Discovery of APD811: an orally available
prostacyclin receptor agonist for the treatment of
Pulmonary Arterial Hypertension (PAH)
Graeme Semple
Arena Pharmaceuticals
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
1
Pulmonary Arterial Hypertension
•
PAH is a disease of the small pulmonary arteries characterized by vascular
proliferation and remodeling
•
Impaired production of vasoactive mediators, such as prostacyclin and NO,
accompanied by prolonged overexpression of vasoconstrictors like ET-1 are
thought to be responsible for the pathogenesis of PAH
•
PAH results in a progressive increase in pulmonary vascular resistance and,
ultimately, right ventricular failure and death (50% survival 5 years post diagnosis)
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
PAH Classification and Current Therapies
• Class I: Patients who have no symptoms of any kind, and
for whom ordinary physical activity does not cause
fatigue, palpitation, dyspnea or anginal pain.
• Class II: Patients who are comfortable at rest but have
symptoms with ordinary physical activity
• Class III: Patients who are comfortable at rest but have
symptoms with less-than-ordinary effort
– Class II and III patients are treated with ET antagonists and PDE5
Inhibitors
• Class IV: Patients who have symptoms at rest.
– Currently treated with Prostacyclin analogues
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Epoprostenol for Class IV PAH – Clinical Data
Current therapy
With Epoprostenol
Current therapy
Without Epoprostenol
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Current Prostacyclin analogues for PAH
Epoprostenol
Treprostinil
Iloprost
Beraprost
(Flolan)
(Remodulin)
(Ventavis)
(Dorner)
COOH
HO2C
HO2 C
HOOC
O
O
O
OH
OH
Infection
Sepsis
Severe rebound PAH
•
•
OH
OH
Infection
Injection site pain
sepsis
OH
OH
Treatment 6-9 x/day
Intermittent coverage
OH
OH
4x/day
Intermittent coverage
Prostacyclin analogues have sub-optimal delivery routes
• Continuous i.v. or s.c. infusion (Epoprostenol, Treprostinil); Inhaled aerosol 6-12x/day
(Iloprost)
• Oral 4x/day with efficacy limited to < 6 mo (Beraprost)
An orally active qd IP agonist could be a useful addition for the treatment of PAH
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
5
Prostacyclin Receptor Agonist: Product Profile
• Indication: pulmonary arterial hypertension
– Efficacy equal or greater than I.V. or inhaled prostacyclin
analogs in Class IV patients
– Ideally, able to be used in less severe cases
• High potency and selectivity for IP receptor
• Oral delivery
• PK profile suitable for once daily dosing
– Long half-life with low peak-trough changes in drug level
– Key to tolerability in clinic
• Compatible with co-administration of other PAH drugs
• Clean off-target safety profile
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
IP agonists – testing scheme for PAH
Human/rat IP receptor cAMP assay
Human IP RBA
Melanophores (EP1, EP3, TP, FP)
cAMP (DP1/EP2/EP4)
RBA DP1/EP2/EP4
GPCR panel (spot check)
Human platelet aggregation
PK, CyP inhibition, hERG, rat PRP
Potency EC50 < 50 nM
Selectivity > 300x
DP1 > 100x
IC50 <100 nM
t½ suitable for
1-2x/day dosing
%F > 30
CyP > 10uM
hERG > 5uM
PAH model (rat)
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
7
Animal Model of PAH
● Monocrotaline (MCT), a pyrrolizidine alkaloid from Crotalaria
spectabilis (showy rattlebox), is activated metabolically in the
liver to monocrotaline pyrrole which is then transported to the
lungs and becomes pneumotoxic.
● Since subcutaneous injection of MCT can cause PH, medial
hypertrophy of the pulmonary arteries, and severe pressure
overload-induced right ventricular hypertrophy, MCT has been
widely used as an animal model of PAH
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Comparison of Structures of Prostanoid and Known
Nonprostanoid Ligands
Prostanoids
HO2C
HO2C
O
O
H
H
H
OH
H
OH
OH
OH
Beraprost
Prostacyclin (PGI2)
Nonprostanoids
O
OH
N
N
N
N
O
N
O
O
O
CO2H
O
NS304
N
FK788 (Fujisawa)
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
CO2H
ONO-1301
CO2H
Compound Design
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
10
Initial Design for IP receptor Agonists
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Initial Design for IP receptor Agonists
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Synthesis of tetrahydronaphthalene core
O
OH
TBDPSCl
imidazole
DMF
25 oC, 10hr
90%
O
O
3.5 eq. CO(OEt)2
3.5 eq. NaH
toluene
O
O
OEt
110 oC, 2hr
3.5 eq. Et3SiH
TFA
1.0 eq. LAH
THF
OEt
25 oC, 10hr
OTBDPS
0oC, 10 min
OTBDPS
OTBDPS
5-hydroxy tetralone
O
OH
OTBDPS
1.0 eq. TBAF
THF
OH
OH
O
K2CO3
DMF
Br
60 oC 3hr
90%
OH
OTs
TsCl
O
O
O
O
Et3N
O
O
A
Yield 90% X 80% X 80% X 90% X 70% X 90% X70% = 23% (7 steps) | Two purifications on SiO2
• 7 Steps to protected scaffold/acid portion with appropriate leaving
group for alkylation reactions
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Synthesis of Substituted 3,4-diphenyl-pyridazinones
O
O
O
O
N
N
PhCH2NHNH2
O
POCl3
N
N
OH
Cl
O
O
N
N
R2-PhB(OH)2
Pd(PPh3)4
NH
N
AlCl3
R2
R2
i) tBuOK, A
ii) HCl/dioxan
O
N
N
O
R1
R2
1
i) tBuOK, A
ii) HCl/dioxan
O
O
Br
O
Ph
Br
NH2NH2
Br
O
NH
N
R1-PhB(OH)2
Pd(PPh3)4
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
R1
NH
N
CO2H
3,4-Diphenylpyridazinones SAR
R1
R2
EC50 hIP*
IA
EC50 rIP*
IA
EC50 hDP1#
(nM)
(%)¶
(nM)
(%)¶
(nM)
1a
H
H
969
60
2190
70
21
1b
4-OMe
H
2670
47
>10000
-
n.d.
1c
3-OMe
H
60
88
310
96
17
1d
3-Me
H
180
97
370
72
25
1e
3-F
H
380
63
900
97
44
1f
3-Cl
H
60
77
360
62
61
1g
3-OMe, 2-F
H
37
97
350
85
6
1h
H
3-OMe
1720
87
>10000
-
n.d.
1i
H
3-F
1060
88
2370
99
n.d.
1j
H
4-OMe
8.5
80
12.5
93
1.7
1k
H
4-Me
24
67
120
99
n.d.
1l
H
4-F
114
89
1500
93
n.d.
1m
H
4-OMe, 2-F
20
78
112
76
31
1n
H
4-OMe, 3-F
10
80
51
75
3
1o
3-OMe
4-Me
9.5
81
28
107
11
1p
3-OMe
4-F
62
91
620
102
24
* = EC50 in the HTRF cAMP human or rat IP receptor assay ¶ = Intrinsic activity (efficacy) relative to 1µM iloprost as the positive control
# = EC50 in a melanophore assay
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Separation of Enantiomers
•
•
•
Chiral resolution of the tetrahydronaphthyl building block allowed synthesis of each
enantiomer separately
The bulk of the activity was observed in one isomer
However, no improvement in selectivity was seen
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Synthesis of Substituted 4,5-diphenyl-pyridazinones
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
17
4,5-Diphenylpyridazinones SAR
R1
R2
EC50 hIP*
IA
EC50 rIP*
IA
EC50 hDP1#
Human platelet
(nM)
(%)¶
(nM)
(%)¶
(nM)
IC50 (nM)@
2a
H
H
100
75
260
88
180
325
2b
H
3-OMe
140
101
690
81
48
n.d.
2c
H
3-F
60
82
410
103
88
191
2d
H
3-Cl
86
93
260
98
n.d.
n.d.
2e
H
4-OMe
1060
73
> 3000
-
n.d.
n.d.
2f
H
2-F
120
106
420
99
31
220
2g
H
2,3-F2
38
87
110
101
36
87
2h
H
2-F, 3-OMe
10
78
40
98
40
64
2i
2-F
H
140
91
370
116
n.d.
n.d.
2j
3-F
H
260
100
790
121
n.d.
n.d.
2k
4-F
H
20
80
170
104
n.d.
230
2l
3-OMe
H
770
74
3500
99
n.d.
n.d.
2m
4-OMe
H
4
72
11
105
n.d.
330
2n
4-F
2,3-F2
6
85
122
96
44
62
* = EC50 in the HTRF cAMP human or rat IP receptor assay ¶ = Intrinsic activity (efficacy) relative to 1µM iloprost as the positive control
# = EC50 in a melanophore assay @ = Inhibition of ADP-induced human platelet aggregation
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
18
Compound 2g Extended Profile
O
N
N
O
O
F
F
OH
2g
• hIP, cAMP = 38 nM (n = 18)
• rIP, cAMP = 110 nM (n = 17)
• h Platelet
= 90 nM (n = 6)
• DP1, cAMP
= 850 nM (n = 8)
• DP2, EP1, EP2, EP3, EP4, FP, TP , cAMP = NR
• CYP Inhibitions : Clean
• hERG Patch Clamp: 16% inhibition @ 3 µM
• Water Solubility (sodium salt): 2.2 mg/mL (pH 7)
• PK profile: Dose(mg/kg) IV = 2, PO = 3
IV t1/2 = 2.3 h; P.O t1/2 = 3.2 hr
F = 44.2%
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
In Vivo POC compound
Monocrotoline administered on Day 1
Rats dosed twice daily with test compound or vehicle for 21 days
Right ventricular weight measured on day 21
250
2g s.c. b.i.d.
200
150
**
**
100
50
(19)
(13)
(9)
(9)
(20)
Ve
h
pk
+
m
M
C
T
1
M
10
30
m
pk
PK
0
Sh
am
RV weight (normalized to Sham)
•
•
•
**P<0.001 vs. MCT + Vehicle
Active in vivo s.c. but ‘optimized’ compounds from this series not active p.o.
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Second Generation Design for IP receptor Agonists
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Second Generation Design for IP receptor Agonists
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Cyclohexyl-Carbamate Synthetic Route
• Significantly shorter, high-yielding synthesis
– Overall yields typically >40%
• Reduced lipophilicity, no chiral centre
• Improved selectivity vs DP1
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
23
Early SAR : Relative Stereochemistry Requirements
trans-cyclohexyl
cis-cyclohexyl
•R=H; hIP EC50 = 9.6 nM*
•R=H; hIP EC50 = 68 nM
•R=4-Cl; hIP EC50 = 8.5 nM
•R=4-Cl; hIP EC50 = 46 nM
•R=4-OMe; hIP EC50 = 3.3 nM
•R=4-OMe; hIP EC50 > 1000nM
(* = EC50 in the HTRF cAMP human IP receptor assay)
•
A clear preference for the trans-stereochemistry was noted
•
Further analogues were prepared using only the trans-cyclohexyl
core
24
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Carbamate Series SAR
R1
R2
EC50 hIP*
IA
EC50 hDP1#
EC50 rIP*
IA
(nM)
(%)¶
(nM)
(%)¶
(nM)
Human platelet
IC50
PK Properties (rat)
(nM)@
3a
H
H
9.6
91
365
89
355
25
-
3b
H
4-Cl
8.5
85
530
88
850
38
T1/2 : 6.7h; F: 57%
3c
H
4-OMe
3.3
83
165
91
240
22
T1/2 : 0.3h; F: 100%
3d
H
4-Me
3.9
81
174
99
320
39
-
3e
H
4-F
4.8
89
535
91
560
12
T1/2 : 3.9h; F: 100%
3f
H
3-F
8.7
85
284
83
2760
18
T1/2 : 3.4h; F: 69%
3g
H
4-Cl, 3-F
3.4
85
400
92
2050
23
T1/2 : 5h; F: 88%
3h
4-OMe
3-F
5.2
70
1570
60
1030
43
-
3i
4-Cl
3-F
18.5
70
3190
44
1140
n.d.
-
3j
4-F
4-F
41
65
n.d.
862
n.d.
-
* = EC50 in the HTRF cAMP human or rat IP receptor assay ¶ = Intrinsic activity (efficacy) relative to 1µM iloprost as the positive control
# = EC50 in a HTRF cAMP assay @ = Inhibition of ADP-induced human platelet aggregation
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
25
Further Profiling of Potential Lead Compounds
O
N
O
O
O
O
N
O
O
O
OH
OH
F
Cl
3b
hIP Ki
= 8 nM
hIP, cAMP = 8 nM
rIP, cAMP = 530nM
hPlatelet
= 38 nM
DP1 cAMP
= 750nM
EP2 cAMP
= NR
EP4 cAMP
= NR
3f
hIP Ki
= 14 nM
hIP, cAMP = 8 nM
rIP, cAMP = 280nM
h Platelet
= 18 nM
DP1 cAMP
= 3000nM
EP2 cAMP
= NR
EP4 cAMP
= NR
hERG (astemizole binding) = NR
HepG2 cell (intracellular calcium,
cell proliferation, membrane intergrity) : NR
Water solubility = 1.0mg/ml (pH7)
Microsomal stability t/12 h > 60' , r > 60'
CYP Inhibitions HLM : clean
Ames, hERG Patch, DP1 RBD, GPCR- screen,
clean
hERG (astemizole binding) = NR
HepG2 cell (intracellular calcium,
cell proliferation, membrane intergrity) : NR
Water solubility = 2.6 mg/ml (pH7)
Microsomal stability t/12 h > 60' , r > 60'
CYP Inhibitions HLM : clean
Ames, hERG Patch, DP1 RBD, GPCR- screen,
clean
Rat PK Dose(mg/kg) IV = 2, PO = 10
T1/2: IV = 6.7 hr; PO = 5.4 hr.
CL = 0.427 L/hr/kg
(Vss) = 2.742 L/kgL/kg).
Cmax (po): 3.703 µg/mL at 1.5 hr.
Oral bioavailability (%F) = 57.4%.
Rat PK Dose(mg/kg) IV = 2, PO = 10
T1/2: IV = 3.4 hr; PO = 2.9 hr.
CL = 1.205 L/hr/kg
(Vss) = 2.749 L/kg
Cmax (po): 3.423 µg/mL at 0.3 hr.
Oral bioavailability (%F) = 69.0%.
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
26
Rat PAH model: Carbamates
Right Ventricular Weight
Mortality
1.00
*
Survival Rate (%)
RV/LV+S
0.75
0.50
*
0.25
100
p<0.001 Vs. MCT +Vehicle
(9)
0.00
75
Sham
Vehicle
Sham+ +
Vehicle
50
MCT + Vehicle
MCT+Vehicle
MCT+AR392830
30mpk
MCT + 3b 30mg/kg
25
MCT+AR392830
10mpk
MCT + 3b 10mg/kg
e
MM
CT C
+T
3+b 8
1300
m10
g/ m
kgp
k
MM
CT C
+T +
3b 8
3300
m30
g/ m
kgp
k
0
M
C
T
+
Ve
Sh
hi
cl
am
0
1.00
7
14
21
Day
* * P<0.001 vs. MCT
* P<0.05 vs. MVT
100
*
0.50
**
0.25
(9)
Survival Rate (%)
RV/LV+S
0.75
75
50
Sham
Sham++Vehicle
Vehicle
MCT+Vehicle
MCT + Vehicle
25
MCT + 3f 30mg/kg
MCT+AR392831
30mpk
MCT + 3f 15mg/kg
MCT+AR392831
15mpk
0
0
5
10
15
20
25
Day
M
MC
CTT
++
38f 3
310 3
m0
g/m
kgpk
M
MC
CT T
++ 8
3f 3
151
m15
g/ m
kg p
k
M
C
T
+
Ve
Sh
hi
c
am
le
0.00
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
27
3b MCT data
Pulmonary artery pressure
Sham
MCT
MCT + 3b
p<0.01
35
50
30
40
mPAP(mmHg)
30
20
10 (9)
(5)
(5)
(5)
0
25
20
15
10
5
(9)
(8)
(9)
(5)
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
030
3m0
gm/
kpg
k
MM
CCT
T+
+3
8b3
Ve
hi
cl
e
+
C
T
M
M M
CT C
+T +
3b 83
300
m30
g/ m
kgpk
M
C
T
+
V
eh
ic
le
S
ha
m
0
Sh
am
% wall thickness (%)
p<0.01
Pharmacokinetics of 3b in Male Sprague-Dawley Rats
O
N
O
O
O
IV Parameters
3b
Dose (mg/kg)
2
T1/2 (hr)
OH
Cl
6.7
Cmax (µg/mL)
6.540
AUC(0-INF)(hr*µg/mL)
5.093
Cl_obs (L/hr/kg)
0.427
MRTlast (hr)
Vss (L/kg)
4.2
2.742
Calc. Conc. (ng/mL)
100000
3b IV
AR392830
IV
3b PO
AR392830
PO
10000
1000
100
10
1
0
4
8
12
16
20
24
Time (hr)
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
PO Parameters
3b
Dose (mg/kg)
10
T1/2 (hr)
5.4
Tmax (hr)
1.5
Cmax (µg/mL)
3.703
AUC(0-INF)(hr*µg/mL)
14.629
MRTlast (hr)
3.8
%F
57.4
29
Pharmacokinetics of 3f in Male Sprague-Dawley Rats
O
N
O
O
O
IV Parameters
3f
Dose (mg/kg)
2
T1/2 (hr)
OH
F
3.4
Cmax (µg/mL)
3.630
AUC(0-INF)(hr*µg/mL)
2.300
Cl_obs (L/hr/kg)
1.205
MRTlast (hr)
Vss (L/kg)
2.5
2.749
Calc. Conc. (ng/mL)
100000
AR392831
IV
3f IV
AR392831
PO
3f PO
10000
1000
100
10
1
0.1
0
4
8
12
16
20
24
PO Parameters
3f
Dose (mg/kg)
10
T1/2 (hr)
2.9
Tmax (hr)
0.3
Cmax (µg/mL)
3.423
AUC(0-INF)(hr*µg/mL)
7.938
MRTlast (hr)
2.7
%F
69.0
Time (hr)
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
30
Physical Characterization
• 3b sodium salt
Early Candidate Solid-state Testing :
− Crystalline, anhydrous form with high melting onset
− Non hygroscopic (pure sample uptake <2% of water at 90%RH)
− High critical water activity (>0.75)
− Hydrate form solubility ≈ 2.6 mg/mL
• 3f sodium salt
Early Candidate Solid-state Testing :
− Crystalline, but a hydrate
− Non hygroscopic (pure sample uptake <2% of water at 90%RH)
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
3b & 3f Na-salts
1.0
TAINSTDB 12095 79443 AR392831-Na salt from E01098-11
TAINSTDB 12095 79400 AR392831-Na-salt fromE01098-11
102
3f
0.5
59.75°C
104
0.5
TAINSTDB 12094 88060 AR392830-Na-salt E01098-17-1
3bTAINSTDB 12094 88484 AR392830 E01098-17-1
100
3.420%
0.0
228.49°C
86.73J/g
102
0.0
96
-1.0
94
100
0.1169%
(0.001538mg)
Weight (%)
139.06°C
15.65J/g
82.77°C
114.6J/g
-1.5
0.7899%
(0.01039mg)
-1.0
98
Heat Flow (W/g)
-0.5
-0.5
Weight (%)
Heat Flow (W/g)
98
-1.5
92
-2.0
100.47°C
96
90
-2.5
-2.0
140.33°C
-3.0
0
50
100
150
Exo Up
200
235.08°C
88
300
250
94
0
Universal V4.1D TA Instruments
Temperature (°C)
50
100
150
Exo Up
Adsorption/Desorption Isotherm AR392831-Na-salt E01017-36B
200
-2.5
300
250
Universal V4.1D TA Instruments
Temperature (°C)
Adsorption/Desorption Isotherm for AR392830-E01098-7-1
1.6
1.8
Adsorption
Adsorption
Desorption
Desorption
1.4
1.6
1.2
1.4
Weight (% change)
Weight (% change)
1.2
1.0
0.8
0.6
1.0
0.8
0.6
0.4
0.4
0.2
0.2
0.0
0.0
0
10
20
30
40
50
60
70
80
90
100
%RH
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
0
10
20
30
40
50
%RH
60
70
80
90
100
Scale-Up Synthesis Route
•
•
•
Efficient 2 pot synthesis from available building blocks
Avoids Rh catalysed diazoacetate chemistry
Extra PPE required for handling API
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
33
Cross-Species Pharmacokinetic Profile Comparison
100000
Mouse - 2 mg/kg
Rat - 2 mg/kg
Dog - 0.2 mg/kg
Monkey - 0.1 mg/kg
IV
10000
1000
100
10
1
0.1
Plasma Conc. (ng/mL)
Plasma Conc. (ng/mL)
100000
Mouse - 10 mg/kg
Rat - 10 mg/kg
Dog - 0.2 mg/kg
Monkey - 0.1 mg/kg
PO
10000
1000
100
10
1
0.1
0
10
20
30
40
50
60
0
10
Time (hr)
20
30
40
50
Time (hr)
• APD811 had an extended terminal phase across species
Enterohepatic recycling?
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
60
APD811 : Bile Duct Cannulated Rats
Plasma Conc. (ng/mL)
10000
Historical Control
Bile duct cannulated
IV
Parameter
Bile Duct
Cannulation
Historical
Control
Dose (mg/kg) IV
2.00
2.00
T1/2 (hr)
2.21
6.72
AUC(0-INF) (hr*µg/mL)
4.53
5.09
Vss (L/kg)
1.31
2.74
0.551
0.427
Clbile (L/hr/kg)
0.00518
-
Clrenal (L/hr/kg)
0.0000815
-
% of Dose in Bile
0.889
-
% of Dose in Urine
0.0208
-
• Male SD rat bile duct cannulated
• IV administration at 2 mg/kg
1000
• Collected plasma, bile and urine from 0 to 48 hr
100
Clsystemic (L/hr/kg)
10
0
5
10
15
20
25
Time (hr)
APD811
Percent%of
AR393820
Relative
toDose
Dose
Relative to
1.5%
• APD811 undergoes enterohepatic
recirculation
• APD811 biliary and renal elimination
account for <1% of the total dose
• Metabolism is the primary elimination
pathway for APD811
1.0%
0.5%
e
rin
U
B
ile
0.0%
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
APD811 In Vivo Metabolic Pathways in the Rat
O
N
O
O
O
S
O
N
H
O
O
M1
Taurine conjugate formed
in liver is excreted in bile
(low levels in plasma) and
can be reabsorbed leading
recirculation of parent
Cl
O
N
O
O
O
APD811
OH
Cl
HO
HO
O
O
N
O
Cl
N
O
O
M2
O
O
O
OH
Cl
O
S
N
H
O
O
M3
Metabolites were all significantly
less active at IP receptor
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
APD811 Pharmacokinetics in Cynomolgus Monkeys
Plasma Conc. (nM)
10000
PO 0.1 mg/kg
PO 0.5 mg/kg
1000
100
10
Human
21GF
Ki 7 nM
Human IP
Ki 7nM
1
Monkey
21GF
Ki 1 nM
Monkey IP
Ki 1nM
0.1
0
5
10
15
20
25
Time (hr)
Dose
(mg/kg)
Tmax
(hr)
T1/2
(hr)
Cmax
(nM)
Ctrough
(nM)
Cmax/Ctrough
0.1
2.67
17.5
28.0
5.67
5
0.5
4.17
33.5
215
67.8
3
• Low peak to trough ratio
• Suitable for once-a-day dosing
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Prostacyclin Receptor Agonist Program at Arena: Overview
• Several series of novel, orally available, highly potent and
selective IP receptor agonists identified
• Our lead compound APD811 had good bioavailability
across species and was efficacious in a rat model of PAH
• DMPK, safety and pharmaceutical profiles suggest once
daily dosing, with minimal peak-to-trough ratio
• Clinical Development is underway
– Similar PK profile observed in human subjects in SAD
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
Acknowledgments
Medicinal Chemistry
Thuy-An Tran
Young-Jun Shin
Bryan Kramer
Juyi Choi
Ning Zou
Pureza Vallar
Peter Martens
P. Douglas Boatman
Tawfik Gharbaoui
Pharmaceutical Development
Anna Shifrana
Anthony Blackburn
Process Chemistry
Sagar Shakya
DMPK
Mike Morgan
Woo Hyun Yoon
Biology
John Adams
Zhuangjie Li
Ruoping Chen
Chen Liaw
Huong Dang
Dan Connolly
Tong Zhang
4th RSC/SCI GPCRs in Medicinal Chemistry, September 17-19, 2012 Surrey, UK
39