Lecture 14

Question 1

Uses of antibodies in therapy

Answer 1

Cancer (antibodies as magic bullets e.g. anti-CD52 which are found on white blood cells)

Question 2

Examples of successful antibodies to treat cancer

Answer 2

-CD20 antibodies such as rituximab which recognises B cells. It’s a good acitivator of complement and ADCC

• Anti-Her2 antibodies (herceptin) which recognises Her2. The antibody locks the receptor, stopping the tumour from growing but it can evoke ADCC

Question 3

Which antibodies deplete leukocytes and their uses

Answer 3

Antibodies to CD52, CD3, CD4 to help with organ transplantation and treating graft vs host autoimmune diseases

Question 4

Which antibodies help with blocking cytokines

Answer 4

Antibodies to TNF-alpha, IL-1, IL-6, complement

Question 5

What can immune checkpoint inhibitors do

Answer 5

T and B cells can be switched off. Such as antibodies to CTLA-4 (expressed by t cells once) and PD-1 (expressed by many)

Question 6

How do cancers subvert immune responses

Answer 6

By down regulating the cells that expect to kill them. For example producing cytokines including Tregs and expressing checkpoint inhibitors

Question 7

what does PD-1 interact with

Answer 7

PD ligands which are often presented on tumour cells which switches them off.

Question 8

What can CTLA-4 and PD-1 act as

Answer 8

Immune checkpoints which are useful in dampening immune responses and exploiting cancer cells

Question 9

Order of efficiency

Answer 9

Complement activations: IgGe -> IgG1 -> IgG2
Fc receptors on phagocytes: IgG1 = IgG3 -> IgG4
Fc receptors on NK cells: IgG1 = IgG3
FcRn (determines half life which is important in prolonging all subclasses)

Question 10

What can modifications of Fc region allow

Answer 10

Can promote binding to neonatal Fc receptors which increases half life

Question 11

What dpes C1Q bind to

Answer 11

Binds to the hinge going into the CH2 domains

Question 12

What is FcyR1 and FcyR2

Answer 12

“lower hinge” which is important in phagocytes

Question 13

What is fCRYr3a found on

Answer 13

Natural killer cells

Question 14

what does FcryRN involve

Answer 14

Regions between the ch2 and ch3 domains - could mutate these and improve the properties of antibodies.

Question 15

What does glycoengineering allow

Answer 15

Allows us to engineer the carbohydrate rather than the protein

Question 16

What does removal of fucose improve

Answer 16

Removal of fucose at conserved asparagic 297 residue improves the IgG interaction with FcyR2 which improves ADCC.

Question 17

How can we improve antibodies for therapy

Answer 17

Improving the properties of antibody by protein or glyco-engineering to improve half life (by improving or removing effector functions).

Alterations of glycolysation of IgG can improve interaction with FcRN (increasing half life) and interaction with FcR on NK cells

Glycolysation of Fc receptors influences effector functions and half life

Question 18

What can antibody fragments be useful for

Answer 18

Sometimes big antibody fragments are hard to get into solid tumours

Question 19

How does Bi-specificity work

Answer 19

Bi-specific antibodies consist of 2 fabs in different targets that bring effector cells close to the cell you want to kill

Question 20

Modifications in bi-specificity

Answer 20

Fab fragments and single chain antibodies (smaller antibody fragments may enhance phamacokinetic properties compared to full length antibodies.

Question 21

What does Fragment antigen binding consist of

Answer 21

A variable domain and the first constant region of each heavy and light chain

Question 22

What do Single chain variable fragments consist of

Answer 22

Light chain and heavy chain variable regions joined by a linker peptide

Question 23

Passive immunisation for COVID

Answer 23

Covalescent sera had limited efficiacy.

Monoclonal antibodies to SARS cov-2 consisted of Sotrovimab

Question 24

Advantages of passive over active immunisation

Answer 24

• Immediate protection (up to 4 weeks)
  -Suitable for immunocompromised patients
  -May relieve sever symptoms

Question 25

Disadvantages of passive immunisation

Answer 25

No long-lasting protection
Not very effective against latest variants
May promote escape mutants
Expensive to produce and administer

Question 26

Future prospects for antibodies

Answer 26

Antibodies to conserved epitopes
Coctials of antibodies to different or bi-specifics

Question 27

What antibodies can be used to treat excessive inflammation

Answer 27

Anti-interleukin 6 receptor (Toxilizumab)
Anti-C5a (Vilobelimab)

Question 28

Car-2 t cells (chimeric antigen receptors)

Answer 28

T cells can be engineered to recognise tumour antigens
Treats acute leukocute lymphocytic leakemia

T cells are isolated from patients tumour
They’re engineered in vitro to express a chimeric antigen receptor
CD19 is fused to signalling domains which contain ITAB motifs (when reinjected it will bind to CD19 on tumour cells and t cells will become active)

Question 29

Immunotherapy in the future

Answer 29

• Soluble t receptors
• Cancer vaccines (induce immune responses against tumour)

-tumour infiltrating lymphocyte therapy

-Gene editing of antibody genes in vivo (CrispR Cas9)- engineering the immune response to produce antibodies of the right type

-Modulating innate immune cells - macrophages tend to be immunosuppressive

-Use of gamma delta T cells for cancer