Aw Biologicals Flashcards
Biologicals are isolated from 3 sources…
Humans
Microorganism
Animal
Three eg of biologicals
Vaccines
Recombinant proteins and peptides
Gene therapy
Why are bio at the front of the market.
They’ve already evolved to rurally bind to a particular target which is an advantage
May be used to treat conductions where there is nothing else available:
-oncology -rheumatology -cardiology
In 2006 the bio market was % of sales and worth…
10% and worth £35 bn
Earliest example of a biological
Insulin
Fuzeon
Aniti HIV fuzeon inhibitor
Fuzeon works by
Blocking entry of HIV into CD4 or T cells
Fuzeon mimics
GP41 on the surface of the virus, parenting normal fusion.
Why can we used fuzeon with other theroapies?
Targets alternative mechanism
Fuzeon is composed of ….. And is produced…
36 amino acids, produced synthetically
HIV membrane contains trimeric glycoprotein spikes containing …
gp41 and gp120 subunits
Fusion begins with ….. binding to CD4 chemikine receptor and co receptor
Gp120
Binding to CD4 chemokine receptor causes
Conformational change in gp120 - move aside exposing GP41
GP41 is made up of …
two heptad repeat domains, HR1 (tightly wound could) and HR2 (random chain - closest to virus)
How do the membrane come into contact?
H2 coils into h1, zipping together, punches a fusion pre into both membranes, allows HIV caspid to pass
Fuzeon mimics… Which has the what effect…
H2 region Of gp41
Prevents zipping so membranes never come into contact
Advantages of fuzeon
- Revolutionary class of HIV therapy
- unique mode of action - no cross resistance with other classes
- Shows antiviral activity in vitro against wild-type virus as well as virus resistant to all three of the currently available classes of antiretroviral
Disadvantages of fuzeon
Treatment is £13000 a year
Administered by sub cut bd
Why this admin technique
Not orally bio, does not obey lipinksis rules
Many ionisable groups so rapidly excreted and endogenous proteases degrade so short half life
Problems with biologicals
Proteins and peptides are not good drug like molecules
Why are we particularly concerned with extending half life?
Reduced cost of therapy
Improve quality of life
Four main ways to produce biologicals….
- Synthetically (peptides such as Fuzeon)
- Human cell lines
- Yeast cells (humanised)
-Bacterial cells
Compare yield and PTM of human, yeast, baeria
Human, retains PTM, low yeild
Yeast, retains PTM, better yeild
Bacterial does not retain PTM but has much better yield
Most common method of production at the moment?
Bacterial
Can only produce blogs also synthetically if…
Small insulin, fuzeon, 6000 DA.
Mab are often 100000
Four PTMs
-Phosphorylation -Sulfation -Acylation -Glycosylation (addition of carbohydrates
Two major gylcosylatiosn
O and n linked
O linked is important …..
protein targeting to specific receptors
Eg blood antigens are o linked
N linked is important becuase…
N-linked glycosylation plays important roles in protein regulation and serum half-life
N-linked carbohydrates play an important role in the PK properties of Biological Therapeutics
Where can n link?
Asparagine
Where can o link
Serene
Why does adding a carb change the PK so much?
They are about the same size as the protein
Can you repeat gylcosylatiosn in the lab?
No, variety of sugars attached in variety of ways, cannot repeat synthetically at scale
Filgrastin is used…..
After chemo to replenish marrow (neutropenia)
Class of filgrastin?
Filgrastim is a human granulocyte colony-stimulating factor (G-CSF).
Filgrastin is a ….. aa protein made by
175
Recombinant DNA technology
18800 da
Colony stimulating factors are…. Which act on…
Glycoproteins, which act on hematopoietic - binding and stimulating proliferation, differentiation commitment, and some end-cell functional activation
Dose and frequency of filgrastin varies as per caner but.
Dosing ranges: - 3 – 70 micrograms DAILY
Each regim lasts between 7 days to 1 month.
Elimination half life of filgrastin
3.5 hours
Bacterial production of filgrastin by
E. coli with the human colony stimulating factor gene inserted
How does the ecoli made filgrastin differ from human
PTM- non glycosylated
Hence short half life
Pegylation
PEGylation, is a process of attaching the strands of polyethylene glycol (PEG) polymer to molecules
Typically 20-40 kDa
Peg has lots of o in it, how does this work to our advantage?
Water surrounding increases size and mass of molecule even more, (reduced renal filtration and clearance of filgrastin) increases half life
Immune advantage of PEG
Masks from immune system
reduced immunogenicity and antigenicity
How do we achieve peg
incubation of a reactive derivative of PEG with the target macromolecule
Five advantages of peg
- Improved drug solubility
- Reduced dosage frequency, without diminished efficacy with potentially reduced toxicity
- Extended circulating life
- Increased drug stability
- Enhanced protection from proteolytic degradation
Two commercial advantages of peg
- Opportunities for new delivery formats and dosing regimens
- Extended patent life of previously approved drugs
Pegfilgrastim (NEULASTA)
covalent conjugate of recombinant methionyl human G-CSF (Filgrastim) and monomethoxypolyethylene glycol
Admin of neulasata
Neulasta is administered by sub-cutaneous injection, ONCE A FORTNIGHT.
39kD … Increased half life
Other Glycoslation ideas being explored
Synthetic
Albumin
Polysialic acid
Cellular gylcosylatiosn
