week 8 part 2 Flashcards
Why do most compounds not become medicines?
- complex disease targets
- Too long in the body
- Adverse reactions
- Poor Absorption
- Low levels in the body
- Not effective enough
- Not sufficiently selective
- Side effects
- Unsafe
- Unstable
- Competition
- Impractical to make
What is pharmacogenomics?
The application of genomic technologies such as gene sequencing, statistical genetics, gene expression analysis to drugs in the clinical development and on the market
What does pharmacogenomics apply to?
large-scale systematic approaches of genomics to speed the discovery of drug response markers, whether they act at the level of the drug target, drug metabolism, or disease pathways.
What is the potential implication of pharmacogenomics in clinical research/medicine?
disease could be treated according to genetic and specific individual markers, selecting medications and dosages that are optimized for individual patients
What is the possibility of defining patient population genetically?
improve outcomes by predicting individual responses to drugs, and could improve safety and efficacy in therapeutic areas such as neuropsychiatry, cardiovascular medicine, endocrinology (diabetes and obesity) and oncology
Where does genetics and genomic fits in?
Its Important in target validation, you can use omics and genetics to identify and validate targets
in lead candidate stage where you are testing for molecule in animal model. what should you look for?
at evolutionary fidelity of animal model
does target in animal model predict action of that target in humans or have evolutionary events caused the function of that target to divergence in animals
What happens in phase I in humans?
- use expression data
- Pathway knowledge
- Anticipate common adverse events that is related to safety
What happens in phase II in humans?
- look at efficacy of drugs
2. Look at common variants
What is pharmacovigilance?
the practice of monitoring the effects of medical drugs after they have been licensed for use, especially in order to identify and evaluate previously unreported adverse reaction
Target ID and validation?
Identification of drug targets based on biological rationale and known small molecule tractibility
Hit and Lead ID
Configure and run high throughput screen to ID bioactive small molecules
identify drug-like lead molecules
Lead to Candidate
Medicinal chemistry to optimise lead properties
Back up lead
Evaluate drug pharmacology in preclinical model
Phase I
Evaluate clinical pharmacology of candidate drug in 20-100 healthy human volunteers
Phase II
Determine therapetuic dose
Evaluate drug efficacy to achieve POC
conducted in 100-200 patients
Phase III & Market
Large comparative study (compound vs placebo) in 1000s of patients to establish clinical benefit and safety
Drug launch and subsequent safety surveillenace
What is Target Validation?
Target validation is the process by which the predicted molecular target – for example protein or nucleic acid – of a small molecule is verified
ongoing process
What does Target Validation include?
- Determining structure-activity-relationship of small molecules
- Generating a drug-resistant mutant of presumed target
- knockdown or overexpression of presumed target
- Monitoring the known signalling systems downstream of presumed target
When can you say a target is validated?
when a drug has been working in the clinic safety and effectively for many years
What is a great example of target validation?
Cox-2
What is Cox-2?
Pain target
target of cox2 inhibitors
What is a dual inhibitor?
Aspirin
Work on Cox-1 and Cox-2
What showed great efficacy in pain?
Selective Cox-2 inhibitors
What is integral to target validation?
Population safety
What is Cox-2 directly marketed in the US for pain?
Age related pain osteoarthritis
What was Cox-2 marketed as?
Tool for healthy life style
What are the 2 Cox enzymes?
Cox-1 and Cox-2
Exist in blood vessels
in an equilibrium
What happens when you inhibit COX2?
Disrupt that equilibrium and it causes clumping of platelets
make platelets much more easily coagulable
it causes an increase in vascular events
What did they found out ?
Cox2 inhibitors had 50% of cardiovascular events than people that didnt take Cox2 inhibitors
When a drug described as safe?
At the right dose
What are the perspectives on target validation and safety?
- Biology
- Variation
- Similarity
- Tractability
What is biology?
- Biological mechanism
- Disease association
- Tissue expression
- Pathways
What is variation?
- Genetic variation
- Isoform/splicing
- Epigenetics
What is similarity?
- Orthology (animal models)
2. Homology (off target effects)
What is tractability?
- Druggable
- Biopharmable
- Other e.g. siRNA
- Robust assay
What fits into the target discovery and validation?
- Talking about genetics and genomics
What are some examples of validating targets?
- Look at cell models - cancer cell models to see if a gene is differentially expressed in cancer
- Clinical samples
- RA - looking at synovium of arthritis patients to look at genes that are upregulated/downregulated - Look at animal models
What do you look for in a gene expression proteomics?
Altered expression in the disease state using genetics
What do we need to consider for a target?
Pathway context
What is a pathway in drug discovery?
A target in a linear pathway
modulate that pathway
downstream effect which is specific and predictable
What is the reason why many drugs have side effects and adverse effects or lacking efficacy?
Pathways are complex
knowledge of pathway is incomplete
What may a target acting as a single critical node control?
influence many processes
What can network interactions be?
Redundant
What can drugs interact with?
Multiple targets
What are a consequence of interaction with multiple targets?
Efficacy and safety
What are crucial considerations in drug discovery?
- Pleiotropy
2. Redundancy