Transcript The chemical design of new antimalarial agents based on

LCC
Hybrid molecules as strategy for the design
of new anti-infective agents
International Symposium « From synthetic chemistry to synthetic biology »
Collège de France
Paris, 5 mai 2009
Bernard MEUNIER
Laboratoire de Chimie de Coordination du CNRS, Toulouse (1979-2006)
et PALUMED, Toulouse-Castanet (depuis février 2006)
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A hard time for Drug Discovery !
- Drug discovery is highly challenging:
- Difficulties to create new drugs
- Economical constraints (new drugs should be cheap,
even at no-profit level in some cases)
- Longer time « from Patent to Market »: 12-15 years,
compared to 8 years in the 1960s.
- Increase of the R&D costs: 0.8 to 1.4 billion USD !
Break of costs: 10% for discovery, 15% for pre-clinical,
15% for manufacturing and process, 55% for clinical
trials and 5% for marketing.
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Decrease of the number of approved drugs
Only 17 new molecular entities approved by the FDA in 2007.
Molecules
Costs
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3
Genomics as an answer for drug discovery ?
- Glaxo (GSK) spent 7 years on genomic studies on
bacteria to evaluate more than 300 gene products as
potential targets.
- 70 high-through-put screening (HTS) were then
performed without success (with large libraries:
300,000 to 500,000 chemicals).
- Total cost of the GSK campaign was above 150 M €.
Conclusion: there is no « fast-track » from gene to target.
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Future trends in drug discovery
- Back to natural products as source of new drugs
and as inspiration for new scaffolds ! (We should
remember Pierre Potier’s predictions).
- “Chemical genetics”: study of a gene function with
chemical tools (not by genetic knockout as in classical
genetics).
Observations during clinical trials are in fact “reverse chemical
genetics” ! The phenotypic effect of Viagra on the erectile function
has been discovered during a clinical trial as vasodilatator for the
treatment of heart disease.
- Dynamic combinatorial librairies (Lehn et al.)
- Development of computational methods to perform
virtual screening of targets.
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Small molecules as drugs: the downfall or a real future ?
- Fast development of “biopharmaceuticals” (proteins,
DNA or RNA) over the last two decades.
- New efficient vaccines.
- Highly specific antitumoral antibodies….etc.
- In 2008, the drug market is still dominated by small
molecules (80%), but this ratio will decrease, slowly or
quickly ? (the high cost of “biological drugs” will
probably limit their developments).
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Limits for health costs ?
- Health costs reached 16% of the gross domestic
product (GDP) in the USA in 2005.
- What will the limit (or the plateau) for health costs in
a developed country: 20%, 25% ?
- A Swedish survey in 2003 indicates that the annual
cost of antirheumatic antibodies is 12,000 €/year,
compared to a cost of 170 €/year/person for chemical
drugs. 12,000 euros = the price of a medium-size car.
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Did we reached the limits of the vast chemical space ? No
Fink and Reymond
generated in 2007 a
database of 26 million
molecules with up to 11
atoms of carbon,
nitrogen, oxygen and
fluorine that are feasible
(only 63,850 molecules of
this limited chemical
space are already in
public databases, i.e.
0.24%).
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Cartoon view of the chemical space and
discrete areas occupied by inhibitors of
kinases, proteases, ….etc.
8
Why making hybrid molecules as potential drugs ?
- Nature is making hybrid molecules !
- The antitumoral bleomycin is a good example of a
hybrid molecule with three different domains (DNA
binding, metal binding and cell penetration).
H2N
*
O
NH2
H
N
NH2
*
N*
N
CH3
Metal binding
domain
O
H2N
CH3 HN *
O
Cell penetration
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DNA binding domain
O
HO
O
N
H
N*
H
N
O
O
NH
O
CH3 HO
CH3
S
N
N
R
S
bleomycin A2 R = -NH-(CH 2)3-S +(CH 3)2
bleomycin B2 R = -NH-(CH 2) 4-NH-C(=NH)-NH 2
N
H
L-gulose-D-mannose
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Different strategies for making hybrid molecules
A = one single target
single target
single target
(double-edged sword molecules)
B = two independent targets
target 1
target 2
(the two entities of the hybrid molecule
act independently on the targets)
C = two related targets
target 1
target 2
(both entities of the hybrid molecule
act at the same time)
B. Meunier, Acc. Chem. Res., 41, 69-77 (2008)
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Mechanism-driven design of trioxaquines®
Requirements for antimalarial drug design:
(i) bitherapy is recommended to avoid the emergence of resistant parasite strains
(=> hybrid molecules)
(ii) different pharmacokinetics of two independent drugs are generating
difficulties in bitherapy.
Trioxaquines are based on a strategy using «hybrid molecules with
a dual mode of action»*. The two active entities are covalently
linked to synchronize their biodisponibility.
trioxane
pharmacophore n° 1
linker
quinoline
Trioxane-linker-quinoline =
« trioxaquine »
pharmacophore n° 2
The trioxaquines are highly active on chloroquine-resistant Plasmodium falciparum.
Dechy-Cabaret et al., CNRS patent, April 2000.
*For
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a review, see Meunier, Acc. Chem. Res., 2008, 69-77
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Current status of the development of trioxaquines
- 120 trioxaquines and trioxolaquines have been prepared
by Palumed and evaluated in vitro (IC50 values) between
February 2003 and December 2006.
- 77 of these hybrid molecules have been evaluated in vivo
(mice model, determination of CD50 and CD90 values).
- 6 of these trioxaquines have been further evaluated.
- PA1103 has been selected in January 2007 for
development by Sanofi-aventis (= SAR116242).
- 3 kg have been prepared in March 2008. 12 kg of the GMP
product are currently in production.
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Structure of the trioxaquine PA1103/SAR116242
PA1103 is a 50/50 mixture of two diastereoisomers
Coslédan et al., PNAS, vol. 105, 17579-17584 (2008)
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Properties of PA1103 (selected as drug-candidate)
- Molecular weight: 460 (base form) (OK with the Lipinski’s rules)
- Crystalline form, log P calc. = 4.9
- Stable at 50 °C for months.
- Stable at acid pH values for hours.
- Ames negative.
- Cardiosafety is OK.
- Good metabolic profile (only one main metabolite).
- PK studies (rat): biodisponibility = 30-35%.
- IC50 value on P. falciparum CQ-resistant FcM29 = 9 nM.
- IC50 values on six different strains = from 7 to 15 nM.
- PA1103 is active on clinical isolates (Africa).
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PA1103 has a dual mode of action:
. Inhibition of heme polymerization like chloroquine.
. Alkylation of heme like artemisinin.
. Active on the early stages of the multiplication within
the red bloods like artemisinin.
. Active on gametocytes like artemisinin.
Coslédan et al., PNAS, vol. 105, 17579-17584 (2008).
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New antibiotics: a real medical need
• « After the decline: facilitating a renewal in antibiotic
development » WHO (2004) and EASAC (European Academies
Science Advisory Council, 2007).
• « Despite the critical need for new antimicrobial agents, the
development of these agents is declining. Solutions
encouraging and facilitating the development of new
antimicrobial agents are needed » (Spellberg et al., Clinical Infectious
Diseases, 2004, 38, 1279-1286).
• In 2004, among 506 drug-candidates in development in
pharma’ and biotech’ companies, 67 are for cancer, 33 for
inflammation, 34 for metabolic disorders and only 6 for
bacterial infectious diseases (same authors as above).
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PALUMED has identified three different targets for new antibiotics
• Nosocomial infections (vancomyquine®).
The number of MRSA-related hospitalization doubled within 7 years (19992005) and the number of deaths due to nosocomial infections (19,000/year) is
higher than that related to AIDS (E. Klein et al. CDC-Atlanta,
www.cdc.gov.eid, December 2007).
•
An anti-MRSA antibiotic active by oral administration (cephaloquine®).
A cephalosporin-antibiotic active by oral route is deeply needed.
•
An antibiotic active on drug-resistant gram-negative bacteria (bactamiquine®).
Multidrug-resistant gram-negative bacteria are responsible for nosocomial pneumoniaattributed mortality (Pseudomonas aeruginosa, Acinetobacter spp, …).
Names in blue are corresponding to PALUMED’s programs.
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Antibioquines® as new antibiotics
- To fight bacteria resistant to
classical antibiotics, PALUMED
extended the concept of hybrid
molecules named « antibioquines® »
(Patent applications 2004, 2009).
- Concept : covalent attachment of
an aminoquinoline entity (AQ) to an
antibiotic skeleton.
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Linker
Antibiotic moiety
HN
R1a
R1b
N
18
Bactericidal activities of vancomyquines compared to vancomycin, linezolid,
telavancin and daptomycin against S. aureus MRSA with 50% of human serum
Vancomycin
Telavancin
Daptomycin
PA1247
PA1274
PA1409
PA1410
PA1418
-
-
-
-
-
-
-
-
-
Q
L
-
-
-
-
-
-
N-R
MIC without serum
-
-
-
-
-
-
-
-
1
0.5
0.5
0.125
0.25
0.125
0.5
0.25
MIC with serum
2
2
4
0.5
0.5
0.5
0.5
0.25
3
Concentration: 1 mg/mL
(MIC values obtained by macro-methods)
2
Control
Vancomycin
1
Daptomycin
0
D log cfu
Only vancomyquines are able to
reduce the bacterial colonies by
4.5 log units within 24 h at 1 mg/mL
compared to vancomycin, telavancin,
linezolide or daptomycin.
Linezolid
-1
Telavancin
-2
PA1410
-3
PA1247
PA1274
PA1409
PA1418
-4
For PA1409: 1 mg/mL = 0.57 mM
-5
0
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8
12
Time (h)
16
20
24
19
PA1409: influence of inoculum on its bactericidal activity against
S. aureus MRSA (clinical isolate mR) with 50% of human serum
MICs (values obtained by macro-method, bactericidal conditions)
Vancomycin
Daptomycin
Inoculum: 105 CFU/mL
MIC without serum
MIC with serum
Inoculum: 107 CFU/mL
MIC without serum
MIC with serum
1
2
2
2
2
2
Telavancin
0.5
2
16
8
PA1409
0.125
0.5-1
2
2
0.5
1
PA1409 is the
most active at
a low dose
Bactericidal activities at a concentration = 2 mg/mL
Small inoculum: 105 CFU/mL
3
High inoculum: 107 CFU/mL
2
Control
1
Control
D log cfu
0
Vancomycin
PA1409
Telavancin
-1
-2
Telavancin
Daptomycin
-3
Vancomycin
-4
Daptomycin
PA1409
-5
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Time (h)
0
4
8
12
16
Time (h)
20
20
24
Bactericidal activity on E.faecalis VSE (Isolat U38) or VRE Van A (CIP106996) with
50% of human serum at 4 µg/mL
Studies 08-831/37 et 07-831/23
Vancomycin
E.faecalis VSE:
1
1
1–2
0.06
MIC with serum
4
4
4
2-4
256
8
1
1
> 256
4
4
2-4
MIC with serum
E. faecalis VSE- 4 µg/mL
E. faecalis VRE - 4 µg/mL
5
Control
4
3
3
2
2
1
Vancomycin
0
Telavancin
-1
-2
Vancomycin
Telavancin
1
Daptomycin
0
-1
PA1409
-2
Daptomycin
-3
Δlog CFU/mL
Δlog CFU/mL
5
Control
4
PA1409
MIC without serum
MIC without serum
E.faecialis VRE:
Daptomycin
Telavancin
-3
PA1409
-4
-4
-5
-5
0
4
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8
12
Time (h)
16
20
24
0
4
8
12
Time (h)
16
20
21
24
Bactericidal activity on E.faecium VSE (Isolat B1003) or VRE Van A (CIP107387) with 50%
of human serum at 16 µg/mL
Studies 08-831/38 et 08-831/29M
Vancomycin
E.faecium VSE:
0.5
0.06
0.06
MIC with serum
2
2-4
1
0.125
MIC without serum
> 256
2-8
0.25
4-8
MIC with serum
> 256
256
8 - 16
64
E. faecium VSE-16 µg/mL
E. faecium VRE-16 µg/mL
5
5
4
4
Control
3
3
2
2
1
Vancomycin
PA1409
Δlog CFU/mL
Δlog CFU/mL
PA1247
0.5
MIC without serum
E.faecium VRE:
PA1409
Telavancin
PA1247
0
-1
Control
Vancomycin
Telavancin
1
PA1247
PA1409
0
-1
Telavancin
-2
-2
-3
-3
-4
-4
-5
-5
0
4
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8
12
Time (h)
16
20
24
0
4
8
12
Time (h)
16
20
22
24
Vancomyquines®: highly active in vivo on MRSA and PRSP (mice)
- Vancomyquine PA1409 is curative by iv route on mice infected
by MRSA (septicemia): CD100 = 5 mg/kg.
The CD50 value of PA1409 on MRSA = 1 mg/kg.
(infection by sc, iv treatment at t°+ 1 h and t° + 4 h)
On MSSA: CD80 of PA1409 = 4 mg/kg.
On the same MRSA model, the CD100 values of competitors are :
Vancomycin: CD100 = 20 mg/kg (no cured mice at 1 mg/kg, CD50 > 5 mg/kg).
Telavancin: CD100 = above 20 mg/kg (CD50 = 10 mg/kg).
Daptomycin: CD100 = 10 mg/kg (CD50 = 6 mg/kg).
PA1409 is more potent than all the other competitors.
- Vancomyquines are curative at 3 mg/kg (sc route) on mice infected
by PRSP (no cured animals with vancomycin in the same conditions).
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AUC/MIC ratios of PA1409 and vancomycin
Dog - adult beagle - 2.5 mg/kg - iv injection - glucose 5 % - Win Non Lin version 5.2 software analysis
PA1409
Vancomycin
AUC (minxmg/ml)
17105 ± 755
1143 ± 40
MIC90 (mg/ml)*
0.25
1
AUC/MIC
68420
1143
*MIC90 from eleven MRSA strains
The AUC/MIC ratio for PA 1409 is 60 times that of vancomycin.
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Acknowledgements
Mechanism of action of artemisinin derivatives
Anne ROBERT (CNRS Fellow), Jérôme CAZELLES (PhD 2000),
Monserrat RODRIGUEZ (post-doct, Spain) Katalina SELMECZI (post-doc, Hungary),
Sophie A. -L. LAURENT (PhD 2006) Fatima BOUSEJRA-EL GARAH (PhD student)
Financial support : CNRS, PALUMED, ANR and EU-Antimal
Synthesis of trioxaquines
Frédéric COSLEDAN (Palumed), Christine SALLE (Palumed),
Odile DECHY-CABARET (PhD 2001), Christophe LOUP (CNRS),
Jérôme CAZELLES (Palumed), Anne ROBERT (CNRS Fellow)
Heinz GORNITZKA (X-ray structures)
Financial support : PALUMED, CNRS, ANR, Conseil Régional Midi-Pyrénées and EU-Antimal
Biological activities of trioxaquines
Frédéric COSLEDAN (Palumed), Françoise BENOIT-VICAL (INSERM Fellow), Joël
LELIEVRE (PhD), Angélique ERRAUD (Palumed), Carine AUGE (Palumed), Céline
BERRONE (Palumed), Katia JONOT (Palumed)
Support : PALUMED, ANR, CHU-Rangueil and EU-Antimal
Academic collaborations: J. F. MAGNAVAL, J. P. SEGUELA and A. BERRY (Toulouse Hospital, CHURangueil), P. KREMSNER (Lambaréné, Gabon), D. DIVES (Lille, Inserm), D. MAZIER (Paris, Inserm).
Collaboration with Sanofi-Aventis : Jean-Pierre MAFFRAND, Laurent FRAISSE, Alain PELLET
For informations on PALUMED: see www.palumed.com
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Acknowledgements (antibiotics)
Synthesis and PK data of antibioquines
Muriel SANCHEZ, Jérôme CAZELLES,
Michel NGUYEN, Camille CATHARY, Laurence PAGES
Biological activities of antibioquines
Charlotte DUVAL
Collaborations:
Christine ROQUES, Faculty of Pharmacy - Toulouse (FONDEREPHAR)
Pierre-Louis TOUTAIN, Veterinary School of Toulouse
Roland LECLERCQ (CHU-Caen)
Bruno FANTIN (CHU-Beaujon, Paris)
Financial support: PALUMED
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