Wk 18: Advanced biologics - Monoclonal antibodies

Question 1

What are CDR sequences?

Answer 1

Complementarity determining region:

• Allow diversity of antibodies
• Sites for manual engineering of mAbs

Question 2

What are the challenges of mAb development?

Answer 2

• Folding errors + aggregation
• Charge heterogeneity
• Variant glycosylation patterns

Question 3

What are the problems of charge heterogeneity?

Answer 3

Can affect binding profile to target:
- Target epitope binding

• Fc fragment effector functions

OR affect aggregation propensity of mAb in formulated form

Question 4

What are the problems of variant glycosylation patterns?

Answer 4

Affects:
- Immunogenicity of therapeutic

• Binding affinity at Fc-fragment

Question 5

How can the half life be engineered?

Answer 5

Glycosylation, mAb surface charge + mAb-target binding strength:
- Fusion to another protein inc size + HL

• Conjugation to polymers (PEGylation) inc HL
• CH2 + CH3 interface is site for specific mutation that change HL

Question 6

How can Fc domain interaction be modulated?

Answer 6

Mutations to Fc fragment domain

Question 7

What is PEG?

Answer 7

• Polyethylene glycol
• Long polymer chain
• Both hydrophilic + lipophilic, watersol + nontoxic
• Synthesised from chains of ethylene oxide
• Linked to protein/peptide through reactive molecular groups of aa side chain (lysine)

Question 8

Why were mouse antibodies shown to have limited use as therapeutic agents?

Answer 8

• Short serum HL
• Inability to trigger human effector functions
• Triggered human anti-mouse antibody response

Question 9

What is sdAb?

Answer 9

Single monomeric variable Ab domain + lacking light chain + CH domain of heavy chain in conventional fab region

Question 10

Where was the first sdAb first engineered from?

Answer 10

VHH domain of heavy chain Ab in camelids (alpacas, camels)

Question 11

What are the advantages of single domain antibodies?

Answer 11

• High stability to function in extreme conditions
• Good penetrability which cross BBB
• Recognise novel epitopes that regular size Ab can’t
• Improve bioavailability
• Expressed in prokaryotic + eukaryotic systems

Question 12

What are antibody drug conjugates?

Answer 12

• Use targeting ability of mAb to deliver potent cytotoxic payloads to target
• Improve therapeutic index of antineoplastic agents by restricting systemic delivery to cells that express target antigeen

Question 13

What is monomethyl auristatin E?

Answer 13

• Synthetic antineoplastic agent: inhibits tubulin polymerisation
• Toxic tf linked to mAb

Question 14

What is mesothelioma?

Answer 14

Cancer that develops in lining that covers outer surface of body organs (linked to asbestos exposure)

Question 15

What is used as a therapeutic target for mesothelioma?

Answer 15

Mesothelin:

• Cell surface glycoprotein + tumour differentiation antigen expressed in aggressive tumours
• Cancer biomarker

Question 16

What is used to treat mesothelioma?

Answer 16

• SS1P: anti-mesothelin immunotoxin - SS1 Fv fused to PE38
• Amatuximab: chimeric anti-mesothelin mAb containing SS1 Fc
• IL 12-SS1 Fv: mAb recognises mesothelin + IL-12 + contains SS1 Fv toxin

Question 17

In which area does resistance occur when treating mesothelioma?

Answer 17

Region 1 - protein to protein interactions inhibiting mAb binding

Question 18

Where is recombinant mesothelin expressed?

Answer 18

Peritoneal tumour

Question 19

What is IL12?

Answer 19

Proinflammatory cytokine that bridges innate + adaptive immunity to active natural killers, NKT + T cells