Lecture 6- Monoclonal antibodies

Question 1

What are monoclonal antibodies?

Answer 1

Monoclonal antibodies are monovalent antibodies which bind to the same epitope of an antigen and are produced from a single B-lymphocyte clone

Question 2

antibodies are produced by

Answer 2

plasma cells (mature B cells)

Question 3

​which part of the antibody recongises antigen

Answer 3

• Fab (fragment antigen binding) part of antibody recognises antigen
  
  • Hypervariable regions meaning that antibody can recognise an infinite number of antigens
    
    • Paratope region on antibody reacts with epitope (antibody binding site) of antigen

Question 4

which part of the antibody interacts with the cell surface receptors on other cells

Answer 4

• Fc (fragment crystallizable region) region
  
  • Interacts with cell surface receptors on other cells

Question 5

Monoclonal antibodies in clinical practice

Answer 5

• Diagnostics
  
  • E.g. immunohistochemistry (ELISA)
• Therapeutics

Question 6

Production of monoclonal antibodies

Answer 6

e.g. Hybridoma technology

• First generated in mice in 1975 using a hybridoma technique
• The generation of hybridomas involves immunising a certain species against a specific epitope on an antigen and then harvesting the B-lymphocytes from the spleen of the mouse
• The B-lymphocytes are then fused with an immortal myeloma cell line not containing any other immunoglobulin-producing cells
• The resulting hybridoma cells are then cultured in vitro so only the hybridomas (i.e. the fusion between the primary B-lymphocytes and myeloma cells) survive
• Selected hybridomas are found making a specific desired clonal antibody

Question 7

Types of monoclonal antibodies drugs

Answer 7

• Naked monoclonal antibodies
• Conjugated monoclonal antibodies
• Bispecific monoclonal antibodies

Question 8

Naked monoclonal antibodies

Answer 8

• Derived from mice (murine)
  
  • Recognised as foreign- rapidly cleared and destroyed
• Chimeric (65% human)
• Humanised (>90% human)
• Fully human (100% human)
  
  • Significant immunogenicity

Question 9

Conjugated monoclonal antibodies

Answer 9

• Monoclonal antibody is linked to a potent drug to allow targeted delivery to cancer cell
  
  • Tumour specific antigen is targeted by monoclonal antibodies
  • Drug (cytotoxic agents) internalised 9receptor mediated endocytosis) by cancer cell and killed
    
    • E.g. lysosomal degradation: ADCC and induction of apoptosis
• Limits systemic exposure
• ADCs (antibody-drug conjugates) are designed to allow for the use of highly potent, normally intolerable, anticancer cytotoxic agents

e.g. B/T cell lymphoma

Question 10

Bispecific monoclonal antibodies e.g. Mosunetuzumab

Answer 10

• Utilise 2 binding domains of antibody structure
• Bind onto 2 different cell populations–> bringing the two populations into close proximity e.g. T cell and malignant B cell (enhanced cell mediated cytotoxicity)
• In clinical trials

Question 11

How do they work in cancer?

Answer 11

Binding with cell surface receptors to either activate or inhibit signalling within the cell

1. Binding with cell surface receptors to activate:
   
   • antibody-dependent cell-mediated cytotoxicity (ADCC) or
   • complement-dependent cytotoxicity (CDC)
2. Internalization (ie being taken in by the cell through the membrane) for antibodies delivering toxins into the cancer cell
3. Blocking inhibitory effects on T cells (checkpoints). Thus activating T cells to help ‘kill’ the cancer cells

Question 12

Monoclonal antibodies in haemtology

Answer 12

• Understanding what antigens are present on cancer cells and on normal tissue we could try to develop specific targeted treatments.
• Cluster of differentiation (CD) classification.

Question 13

What type of cancer is lymphoma?

Answer 13

• Lymphoma divided into B and T cell neoplasms – clonal proliferations of lymphoid cells
• It typically causes enlargement of lymph nodes
• The spleen, bone marrow and other areas of the body such as liver, skin, testes and bowel (‘extra-nodal’) may also be involved

Question 14

People with lymphoma often complain of

Answer 14

• drenching night sweats
• fevers
• weight loss .. But some have none of these symptoms

​

Question 15

lymphoma b cells express

Answer 15

CD20 - therefore creation of mAb which binds to CD20 e.g. Rituximab

Question 16

types of B cell lymphoma

Answer 16

• follicular lymphoma
• diffuse large B cell lymphoma

Question 17

clinical examples of lymohoma

Answer 17

Question 18

Lymphoma treatment

Answer 18

• Chemotherapy
• Radiotherapy
• Monoclonal antibody therapy
• Emerging new targeted therapy
• Stem cell transplantation

Question 19

mAbs in Lymphoma

Answer 19

Question 20

Side effects of monoclonal antibodies in treatment of lymphoma

Answer 20

• Some have no or mild symptoms eg mild fatigue
• Many have a mild reaction to the 1st infusion and then tolerate subsequent treatments well
• A few people will have severe infusion related reactions as their immune system reacts to the presence of a ’foreign’ protein

Question 21

monoclonal antibodies in solid cancer

Question 22

monoclonal antibodies in autoimmune disease

Answer 22

Question 23

monoclonal antibodies in cardiology

Answer 23

Question 24

monoclonal antibodies in endocrine disorders

Answer 24