Lecture 11.2: Biopharmaceuticals Flashcards
What is a Biopharmaceutical (Bio-P)?
- A biological macromolecule or cellular component,
such as blood product, used as a pharmaceutical - A pharmaceutical derived from a biological source and
especially one produced by biotechnology
What biopharmaceuticals have been harvested from cadavers? (1)
Human Growth Hormone
What are 1st Generation Bio-Ps? Example?
- Simple copies of human proteins
- Put the appropriate part of the human genome into an
expression system, harvest, purify and use - Insulin
What are 2nd Generation Bio-Ps? Examples?
- Have undergone some form of ‘engineering’
- Either a change to the genome prior to transfection, or
a change to the purified product - Faster and longer acting insulin (aa sequence altered)
- Erythropoietin (CHO residue added to prolong half-life)
Types of Potential Modifications that can be made to Bio-Ps? (3)
- Alteration of nucleotide sequence
- Creation of fusion proteins
- Humanising the protein
What is the structure of Etanercept? What is it used for?
- Fusion Protein
- Combination of TNF receptor combined with IgG
antibody - Used in RA
Why is Humanising protein’s important?
- Makes it less immunogenic
What is Herceptin? What is it used to treat?
- A humanized mouse Mab directed to the HER2
receptor (human epidermal growth factor receptor) - Used in the treatment of metastatic breast cancer
when the tumour over-expresses HER2 (proto-
oncogene)
Herceptin MOA
Blocks HER2 by promoting its internalisation, blocks tyrosine kinase activity of HER2
What are Oligonucleotides?
An alternative way of modifying genetic material – without really changing a gene
Antisense Oligonucleotides MOA
- 15-25 base pairs long
- Can enter cells via endocytosis & diffusion
- Complementary to a gene you wish to influence
- Form a triplex with DNA or a duplex with mRNA
- Act by either causing RNA cleavage OR RNA blockage
What is Eteplirsen?
- Antisense Oligonucleotide
- Targets the dystrophin gene in Duchenne Muscular
Dystrophy - Removes a faulty exon, resulting in a functional
protein
What is Short interfering RNA (siRNA)?
- Short lengths of RNA induce an enzyme complex (RNA
induced silencing complex, RISC) - Results in selective degradation of the corresponding
mRNA - Very effective in gene silencing
What is NOAEL?
No Observable Adverse Effect Level
How are gene therapies transported into desired site?
Via vectors, often viruses
A Gene Delivery System must have..? (4)
- Capacity: to deliver large amounts of material
- Efficacy: to enter & be utilised by cells
- Longevity
- Safety: especially important when using viral vectors
Gene Delivery Strategies: In-vivo
Administration of the vector to the patient
Gene Delivery Strategies: Ex-vivo
Cells removed from patient, altered, then re-administered
Vectors must be…? (4)
- Safe
- Efficient (insert into target cells)
- Selective (only expressing desired protein and no
other viral proteins) - Persistent (potentially an issue in cells with high
turnover)
Retroviruses as Viral Vectors: Pros
- Excellent if introduced into stem cells
- All daughter cells express the desired protein
- Principally used for ex-vivo infections
Retroviruses as Viral Vectors: Cons
- BUT, retroviral integrase inserts the therapeutic gene
randomly -> damage? - May need to alter the viral envelope so that it infects
the cell of interest - Don’t really cross the nuclear membrane – this breaks
during cell division, so retroviruses only useful for
targeting dividing cells
Adenoviruses as Viral Vectors: Pros
- High expression rates, don’t insert into the host
genome = limited risk of disturbing other genes - Good for in-vivo transfection
Adenoviruses as Viral Vectors: Cons
Viral genome needs to be engineered to reduce the likelihood of causing widespread infection
Other Viral Vectors (2)
- Disabled HIV
- Herpes (long-lived, does not associate with host DNA,
lon-lived in neural tissue)
What other structures can be used as vectors for gene therapies? (3)
- Liposomes
- Microspheres (spheres loaded with plasmid DNA)
- Plasmids
How is an inserted gene controlled?
- Co-administration of an inducible promoter e.g. target
gene linked to a promoter activated by doxycycline - Linking target gene to a tissue specific promoter would
further enhance activity
What is CRISPR?
- Clustered Regularly Interspaced Palindromic Repeats
- Ability to target nucleases (especially Cas9) to edit
genes of interest - Has the potential to repair faulty genes
