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Year 3 - Biotechnology > 10 - MAb in Inflammation > Flashcards

10 - MAb in Inflammation Flashcards

1
Q

Describe the process of inflammation

A
  • A protective response involving host cells, blood vessels, and proteins
  • Potentially harmful process b/c components of inflammation that are capable of destroying microbes can also injury bystander normal tissue
  • Components of inflammatory process include WBCs and plasma proteins normally present in the blood
    • Inflammatory reaction’s goal is to bring these to the site of infection and/or tissue damage
  • Inflammation is induced by chemical mediators produced by damaged host cells
  • Normally controlled and self-limited
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2
Q

What are the goals of inflammation?

A
  • Eliminate initial cause of cell injury
  • Remove necrotic cells and tissues
  • Initiate process of repair
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3
Q

Components of inflammation

A
  • Blood cells – platelets, granulocytes, monocytes/macrophages, lymphocytes, fibroblasts
  • Proteins – complement, coagulation, kininogens, proteoglycans
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4
Q

Onset of acute vs. chronic inflammation

A
  • Acute = fast (minutes, hours, days)

- Chronic = slow (days, months, years)

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5
Q

Causative agents of acute vs. chronic inflammation

A
  • Acute = bacteria and injured tissues

- Chronic = persistent acute, viral infection and autoimmune

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6
Q

Cellular mediation of acute vs. chronic inflammation

A
  • Acute = mainly neutrophils

- Chronic = monocytes/ macrophages, lymphocytes, and plasma cells

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7
Q

Outcome of acute vs. chronic inflammation

A
  • Acute = resolution, abscess formation, and/or chronic inflammation
  • Chronic = tissue destruction, fibrosis, necrosis
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8
Q

Severity of local and systemic signs of acute vs. chronic inflammation

A
  • Acute = prominent

- Chronic = less prominent, may be subtle

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9
Q

Causes of chronic inflammation

A
  • Persistent injury or infection (ulcer, TB)
  • Prolonged exposure to a toxic agent (pulmonary silicosis – silica in the lung)
  • Autoimmune disease – self-perpetuating immune reaction that results in tissue damage and inflammation (RA, systemic lupus erythematosus, MS)
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10
Q

Components of chronic inflammation

A
  • Lymphocyte, monocytes/macrophage infiltration
  • Tissue destruction by inflammatory cells
  • Repair w/ fibrosis and angiogenesis (new vessel formation)
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11
Q

Systemic effects of inflammation

A
  • Inflammatory cytokines generated by inflammation reactions may have protective and pathologic effects on systemic organs
  • Systemic protective effects – brain, liver, bone marrow
  • Systemic pathologic effects – heart, endothelial cells, blood vessels, and multiple tissues such as skeletal muscle
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12
Q

Anti-inflammatory drugs

A
  • Steroidal anti-inflammatory drugs
    • Corticosteroids are cornerstone of therapy for inflammatory condition
    • Reduce inflammation or swelling by binding to cortisol receptor
  • Non-steroidal anti-inflammatory drugs
    • NSAIDs alleviate pain by counteracting the COX enzyme
    • COX enzyme synthesizes prostaglandins, creating inflammation
    • NSAIDs prevent prostaglandins from ever being synthesized, reducing or eliminating the pain
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13
Q

Inflammation and the immune system; how do drugs fit into this?

A
  • Inflammation always involved local vascular system, immune system, and various cells w/in the injured tissue
  • Immunomodulatory agents are often referred to as disease-modifying anti-rheumatic drugs (DMARDs)
    • Anti-metabolites = methotrexate, azathioprine, leflunomide
    • Gold salts = D-penicillamine, chloroquine, sulfasalazine
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14
Q

What do biologic DMARDs do?

A
  • Block TNF-alpha or interleukin-1 pathways
  • Block lymphocyte activation or migration
  • Deplete lymphocyte subsets
  • Target allergic inflammation
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15
Q

Rheumatoid arthritis – sx, cause, drug treatments

A
  • Most prevalent arthritis in autoimmune arthritis
  • RA sx = joint pain/swelling/stiffness, general physical sx (fatigue, muscle pain), weakness, worse joint stiffness after sleeping or prolonged sitting
  • Exact cause unknown; may result from a combination of genetic predisposition, environmental influences, and immune system
  • Over time, RA can cause progressive damage to cartilage, bone, and joint-related tissue
  • Steroids, NSAIDs, and DMARDs have been demonstrated to interrupt and delay the inflammatory course of RA
    • Downsides = significant SE and not sufficient for many px
  • Biologic DMARDs -> Enbrel, Humira, etc.
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16
Q

Tumour necrosis factor (TNF)

A
  • Family of cytokines which are involved in regulating immune response -> TNF-alpha and TNF-beta
  • Produced mainly by macrophages but also by a broad variety of other cell types including lymphoid, mast and endothelial cells
  • TNF plays major role in many autoimmune and inflammatory conditions (ex: high concentration in synovial fluid in RA, psoriatic arthritis, and ankylosing spondylitis)
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17
Q

Pathophysiology of TNF

A
  • Abnormal immune response to unknown stimuli
  • Prolonged inflammation
  • Damage to healthy body structures followed by increased tissue growth
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18
Q

Physiology of TNF

A
  • Inflammatory mediator (heat, swelling, redness, pain)
  • Increased tissue damage (apoptosis)
  • Increased cellular proliferation and aggregation
  • Regulation of immune cells/ cytokine release (ex: interleukin-1)
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19
Q

Role of TNF-alpha in RA

A
  • Drives events in pro-inflammatory cytokines cascade
  • Triggers production of other pro-inflammatory cytokines, including IL-1, -6, and -8
  • Facilitates activation of T lymphocytes by foreign antigens
  • Causes T cell accumulation in tissues and neutrophil accumulation in the synovial fluid
  • Stimulates fibroblasts and macrophages to release destructive enzymes (MMPs)
  • Stimulates osteoclastogenesis directly through differentiation of progenitor cells and through enhanced expression of RANKL
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20
Q

Examples of TNF-alpha antagonists

A
  • Infliximab (Remicade) = mouse/human chimeric anti-TNF-alpha monoclonal antibodies (IgG1)
  • Etanercept (Enbrel) = TNF-alpha receptor p75-Fc fusion protein
  • Adalimumab (Humira) = fully human anti-TNF-alpha monoclonal antibodies (IgG1)
    • Humira = human immunoglobulin rheumatoid arthritis
    • Currently FDA approved for px w/ RA (moderate and severe), Crohn’s disease (moderate and severe), psoriatic arthritis (active), and ankylosing spondylitis (active)
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21
Q

Crohn’s disease – what is it and when are TNF-alpha antagonists indicated

A
  • Inflammatory bowel disease
  • Patchy ulcers in interstitial tract that may cause fistulas and fibrosis
  • TNF-alpha antagonists indicated for severe active disease not responsive to a full course of conventional tx
    • Also indicated for fistulizing Crohn’s disease
22
Q

Ankylosing spondylitis - what is it and when are TNF-alpha antagonists indicated

A
  • Chronic inflammatory disease of the spine and tendons
  • Progressive stiffening of spinal joints leading to bony ankylosis
  • May affect organs (eyes, heart, lungs)
  • TNF-alpha antagonists indicated for reduction of signs and sx
  • Poor response to conventional tx
23
Q

Psoriatic arthritis - what is it and when are TNF-alpha antagonists indicated

A
  • Inflammatory arthritis associated w/ psoriasis
  • Non-symmetrical, no predictable joints
  • Pain and tenderness more pronounced than RA
  • TNF-alpha antagonists indicated for active progressive disease w/ inadequate response to conventional therapy
24
Q

Mechanism of Humira

A
  • Recombinant MAb that binds to human tumour necrosis factor alpha (TNF-alpha) to prevent its binding to TNF-alpha receptor, thereby interfering w/ endogenous TNF-alpha activity (only binds to soluble TNF-alpha, not receptor bound)
  • Humira doesn’t block TNF-beta from binding to the same receptor
  • Reduces signs and sx of RA and inhibits the progression of structural damage
25
Q

What is the difference between ACR20, ACR50, and ACR70? When are they used?

A
  • ACR20 = 20% improvement from baseline on therapy
  • ACR50 & ACR70 = 50% and 70% improvement respectively
  • Used to assess data in clinical trials
26
Q

PD and PK of Humira

A
  • Decreases C-reactive proteins (reactants of inflammation), ESR (erythrocyte sedimentation rate; non-specific screening test that indirectly measures how much inflammation is in the body) and cytokines (IL-6)
  • Decreases serum levels of matrix metalloproteinase (MMP-1 and MMP-3)
    • MMPs are responsible for tissue remodeling and cartilage destruction
  • Clearance increased in the presence of anti-adalimumab Abs and decreased in px > 40 y/o
27
Q

Dosage and administration of Humira

A
  • SC injection 40 mg once every other week
    • Can be used every week in px not receiving methotrexate
  • Often used in conjunction w/ methotrexate in RA (methotrexate prolongs Humira t1/2)
  • May be administered w/ other DMARDs
28
Q

Drug interactions and adverse effects of Humira

A
  • Kineret (Anakinra) -> not recommended b/c may increase risk of infections & neutropenia
  • Methotrexate decreases clearance of adalimumab
  • Vaccines -> not recommended to administer live vaccines during Adalimumab therapy
  • > 10% = CNS (headache), dermatologic (rash), respiratory
  • 5-10% = CV (HTN), endocrine & metabolic, GI, genitourinary (UTIs)
29
Q

Infliximab (Remicade) – function, administration (IV, PO, IM) and indication

A
  • For RA, approved in combination w/ MTX for reducing signs and sx, inhibiting progression of structural damage, and improving physical function
  • Neutralizes biological activity of both soluble and transmembrane forms of TNF-alpha, but doesn’t neutralize TNF-beta, preventing TNF-alpha from binding to its receptor in the cell
  • The only anti-TNF agent given IV (longest potential dosing interval)
30
Q

Mechanism of infliximab

A
  • Bind to human TNF-alpha w/ high specificity, affinity, and avidity
  • Targets all TNF-alpha including soluble, transmembrane and receptor bound
31
Q

PK and dose of infliximab

A
  • Recommended dose = 3 mg/kg IV infusion
  • Given on induction schedule at 0, 2, and 6 weeks followed by infusions q8weeks
  • Px w/ incomplete responses may be given up to 10 mg/kg IV q4weeks
32
Q

Antibodies against Remicade and adverse effects

A
  • As a chimeric antibody, infliximab is expected to have a higher rate of immunogenicity
  • Package insert mentions a rate of formation of antidrug antibodies of ~ 10%; literature cites higher rates
  • Px w/ antidrug antibodies are more likely to have higher rates of drug clearance, reduced efficacy, and 2-3-fold increase in incidence of infusion reactions
  • SE = increased risk of serious and opportunistic infections, malignancy, and heart failure
  • Significantly increased incidence of seroconversion for anti-nuclear (ANA) Abs and anti-dsDNA Abs
33
Q

Etanercept (Enbrel) – function and indication

A
  • Dimeric soluble fusion protein composed of parts of the ligand binding regions of the p75 high-affinity type 2 TNF receptor (which binds both TNF-alpha and TNF-beta) linked to parts of the IgG1 Fc regions
  • Doesn’t induce complement-mediated lysis of cells expressing TNF on their surface
  • FDA approved for use in px w/ moderate to severe active RA (alone or in combo w/ MTX) and polyarticular juvenile RA, PsA, AS
34
Q

Dosing of Enbrel

A

For adults w/ RA, PsA, or AS recommended dose is 50 mg SC weekly, given either as one 50 mg injection or two 25 mg injections on the same day or up to 4 days apart

35
Q

Abatacept (Orencia) – indication and function

A
  • Indicated for use as monotherapy or in combination w/ DMARDs in px w/ moderate to severe active RA who have had an inadequate response to DMARDs or TNF antagonists
  • Fusion protein consisting of the extracellular domain of human cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and a modified Fc portion of IgG1
    • Doesn’t fix complement due to the modification of Fc portion
36
Q

Mechanism of abatacept

A
  • Interaction of CD80 and CD86 w/ CD28 is the costimulatory signal for full activation of T-lymphocytes
  • Abatacept is a co-stimulation modulator that binds CD80 and CD86 and blocks their interaction w/ CD28 => inhibiting T-cell activation
  • Affinity of abatacept for its ligand is greater than the natural ligand CD28
37
Q

Efficacy and PD of abatacept

A
  • In vitro studies demonstrated abatacept decreases T-cell proliferation and inhibits production of TNF-alpha, IFN gamma, and IL-2
  • In vivo study -> suppressed inflammation, decreased anti-collagen antibody production, and reduced antigen specific production of IFN gamma
  • Half-life around 13 days
38
Q

Dosing of abatacept

A
  • Comes lyophilized and is administered after reconstitution in water by IV infusion over 30 mins
  • Dose depends on body weight
  • Dosing regimen = 1st and 2nd dose given 2 weeks apart followed by monthly dosing thereafter
39
Q

Omalizumab (Xolair) – function and indication

A
  • Medication originally designed to reduce sensitivity to allergens
  • Approved for tx of px 12 years and older w/ moderate to severe allergic asthma
  • Specifically binds to free human IgE in the blood and interstitial fluid and membrane-bound form of IgE (mIgE) on the surface of mIgE-expressing B lymphocytes
  • Doesn’t bind to IgE that is already bound by the high affinity IgE receptor (Fc-epsilon—RI) on the surface of mast cells, basophils, and antigen-presenting dendritic cells
  • Is a glycosylated IgG1 MAb
40
Q

Allergic asthma

A
  • One of the most common allergic diseases
  • Allergy occurs more frequently in individuals w/ higher serum IgE levels (though some allergic individuals have very low serum IgE and some people w/ very high IgE have no allergic problems)
41
Q

Dosing, administration, and SE of omalizumab

A
  • Administered SC once every 2-4 weeks
  • Dosing schedule (2 vs 4 weeks and the dosage of each injection) for each pt depends on serum IgE levels and body weight
    • Rationale = IgE present at the time of the first injection and produced during the intervals of successive injections must all be neutralized by omalizumab
  • Main SE = anaphylaxis; small increased risk of stroke and heart disease
42
Q

Natalizumab (Tysabri)

A
  • Recombinant humanized IgG4K MAb
  • Approved as monotherapy for the tx of px w/ relapsing forms of MS to delay accumulation of physical disability and reduce frequency of clinical exacerbations
43
Q

Pathophysiology of MS

A
  • Cause unknown – theory of “molecular mimicry”
  • Antigens expressed by APC may have cross-sensitivity to myelin antigens
  • Inflammatory process causes damage to the barrier (cytokine mediated, reactive metabolites)
  • Upregulation of adhesion molecules – T-cell binding via integrins, T-cells enter the CNS
  • Macrophage activation and attack on myelin sheath (inflammatory mediators play a role)
44
Q

What are integrins?

A
  • Heterodimers of noncovalently associated glycoproteins composed of 2 subunits, alpha and beta
  • Cell adhesion receptors involved in interactions between cell-extracellular matrix and cell-cell interactions
  • The main way that cells bind to and respond to the extracellular matrix and are involved in a variety of cellular functions such as wound healing, cell differentiation, homing of tumour cells, and apoptosis
45
Q

Adhesion of leukocytes to BBB

A
  • Over 24 different types of integrins present on the surface of leukocytes
  • Most important integrin in adhesion to the CNS vascular endothelium is VLA-4 (very late antigen)
  • VLA-4 = transmembrane alpha-4 integrin receptor consisting of alpha-4 subunits and beta-1 subunit
    • Binds to V-CAM-1, an adhesion molecule expressed on the CNS vascular endothelium (V-CAM-1 = member of immunoglobulin gene superfamily)
  • Expression of both V-CAM-1 and activated VLA-4 is increased in px w/ MS due to inflammatory mediated cytokine release
    • Leads to binding of VLA-4 on surface of leukocytes to V-CAM-1 on CNS vascular endothelium => transmigration of leukocytes into CNS
46
Q

Mechanism of natalizumab

A
  • Binds to alpha-4 subunit of alpha-4-beta-1 and alpha-4-beta-7 integrins expressed on the surface of all leukocytes
    • Competitively inhibits alpha-4 subunit-mediated adhesion of leukocytes to the adhesion molecules VCAM-1, MadCAM-1, fibronectin, and osteopontin
  • Natalizumab exerts its beneficial effects in MS by:
    • Inhibiting migration of immune cells into the CNS
    • Inhibiting interactions between beta 4-integrin and its ligands, thereby possibly reducing immune cell activation and promoting apoptosis of lymphocytes
47
Q

Dosing, administration, and SE of natalizumab

A
  • IV infusion 300 mg once every 4 weeks (not dosed by body weight)
  • Can only be mixed in a normal saline IV bag
  • Common SE = infusion related reactions, headache, fatigue, depression, UTI, LRTI, arthralgias
48
Q

AFFIRM trial

A
  • Phase 3 clinical trial
  • Compared natalizumab vs. placebo
  • Results => natalizumab significantly reduced:
    • Cumulative probability of sustained disability progression
    • Annualized rate of clinical relapse
    • Risk of relapse
49
Q

SENTINEL trail

A
  • Compared natalizumab vs. placebo but both groups of px were also being treated w/ Avonex
  • Results => natalizumab significantly reduced:
    • Cumulative probability of sustained disability progression
    • Annualized rate of clinical relapse
    • Development of lesions over the effect produced by Avonex alone
50
Q

Natalizumab use today

A
  • SENTINEL trial showed that 2 px died of PML after receiving natalizumab + avonex
    • PML = opportunistic infection of the brain, which usually leads to death or severe disability
  • Due to increased risk of PML, natalizumab is generally recommended for px who have had an inadequate response so, or are unable to tolerate alternate MS therapies
  • Only available through a restricted distribution

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