Engineered Abs

Question 1

What is the HAMA response?

Answer 1

Human Anti Mouse Antibody response. Type 3 hypersensitivity reaction in response to rodent mAbs. Formation of immune complexes via DIC leads to anaphylactic reaction (rash to renal failure). Affects 1/2 to 2/3 of patients who take rodent Abs

Question 2

Give an example of a rodent mAb

Answer 2

Zevalin - mouse IgG1 - anti Cd20 - targets malignant B cells for apoptosis or ADCC or kills B cells by using isotype attached (beta emission)

Question 3

What are the 2 ways of humazing rodent mAbs

Answer 3

Chimerizing, CDR grafting

Question 4

How are chimeric mAbs formed?

Answer 4

Combination of human constant region genes with mouse variable region. Insert plasmid into CHO expression system. Results in 70% human and 30 % mouse.

Question 5

What are 2 examples of chimeric mAbs?

Answer 5

Infliximab - anti TNF-a - treat inflammatory disease .e.g RA. Stops TNF-a binding to receptor.
Basoliximab - anti IL-2 - immunosupresion - inhibit T cell activation which results in acute rejection - organ rejection

Question 6

How do we produce humanised mAbs?

Answer 6

CDR grafting

Question 7

What are the advantages of humanised mAbs?

Answer 7

Reduced antigenicity, Increased effector function

Question 8

What are some examples of humanised mAbs?

Answer 8

Vedolizumab - IgG1 - Integrin a4b7 - anti inflam - crohns

Gemtizumab - IgG4 - CD33 - AML

Question 9

What is a scFV?

Answer 9

Vh and Vl joined by a flexible hydrophilic peptide linker (15AA e.g. (Gly4Ser)3). Can form diabodies or triabodies.

Question 10

What is an example of a scFv?

Answer 10

Abciximab - targets gpIIb/IIIa - inhibits platelet aggregation - used after surgery to prevent blood clots

Question 11

What are the pros/cons of using scFvs as therapeutics?

Answer 11

Small, can access epitopes that larger Abs cannot. However, have shorter half life (cleared by kidney), can form aggregates and do not have an Fc region so cannot produce effector functions.

Question 12

What is a BiTE? What are two examples.

Answer 12

Bispecific T Cell Engager Ab - brings T cells to Tumour cells. E.g. Blinutomab - CD3 and CD19 (ALL), Solitomab - EPCAM and CD3 (lung cancer)

Question 13

How do we produce human VH fragments

Answer 13

Camelisation - addition of VHH sequences to increase the solubility of human VH - useful in research due to small size

Question 14

What are plantibodies?

Answer 14

Antibodies produced using transgenic plants. E.g is CaroRX - anti S. Coccus IgG - dental caries - uses tobacco plant