advanced biopharmaceuticals Flashcards
peptide
a chain of amino acids, typically less than 50
produced with solid-phase synthesis
protein
a longer amino acid chain with secondary structure, typically over 50
production: 100-1000 liters, pilot plant, probes for pressure, biomass, carbon source, pH, dissolved O2, temperature
post-translational modifications
hard to control
introduced enzymatically making them a challenge to reproduce –> reason why biologics are biosimilar and not generics
common degradation pathways
deamination of asparagine residues
disulfide exchange
disulfide exchange
sulfide bonds on the protein are reshuffled and the catalytic base is regenerated
conditions that lead to degradation
high temperature
high/low pH
low temperature –> solute freezes and protein aggregates outside of ice
forced deamination
oxidation
photostability
non-linear kinetics of fibrillation processes
can occur rapidly hours after shaking
lag –> elongation –> steady
lag phase
0 to 24 hours
system forming little seeds and proteins come together and grow into fibers; nucleation size are formed
elongation phase
32 to 48 hours
steady phase
56 to 72 hours
biomimicry
mimic what nature is doing
sugars like trehalose
stabilize protein formulations in the solution and the solid state
very high viscosity in glass state to freeze out motions
How can the derivatization of peptide/protein drugs enhance the half-life?
by binding albumin through a long hydrophobic tail attached to the insulin (reason why over 98% of insulin is bound to albumin in the blood)
strategies to deliver peptide therapeutics via nonparental routes
intranasal delivery – Miacalcic and Synarel
permeation enhancer – SNAC
intranasal delivery – Miacalcic and Synarel
drugs directly absorbed into circulation (avoid first pass metabolism)
drug can directly pass into the brain, avoid potential issues with needing to cross the BBB
permeation enhancer – SAC
fluidizes the membrane
helps deliver peptides orally
nonparental routes of delivery key considerations
high potency
wide variability
tolerability and safety
cost of goods (very expensive)
primary mechanism responsible for RNA cleavage
the hydroxyl group on the 2’ position of the ribose sugar leads to the cleavage of the backbone
why is RNA less stable toward backbone cleavage than DNA?
DNA does not contain an -OH in the 2’ position
replace the 2’ -OH group in RNA with another group (like NH2, F) leads to a more stable version
shorter RNAs
particularly siRNA drugs
made with solid-supported chemical synthesis
longer RNAs
particularly mRNA drugs with thousands of nucleotides
manufactured with cell free in vitro transcription
why are modified nucleotides incorporated into RNA drugs?
to reduce immune reaction toward mRNA (like SpikeVax and COVID vaccines)
to stabilize the RNA
n-methyl pseudouridine
modified nucleotide that replaces some uridines in some mRNA to reduce degradation and immune response
enzymes don’t recognize the modified nucleotide so a person does not elicit an immune response when receiving an mRNA vaccine (immune response would then be against a protein)
MOA for siRNA drugs
degradation of specific complementary mRNA
the protein corresponding to the mRNA does not get synthesized while siRNA is present
galNAC-galactose N acetyl group attached to siRNA gets uptaken to extend half life
How can exceptional stability and half-life be achieved with chemical modifications at the 2’-positions on the D-ribose sugars?
through replacing the 2’ -OH group with another functional group like F or OMe to prevent the degradation mechanism
this stabilized the RNA towards hydrolytic cleavage
GalNAC ligand
in LEQVIO
targets the liver to degrade the mRNA of the PCSK9 enzyme
lowers cholesterol levels
high stability is made possible by a fully synthetic structure
liver targeting
targeting ligands attached to the 3’ or 5’ ends of the RNAs can extend the half life of siRNAs
biosimiliars
post translational modification (PTMs) make the difference between different types of biosimilars
how does sugar stabilize proteins?
alcohol in the sugar replaces hydrogen bonds –> water is viscous and moves quickly –> sugar makes it like glass –> things cannot aggregate –> more stable
