antibody technology 1 Flashcards
(19 cards)
define biologic
medicinal product whose synthesis, extraction ot manufacture involves living sources
incl protein based therpauetics, gene and cellular therpies, vaccines, blood products for transfusion, diagnostic reagents
what was the firsr protein biologic
insulin - used to treat diabeties
risks associated with insulin
immunogenicity = diabetics developing immunity
post translational modifications = issues around stability
injectable (will not be absorbed via oral route)
advantages of adopting a biopharmaceutical approach versus small molecule
- Tackles resistance to small-molecule intervention. Receptors with large complex binding sites require a molecule that makes sufficient contacts, may not be achieved with a small molecule
- potential for higher affinity and selectivity - selection between closely related receptor targets
- potential for diverse molecular mechanisms of action - interactions with messenger molecule rather than target
risks of adopting a biopharmaceutical approach versus small-molecule
lack of efficacy and pharmacokinetic challenges
- such as administration and delivery to target tissue - injectable rather than oral
- species variation in protein sequences. production in another species may give rise to immunogenicity (potential for bigger immune response)
manufacture
- a complex process that may have issues around reproducibility
- purity of the synthetic process
- consistency between batches
what are the 5 imminoglobulin subgroups
IgA
IgD
IgE
IgM
IgG
think MADGE
which is the main circulating immunoglobulin
IgG
describe the structure of an antibody
Y domain (shaped like a Y)
Fab: antigen binding fragment domain - incl variable region responsible for antigen recognition
Fc - fragment constant: directs cellular interactions and immunogenic response, and interaction with Fc receptor
4 polypeptide chains: 2 heavy and 2 light - joined by disulfide bonds
describe how the strcture of the Fab region gives rise to millions of distinct immunoglobulin antibodies
complex gene organisation geenrates diverse amino acid sequences in the VH and VL domains, responsible for antigen recognition
there are 3 hypervariable regions with constant in between - these are also called complemtarity determining regions between framework regions
hypervariable regions are on the external surface = binding with antigens
framework regions provide scaffold
varying lengths of amino acid chain = even more variability
what does infliximab bind to
TNF alpha
inflammatory growth factor
tumour necrosis factor
binds to varying CDR regions
how are polyclonal antibodies raised
mant fifferent igG molecules with high affinity for antigen purified from serum after immunisation
how are monoclonal antibodies raised
igG profucing B cells isolated from immunised mouse
= identical IgG molecules
Compare monoclonal antibody generation with small molecule drug discovery
- applicable to any antigen
- structural knowledge of binding site not required
- IgGs can be identified by high affinity binding and then molecular propertied elucidated
what are human anyi-mouse antibodies
antibody found in humans which reacts to immunoglobins found in mice
what may contribute to the lack of efficacy of IgG that are produced in mice
rise of humam anti mouse antibodies (antibody found in humans which reacts to immunoglobins found in mice)
mouse Fc domains also contributing to lack of efficacy
producing monoclonal antibodies steps
antigen immunisation of mouse
isolate immune cells
antibody-forming cells form hybridomas by fusing with tumour cell
hybridoma screened for production of desired antibody
antibody-producing hybridomas clones
clonal expansion
monoclonal antibodies
what antibodies are required for clinical IgG biologics
chimeric or humanised
Mechanisms of action of IgG
- receptor antagonism and inhibition
- antagonism of stimulating growth factor/messenger
- agonism eg. at death receptors - linked to tumour apoptosis
- antibody directed cell cytotoxicity - eg destruction of cell-mediated mechanisms leading to destruction
how does tocilizumab work in COVID related cytokine storm
COVID-19 enters alveolar epithelial cells, activating inflammatory macrophages and T cells that produce IL6. This is a cytokine that leads to inflammation that can eventually lead to multiorgan faulire and lung damage
tocilizumab worked to block the IL6 receptor and therefore reducing its inflammatory effects. This reduces the patients need for ventilation and rik of death due to organ failure
HOWVER trials have mixed opinions about effectiveness
