Block E - IP lecture 3

Question 1

what are classical DMARDs/ convential cynthetic DMARDs ?

Answer 1

These are disease modifying anti rheumatoid drugs , not used for pain management normally used in combination.

Question 2

examples ?

Answer 2

Sulphazalazine,

Methotrexate,

Leflunomide

hydroxylchloroquine

Question 3

wxplain how sulphazalzine came about ?

Answer 3

Designed in 1938 specially for use in rheumatoid arthritis, the idea was to combine an antibacterial drug and anti-inflammatory agent. Two drugs are mesalazine and sulphapyridine, 90% of sulphapyridine is absorbed compared to 20-30% of mesalazine absorbed.

Question 4

what can it also be used for .

Answer 4

ulcerative colitis (UC)

Question 5

mode of action ?

Answer 5

Both breakdown products may contribute, as well as intact molecule,

Inhibits B cell activity- reduces IgG and rheumatoid factor (RF) production

Inhibition of NFκB translocation to nucleus for in vivo studies

Inhibition of cytokine, chemokine and adhesion molecule synthesis

Osteoclast formation

Question 6

adverse effects ?

Answer 6

Skin reactions - rashes

gastro-intestinal intolerance

Hematological effects - especially in patients with RA

leucopenia

neutropenia

Thrombocytopenia

Blood counts should be undertaken during first 3 months

Question 7

why is it a pharmacological nightmare ?

Answer 7

Not a very potent or selective drug (affinity moderate- need to use lots of drug),

Therefore, the potential for off-target effects is high - leads to adverse effects,

However - it works, is cheap and side-effects manageable,

Safe to use in pregnancy at a low dose alongside folic acid supplement and can be continued preoperatively.

Contains short half-life of 3-4 hours

Question 8

methotrexate mode of ation. ?

Answer 8

Defined Mechanisms of Action (differ between high and low doses).

inhibits dihydrofolate reductase - therefore inhibits purine/pyrimidine synthesis, DNA synthesis and cell proliferation, including T-cell and B-cell populations, osteoclasts and fibroblasts

Stimulates the release of adenosine (low dose therapy) - Adenosine has potent anti-inflammatory effects through A2a and A3 receptors

A first-line drug in treating rheumatoid arthritis

Often used in combination with other agents such as sulphasalazine and steroids

Highly effective in a significant proportion of patients

Adverse effects are predictable from inhibition of cell proliferation and dependent on dose used

e.g. Bone marrow depression and blood dyscrasias

Question 9

adverse effects ?

Answer 9

Skin reactions - rashes

gastro-intestinal intolerance

Hematological effects - especially in patients with RA

leucopenia

neutropenia

Thrombocytopenia

Liver issues

Elevation of liver enzymes

CNS problems – fatigue and headaches

Not recommend in pregnancy

Question 10

why does mechanims matter

Answer 10

Develop better drugs/medicines that mimic the true effect of Sulphalazine/Methotrexate (targeted approach - without side effects).

Better biomarkers which can recognise quickly if csDMARD is working

Pharmacogenomics - Improve personalised medicine

Question 11

what are modern DMARDs- biologics ?

Answer 11

This is targeted where the mechanism of action is known.

Biological DMARDs (bDMARD);

Immunomodulatory (target cytokines and immune cells),

Antibodies designed to target inflammatory mediators

Used if patients respond inadequately to classical DMARDs such as methotrexate,

Blood cells counts, liver and kidney functions need to be taken before biological DMARDs are used.

Question 12

target for immuno-modulation ?

Answer 12

Can target pro inflammatory cytokines including IL-6, IL-23, IL-1 , Il-17 and TGF beta.

Can also directly target B and T cell function to modify disease progression

Question 13

what cytokines do bMARDs target ?

Answer 13

So from our knowledge of RA what would be the key inflammatory cytokines to target?

Tumour necrosis factor alpha (TNFα) produced by B/T cells and macrophages causes potent inflammation and leads to cartridge destruction.

Interleukin 1 beta (IL-1β) contributes to RA by recruiting and activating other immune cells

Interleukin 6 (IL-6),

Interleukin 17 (IL-17)

Question 14

2 forms of TNF alpha ?

Answer 14

1st form is membrane bound TNF alpha which is converted to 2nd soluble form by TNF converting enzyme (TACE).

When targeting TNF alpha need to be aware there are 2 forms with different molecular weights

Question 15

TNF alpha receptors ?

Answer 15

There are 2 TNF alpha receptors (TNFR-1 and TNFR-2), share similarities in structure , both are trimers and contain extracellular portions. However, the intracellular portions differ with different downstream effects.

Question 16

TNFR2 ?

Answer 16

TNFR2 predominantly signal with TRAF 2 leading to NFkB

Question 17

TNFR 1 ?

Answer 17

TNFR1 is associated with apoptosis

Question 18

transcriptional productis of TNF alpha signalling ?

Answer 18

TNFa - binds to receptor to produce more TNF and IL-1 considered an autocrine route

Il-1b

Upregulation of adhesion molecules (ICAM-1, VCAM-1)

Cytokines that further enhance the immune response

Activators of inflammatory pathways (arachidonic acid metabolites, super-oxides and nitric oxide)

Question 19

strucutre of infliximab ( remicade ) ?

Answer 19

This targets TNF, Fc portion of antibody is on the bottom and Fab portions are present on the arms. The first generation used chimeric human and mouse antibody, the human portion prevents rejection by body.

Infliximab is a monoclonal IgG1 antibody for treatment of RA developed in 2000.

Question 20

mechanism of action ?

Answer 20

Binds and neutralizes both soluble and membrane bound TNFa - inhibits further activity.

By antibody binding to the soluble and insoluble form of TNF alpha receptors this prevents TNF alpha from binding to receptors and downstream signalling of NFkB and apoptosis.

Administered intravenously every 8 weeks at a dosage of 3-5mg/kg

Question 21

other postilated mechanisms ?

Answer 21

Antibody dependent cell-mediated cytotoxicity (ADCC)

Lysis of TNFa-expressing cells through complement (C’) activation .

Infliximab binds to membrane bound TNF on T cells , initiating the complement cascade which results in complement coating the antibody and recruiting dendritic cells which engulf and breakdown T cells.

Question 22

Entenercept ?

Answer 22

Etanercept is a recombinant fusion developed in the year 2000 for the soluble TNF receptor linked to the Fc portion of human IgG. This binds to the TNF receptor inhibiting TNF mediated responses.

Etanercept is not recombinant antibody- Soluble TNFα receptor fused to Fc domain of human IgG

Question 23

Adalimumab ?

Answer 23

Adalimumab recombinant IgG antibody which binds to soluble and insoluble TNF alpha receptors with high affinity.

Question 24

Anakinra ?

Answer 24

Anakinra

Recombinant human IL-1 receptor antagonist – binds directly to IL-1 receptor preventing binding of Il-1 , administered sub cutaneous

Question 25

Targeting T cells ?

Answer 25

T-cells respond to APCs and expand/differentiate leading to the release of pro-inflammatory mediators

Anti CD80/86-CD28 inhibitor development (Abatacept),

Abatacept is a fusion protein constituted by an Ig fused to the extracellular domain of a cytotoxic T-lymphocyte antigen-4 (CTL4),

It binds with high affinity to the CD80/86 ligand on APCs,

It blocks the interaction between the APC and T-cell.

Question 26

Abatacept ?

Answer 26

Abatacept results in decreased T cell proliferation and cytokine production , it is administered intravenously.

Question 27

side effects ?

Answer 27

Side effects include hypersensitivity , risk of serious infections, no studies about use in pregnancy.

Question 28

Targeting T cell activation ?

Answer 28

CD28 is found on T cells, CD80/CD86 are found on APC which can be macrophages and dendritic cells. Abatacept binds directly to CD80/CD86 and prevents the interaction between CD28 on APC and CD80/CD86 on APC.

Question 29

Targeting B cels ?

Answer 29

B-cells not only give rise to antibody producing plasma cells but are also highly effective APCs,

Anti-CD20 antibody development (Rituximab) – to deplete B cells

Chimeric murine-human monoclonal antibody – binds to the CD20 membrane receptor

Beneficial when anti-TNF therapy has failed

Side effects – infusion reaction (30-40% of patients) – consists of headache, fever, rash, hypotension, amongst others.

Question 30

CD20 ?

Answer 30

on B cells

Question 31

rituximab ?

Answer 31

CD20 on B cells , rituximab binds to the receptors on B cells and depletes B cell population, particular beneficial in RA patients who are autoantibody positive.

Question 32

targeted synthetic DMARDs ?

Answer 32

tsDMARDs – JAK inhibitors (New group of small molecule drugs to target RA)

Target the Janus-kinase (JAK) pathway

Receptor associated intracellular proteins critical for signal transduction from some cytokine receptors, not TNF alpha.

IL-2, IL-6 and Interferons of particular interest.

Inhibitors - Effective in inflammatory disease by intracellularly blocking tyrosine kinase.

Question 33

JAK inhibitors ?

Answer 33

JAK are important mediators of down stream pro inflammatory cytokines. Once the ligand binds to it’s receptors could be IL-2, this phosphorylates JAK leading to phosphorylation and activation of STAT. STAT dimers form after phosphorylation and these translocate to the nucleus where they lead to transcription of inflammatory cytokines.

By blocking this pathway , this prevents several pro inflammatory cytokine transcription pathways form occurring.

Question 34

2 JAK inhibitors have been approved for use in RA - pharmacological aspects ?

Answer 34

Two JAK inhibitors approved for use in RA these contain a small molecular weight and specific targets

Question 35

Tofactinib ?

Answer 35

JAK 1 & 3 inhibitor (little affinity for JAK 2)

• Effective in moderate-severe RA in monotherapy or in combination with methotrexate.

Effective in patients who show little efficacy for classical DMARDs

Side effects include increased susceptibility to infections , headaches, hypertensions, naseua and diarrhoea

High doses are associated with deep vein thrombosis and pulmonary emboli

Question 36

Barcitinib ?

Answer 36

Baricitinib

• JAK 1 & 2 inhibitor – no affinity for JAK 3
• Administered as a monotherapy or in combination with methotrexate.

Side effects include increased cholesterol levels , upper airway infections , nausea

Not recommended with patients with impaired kidney functions