Immunotherapy

Question 1

What are the two immunomodulators called?

Answer 1

Immunosuppressants
Immunostimulants

Question 2

What are the three biologics?

Answer 2

Antibodies
Cytokines
Cell Therapy

Question 3

What are the differences between small molecules and biologics?

Answer 3

Small molecules
small size, stable, simple, non-specific, oral, high permeability, enzymes, oxidases(hepatic), hydrolases, conjugating enzymes, easily distrubuted in circulation and there is NO immunogenicity

Biologics
Large molecules, unstable, complex, specific, parenteral, invasive roye, low permeability, enzymes inc nucleases, peptidases, proteinases and hydrolases, limited distribution via circulation and lymphatics. there is immunogenicity

Question 4

What are cytokines?

Answer 4

Cytokines are a family of small proteins used for communication in the immune system.
They play diverse roles in the regulation of an immune response: type, magnitude, location.

Question 4

What are cytokines?

Answer 4

Cytokines are a family of small proteins used for communication in the immune system.
They play diverse roles in the regulation of an immune response: type, magnitude, location.

Question 5

What do cytokines do?

Answer 5

Cytokines may drive inflammation, or dampen inflammation.
Cytokines are also important for the development or differentiation of immune cells.
Depending on the situation, we may wish to block or enhance a cytokine response.
(Note that classification of cytokines as pro- or anti-inflammatory will vary depending on the disease. Example shown is for rheumatoid arthritis.)

Question 6

How are recombinant cytokines produced?

Answer 6

Uses recombinant DNA technology
Joining together of DNA from different sources.
Allows genes from one organism to be transferred to another for propagation or expression (protein product).
The human gene for the cytokine of interest is inserted into a vector (a DNA molecule used to carry the gene of interest into a cell and drive its expression. e.g. plasmid)
The vector + gene is introduced into a cell (e.g. E. coli) which produces the protein product.

Question 7

What is the structure of antibodies like?

Answer 7

Composed of two heavy and two light chains.
Each chain has two regions: variable (one Ig domain) and constant (3-4 Ig domains).
Fc region: binds to cell surface receptors and complement proteins to mediate antibody functions.
Complementarity-determining regions (CDRs) are short, hyper-variable sequences of amino acids in the variable region of the antibody. They bind to antigen and determine antigen specificity.

Question 8

What alters antibody functions?

Answer 8

Viruses, toxins, host proteins
Depend on Fc region: species mismatch will decrease function
ie blocking neutralisation, complement activation, ADCC, Opsonisation and phagocytosis

Question 9

What is passive immunization?

Answer 9

Passive immunity is provided when a person is given antibodies to a disease rather than producing them through his or her own immune system

Question 10

What is cell therapy?

Answer 10

Giving a patient new cells to:
Replace damaged cells
Change the function of existing cells
Kill tumour cells
Stem cells and/or immune cells most commonly used.
Allogeneic or Autologous

Question 11

What is allogenic?

Answer 11

Taken from different individuals of the same species

Question 12

What is autologous?

Answer 12

An autologous stem cell transplant uses healthy blood stem cells from your own body to replace your diseased or damaged bone marrow.

Question 13

What are the advantages and disadvantages of autologous cell therapies?

Answer 13

ADV
Recognised as ‘self’ by the immune system - no rejection risk
No graft -vs- host disease
Can give multiple doses
DISADV
Expensive
delay in treatment
starting material may not have necessary characteristics

Question 14

What are the adv and disadv of allogeneic cell therapies?

Answer 14

adv
can be manufactured at scale and banked
available immediatly
reproducibility - donors screened for desirable characteristics
disadv
immunogenic - risk of rejection
graft vs host disease

Question 15

What are small molecule immune suppressants used for?

Answer 15

Broad inhibition of the immune response (non-specific)
Given prophylactically to prevent organ transplant rejection, or for the treatment of autoimmune disease.
(includes short peptides)

Question 16

What is Azathioprine and what does it do?

Answer 16

Azathioprine is a prodrug.

It inhibits purine synthesis, purine are required to produce DNA and RNA by inhibiting by purine synthesis less DNA and RNA are produced for the sys thesis of WBC therefore immunosuppression

It is converted to the active metabolites 6-mercaptopurine (6-MP) and thioguanine (6-TGN).
Metabolites of azathioprine inhibit purine synthesis and halt DNA replication via incorporation into newly synthesised DNA (Remember! T and B cells are actively replicating cells)
6-thioguanine triphosphate inhibits activation of rac1 in T cells (downstream of CD28), inducing apoptosis.

Severe acute Crohn’s disease, severe SLE, non-responding rheumatoid arthritis, severe refractory eczema, suppression of transplant rejection, myasthenia gravis

Increases risk of cancer and infection, bone marrow depression (esp. in those with a genetic deficiency in thiopurine S-methyltransferase.), vomiting, pancreatitis, thrombocytopaenia.
Thiopurine S-methyltransferase methylates 6-mercaptopurine to methylmercaptopurine (inactive).

Question 17

What is cyclosporine? and what does it do?

Answer 17

Cyclosporine is a calcineurin inhibitor, a cyp450, cyp3a4, p gycoprotein inhibitor. Inhibits synthesis of interleukins which are essential for the proliferation of T cells

Cyclic peptide of 11 amino acids.
Produced from a fungus, Tolypocladium inflatum
A calcineurin inhibitor.

Calcineurin would normally be activated by signalling through the T cell receptor, increasing production of the cytokine, IL-2.
IL-2 drives T cell differentiation.
Cyclosporine forms a complex with a cytosolic protein (cyclophilin) in lymphocytes.
The complex inhibits calcineurin, reducing synthesis of IL-2.
Severe acute ulcerative colitis, severe active rheumatoid arthritis, severe atopic dermatitis (short-term), severe psoriasis, organ transplantation, bone-marrow transplantation.
Decreases resistance to infection (live attenuated vaccines not advised).
Nausea, tiredness, hair growth, tremor, high blood pressure, kidney dysfunction.
May increase long term risk of cancer.

Question 18

What is methotrexate and what does it do?

Answer 18

Inhibits dihydrofolate reductase (important for synthesis of purines and pyrimidines) when used as a chemotherapeutic agent.
Also used as an immunosuppressant in severe Crohn’s disease, moderate to severe active rheumatoid arthritis.
Broader mechanism of action in RA than in cancer.
Once a week dosing.
Cautions: bone marrow suppression (fall in WBC and platelet counts), GI, Liver and pulmonary toxicity

Question 19

How does methotrexate work in rheumatoid arthirits?

Answer 19

Folate antagonism - blocks folate - folate causes proliferation of inflammatory cells - Folate metabolism is required for DNA synthesis

Adenosine Accumulation - Adenosine has anti-inflammatory effects on immune cells

Inflammatory signalling pathway - Downstream signalling of e.g. cytokine receptors

regulating - RANKL/RANK/OPG can cause bone erosion

Immune system - regulate CD4+T Alters ratio of Th17 to Treg cells

Question 20

What is fingolimod? what does it do?

Answer 20

A sphingosine 1-phosphate receptor modulator used in Multiple Sclerosis.
Prevents egress of T cells from lymph nodes (reduces recirculation of autoreactive T cells to the CNS).
Increases proportion of Treg cells.
Can cause persistent bradycardia therefore not recommend in patients with pre-existing cardiac disorders.
Increased risk of skin cancers and lymphoma, congenital malformations, liver injury and herpes meningoencephalitis

Question 21

Other examples

Answer 21

cladribine
sulfasalazine
tacrolimus
leflunomide
hydroxychloroquine
mycophenolate mofetil
sirolimus (rapamycin)

Question 22

What are corticosteroids?

Answer 22

Steroid hormones produced in the adrenal cortex.
E.g. cortisol (glucocorticoid) and aldosterone (a mineralocorticoid).
Synthetic versions can be used to modify the immune response (anti-inflammatory at low doses, immunosuppressive at higher doses).
Dexamethasone
Prednisolone
Reduce migration on immune cells to sites of inflammation, inhibit NFkB (pro-inflammatory transcription factor), drive production of IL-10.
Commonly used to control acute inflammation.

Question 23

Examples of immunosuppressant antibodies?

Answer 23

Muromonab
CD3
Kills T cells (e.g. ADCC)
acute transplant rejection
Basiliximab
CD25
Antagonist – stops IL-2 binding to its receptor and inhibits T cell activation
prophylaxis for kidney transplant rejection
Alemtuzumab
CD52
Depletes T and B cells (ADCC)
MS, B cell chronic lymphocytic leukaemia

Question 24

What are antibody mediated blocade of TNF - a?

Answer 24

TNF-α is a pro-inflammatory cytokine.
Acts on multiple different cell types to drive inflammation.
Implicated in the pathogenesis of autoimmune and autoinflammatory diseases (e.g. RA, psoriasis, ankylosing spondylitis, Crohn’s disease, ulcerative colitis)
Infliximab, adalimumab, etanercept, golimumab, certolizumab.

Question 25

What is TNF a?

Answer 25

TNF-α is a pro-inflammatory cytokine.
Acts on multiple different cell types to drive inflammation.
Implicated in the pathogenesis of autoimmune and autoinflammatory diseases (e.g. RA, psoriasis, ankylosing spondylitis, Crohn’s disease, ulcerative colitis)
Infliximab, adalimumab, etanercept, golimumab, certolizumab.

Question 26

How do sentinel cells recognise damage and infection? What does it lead to?

Answer 26

Pathogen-associated Molecular Patterns (PAMPs) are molecular signatures shared across groups of bacteria, fungi or viruses, but not commonly found on host cells.
Damage (danger)-associated Molecular Patterns (DAMPs) are host proteins released from cells or generated from tissues following injury.

Individual cells of the innate immune system express a variety of germline encoded Pattern Recognition Receptors (PRR). e.g. Toll Like Receptors (TLR).
Recognition of PAMPs or DAMPs by PRR leads to activation of immune cells.
inflammatory cytokine production
enhanced antigen presentation
internalisation/destruction of pathogens

Question 27

What is imiquimod?

Answer 27

Via TLR7
Genital warts, superifical basal cell carcinoma (after surgical removal), Bowens disease, actinic keratosis.

Question 28

What is GM-CSF?

Answer 28

Granulocyte Monocyte Colony Stimulating Factor (GM-CSF)
Sargramostim/Leukine
Stimulates generation of immune cells (neutrophils, monocytes, macrophages, DCs)
Used to help regenerate immune function after a bone marrow transplant.

Question 29

What are type 1 interferons?

Answer 29

Produced by virus-infected cells very early after infection
Acts on neighbouring cells to increase resistance to viral infection
Increases MHC-I expression and antigen presentation – infected cells can be identified by Cytotoxic (CD8+) T cells
Activates NK cells

Question 30

What are interferon - beta?

Answer 30

For the treatment of relapsing-remitting MS.
Serum levels of endogenous IFN-beta reduced in MS.
Examples: Betaferon (bacteria), Avonex, Rebif (CHO cells).
Treatment may fail if the patient begins to produce neutralising antibodies to interferon-beta.

Question 31

What are checkpoint inhibitors?

Answer 31

Tumour cells can express a protein on their surface called PD-L1.
PD-L1 binds to PD-1 on T cells
This sends a negative signal to the T cell, inactivating it.
PD-L1/PD-1 inhibitors (e.g durvalumab, atezolizumab, avelumab) can release this inhibition, allowing the T cell to kill the tumour cell.

Question 32

What are CAR T cells?

Answer 32

T cells needs antigens to be “presented” to them.
An antigen presenting cell (e.g a Dendritic cell) processes antigens into short peptides and displays them on MHC molecules.
The T cell receptor “sees” the antigen bound to MHC and becomes activated (Remember! Also requires a second, costimulatory signal).

Question 33

What are CAR T Cells as an immunology primer?

Answer 33

The T cell can then seek out its target cell, which will also have MHC-antigen complexes on the cell surface.
We could expand and activate some tumour specific T cells in the lab and give them back to the patient.
BUT! Tumour cells often downregulate processing and presentation of antigens to hide from T cells.

Question 34

What is CAR T cell therapy?

Answer 34

Used to treat B cell Acute Lymphoblastic Leukaemia (B-ALL)
The patients T cells are genetically modified to express a chimeric antigen receptor (CAR)
Recognizes a protein antigen on the surface of leukaemia cells WITHOUT the need for processing and presentation on MHC molecules.
This directly instructs the T cells to kill the tumour cells.

Question 35

What is Yescarta?

Answer 35

Acute lymphoblastic leukemia (ALL)Diffuse large B-cell lymphoma (DLBCL)
~ 60% disease free survival / remission.
Target antigen is CD19
Autologous
Persist for 1-7 years.

Question 36

What are toxicities?

Answer 36

In 25-50% of patients, in vivo T cell expansion and cytokine production at higher that physiologic levels are observed.
This can activate other arms or the immune system erroneously, and have toxic effects.