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Medicinal Informatics. Automated Design of ligands with targeted polypharmacology Jérémy Besnard PhD University of Dundee ELRIG Drug Discovery '13 Manchester 3rd September 2013. Background. Increasing cost of R&D High failure rate for compounds in Phase II and III. - PowerPoint PPT Presentation
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Automated Design of ligands with targeted polypharmacology
Jérémy Besnard PhDUniversity of Dundee
ELRIG Drug Discovery '13 Manchester3rd September 2013
MedicinalInformatics
Background• Increasing cost of R&D• High failure rate for compounds in
Phase II and III
Phase II failures: 2008–2010. The 108 failures are divided according to reason for failure when reported (87 drugs). The total success rate is 18 % between 2008 and 2009 (Arrowsmith, Nature Reviews Drug Discovery 2011)
Possible solution• Improve efficacy and safety by better
understanding polypharmacological profile of a compound
Two proteins are deemed interacting in chemical space (joined by an edge) if both bind one or more compound. Paolini et al. Nature Biotechnology, 2006
Designing Ligands• Challenging to test one compound
versus multiple targets: costs, which panel to use, more complicated SAR, increasing difficulty of multiobjective optimisation
• Computational methods can provide–Design ideas–Prediction of activities–When possible ADME predictions
Design ideas – De Novo Drug Design
• Compound structures are generated by an algorithm
• Predefined rules to create/modify structures
• User defined filters–Molecular property space (MW,
LogP)–Primary activities to improve–Side activities to avoid
Can we design against a polypharmacological profile?
• Drug Design is a multi-dimensional optimisation problem
• Polypharmacology profile design increases the number of dimensions but not the type of the problem– Multiple biological activities– ADMET properties– Drug-like properties
• Automating drug design is the strategy we have taken to deal with the design decision complexity of multi-target optimisation
Drug Optimisation Road
• Decisions:–Exploration– Improvement
• Guides–Structure–Previous SAR–Med Chem
KnowledgeBiologically active chemical space
Synthesised CompoundsDecision to synthesize
Lead
ClinicalCandidate
Algorithm
Compounds
Generate Virtual compounds
Backgroundknowledge
Med Chemdesign rules
MachineLearning
Predict propertiesPhys-Chem
Activities (primary and anti target)
Novelty
Define Objectives
Results expandknowledge-base
Patent WO2011061548A2
Multi-objective
prioritization
Final Population
Synthesisoptimal molecules
Test in bio-assays
Assess molecules
Top cpds + Random set
X run
Analyse
Background knowledge• ChEMBL
– 30 years of publications
Total ~ 3M endpoints
Total 40,000 papers
Total ~ 660,000 cpds
Algorithm
Compounds
Generate Virtual compounds
Backgroundknowledge
Med Chemdesign rules
MachineLearning
Predict propertiesPhys-Chem
Activities (primary and anti target)
Novelty
Define Objectives
Results expandknowledge-base
Patent WO2011061548A2
Multi-objective
prioritization
Final Population
Synthesisoptimal molecules
Test in bio-assays
Assess molecules
Top cpds + Random set
X run
Analyse
Transformations
Try to find new transformations
• Set of ~700– Tactics to design analogs – Not synthetic reactions– Derived from literature
• Semi-automatic
Algorithm
Compounds
Generate Virtual compounds
Backgroundknowledge
Med Chemdesign rules
MachineLearning
Predict propertiesPhys-Chem
Activities (primary and anti target)
Novelty
Define Objectives
Results expandknowledge-base
Patent WO2011061548A2
Multi-objective
prioritization
Final Population
Synthesisoptimal molecules
Test in bio-assays
Assess molecules
Top cpds + Random set
X run
Analyse
Model• Categorical model
–Active if activity < 10μM• Use 2D structural information
O
O
O
O
1 0 0 1 1 0 0 0 1 0
BayesianGood feature:23 times in training set,15 times in active molecule:Weight = 2.46
“A molecule”
Bad feature:360 times in training set,Never in active molecule:Weight = -1.91
Moderate good feature:389 times in training set,7 times in active molecule:Weight = 0.10
Moderate bad feature:4 times in training set,Never in active molecule:Weight = -0.06
Score= 2.46 + 0.10 -1.91 -0.06 = 0.59
High score means high confidence of activity.Low (negative) score means high confidence of inactivityScore ~ 0: either cancellation of good and bad, or unknown
W. Van Hoorn, Scitegic User Group Meeting, Feb 2006, La Jolla
Algorithm
Compounds
Generate Virtual compounds
Backgroundknowledge
Med Chemdesign rules
MachineLearning
Predict propertiesPhys-Chem
Activities (primary and anti target)
Novelty
Define Objectives
Results expandknowledge-base
Patent WO2011061548A2
Multi-objective
prioritization
Final Population
Synthesisoptimal molecules
Test in bio-assays
Assess molecules
Top cpds + Random set
X run
Analyse
Prioritization• Objectives
– Activity– CNS score or QED – Anti Target
• Example– Receptor 1 and 2
activity– Good CNS score– No α1 (a, b and d)
activity– -> n dimensions
Achievement Objective
Objective 1O
bjec
tive
2
QED: see Bickerton et al., Quantifying the chemical beauty of drugs. Nature Chemistry, 4(February 2012)
Algorithm
Compounds
Generate Virtual compounds
Backgroundknowledge
Med Chemdesign rules
MachineLearning
Predict propertiesPhys-Chem
Activities (primary and anti target)
Novelty
Define Objectives
Results expandknowledge-base
Patent WO2011061548A2
Multi-objective
prioritization
Final Population
Synthesisoptimal molecules
Test in bio-assays
Assess molecules
Top cpds + Random set
X run
Analyse
Experimental Validation • Does it actually work?• Evolution of a drug (SOSA)
– Look at possible side activity of drugs
• Donepezil: acetylcholinesterase inhibitor used for Alzheimer disease
• Potential activity for dopamine D4 receptor
• Confirmed experimentally at 600nM: design ligands with Donepezil as a hit to improve D4 activity
• Dopamine D2 receptor studied (lower prediction, not active)
Wermuth, C. G. Selective optimization of side activities: the SOSA approach. Drug discovery today, 11(3-4), 2006
What are Dopamine D2 and D4 receptors?
• Belong to the GPCR family• Mainly present in the CNS• Involved in cognition, memory,
learning…• Targets for several neuropsychiatric
disorders like Parkinson’s disease, Schizophrenia, Attention-deficit hyperactivity disorder, Bipolar disorder…
• Data (4,400 activities for D2 and 1,500 for D4) and screening facilities available
Two studies• Two receptors as objectives
–D2: will lead to work on selectivity toward multiple receptors
–D4: will lead to work on selectivity and novelty
D2 as objective• 1st series of compounds with high D2
prediction
Results
CNS penetration for compound 3: brain/blood ratio = 0.5
Next objectives: reduce anti-target activity
• Polypharmacology primary activity– Combination profile of multiple GPCRs: 5HT1a, D2, D3, D4
• Selectivity over alpha 1 anti-targets– Alpha 1a, 1b and 1d– Inhibitors induce vasodilatation
• Novelty: remove known scaffolds• Good phys-chem properties: need to cross blood-
brain-barrier
• Multiple calculations and look at the results for synthetically attractive compounds
Optimisation results for 5-HT1A/D2/D3/D4/CNS/α1 selectivity/CNS objectives
Highest ranked compound
Path
Results
N
O
N
N
X
1 - 2
R
NN N
O
Y
X1 - 3
Selectivity• Need to include selectivity in the
algorithm:–Alpha adrenoreceptor 1 inhibitors
versus other targetsavg_selectivity
0.001
0.01
0.1
1
10
100
GFR-VII-266
GFR-VII-269
GFR-VII-273
GFR-VII-274
GFR-VII-280-HCl
GFR-VII-280
GFR-VII-281
GFR-VII-285
GFR-VII-287
GFR-VII-290
GFR-VII-327
GFR-VII-328
GFR-VII-329
GFR-VII-330
GFR-VII-331
GFR-VII-332
Ratio Ki D2 receptor / Ki α Receptor
D4 objective
• Improve D4 activity• Good ADME score Bayesian = 25
D4 Ki=614nM
Bayesian = 105D4 Ki=9nM
Screening data
Ki Binding Assays (nM)
Bayesian Model Predictions
Experimental Data• Compound 13 is selective for D4
receptor with pKi = 8• It crosses the BBB (Ratio of 7.5)• In vivo experiments on with
comparison to D4-KO mouse showed effects that the compound acts on target
Morpholino series• However Cpd 13 is commercial and
thus not novel• New objective: starting from 13, keep
activity, filter non-novel chemotype, D4 selectivity over other targets, CNS penetrant
• Example of top ranked compound
Morpholino series• 24 analogues were synthesised
around 2 scaffolds
Matrix of results
Lead Series Criteria Met• Ki<100nM• Highly novel chemotype at level of
carbon framework• Chemotype is D4 selective• CNS penetrable • Patent filing (WO2012160392)
Further characterization• Functional data
– Compounds are antagonist or inverse agonist• hERG (K ion channel): inhibition can cause sudden
death– 27s: EC50 = 3μM
• Blood-Brain-Barrier– 27s: in vivo brain/blood ratio of 2.0
• Stability– Compound itself: oxidation possible indoline > indole– Metabolic stability: high clearance > need improvement(Cli, = 25 mL/min/g)
Compound 27s can be classified as a lead for D4 selective inverse agonist. From the series, there is also a potential of dual 5HT1A/D4 ligands
How to improve the algorithm
• Better model: better prediction can help reducing false positives and detect potential other activities
• Different methods– Predictions: other machine learning, 2D/3D
similarity (USR-USRCAT), docking– Idea generator: real synthetic reactions, group
replacements (MMPs)• More knowledge on the method itself
– Where it works– When to stop
Hussain. Computationally Efficient Algorithm to Identify Matched Molecular Pairs ( MMPs ) in Large Data Sets, J.Chem.Inf.Model., 4, 2010Ballester. Ultrafast shape recognition to search compound databases for similar molecular shapes. Journal of computational chemistry, 28(10), 2007Schreyer. USRCAT: real-time ultrafast shape recognition with pharmacophoric constraints. Journal of Cheminformatics, 4(27), 2012
Conclusion• We have designed an algorithm to generate
and predict compounds against polypharmacological profile
• The algorithm can adapt to the situation: improve activity, selectivity, novelty
• We have shown proof of concept that we can automatically invent patentable compounds
• Results were experimentally validated and it generated a lead compound – this study has been published (Besnard al,. Nature, 492(7428), 2012)
• The technology has been licensed to Ex Scientia Ltd (spin off - http://www.exscientia.co.uk/ )
• Ex Scientia in its first year has had further successes applying the algorithm to the design of various other gene families including ion channels, GPCRs and enzymes (“stay tuned”)
Acknowledgments• Pr. Andrew Hopkins• Richard Bickerton• ALH group
• Pr. Ian Gilbert• Gian Filippo Ruda• Karen Abecassis
• Kevin Read and DMPK group
• Barton group• Brenk group
• Pr. Bryan Roth (UNC-CH - NIH)• Vincent Setola• Roth lab• Pr. William Wetsel (Duke
University Medical School)• Wetsel group
• CLS IT support (Jon)• Accelrys support