ANTICANCER AGENTSANTICANCER AGENTSPROTEIN KINASE INHIBITORSPROTEIN KINASE INHIBITORS
Chapter 21Chapter 21
Protein KinasesProtein Kinases
•Enzymes that catalyse phosphorylation reactions on protein substrates•500-2000 estimated protein kinases in a cell•Protein kinases are present in the cytoplasm•Protein kinase receptors - dual role as receptor and enzyme•Overexpression can result in cancer•Tyrosine kinases, serine-threonine kinases and histidine kinases•ATP used as enzyme cofactor - phosphorylating agent
N
N N
N
N
O
OH OH
H H
H H
O P O
O
O
P O
O
O
P
O
O
O
H H
61
N
N N
N
N
O
OH OH
H H
H H
O P O
O
O
P O
O
O
H H
61
O P
O
O
O
Protein KinasesProtein KinasesTyrosine kinasesTyrosine kinases
HN
O
Protein Protein
H
OH
ATP ADP
HN
O
Protein Protein
H
OP
OHOH
O
Protein KinasesProtein KinasesSerine-threonine kinasesSerine-threonine kinases
Serine
HN
O
OH
Protein Protein
H
ATP ADP
HN
O
O
Protein Protein
H
PO OH
OH
Threonine
HN
O
H3C OH
Protein Protein
H
ATP ADP
HN
O
H3C O
Protein Protein
H
PO OH
OH
Protein KinasesProtein KinasesActive SiteActive Site
•Contains the binding site for the protein substrateContains the binding site for the protein substrate
•Contains the binding site for the ATP cofactorContains the binding site for the ATP cofactor
•Clinically useful inhibitors target the ATP binding siteClinically useful inhibitors target the ATP binding site
•ATP binding site is similar but not identical for all protein kinasesATP binding site is similar but not identical for all protein kinases
•Allows selectivity of inhibitor action Allows selectivity of inhibitor action
1. Protein Kinases1. Protein KinasesATP binding siteATP binding site
N
N
O
H
H
O
HN
H2NOC
H3C
H3C
O
SH3C
Gln-767
Met-769
Leu-768
Ribose pocket
Hydrophobic pocket
Cleft
N
N N
N
N
O
OH OH
H H
H H
O P O
O
O
P O
O
O
P
O
O
O
H H
HBD
HBAN
N N
N
N
O
OH OH
H H
H H
O P O
O
O
P O
O
O
P
O
O
O
H H
Protein KinasesProtein Kinases
•Purine base is buried deep into the binding site•Purine forms two hydrogen bonding interactions to the binding site•Ribose sugar binds to a ‘ribose binding pocket’ •Triphosphate chain lies along a cleft towards the enzyme surface•Triphosphate interacts with two metal ions and amino acids•Specificity surface is an area of unoccupied binding site•An empty hydrophobic pocket lies opposite the ribose binding pocket•The gatekeeper residue is an amino acid situated at the entrance to the hydrophobic pocket•The size of the gatekeeper residue is important in drug design•The nature of amino acids in the binding pockets is important to drug design
N
N
O
H
H
O
HN
H2NOC
H3C
H3C
O
SH3C
Gln-767
Met-769
Leu-768HBD
HBA
Ribose pocket
Hydrophobic pocket
CleftN
N N
N
N
O
OH OH
H H
H H
O P O
O
O
P O
O
O
P
O
O
O
H H
ATP binding siteATP binding site
Protein Kinase InhibitorsProtein Kinase InhibitorsNotesNotes
•Type I inhibitors act on the active conformation of the enzymeType I inhibitors act on the active conformation of the enzyme
•Type I inhibitors bind to the ATP binding site and block access to ATP Type I inhibitors bind to the ATP binding site and block access to ATP
•Type II inhibitors act on the inactive conformation of the enzymeType II inhibitors act on the inactive conformation of the enzyme
•Type II inhibitors bind to the enzyme and stabilise the inactive conformationType II inhibitors bind to the enzyme and stabilise the inactive conformation
•Type II inhibitors are likely to be more selectiveType II inhibitors are likely to be more selective
Type I inhibitorsType I inhibitorsGefitinib, erlotinib, SU11248 and seliciclibGefitinib, erlotinib, SU11248 and seliciclib
Type II inhibitorsType II inhibitorsImatinib, lapatinib, sorafenib and vatalanibImatinib, lapatinib, sorafenib and vatalanib
Gefitinib (Iressa)Gefitinib (Iressa)
NotesNotes•Developed by Astra ZenecaDeveloped by Astra Zeneca•Inhibits the kinase active site of the epidermal growth factor receptorInhibits the kinase active site of the epidermal growth factor receptor•The EGF-receptor is a tyrosine kinase receptorThe EGF-receptor is a tyrosine kinase receptor•Gefitinib is a 4-anilinoquinazoline structureGefitinib is a 4-anilinoquinazoline structure
N
N
HN
OMe
O N
O
F
Cl
4 6
7
3
1 Morpholine
Quinazoline
Aniline
Lead compoundLead compound
Gefitinib (Iressa)Gefitinib (Iressa)
Notes Notes •The secondary amine, electron-donating substituents and small lipophilic group The secondary amine, electron-donating substituents and small lipophilic group are all important for activityare all important for activity•Useful Useful in vitroin vitro activity activity•Lower Lower in vivoin vivo activity due to rapid metabolism activity due to rapid metabolism•Metabolised by cytochrome P450 enzymesMetabolised by cytochrome P450 enzymes
N
N
HN
OMe
OMe
CH3
6
7
4
I; IC50 5 nM
Secondary Secondary amineamine
Small lipophilic groupSmall lipophilic group
Electron-donating Electron-donating substituentssubstituents
N
N
HN
OMe
OMe
CH3
6
7
4
I; IC50 5 nM
Metabolism of the lead compoundMetabolism of the lead compound
Gefitinib (Iressa)Gefitinib (Iressa)
N
N
HN
OMe
OMe
II
OH
N
N
HN
OMe
OMe
CH3
III
OH
+Cytochrome Cytochrome P450 enzymesP450 enzymes
OxidationOxidation
N
N
HN
OMe
OMe
CH3
6
7
4
I; IC50 5 nM
Notes Notes •Methyl group and Methyl group and parapara-position of aromatic ring are susceptible positions -position of aromatic ring are susceptible positions •Blocking metabolism should improve the half life of the drugBlocking metabolism should improve the half life of the drug
Drug designDrug design
Gefitinib (Iressa)Gefitinib (Iressa)
NotesNotes•Fluoro-substituent blocks Fluoro-substituent blocks parapara-hydroxylation of the aromatic ring-hydroxylation of the aromatic ring•Fluorine is similar in size to hydrogen and has no steric effectFluorine is similar in size to hydrogen and has no steric effect•Methyl group is replaced by a chloro substituent Methyl group is replaced by a chloro substituent •Chlorine and methyl group have similar sizes and lipophilicitiesChlorine and methyl group have similar sizes and lipophilicities•Chlorine acts as a bio-isotere for the methyl groupChlorine acts as a bio-isotere for the methyl group•Chlorine is resistant to oxidationChlorine is resistant to oxidation•Compound is less active Compound is less active in vitroin vitro, but more active , but more active in vivoin vivo
N
N
HN
OMe
OMe
Cl
F
IV: IC50 9 nM
N
N
HN
OMe
OMe
CH3
6
7
4
I; IC50 5 nM
Drug designDrug design
Gefitinib (Iressa)Gefitinib (Iressa)
N
N
HN
OMe
OMe
Cl
F
IV: IC50 9 nM
NotesNotes•Morpholine ring increases water solubilityMorpholine ring increases water solubility•Morpholine nitrogen allows generation of water soluble amine saltsMorpholine nitrogen allows generation of water soluble amine salts•Spacer allows morpholine to protrude out of the active siteSpacer allows morpholine to protrude out of the active site•Remains solvated when the drug is boundRemains solvated when the drug is bound•Avoids a desolvation penaltyAvoids a desolvation penalty
MorpholineMorpholine
IonisableIonisableN
N
HN
OMe
OMe
CH3
6
7
4
I; IC50 5 nM
N
N
HN
OMe
O N
O
F
Cl
4 6
7
3
1
Gefitinib
SpacerSpacer
Gefitinib (Iressa)Gefitinib (Iressa)Binding interactionsBinding interactions•Identified by a molecular modelling experimentIdentified by a molecular modelling experiment•Gefitinib is docked with a model binding siteGefitinib is docked with a model binding site•Binds to the ATP binding siteBinds to the ATP binding site•Aniline ring occupies the normally vacant hydrophobic pocket opposite the ribose Aniline ring occupies the normally vacant hydrophobic pocket opposite the ribose binding pocketbinding pocket•Quinazoline binds to the same region as the purine ring of ATP Quinazoline binds to the same region as the purine ring of ATP
N
N
N
OMe
O
F
ClH
N
O
Hydrophobic pocket
Cleft
Met-769
OH2
Thr-830
N
N
N
OMe
O
F
ClH
N
O
HBA
HBA
Hydrophobic pocket
Cleft
Met-769
OH2
Thr-830
N
N
N
OMe
O
F
ClH
N
O
HBA
HBA
Hydrophobic pocket
Cleft
Met-769
OH2
Thr-830
N
N
N
OMe
O
F
ClH
N
O
3. Gefitinib (Iressa)3. Gefitinib (Iressa)
N
HN
O
OMe
OMeMethionine
MeSO3H
N
HN
O
OMe
OH
Phenol
Pyridine
Ac2O
N
HN
O
OMe
OAc
Protecting group
SOCl2
N
N
Cl
OMe
OAc
ArNH2
N
N
NHAr
OMe
OAc
Aniline substituent
NH4OH
MeOH
N
N
NHAr
OMe
OH
R2N(CH2)nBr
N
N
HN
OMe
O N
OAr
Synthesis of gefitinib and analoguesSynthesis of gefitinib and analogues
4. Lapatinib and Etlotinib4. Lapatinib and Etlotinib
NotesNotes•4-Anilinoquinazoline structures - compare gefitinib4-Anilinoquinazoline structures - compare gefitinib•EGF-receptor kinase inhibitorsEGF-receptor kinase inhibitors
Quinazoline ringQuinazoline ring
Aniline ringAniline ringO
F
Cl NH
N
N
O HN
SO2Me
LapatinibLapatinib Erlotinib (Tarceva)Erlotinib (Tarceva)ICIC5050 2 nM 2 nM
N
N
NH
O
O
OMe
OMe
4
Quinazoline ringQuinazoline ring
Aniline ringAniline ring
5. PKI 1665. PKI 166
NotesNotes•Pyrrolopyrimidine structurePyrrolopyrimidine structure•EGF-receptor kinase inhibitorEGF-receptor kinase inhibitor•Different binding mode from ATP or anilinoquinazolinesDifferent binding mode from ATP or anilinoquinazolines
OH
NHN
N
NH
Me
4
HBA HBD
PyrrolePyrrole
PyrimidinePyrimidine
5. PKI 1665. PKI 166Comparison of binding interactionsComparison of binding interactions•ATP and EGF-receptor kinase inhibitors all contain a pyrimidine ringATP and EGF-receptor kinase inhibitors all contain a pyrimidine ring•Different binding modes are possibleDifferent binding modes are possible
HBA HBD
HBD
HBA
OH
NHN
N
NH
Me
4
PKI 166PKI 166
N
N
N
OMe
O
F
ClH
N
O
N
N N
N
N
O
OH OH
H H
H H
O P O
O
O
P O
O
O
P
O
O
O
H H
GefitinibGefitinib
ATPATP
HBA
HBA
OH
NHN
N
NH
Me
4
PKI 166PKI 166
N
N
N
OMe
O
F
ClH
N
O
N
N N
N
N
O
OH OH
H H
H H
O P O
O
O
P O
O
O
P
O
O
O
H H
GefitinibGefitinib
ATPATP
6. Imatinib (Glivec or Gleevec)6. Imatinib (Glivec or Gleevec)
NotesNotes•First protein kinase inhibitor to reach the marketFirst protein kinase inhibitor to reach the market•Selective inhibitor for a hybrid tyrosine kinase (Bcr-Abl)Selective inhibitor for a hybrid tyrosine kinase (Bcr-Abl)•Bcr-Abl is active in certain tumour cellsBcr-Abl is active in certain tumour cells
N
N
N
HN
Me
NH
O
N
NMe
6. Imatinib (Glivec or Gleevec)6. Imatinib (Glivec or Gleevec)Lead compoundLead compound
N
N
HN
I
PyrimidinePyrimidine Anilino substituentAnilino substituent
•Phenylaminopyrimidine structurePhenylaminopyrimidine structure•Identified by random screening of compound librariesIdentified by random screening of compound libraries•Originally identified as a PKC inhibitorOriginally identified as a PKC inhibitor•PKC is a serine-threonine kinasePKC is a serine-threonine kinase
6. Imatinib (Glivec or Gleevec)6. Imatinib (Glivec or Gleevec)Drug designDrug design
N
N
HN
I
N
N
N
HN
II
3'
Inhibits tyrosine Inhibits tyrosine kinases as wellkinases as well
PyridinePyridine
Increased inhibition of PKCIncreased inhibition of PKC
IV(IC50 5 M)
N
N
N
HN
NH
OAmideAmide
IV(IC50 5 M)
N
N
N
HN
NH
O
ConformationalConformationalblockerblocker
6. Imatinib (Glivec or Gleevec)6. Imatinib (Glivec or Gleevec)Drug designDrug design
IV(IC50 5 M)
N
N
N
HN
NH
O
CGP 53716(IC50 0.1 M)
N
N
N
HN
Me
NH
O
ImatinibImatinib
N
N
N
HN
Me
NH
O
N
NMe
PiperazinePiperazine
SpacerSpacer
•Piperazine increases activity, Piperazine increases activity, selectivity and water solubilityselectivity and water solubility•Spacer inserted to avoid Spacer inserted to avoid aniline structureaniline structure
•Increased activity vs Increased activity vs tyrosine kinasestyrosine kinases•No activity against No activity against serine-threonine kinasesserine-threonine kinases
O NH
O
MeS
Met
Gatekeeperresidue
Hydrophobic pocketSelectivity region 1
O
Thr
O
OGlu
H
N
O
O2C Asp
H
Hydrophobic regionSelectivity region 2
6. Imatinib (Glivec or Gleevec)6. Imatinib (Glivec or Gleevec)Binding interactionsBinding interactions•Identified from a crystal structure of an inhibitor-Abl kinase complexIdentified from a crystal structure of an inhibitor-Abl kinase complex•Amide serves as an ‘anchoring group’ and orientates the moleculeAmide serves as an ‘anchoring group’ and orientates the molecule•Amide binds to Glu and Asp Amide binds to Glu and Asp •Glu and Asp are important to the catalytic mechanismGlu and Asp are important to the catalytic mechanism
N
NN
N
H
Me
N
H
O
N N Me
H
O NH
O
MeS
Met
Gatekeeperresidue
Hydrophobic pocketSelectivity region 1
O
Thr
O
OGlu
H
N
O
O2C Asp
H
Hydrophobic regionSelectivity region 2
N
NN
N
H
Me
N
H
O
N N Me
H
O NH
O
MeS
Met
Gatekeeperresidue
Hydrophobic pocketSelectivity region 1
O
Thr
O
OGlu
H
N
O
O2C Asp
H
Hydrophobic regionSelectivity region 2
N
NN
N
H
Me
N
H
O
N N Me
H
O NH
O
MeS
Met
Gatekeeperresidue
Hydrophobic pocketSelectivity region 1
O
Thr
O
OGlu
H
N
O
O2C Asp
H
Hydrophobic regionSelectivity region 2
6. Imatinib (Glivec or Gleevec)6. Imatinib (Glivec or Gleevec)
•Other interactions determine target selectivityOther interactions determine target selectivity•A hydrogen bond to the gatekeeper Thr is essential to activityA hydrogen bond to the gatekeeper Thr is essential to activity•NN-Alkylation eliminates activity-Alkylation eliminates activity
Binding interactionsBinding interactions
N
NN
N
H
Me
N
H
O
N N Me
H
O NH
O
MeS
Met
Gatekeeperresidue
Hydrophobic pocketSelectivity region 1
O
Thr
O
OGlu
H
N
O
O2C Asp
H
Hydrophobic regionSelectivity region 2
6. Imatinib (Glivec or Gleevec)6. Imatinib (Glivec or Gleevec)
•Molecular modelling studies suggest that the piperazinyl group interacts with a Molecular modelling studies suggest that the piperazinyl group interacts with a glutamate residueglutamate residue•Imatinib inhibits protein kinases containing this glutamate residue (Abl, c-Kit Imatinib inhibits protein kinases containing this glutamate residue (Abl, c-Kit and PDGF-R)and PDGF-R)
Piperazinyl Piperazinyl groupgroup
GluGlu
IonicIonicbondbond
Binding interactionsBinding interactions
Conformational Conformational blockerblocker
N
NN
N
H
Me
N
H
O
N N Me
H
O NH
O
MeS
Met
Gatekeeperresidue
Hydrophobic pocketSelectivity region 1
O
Thr
O
OGlu
H
N
O
O2C Asp
H
Hydrophobic regionSelectivity region 2
6. Imatinib (Glivec or Gleevec)6. Imatinib (Glivec or Gleevec)
•Conformational blocker aids selectivityConformational blocker aids selectivity•Binds to a hydrophobic pocket that is not accessible if a larger gatekeeper Binds to a hydrophobic pocket that is not accessible if a larger gatekeeper residue was presentresidue was present
Binding interactionsBinding interactions
N
NN
N
H
Me
N
H
O
N N Me
H
O NH
O
MeS
Met
Gatekeeperresidue
Hydrophobic pocketSelectivity region 1
O
Thr
O
OGlu
H
N
O
O2C Asp
H
Hydrophobic regionSelectivity region 2
6. Imatinib (Glivec or Gleevec)6. Imatinib (Glivec or Gleevec)Drug resistanceDrug resistance•Mutation of the gatekeeper residue to isoleucine introduces resistance (T315I Mutation of the gatekeeper residue to isoleucine introduces resistance (T315I mutation)mutation)•Isoleucine unable to form an important hydrogen bond to the amineIsoleucine unable to form an important hydrogen bond to the amine
Mutation to IsoleucineMutation to Isoleucine
N
O
MeI
HC(OEt)2NMe2
N
O
NMe2
Phenylguanidinederivative
N
N
N
HN
Me
NO2
II
H2Pd/C
Reduction
N
N
N
HN
Me
NH2
III
N
N
N
HN
Me
NH
O
ArAmide
ArCOCl
Acylation
6. Imatinib (Glivec or Gleevec)6. Imatinib (Glivec or Gleevec)Synthesis of imatinib and analoguesSynthesis of imatinib and analogues
N
NN
N
H
Me
N
H
O
F3C
NN
Me
Nilotinib
Met-318
Thr-315
Glu-286
Asp-381
7. Second Generation Bcr-Abl inhibitors7. Second Generation Bcr-Abl inhibitors
Me
Cl
N
O
S
N
N
NN
Me
NN
OH
Dasatinib; BMS-354825
H
H
Met-318
Thr-315
7. Second Generation Bcr-Abl inhibitors7. Second Generation Bcr-Abl inhibitors
N
HN
Cl Cl
OMe
CNMeO
ON
MeN
Bosutinib
NotesNotes•Inhibits two protein kinase targets (Abl and Src)Inhibits two protein kinase targets (Abl and Src)•Currently in clinical trialsCurrently in clinical trials•Less likely to fall prey to drug resistanceLess likely to fall prey to drug resistance
NotesNotes•Allosteric inhibitor of Bcr-AblAllosteric inhibitor of Bcr-Abl•Does not bind to ATP binding siteDoes not bind to ATP binding site•Stabilises inactive form of the enzymeStabilises inactive form of the enzyme•Binds to an autoregulatory cleftBinds to an autoregulatory cleft•Potential agent for treating leukaemiaPotential agent for treating leukaemia
NH
MeO
N
N
NH2
O
GNF-2
MeO
HN CO2H
Me
SO O OMe
MeO OMe
ON012380
7. Second Generation Bcr-Abl inhibitors7. Second Generation Bcr-Abl inhibitors
NotesNotes•Binds to the protein substrate siteBinds to the protein substrate site•Currently under studyCurrently under study
8. Inhibitors of cyclin-dependent kinases8. Inhibitors of cyclin-dependent kinasesCyclin-dependent kinasesCyclin-dependent kinases
•CDKs are involved in control of the cell cycle and are overexpressed in many cancer cellsCDKs are involved in control of the cell cycle and are overexpressed in many cancer cells
•Serine-threonine kinasesSerine-threonine kinases
•Activated by cyclinsActivated by cyclins
•Inhibited by cyclin-dependent kinase inhibitorsInhibited by cyclin-dependent kinase inhibitors
•Synthetic inhibitors bind to the ATP binding siteSynthetic inhibitors bind to the ATP binding site
8. Inhibitors of cyclin-dependent kinases8. Inhibitors of cyclin-dependent kinases
N
OH
Me
HO
OH
O
O
Cl
Flavopiridol
HBAHBD
•Benzopyran binds to the adenine binding regionBenzopyran binds to the adenine binding region•Piperidine binds to the region occupied by the first phosphate of ATPPiperidine binds to the region occupied by the first phosphate of ATP•Phenyl lies over the ribose binding pocketPhenyl lies over the ribose binding pocket•Undergoing clinical trialsUndergoing clinical trials
BenzopyranBenzopyran
PiperidinePiperidine Phenyl Phenyl ringring
8. Inhibitors of cyclin-dependent kinases8. Inhibitors of cyclin-dependent kinases
N
OH
Me
HO
OH
O
O
Cl
Flavopiridol
HNR O
N NO
NHMe
MeO
Me
Staurosporine; R=H7-Hydroxystaurosporin; R=OH
7HBAHBD
BenzopyranBenzopyran
PiperidinePiperidine Phenyl Phenyl ringring
7-Hydroxystaurosporin is 7-Hydroxystaurosporin is undergoing clinical trialsundergoing clinical trials
Shows selectivity for CDK2Shows selectivity for CDK2Undergoing clinical trialsUndergoing clinical trials
R-Roscovitine (seliciclib)
N
N N
N
MeMe
HN
NH
HO
Me
9. Kinase Inhibitors of FGF-R and VEGF-R9. Kinase Inhibitors of FGF-R and VEGF-RFGF-R and VEGF-RFGF-R and VEGF-R
•FGF-R = fibroblast growth factor receptorFGF-R = fibroblast growth factor receptor
•VEGF-R = vascular endothelial growth factor receptorVEGF-R = vascular endothelial growth factor receptor
•Associated with angiogenesisAssociated with angiogenesis
•Inhibitors bind to the ATP binding siteInhibitors bind to the ATP binding site
•Currently undergoing clinical trialsCurrently undergoing clinical trials
•SU 5416 in clinical trials for SU 5416 in clinical trials for treatment of colorectal treatment of colorectal cancercancer•Oxindole binds to same Oxindole binds to same region as adenine of ATPregion as adenine of ATP
NH
O
NH
Me R
Me
SU 5416, R=HSU 6668, R=CH2CH2CO2H
9. Kinase Inhibitors of FGF-R and VEGF-R9. Kinase Inhibitors of FGF-R and VEGF-R
HBA
HBD
Phase III clinical trials in Phase III clinical trials in 20062006
N
N
HN
N
Cl
PTK 787 / ZK 222584
PyrrolePyrrole
OxindoleOxindole
AnilinoAnilinosubstituentsubstituent
PhthalazinePhthalazine
PyridinePyridine
10. Multi-tyrosine receptor kinase inhibitors10. Multi-tyrosine receptor kinase inhibitorsNotesNotes
•Designed to be selective against a range of tyrosine receptor kinases implicated in Designed to be selective against a range of tyrosine receptor kinases implicated in tumourstumours
•Drug resistance unlikely to occur for all kinase targetsDrug resistance unlikely to occur for all kinase targets
•Equivalent of combination therapy (poly-pharmacology)Equivalent of combination therapy (poly-pharmacology)
•Sometimes called ‘dirty drugs’Sometimes called ‘dirty drugs’
•Promising agents against tumours that are driven by several abnormalitiesPromising agents against tumours that are driven by several abnormalities
10. Multi-tyrosine receptor kinase inhibitors10. Multi-tyrosine receptor kinase inhibitors
NotesNotes•Sorafenib approved as a VEGF-R kinase inhibitorSorafenib approved as a VEGF-R kinase inhibitor•Sunitinib approved in 2006 - inhibits VEGF-R, PDGF-R and KIT receptor kinasesSunitinib approved in 2006 - inhibits VEGF-R, PDGF-R and KIT receptor kinases•Vatalanib undergoing clinical trialsVatalanib undergoing clinical trials
F
NH
O
NH
Me
Me
O
NH
NEt2
Sunitinib
N N
NH
N
Cl
Vatalanib
N
N
O
H3C O
NHN
OCl
CF3
Sorafenib IC50 12 nM
H
H
10. Multi-tyrosine receptor kinase inhibitors10. Multi-tyrosine receptor kinase inhibitorsDesign of sorafenibDesign of sorafenib•Lead compound found by high throughput screening Lead compound found by high throughput screening •200 000 compounds tested200 000 compounds tested•Tested against recombinant Raf-1 kinaseTested against recombinant Raf-1 kinase
UreaUreaHN
HN
OS
MeO2C
H
Lead compound; Lead compound; ICIC5050 17 17 MM
10. Multi-tyrosine receptor kinase inhibitors10. Multi-tyrosine receptor kinase inhibitorsDesign of sorafenib - variation of substituentsDesign of sorafenib - variation of substituents
HN
HN
OS
MeO2C
Me
II; ICII; IC5050 1.7 1.7 MM
HN
HN
OS
MeO2C
O
III; Poor activityIII; Poor activity
NotesNotes•Methyl substituent is optimum for activityMethyl substituent is optimum for activity•10-fold increase in activity10-fold increase in activity•Phenoxy group is bad for activityPhenoxy group is bad for activity
HN
HN
OS
MeO2C
H
Lead compound Lead compound ICIC5050 17 17 MM
10. Multi-tyrosine receptor kinase inhibitors10. Multi-tyrosine receptor kinase inhibitorsDesign of sorafenib - variation of ringsDesign of sorafenib - variation of rings
NotesNotes•Variation of rings also carried out systematicallyVariation of rings also carried out systematically•Isoxazole ring is not good for activityIsoxazole ring is not good for activity•Conventional medicinal chemistry strategies fail to achieve further improvementConventional medicinal chemistry strategies fail to achieve further improvement
VI; Poor activityVI; Poor activity
HN
HN
O
N
O
IsoxazoleIsoxazoleHN
HN
OS
MeO2C
H
Lead compound Lead compound ICIC5050 17 17 MM
10. Multi-tyrosine receptor kinase inhibitors10. Multi-tyrosine receptor kinase inhibitorsDesign of sorafenibDesign of sorafenib
NotesNotes•Parallel synthesis - 1000 analogues synthesised with all possible Parallel synthesis - 1000 analogues synthesised with all possible combinations of rings and substituentscombinations of rings and substituents•Structure IV has slightly increased activity - contradicts results from Structure IV has slightly increased activity - contradicts results from conventional studiesconventional studies•Isoxazole ring and phenoxy substituent are good for activity when combined Isoxazole ring and phenoxy substituent are good for activity when combined in the same structure - synergistic effectin the same structure - synergistic effect•Structure IV taken as new lead compoundStructure IV taken as new lead compound
HN
HN
OS
MeO2C
H
IV; ICIV; IC5050 1.1 1.1 MM
HN
HN
O
N
O
O
Lead compound Lead compound ICIC5050 17 17 MM
IsoxazoleIsoxazole
PhenoxyPhenoxygroupgroup
IV; ICIV; IC5050 1.1 1.1 MM
HN
HN
O
N
O
O
10. Multi-tyrosine receptor kinase inhibitors10. Multi-tyrosine receptor kinase inhibitorsDesign of sorafenibDesign of sorafenib
IV; ICIV; IC5050 1.1 1.1 MM
HN
HN
O
N
O
O
IsoxazoleIsoxazole
PhenoxyPhenoxygroupgroup
HN
HN
OS
MeO2C
H
PyridinePyridineHN
HN
O
N
O
O
N
V; ICV; IC5050 0.23 0.23 MM
•Ring variationRing variation•5-fold increase in activity5-fold increase in activity•Increase in aqueous Increase in aqueous solubility and cLogsolubility and cLogPP
Lead compound Lead compound ICIC5050 17 17 MM
10. Multi-tyrosine receptor kinase inhibitors10. Multi-tyrosine receptor kinase inhibitorsDesign of sorafenibDesign of sorafenib
HN
HN
OS
MeO2C
H
Lead compound Lead compound ICIC5050 17 17 MM
1000-fold increase in activity1000-fold increase in activity
N
N
O
CH3O
NHN
OCl
CF3
H
H
Sorafenib ICSorafenib IC5050 12 nM 12 nM
IV; ICIV; IC5050 1.1 1.1 MM
HN
HN
O
N
O
O
IsoxazoleIsoxazole
PhenoxyPhenoxygroupgroup
PyridinePyridineHN
HN
O
N
O
O
N
V; ICV; IC5050 0.23 0.23 MM
RingRingvariationvariation
SubstituentSubstituentvariationvariation
SubstituentSubstituentvariationvariation
N
N
O
CH3O
NHN
OCl
CF3
H
H
Sorafenib ICSorafenib IC5050 12 nM 12 nM
10. Multi-tyrosine receptor kinase inhibitors10. Multi-tyrosine receptor kinase inhibitorsSorafenib - binding interactionsSorafenib - binding interactions
NotesNotes•Urea functional group acts as a binding anchor (compare imatinib)Urea functional group acts as a binding anchor (compare imatinib)•Hydrogen bonds are formed to catalytic Asp and GluHydrogen bonds are formed to catalytic Asp and Glu•Binding orientates the moleculeBinding orientates the molecule•Positions each half into two selectivity regionsPositions each half into two selectivity regions
N
N
O
CH3O
NHN
OCl
CF3
H
H
HBA
HBD
HBA HBD
11. Inhibitors of heat shock protein 9011. Inhibitors of heat shock protein 90
NotesNotes
•HSP 90 is a kinase protein and acts as a molecular chaperoneHSP 90 is a kinase protein and acts as a molecular chaperone
•Important to survival of cells - inhibition likely to lead to cell deathImportant to survival of cells - inhibition likely to lead to cell death
•HSP 90 interacts selectively with many of the proteins implicated in tumoursHSP 90 interacts selectively with many of the proteins implicated in tumours
•Targeting HSP 90 may be effective against tumour cells resistant against other Targeting HSP 90 may be effective against tumour cells resistant against other drugsdrugs
•Resistant cells contain mutated proteins - rely more on HSP 90 during the Resistant cells contain mutated proteins - rely more on HSP 90 during the folding processfolding process
•Resistant cells likely to be more vulnerable to inhibitors of HSP 90Resistant cells likely to be more vulnerable to inhibitors of HSP 90
11. Inhibitors of heat shock protein 9011. Inhibitors of heat shock protein 90NotesNotesInhibitors bind to the ATP binding site Inhibitors bind to the ATP binding site Lead compound - geldanamycinLead compound - geldanamycin
OMeHN
O
OMeOOH
Me
O
MeOMeMe
MeO
H2N
O
•Natural productNatural product•Potent inhibitorPotent inhibitor•Urethane group is crucial to activityUrethane group is crucial to activity•Binds to region occupied by adenineBinds to region occupied by adenine•Poor solubilityPoor solubility•Reactive quinone moietyReactive quinone moiety
QuinoneQuinone
UrethaneUrethane
11. Inhibitors of heat shock protein 9011. Inhibitors of heat shock protein 90Geldanamycin analoguesGeldanamycin analogues
OMeHN
O
NH
OOH
Me
O
MeOMeMe
MeO
H2N
O
TanespimycinTanespimycin
OMeHN
O
NH
OOH
Me
O
MeOMeMe
MeO
H2N
O
NMe
AlvespimycinAlvespimycin
OMeHN
O
NH
HOOH
Me
OH
MeOMeMe
MeO
H2N
O
IPI 504IPI 504