = 4.9

O S O OH

NC

Diol NC incorporation

3 4

Compound 4 (3S,4S) hTRPV4 IC50 = 32 nM cLogP = 3.6 LE = 0.40, LLE = 3.9 b)

O S O OH

O S O OH 3 4

Cl

Compound 9 (3S, 4S) hTRPV4 IC50 = 50 nM cLogP = 2.9, LLE = 4.4

N O S O Cl

OH

Cl

Compound 10 (3R, 4S) hTRPV4 IC50 = 159 nM cLogP = 2.9, LLE = 3.9

Figure 3. (a) Replacement of phenoxy ether functionality with sulfone, leading to 7. (b) Additional stereoisomers of sulfone pyrrolidine diol 7.

An investigation of the PK properties of 7 further substantiated the diol chemotype (Table 1). Following intravenous (i.v.) dosing in rat (1 mpk), 7 exhibited reduced clearance adjusted for unbound fraction23 (CL/fu = 9) relative to parent compound 6 (CL/fu = 30), suggesting that the potency-enhancing diol functionality did not pose an additional metabolic liability. Furthermore, high permeability24 (450 nm/sec) and 100% oral bioavailability (F, 2 mpk p.o.) were maintained despite an elevated total polar surface area (PSA = 136). This could be rationalized by a reduction in solvent-accessible PSA due to conformational restriction imparted by intramolecular hydrogen bonds, which were confirmed by vibrational circular dichroism (VCD) studies.25,26,27. In addition, despite elevated total clearance (25 mL/min/kg), the mean residence time28 of 7 (MRT = 1.7 h) was nearly equivalent to that of 6 due to its higher volume of distribution (Vdss = 2.3 L/kg).

Table 1. PK properties (rat) of Compounds 5, 6 and 7a



Cmpd PSA

Perm

CL

CL/fu

(nm/sec) (mL/min/kg)

aPSA

Page 6 of 37

Vdss

MRT

F

(L/kg)

(h)

(%)

5

111

370

74

15

2.4

0.6

46

6

116

780

9

30

1.1

2.0

100

7

136

450

25

9

2.3

1.7

100

= total polar surface area; Perm = artificial membrane permeability; CL = total clearance; fu = fraction unbound (rat);

Vdss = volume of distribution; MRT = mean resonance time; F = oral bioavailability

A comparison of the PK properties of 7 with corresponding ether 5 provided additional validation of the sulfone structural class. Ether 5 featured higher total clearance (74 mL/min/kg) and clearance adjusted for unbound fraction (CL/fu = 15) as well as a shorter MRT (0.6 h), potentially due to oxidative metabolism of the phenoxy ether moiety. Furthermore, ether 5 exhibited reduced oral bioavailability (46%) in relation to sulfone 7. In order to facilitate analog preparation, a generalized29 synthetic route toward the sulfonefunctionalized pyrrolidine diols was established (Scheme 1). Chiral resolution of known tert-butyl-3hydroxy-4-methylenepyrrolidine-1-carboxylate30 provided the requisite (S)-isomer 11. Formation of the corresponding mesylate followed by SN2-displacement with an aryl thiol under basic conditions afforded thioether 12. Oxidation with m-CPBA generated sulfone 13 which then underwent a dihydroxylation to give diol 14 in high diastereomeric fidelity. Establishing the sulfone moiety prior to treatment with osmium tetroxide proved critical, as dihydroxylation of thioether 12 proceeded with significantly lower diastereoselectivity.31 With advanced intermediate 14 in hand, acid-mediated cleavage of the Boccarbamate followed by sulfonamide formation under standard conditions generated targeted compounds of generic structure 15.

Scheme 1. General synthesis of sulfone pyrrolidine diolsa


Page 7 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Journal of Medicinal Chemistry R

HO a, b

N Boc

11

12

13 R

O S O OH OH N Boc 14

aReagents

d

c

N Boc

R

O S O

R

S

N Boc

O S O OH OH

e, f N O S 15 O

R'

and conditions: (a) MsCl, TEA, DCM; (b) arylthiol, K2CO3, DMF (74-81% over 2 steps); (c) m-CPBA, DCM (59-

89%); (d) OsO4, NMO, THF (81-98%, >95:5 dr); (e) HCl/1,4-dioxane or TFA, DCM; (f) arylsulfonyl chloride, NaHCO3, THF (26-85% over 2 steps).

With a superior balance of potency and PK properties being the ultimate goal, the versatility of this synthetic sequence allowed the structure-activity relationships of both the aryl sulfonamide and sulfone moieties to be explored (Table 2). Compound 16 features the installation of a fluoro substituent at R2 that proved to be a potency enhancer in the aforementioned azetidine17 and phenoxy ether pyrrolidine20 structural classes. While Compound 16 indeed demonstrated slight improvements in TRPV4 activity (IC50 = 2.0 nM) and LLE (5.6) relative to its des-fluoro counterpart 7, these benefits were counterbalanced by an erosion in PK properties as exemplified by higher clearance adjusted for unbound fraction (CL/fu = 14), shorter MRT (0.8 h) and reduced oral bioavailability (51%). One possible rationalization of the higher unbound clearance associated with 16 is that its more electrophilic aryl sulfone functionality was subjected to increased nucleophilic addition by glutathione (GSH), which was suggested by trapping experiments in rat liver microsomes in which only 46% of parent remained after incubation (30 min). Analogous studies with compound 7 showed 89% of parent remaining after incubation.

Table 2. Structure-activity relationships of sulfone pyrrolidine diolsa



R2

O S O OH

1

R

OH N O S O R3

Cmpd

R1

R2

R3

R4

IC50

Page 8 of 37

LLE

PSA

(nM)

R4

CL

CL/fu

(mL/min/kg)

Vdss

MRT

F

(L/kg)

(h)

(%)

7

CN

H

Cl

Cl

7.9

5.2

136

25

9

2.3

1.7

100

16

CN

F

Cl

Cl

2.0

5.6

136

25

14

1.2

0.8

51

17

CN

H

CN

Cl

2.0

6.8

160

82

7

2.6

0.5

25

18

CN

H

Cl

CN

3.2

6.9

160

35

4

2.2

1.0

15

19

Cl

H

Cl

CN

3.2

5.8

136

49

12

4.5

1.6

100

ahuman

TRPV4 IC50 values measured by a calcium flux FLIPR assay (see Supporting Information for details); LLE = lipophilic

ligand efficiency; PSA = total polar surface area; CL = total clearance; fu = fraction unbound (rat); Vdss = volume of distribution; MRT = mean resonance time; F = oral bioavailability

Replacing the ortho-chloro substituent of the aryl sulfonamide with a cyano group (R3 = CN, Compound 17) resulted in a 4-fold increase in potency (IC50 = 2.0 nM) relative to parent compound 7. While the LLE improved to 6.8, the PK properties in rat diminished. In particular, the MRT decreased to 0.5 h due to a rise in total clearance (CL = 82 mL/min/kg), and the oral bioavailability was only 25%. Metabolite ID studies in rat hepatocytes suggested that this increased metabolism was largely driven by glutathione-mediated sulfonamide cleavage. In relation to 17, Compound 18 featured a transposition of the chloro and cyano substituents on the aryl sulfonamide. This modification preserved the excellent LLE of 17 as well as reduced total clearance (CL = 35 mL/min/kg) and clearance adjusted for unbound fraction (CL/fu = 4). While the enhanced metabolic stability was reflected in a longer MRT (1.0 h), oral bioavailability remained poor (F


Page 9 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


= 15%). Given this result, subsequent targets were aimed at reducing PSA in an effort to improve cell permeability and enhance gastrointestinal absorption. To this end, Compound 19 featured a single-point modification involving replacement of the cyano substituent on the aryl sulfone with a chloride (R1 = Cl). Relative to parent compound 18, this maintained potency (IC50 = 3.2 nM) while reducing PSA to 136. Despite an increase in both total CL (49 mL/min/kg) and CL/fu (12), MRT was elongated due to an elevated volume of distribution (Vdss = 4.5 L/kg). Gratifyingly, the oral bioavailability improved to 100%, likely driven by enhanced cell permeability (350 nm/sec) and reduced oxidative (first-pass) metabolism of the aryl sulfone functionality.32 Our interest in Compound 19 was further buoyed by its clean off-target profile. It exhibited high TRP selectivity (TRPA1, TRPV1, TRPM2, TRPM8, TRPC3-C6 IC50 > 30 µM) and weak activity (IC50 > 10 µM) against a panel of receptors including CYP’s, hERG and CaV1.2. Furthermore, it was inactive up to 100 µM in an assay measuring time-dependent inhibition (TDI) of CYP3A4. Additional structural modifications were investigated to reduce lipophilicity in hopes of further enhancing PK properties. This involved the insertion of heteroatoms into the various subunits of the scaffold (Table 3). Compound 20, featuring a pyridyl sulfonamide functionality (Y = N), demonstrated reduced total clearance (CL = 22 mL/min/kg), outstanding clearance adjusted for unbound fraction (CL/fu = 1.2), and nearly a 2-fold improvement in MRT (3 h). Unfortunately, however, the TRPV4 potency of 20 (IC50 = 631 nM) was approximately 200-fold weaker than that of parent compound 19. A significant percentage of this activity could be recovered by the re-introduction of a lipophilic ortho-substituent on the aryl sulfonamide moiety. In a representative example, Compound 21 (R = CF3) demonstrated an in vitro activity (IC50 = 20 nM) and LLE (6.0) comparable to 19. However, 21 also featured a startling erosion of PK properties (CL = 310 mL/min/kg, CL/fu = 66, MRT = 0.2 h, F = 8%), prompting us to shift our attention to other subunits.

Table 3. Incorporation of heteroatoms into the pyrrolidine diol scaffolda



X Cl

Z S O OH OH N Z' S O R

Cmpd

X

Y

Z

Z'

R

IC50

Page 10 of 37

Y

LLE PSA

(nM)

CN

CL

CL/fu

(mL/min/kg)

Vdss

MRT

F

(L/kg)

(h)

(%)

19

CH CH

O

O

Cl

3.2

5.8

136

49

12

4.5

1.6

100

20

CH

N

O

O

H

631

4.9

149

22

1.2

4.1

3.0

62

21

CH

N

O

O

CF3

20

6.0

149

310

66

3.6

0.2

8

22

N

CH

O

O

Cl

5.0

5.7

149

23

11

2.0

1.4

62

O

Cl

20

5.0

143

52

4.8

3.2

1.0

38

NH

Cl

40

4.2

143

48

8.9

2.7

0.9

80

23

CH CH NH

24

CH CH

ahuman

O



Installation of a heteroaromatic sulfone proved to be better tolerated in regard to both TRPV4 activity and PK properties. The most encouraging results were attained with a 2-pyridyl sulfone, in which Compound 22 displayed nearly identical TRPV4 potency (IC50 = 5 nM), LLE (5.7) and MRT (1.4 h) relative to direct comparator 19. Notably, oral bioavailability was reduced (F = 62%), possibly due to limited membrane permeability caused by an increase in total polar surface area (PSA = 149). Structural diversity was further broadened by the exploration of sulfoximine (Compound 2333) and sulfonimidamide (Compound 2434) analogs. While the latter featured excellent oral bioavailability in rat (F = 80%), neither exemplar offered an advantage over parent compound 19 in terms of TRPV4 activity, LLE, or PK properties (CL, MRT, F).


Page 11 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


With the inability of Compounds 20-24 to improve on the overall profile of Compound 19, focus was subsequently shifted toward modifications of the diol subunit (Table 4). Specifically, amino alcohol 25, a direct comparator of 19, emerged as a benchmark compound with exquisite TRPV4 activity (IC50 = 0.3 nM) and exceptional LLE (7.6). Its PK properties in rat were also promising, highlighted by reduced total clearance (CL = 12 mL/min/kg) and CL/fu (2.7) in addition to an MRT of nearly 6 hours. Compound 26, the 2-pyridyl sulfone analog of 25, featured improved oral bioavailability (F = 64%) while maintaining sub-nanomolar potency (IC50 = 0.5 nM) and excellent clearance adjusted for unbound fraction (CL/fu = 3.8). The MRT of Compound 26 (1.9 h), while diminished relative to 25, remained comparable to that of leading diol 19. Importantly, Compound 27, the (3R, 4S)-diastereomer of 26, was equipotent in the FLIPR assay (IC50 = 0.5 nM), thereby constituting divergent SAR relative to the diol chemotype (Figure 3). Furthermore, it exhibited reduced CL/fu (1.7) with similar MRT (2.2 h) and oral bioavailability (56%) in comparison to 26. The encouraging oral bioavailability of 26 and 27 could be due to facilitated gastrointestinal absorption driven by their enhanced aqueous solubility35 (500 µM), which exceeded that of 25 (280 µM). Along with a potential reduction in first-pass metabolism, this could also explain the improvement relative to diols with similar PSA such as 17 and 18, which each exhibited lower aqueous solubility (380, 400 µM, respectively).

Table 4. Profiles of amino alcohols 25, 26 and 27a X Cl

O S O OH 4 3

N O S O Cl

Cmpd

X

stereochem.

IC50

LLE PSA

(nM) 25

CH

3S, 4S

0.3

NH2

CN

CL

CL/fu

(mL/min/kg) 7.6

142

12


2.7

Vdss

MRT

F

(L/kg)

(h)

(%)

4.0

5.7

22


ahuman

Page 12 of 37

26

N

3S, 4S

0.5

7.4

154

12

3.8

1.3

1.9

64

27

N

3R, 4S

0.5

7.4

154

1.7

1.7

0.2

2.2

56



In contrast to the diol exemplars, the off-target profiles of these amino alcohols featured several areas of concern.

For one, compound 25 displayed activity in a phenotypic assay measuring

phospholipidosis36 risk (pMEC = 4.7, response = 425%)37, which is not uncommon to lipophilic amines containing aromatic residues (Table 5). Cationic amphiphilic drugs (CAD’s) have been reported to cause phospholipidosis in humans and activity in the phenotypic screen has correlated with a CAD “likeness” score exceeding 50.38 With a CAD score defined as the sum of indicators of lipophilicity (CHI IAM)39 and basicity (ΔCHI (pH10.5 – pH7.4))39, design elements to address phospholipidosis risk have been well established. Indeed, amino alcohols 26 and 27, each featuring lower lipophilicity (CHI IAM = 42, 36, respectively) and basicity (ΔCHI (pH10.5 – pH7.4) = -2.2, 3.7, respectively) relative to 25 (CHI IAM = 49, ΔCHI (pH10.5 – pH7.4) = 9), were gratifyingly inactive in the phenotypic assay (pMEC < 4).

Table 5. Off-target profiles of amino alcohols 25, 26 and 27a

Phospholipidosis Cmpd

Response37

3A4 TDI (100

3A4 RI IC50

(%)

µM)

(µM)

4.7

425

yes

0.1

40

Design and Optimization of Sulfone Pyrrolidine Sulfonamide

Recommend Documents