2. Some words about
RIOCIGUAT…
First in class
New target
Direct sGC stimulator
Sensitises sGC to NO
Vasodilatation
Orally treatment of PAH
Improves quality of life
Currently in clinical trial, phase III
2
4. Pulmonary Arterial Hypertension
WHO classification
Orphan disease, 30-50 cases per million
Poor prognosis
Symptoms: breathlessness, chest tightness, fatigue
Vascular proliferation and remodelling
Progressive increase in PVR
Right ventricular failure, hypertrophy
and death
Imbalance of vascular effectors
N ENGL J MED 351;16 OCTOBER 14, 2004 « PULMONARY ARTERIAL HYPERTENSION » .FARBER ET AL
4
5. Diagnostic of PAH
4 classes: class I is the least severe and class IV the most
advanced
PAH symptoms non specific
Early diagnostic important
5
7. Diagnostic of PAH
• Evaluation: 6-MWT and right heart catheterisation
The patient walks as far
as possible in 6 minutes
•Safe
•Highly reproductible
•Inexpensive equipment
•Used as primary end
point in clinical trials
ATS. Am J Crit CARE MED 2002
7
8. PAH associated with HIV
0,5% of HIV-patients (6 to 12 times as high as the general
population)
related to the duration of HIV infection, due to
concomitant infections
Mechanism unclear
HIV-1 GP120 may stimulate the
production of ET by macrophages
seems to be independent of the
degree of immunosuppression
N ENGL J MED 351;16 OCTOBER 14, 2004 « PULMONARY ARTERIAL HYPERTENSION » .FARBER ET AL
8
9. PAH associated with others conditions
Scleroderma = systemic sclerosis : prevalence of PAH is
up to 16%
PAH is the leading cause of death
Very poor prognosis
Human herpesvirus
N ENGL J MED 351;16 OCTOBER 14, 2004 « PULMONARY ARTERIAL HYPERTENSION » .FARBER ET AL
9
10. ACTUAL TREATMENTS
• Prostacyclin
• Endothelin
• NO
• PDE5
No curative treatment
10
11. N ENGL J MED 351;14 SEPTEMBER 30, 2004 « TREATMENT
OF PAH » HUMBERT ET AL
11
12. Prostacyclin therapy
PGI2 is producted by metabolisation of arachidonic acid
Induces relaxation
Stimulating AMPc production
N ENGL J MED 351;14 SEPTEMBER 30, 2004 « TREATMENT OF PAH » HUMBERT ET AL
12
13. Epoprostenol Flolan®
Intravenous infusion
Improvement in 6-MWT
Short half-life (3 min)
Iloprost Ventavis®
Delivered by inhaler
Short duration of action
N ENGL J MED 351;14 SEPTEMBER 30, 2004 « TREATMENT OF PAH » HUMBERT ET AL
13
16. Antagonists of ET1-R:
Bosentan Tracleer®
Oral treatment
Improvements in 6-MWT
No dose-response effect
Hepatotoxicity
Sitaxsentan and Ambrisentan: selective of Eta
Tezosentan
N ENGL J MED 351;14 SEPTEMBER 30, 2004 « TREATMENT OF PAH » HUMBERT ET AL
16
18. Nitric Oxide
Vasodilatator
Synthetised by NO synthase in endothelial and epithelial
cells
Inhaled treatments with NO are unsuitable as long term
therapies for PH due to: short life, development of
tolerance, non specific interactions with biomolecules
Toxicity with high dose
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL
18
20. Inhibition of PDE5:
Sildénafil Revatio®
Predominant PDE isoform in the lung that metabolizes
cGMP
Pulmonary vasodilator effect
Oral treatment
Increase of cGMP in smooth muscle
Improved exercise capacity
and pulmonary hemodynamics
No evidence of dose-response relationship
N ENGL J MED 353;20 NOVEMBER 17, 2005 « SILDENAFIL CITRATE THERAPY FOR PAH » GALIE ET AL
20
21. Soluble guanylate cyclase
Heterodimer: larger α subunit and a smaller haem-binding
β subunit
Prosthetic haem moiety on the haem binding domain with
a reduced Fe2+
sGC
GTP cGMP
Potentiated by NO
NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
21
23. Model of the haem binding domain
of human sGC β-subunit
NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
23
24. Structure of sGC
Cleavage of
His N His N 2+ the haem-
histidine bond
N
2+
N 2+N N Fe N N Fe N
Fe
N N NO N NO
Penta coordinated Hexa coordinated Penta coordinated
histidyl haem complex histidine-haem-NO nitrosyl-haem
intermediate complex
Abolition of activation if remove, oxydise or inhibit
Changes in the redox state leads to the formation of an NO
insensitive form of sGC
NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
24
25. NO-sGC-cGMP Signal Transduction Pathway
NATURE REVIEWS 1028 NRD 2038
SEPTEMBER 2006 « NO-
INDEPENDENT STIMULATORS AND
ACTIVATORS OF SOLUBLE SGC »
EVGENOV ET AL
25
26. Differences between systemic
and pulmonary circulation
In response to hypoxia :
Pulmonary arterial pressure Systemic pressure
• Pressure increases in PAs and decreases in renal arteries
• Mitochondria alter the production of ROS (·O2ˉ;ONOOˉ), causes
the PAs constriction due to the oxidation
• Therapies can target the redox
26
EUR RESPIR J 2009; 33: 717-721 « SGC STIMULATORS AS A POTENTIAL THERAPY FOR PAH » E.D. MICHELAKIS
27. Two novel drug class
sGC activators don’t modulate NO signalling at all but
activate the NO unresponsive haem oxidized or haem free
enzyme
NO and haem independent
NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
27
28. NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
28
29. sGC Activators
By binding the unoccupied haem binding pocket
Or by replacing the weakly bound oxidized haem
BAY 58-2667 = Cinaciguat
Intravenous form
Currently in clinical trial
29
30. Two novel drug class
BAY 63-2521: Riociguat
sGC stimulators stimulate sGC directly and enhance the
sensitivity of the reduced enzyme to low levels of
bioavailable NO
NO-independent but haem dependent
Stabilization of the nitrosyl-haem complex
Crucial dependency of Fe2+
NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
30
31. NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
31
33. • 1994: HTS which induce an increase of NO synthesis and
stimulate sGC
• Led to 5-Substituted-2-furaldehyde-hydrazone
• sGC stimulator
• Increase when exposed to light, which is unwanted
• Dec 1994: Ko and co-workers described
indazole derivative YC-1
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL
33
34. Chemical optimization
Based on YC-1
Similar mode of action but (2) and (3) are more potent and more specific
of PDE
Activity worn by 1-(2-fluorobenzyl)-
1H-pyrazolo[3,4-b]pyridine
34
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL
35. In vitro assays and isolated organs
cGMP formation in a sGC overexpressing
Chinese hamster ovarian cell line
Inhibition of contractions induced by phenylephrine on
rabbit aortic rings
35
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL
36. Activity of (2) and (3)
(2): significant decrease of pulmonary arterial
pressure, reversal in right ventricular hypertrophy, but
induction of CYP450
(3): no relevant CYP interaction
because of the more polar
morpholine substituent,
unfavorable PK profile
36
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL
37. Actions on PDE
YC-1: Inhibits PDE 5 with IC-50 of 10µM.
BAY 41-2272 (2): No relevant inhibition of PDE
1,2,5,9 up to 10mM.
BAY 41-8543 (3): No PDE inhibition at
pharmacologically relevant concentration.
NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL 37
39. Activity worn by 1-(2-fluorobenzyl)-1H-pyrazolo[3,4-
b]pyridine
R3-R1: NH2: diamino analogues display a slightly more potent
relaxation of rabbit aorta and positive impact of the amino
group on oral exposure.
R2: pyrimidin C5 : No clear SAR demonstrated on CYP 1A2 et
3A4, wide range of polars substituants and lipophilic groups.
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL 39
40. 40
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL
41. (12) and (20) are derivated from
(3) because of its no relevant
CYP interaction
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF
RIOCIGUAT » MITTENDORF ET AL
41
42. (20): Riociguat
Results for female Beagle dogs:
R2 = N-méthylcarbamate
Freatest PK profile
Selected as a drug development candidate
42
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL
43. CYP and PDE profile
No significant effects on CYP 1A2, 2B6, 2C19, 3A4
Not dose-dependent
BAY 63-2521: IC-50 values for PDE 2,3,4,5,8,9
are > 10µM.
PATENT US 2006/0052397A1 Mar. 9,2006 CARBAMATE-SUBSTITUTED PYRAZOLOPYRIDINES
43
45. F
F F
F
CN
TFA NH3, MeOH
O TFA
+ H2N N 3-dimethylamine
N N N N
HN N N N
CO2Et acroleine
NH2 condensation aminolyse
CO2Et
cyclo- CO2Et CONH2
F F condensation
TFAA, Py NaOMe, MeOH
N N N N
N N
Pinner
deshydratation CN
NH2
HN
F F
F
N NC CN NaOMe, DMF N
N N Ni Raney N
+ N
N 110°C N N
NNPh
NH2 cyclo- N
reduction
malonitrile N N
HN N
addition NH2 NH2
H2N H2N
NNPh NH2
Methyl-4,6-diamino-2-(1-(2-fluorobenzyl)-1H-pyrazolo
[3,4-b]pyrydin-3-yl)-pyrimidin-(-ylmethylcarbamate)
carbamate deprotonation
methylation CHEM MED CHEM 2009 4, 853-865 « DISCOVERY
OF RIOCIGUAT » MITTENDORF ET AL
45
46. In vivo experiments
Models of PAH
Mice exposed to chronic hypoxia (10% O2)
in a ventilated chamber
Rats with 60 mg.kg-1 monocrotaline subcutaneously
injection
EUR RESPIR J 2008; 32: 881-891 « EXPRESSION AND FUNCTION OF SGC IN PAH » SCHERMULY ET AL
46
47. Mice in chronic hypoxia
Right ventricular systolic pressure Right ventricular systolic pressure
Systemic arterial pressure Cardiac frequency
47
EUR RESPIR J 2008; 32: 881-891 « EXPRESSION AND FUNCTION OF SGC IN PAH » SCHERMULY ET AL
50. Clinical trial, phase I
58 healthy male volunteers
Single oral dose 0,25 to 5mg or placebo
No serious adverse events
Effect increased dose dependently at doses of 1mg to 5mg
Mean arterial and diastolic pressures were decreased at
doses of 1mg and 5mg
Systolic pressure not significantly affected
50
51. Pharmacokinetics (1)
n=15 persons
Riociguat plasma concentration
Riociguat plasma concentrations
following a single oral dose of 1mg
and 2,5mg
Changes in PVR from baseline (dose
dependent increase whith pronounced
interindividual variability)
EUR. RESPIR.J.2009; 33: 785-792 « FIRST ACUTE HAEMODYNAMIC STUDY OF sGC 51
STIMULATOR RIOCIGUAT IN PH » F.GRIMMINGER AND COWORKERS
52. Pharmacokinetics (2)
n=5 in 1mg dose group and n=10 in 2,5mg dose group
Vz/f: apparent volume of distribution during terminal phase after oral administration
CL/f: total body clearance of drug from plasma calculated after oral administration
Peak concentration after 0.25-1.5h
Half-life of 10-12h
Dose proportionnality for the both doses (AUC and Cmax): factor dose
had no influence on either parameters
No hepatotoxicity, no abnormalities in laboratory values
52
EUR. RESPIR.J.2009; 33: 785-792 « FIRST ACUTE HAEMODYNAMIC STUDY OF sGC STIMULATOR RIOCIGUAT IN PH » F.GRIMMINGER AND COWORKERS
53. Clinical trial, phase II
During 12 weeks, 3 times a day, orally
75 patients with PAH disease
PVR>300 dyn.s.cm-1
Evaluation of safety and tolerability:
dose<2,5mg had no clinically relevant effects
on vital signs, electrocardiograms, laboratory
values and blood gases
EUR. RESPIR.J.2009; 33: 785-792 « FIRST ACUTE HAEMODYNAMIC STUDY OF sGC STIMULATOR RIOCIGUAT IN PH » F.GRIMMINGER AND COWORKERS 53
54. Pharmacodynamics
mean pulmonary arterial pressure pulmonary
vascular resistance
systemic vascular
resistance
systolic blood pressure
No pulmonary selectivity, but systemic vasodilatation not
accompagnied by any relevant side-effect
54
EUR. RESPIR.J.2009; 33: 785-792 « FIRST ACUTE HAEMODYNAMIC STUDY OF sGC STIMULATOR RIOCIGUAT IN PH » F.GRIMMINGER AND COWORKERS
55. Clinical trial, phase II
Evaluation of exercise capacity with 6MWT
Strong and significant improvements in pulmonary
hemodynamics
Improvement score in 6-MWT after 14 days
(+73,5% after 12 weeks)
Well tolerated, favorable safety profile
http://www.investor.bayer.com/en/
55
56. CONCLUSION
Clinical trial, Phase III
First results are expected in 2011
Trials:
- PAH: Pulmonary Arterial Hypertension sGC-
Stimulator Trial = PATENT
- Chronic Thromboembolic Pulmonary Hypertension
(CTEPH): Chronic Thromboembolic Pulmonary
Hypertension sGC-Stimulator Trial = CHEST
GHOFRANI HA. sGC STIMULATION: AN EMERGENING OPTION IN PAH THERAPY ORAL PRESENTATION AT THE EUROPEAN RESPIRATORY
SOCIETY CONGRESS, BERLIN, GERMANY; OCTOBER 4-8 2008
GHOFRANI HA AND CO RIOCIGUAT TREATMENT IN PATIENTS WITH CTEPH OR PAH. POSTER PRESENTATION AT THE AMERICAN THORACIC SOCIETY
56
INTERNATIONAL CONFERENCE, 15-20 MAY 2009, SAN DIEGO, CALIFORNIA, USA