JT- Antibodies and Autoimmunity

Question 1

How can antibody therapeutics be improved? (2)

Answer 1

• Modify the constant region for better effects
• Alter glycosylation to increase or decrease phagocytosis

Question 2

What mutations enhance ADCC activity in IgG? (3)

Answer 2

• Ser239Asp:Glu330Leu:Ile332Glu → ~100x increased ADCC
• Gly236Ala → 70x increased FcγRIIA binding
• Non-fucosylated variants of rituximab/trastuzumab → ~100x more potent

Question 3

How can effector function be minimized in antibodies? (3)

Answer 3

• LALA mutations (Leu234Ala, Leu235Ala) → reduce FcγR binding
• Asn297Ala → aglycosylated IgG1
• Fc engineering for humanised CD3-specific antibodies → reduce flu-like symptoms

Question 4

What are features of IgG lacking effector function? (3)

Answer 4

• Use of IgG4 subclass (e.g., Natalizumab, Eculizumab)
• Fab-arm exchange → functionally monovalent
• IgG2–IgG4 hybrid (Eculizumab) → lacks FcγR and complement activity

Question 5

How can FcRn interactions improve antibody half-life? (2)

Answer 5

• Met428Leu:Asn434Ser in Avastin → 3–4x longer half-life
• Enhances antitumor activity in mice

Question 6

What are Abdegs and their function? (1)

Answer 6

FcRn-blocking antibodies → reduce pathogenic IgG in autoimmune disease

Question 7

What are bispecific antibodies and what do they do? (2)

Answer 7

• Bind to two different antigens
• Used in immunotherapy (e.g., tumor + CD3 binding for T cell engagement)

Question 8

What are the generations of bispecific antibody engineering? (3)

Answer 8

• Quadroma (1980s) – low specificity, difficult purification
• Knob-into-hole (1997) – specific heavy chain pairing
• CrossMAb (2007–2010) – fixes light chain mispairing

Question 9

How does the DuoBody platform produce bispecific IgG1 antibodies? (6)

Answer 9

• Mutation introduction in CH3 domain (e.g., K409R & F405L)
• Produce and purify parental antibodies
• Mix and dissociate into Fab arms under special conditions
• Promote reassociation into bispecifics
• Achieves ~95% yield
• Final purification step ensures purity

Question 10

What are key barriers for therapeutic antibodies? (1)

Answer 10

Target engagement is difficult due to size and membrane crossing

Question 11

Why is treating dementia with antibodies difficult? (6)

Answer 11

• Involvement of amyloid, tau, alpha-synuclein
• Genetics and neuroinflammation
• BBB limits drug access
• Lack of biomarkers
• Costly, long trials
• Diagnosis and symptom variability

Question 12

How does active amyloid immunotherapy work? (2)

Answer 12

• Introduces Aβ fragments to stimulate immune response
• Antibodies bind and help clear plaques

Question 13

How does passive amyloid immunotherapy work? (2)

Answer 13

• Direct administration of monoclonal antibodies
• Binds Aβ → clears plaques and improves cognition

Question 14

What is the difference between active and passive immunotherapy? (3)

Answer 14

• Active → body produces antibodies
• Passive → external antibodies administered
• Both aim to reduce amyloid plaques

Question 15

What factors may cause failure in Alzheimer’s antibody trials? (5)

Answer 15

• Incorrect target or timing
• Low dose or poor engagement
• Comorbidities
• Incorrect diagnosis
• Ineffective antibodies

Question 16

How do amyloid conditions affect antibody efficacy? (4)

Answer 16

• Early treatment → good outcome
• Late treatment → binds soluble amyloid, less plaque clearance
• Amyloid in vessels (CAA) → inflammation risk
• Plaque-specific antibodies → fewer side effects, more efficacy

Question 17

What were the effects and risks of Donanemab? (2)

Answer 17

• Slowed cognitive decline by up to 35%
• Associated with microbleeds

Question 18

How can antibodies cross the BBB? (3)

Answer 18

• Use bispecific antibodies targeting RMT receptors
• Ensure weak binding, no receptor crosslinking
• Increases brain antibody delivery

Question 19

What are the advantages of antibody engineering for the brain? (3)

Answer 19

• Prevents inflammation
• Increases antibody brain levels (up to 10x)
• Still interacts with Fc receptors on microglia

Question 20

What are other potential antibody targets in dementia? (3)

Answer 20

Tau

ApoE

Cytokines (e.g., TNF-α)