Engineering Antibodies Flashcards
What characteristics of antibodies make them such useful therapeutics?
- They are specific
- They are proteins - hopefully no immune response
What regions do ximab antibodies have?
Consist of the mouse Fab regions fused with human Fc (they are 65% human)
What do zumab antibodies have on them?
Mouse CDRs are engrafted into a human antibody (which is 95% human)
What variations of an antibody can expression of natural monoclonal anitbodies give rise to?
Glycosylation
Charge
Structural stability
What can glyco engineering do?
Ensure you only have certain sugar groups on glycosylated protein
How can you go glyco engineering?
Engineering the cell that you are going to express the antibody in so it doesn’t have the enzyme to put the sugar on the glycine change or make sure you have an excess of the enzyme so everything is pushed in the other direction
How can you link something to an anitbody through engineering?
Engineer additional cysteine residues - these normally make disulphide bonds
Why is IgG4 unusual?
Has a weak heavy chain to heavy chain linkage, when it gets taken into a cell they can come apart
What is pyroglutamation?
A common charge variant - from a point of purity or quality control, you don’t want this
How can you prevent aggregation?
If you get charge changes, may not want to stay in solution or it may attract other molecules, so can change amino acids to bring it to its most stable structure
Why are antibodies engineered?
Humanisation
Glycosylation
Half-life alteration
Conjugation capabilities
Hinge region disulphides
Complement fixation
What can moving a sugar group off an anitbody change its ability to do?
Change its ability to trigger antibody dependent cellular cytotoxicity
What happens when you add mannose groups to antibodies?
More complement mediated cytotoxicity
What can changing CD-R regions do?
Change affinity of antibody
Changes ability to interact with complement especially with C1q and ability to interact with Fc receptors
What is KIH engineering used for?
Used to generate bispecific antibodies
What is KIH engineering?
Interactions between tyrosine (knob) and threonine (hole) residues, improves heterodimer formation
How are CH2 domains brought together?
Through glycan chain interactions
Why are bispecific antibodies useful>
You can link two thing together
What are improved version of the same termed?
Bio better / me better antibodies
How can you get biosimilars to market with 1/20th of the cost?
Once patent runs out, have it prove it has the same specificity as you have already done the safety
What could happen if you increase drug to antibody ratio?
Improve potency, but not as good clearance , exposure, aggregation and toxicity
What happens if you make different attachment sites?
Different binding
Different drug release rate etc.
What are antibody—conjugate uses?
Radio-imaging/radiotherapy
Delivery of a cytokine to a specific cell type
Delivery of a drug or pro-drug to specific cells
Longevity of anitbody in serum
What can you do with cytokines and antibodies?
Can have an anti-cytokine specific antibody
What is the link between human serum albumin and antibodies?
Can link something that binds to HSA, gives it a bigger size so isn’t filtered out so quickly
