an overview of the riociguat, developped by Bayer for PAH (2010)

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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
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3. PLAN
 Pathology
 Treatments
 sGC
 Discovery and development of Riociguat
 Clinical trials
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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
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5. Diagnostic of PAH
 Echocardiography
 6-MWT and right heart catheterisation
 4 classes: class I is the least severe and class IV the most
advanced
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6. 6-Minutes Walk Test
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
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7. 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
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8. 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
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9. ACTUAL TREATMENTS
• Prostacyclin
• Endothelin
• NO
• PDE5
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10. N ENGL J MED 351;14 SEPTEMBER 30, 2004 « TREATMENT
OF PAH » HUMBERT ET AL
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11. 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
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12. 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
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13. 13

14. Endothelin’s actions
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15. 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
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16. 16

17. 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
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18. PDE5 effects
+
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19. 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
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20. 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
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21. + NO
sGC
GTP cGmP
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22. 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
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23. 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
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24. NO-sGC-cGMP Signal Transduction Pathway
NATURE REVIEWS 1028 NRD 2038
SEPTEMBER 2006 « NO-
INDEPENDENT STIMULATORS AND
ACTIVATORS OF SOLUBLE SGC »
EVGENOV ET AL
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25. 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 : oxidation
• Therapies can target the redox
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EUR RESPIR J 2009; 33: 717-721 « SGC STIMULATORS AS A POTENTIAL THERAPY FOR PAH » E.D. MICHELAKIS

26. 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
 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
NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
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27. NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
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28. 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
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29. NATURE REVIEWS 1028 NRD 2038 SEPTEMBER 2006 « NO-INDEPENDENT STIMULATORS AND ACTIVATORS OF SOLUBLE SGC » EVGENOV ET AL
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30. DISCOVERY AND
OPTIMIZATION
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31. • 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
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32. 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
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CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL

33. In vitro assays and isolated organs
 cGMP formation in a sGC overexpressing
Chinese hamster ovarian cell line
 Iinhibition of phenylephrine induced contractions of rabbit
aortic rings
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CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL

34. 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
34
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL

35. 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 35

36. SAR
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37.  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 37

38. Pyrimidine C5: most
fruitful position
38
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL

39. (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
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40. (20): Riociguat
Results for female Beagle dogs:
 R2 = N-méthylcarbamate
 Freatest PK profile
Selected as a drug development candidate
40
CHEM MED CHEM 2009 4, 853-865 « DISCOVERY OF RIOCIGUAT » MITTENDORF ET AL

41. 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
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42. SYNTHESE
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43. F
F F
F
CN
TFA NH3, MeOH
O TFA
+ H2N N 3-dimethylamine
N N N N
HN N N N
CO2 Et acroleine
NH2 condensation aminolyse
CO2 Et
cyclo- CO2 Et 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
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44. 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
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45. Mice in chronic hypoxia
Right ventricular systolic pressure Right ventricular systolic pressure
Systemic arterial pressure Cardiac frequency
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EUR RESPIR J 2008; 32: 881-891 « EXPRESSION AND FUNCTION OF SGC IN PAH » SCHERMULY ET AL

46. Hypertensive rats
 Dose dependent blood pressure decrease
 Single dose
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47. CLINICAL TRIALS
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48. 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
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49. 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 49
STIMULATOR RIOCIGUAT IN PH » F.GRIMMINGER AND COWORKERS

50. 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
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EUR. RESPIR.J.2009; 33: 785-792 « FIRST ACUTE HAEMODYNAMIC STUDY OF sGC STIMULATOR RIOCIGUAT IN PH » F.GRIMMINGER AND COWORKERS

51. 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 51

52. Pharmacodynamics
mean pulmonary arterial pressure pulmonary
vascular resistance
systemic vascular
resistance
systolic blood pressure
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EUR. RESPIR.J.2009; 33: 785-792 « FIRST ACUTE HAEMODYNAMIC STUDY OF sGC STIMULATOR RIOCIGUAT IN PH » F.GRIMMINGER AND COWORKERS

53. Pharmacodynamics (2)
 Both 1 and 2,5mg doses caused clinically and statistically
significant reductions from baseline in mPAP, PVR, SBP
and SVR
 No pulmonary selectivity, but systemic vasodilatation not
accompagnied by any relevant side-effect
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EUR. RESPIR.J.2009; 33: 785-792 « FIRST ACUTE HAEMODYNAMIC STUDY OF sGC STIMULATOR RIOCIGUAT IN PH » F.GRIMMINGER AND COWORKERS

54. 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/
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55. 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
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INTERNATIONAL CONFERENCE, 15-20 MAY 2009, SAN DIEGO, CALIFORNIA, USA

56. http://www.investor.bayer.com/en
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57. Realised by Melanie, Claire, and Laurent
Thanks to Rebecca Desprez-Poulain
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