Proteins & Peptides (Classes 19-20) Flashcards
Give an example of a commonly used protein drug?
Insulin
What are some benefits of protein therapy?
High specificity, target any defective gene, broad range, easier FDA approval
Give an example of an anti-cancer protein therapy (besides monoclonal antibodies)?
Herceptin
What is the largest class of therapeutic proteins?
Antibodies
Name 4 ways protein therapies deliver their therapeutic effects to the body.
Replace a deficient or abnormal protein, Augment existing pathway, provide novel function, Interfere with a molecule or pathway, Deliver a therapeutic payload
What are some classes of protein therapies?
Enzymes, antibodies, blood factors, hormones, interferons, interleukins
What are some clinical conditions that protein therapies are used for?
Diabetes, Cancer, Transplant rejection, Crohn’s disease
What classifies a peptide drug vs a protein drug?
Peptide - 50 Aas or less; Protein - 100 to 1000s of Aas
What is the major disadvantage of protein therapy?
Maintaining stability & high dosing; efficacy requires maintaining 3D structure/high dosing can lead to aggregation or precipitation
What are 4 ways to cause denaturation of proteins (not the chemical rxns)?
Adjust temp, Adjust pH, agitation, Use solvents
What are 3 physical issues that can affect protein stability/efficacy (other than denaturation & not chemical reactions)?
adsorption, aggregation, precipitation
What are 4 chemical reactions that can affect protein stability/efficacy?
Deamidation, Oxidation, hydrolysis, racemisation, Isomerisation, disulfide exchange
What are 2 common sites of attack for protein oxidation (think amino acid residues)?
methionine & cysteine
What are four ways to cause oxidation in proteins?
Irradiation, Air pollutants, Inflammation, Reactive Oxygen Species
What amino acid residues are affected in deamidation?
asparagine & glutamine
What are 2 ways to cause deamidation in a protein?
change pH, change temp
What does TRAIL do on a molecular level?
Induces cell death via TNFa
What is TRAIL used for clinically?
Kill cancer cells
What is the goal of transfection?
Transfer DNA into a cell
In recombinant DNA tech, what do you use to cleave the host plasmid?
Restriction Endonucleases
In recombinant DNA tech, what is the name of the process of closing the 2 ends of the open plasmid after you have inserted new DNA?
Annealing
In recombinant DNA technology, what do you use to put a plasmid with your new gene inside a host cell?
transfection reagent
What is the major challenge of recombinant DNA technology (other than being expensive)?
Scaling up; Requires scaling of producer cells in sterile environment
What is one challenge to using bacterial cells for recombinant DNA technology?
bacteria cannot perform post-translational modifications to proteins
Can protein therapies have generic versions?
No. Only biosimilar versions.
Procrit and Eprex are examples of what kind of protein therapy?
EPO replacement
What is the origin of paclitaxel (ie where does it come from)?
Pacific Yew bark
What are some problems with using cremophor as a dissolution agent?
axon degeneration/demyelination; Rash, chest pain, tachycardia, peripheral neuropathy
What challenge did the use of human albumin overcome in the development of paclitaxel drug for breast cancer?
hydrophobicity/solubility challenge
What is the drug Abraxane comprised of?
paclitaxel and human albumin
What is Abraxane used for?
Metastatic cancer (study was on metastatic breast cancer)
What are 4 things proteins are susceptible which make protein therapies a challenge?
Aggregation, Fragmentation, Oxidation, Deamidation
What is a major challenge for protein therapy in liquid or subQ formulations?
Requires high dose for delivery
Name 3 ways to prevent protein breakdown
lyophilization, polymer encapsulation, cell-based delivery system, virus-based delivery system
What are 4 ways to prevent protein aggregation in a protein therapy?
lower temp, adjust pH, add stabilizing agents, Add detergents
What do detergents do to protect proteins?
Shield hydrophobic regions
What is the process of freeze-drying and dehydrating a protein therapy called?
lyophilization
How much residual water should remain in a lyophilized protein?
1-8%
What is the key to rehydration after lyophilization of a protein therapy?
Slow rate of rehydration; too fast and the protein will not regain native conformation
What is one way to provide a continual delivery system of protein based therapies?
Cell-based delivery system
Name 3 requirements for cell-based therapies
Must be engineered in genome, must be secreted or expressed across membrane, Must be a protein therapy (not a small molecule)
What is the term used to describe when a cell used in cell-based therapy navigates to the site of pathology?
homing
How does viral gene delivery work?
Gene is engineered into genome, Virus delivered into target cells, cell starts producing proteins that initiate curative effect
What are the roles of the variable and constant regions of an antibody?
Variable -> binds the epitope; Constant -> initiates immune response
What are 4 uses for antibody therapies in targeting cancer cells?
block cancer-promoting receptors, localize lethal drugs to specific cells, localize radioactive molecules to kill cancer, localize drug-loaded nonoparticles
What are some mouse (murine) antibody drawbacks?
allergic reactions, short half-lives, inefficient targeting
What is the term for a mouse antibody and what is its suffix?
Murine; momab/monab
What is a term for a mouse Fab region grafted onto a human backbone antibody called? Suffix?
Chimeric; Ximab
What is the term for a mouse hypervariable region grafted onto a human backbone antibody called? Suffix?
Humanized; Zumab
What is the suffix for a fully human antibody?
Umab
What antibody type has the longest half-life?
Recombinant Humanized
What are some challenges of monoclonal antibodies?
low potency, difficult/expensive to develop, low patient compliance with dosage form/admin schedule, hypersensitivity/immune rxns, Formulation/stability issues
What humanized monoclonal antibody therapy is used for brain tumors?
Bevacizumab
What is cetuximab used for?
Cancer
