Biologicals and gene therapy

• What is meant by the term "biological products"?

  -A wide range of products from vaccines to gene therapy

  -Biologicals can be composed from sugars, proteins, nucleic acids etc

  -Can be isolated from humans. animals and micro-organisms
• What are biopharmaceuticals?


  -Proteins, antibodies and oligonucleotides used as drug targets
• First generation biopharmaceuticals:


  -Mainly copies of endogenous proteins or antibodies, produced by recombinant DNA technology.
• Second generation biopharmaceuticals:


  -'Engineered' to improve the performance of the protein or antibody.
• Intrinsic factors of biologicals:

  -Potency

  -Specificity

  -Side effects

  -Delivery
• Drawbacks of biologicals:

  -Cannot be delivered orally if peptide/protein

  -Cannot cross BBB and may require surgery

  -Broken down by ubiquitous proteases even if injected they are rapidly metabolised

  -Cost more to manufacture than organic chemicals and yield may be low

  -Proteins unstable and sensitive to heat and light

  -Poor shelf life
• What are the examples of therapeutic proteins?

  -Peptide hormones like insulin

  -Enzymes

  -Antibodies

  -Used to be extracted from natural sources e.g., pigs by now made by recombinant DNA technology
• Which proteins replace a "missing factor"?

  -Insulin hormone replaces insulin in type I diabetics

  -Somatropin- growth hormone to prevent reduced stature

  -Factor 8 for haemophilia and replaces missing clotting factor in blood
• What is the importance of Erythropoietin?

  -Stimulates production of RBCs in treatment of chronic renal failure

  -Treatment for EPO deficiency anaemia
• What is PDGF and what does it do?

  -Platelet derived growth factor

  -Associated with wound healing
• What are the 2 bone morphogenic proteins and what are their functions?

  -BMP2: orthopaedic surgery, promote bone repair

  -BMP7: promotes vertebral fusion
• Why is tPA clinically important?

  -Tissue plasminogen activator

  -serine protease enzyme that acts as a "clot buster"

  -Administered within 3hrs of stroke onset to improve clinical outcome at 3 months
• What are monoclonal anti-bodies?


  -Very specific antagonists

  -Binds to ligand and neutralise its effect

  -Humanised antibodies that overcome immune response

  -Disease modifying agents
• What are nanobodies?


  -Used to develop treatments for difficult targets e.g., ion channels
• What is gene therapy?

  -Replacement of defective gene(s) with a normal, healthy gene(s) in an effort to prevent, alleviate or cure disease

  -Radical cure for monogenic disease like Cystic Fibrosis

  -
• What disease results from single gene mutations?

  -Cystic fibrosis

  -Mutation in cystic fibrosis transmembrane conductance
• What diseases result from multiple gene mutations?

  -Cancer

  -Heart/cardiovascular disease

  -Neurodegenerative diseases

  -And more
• Germline gene therapy:


  -Uses sperm/egg

  -Possible permanent cure

  -Huge ethical concerns
• Somatic cell gene therapy:


  -Diploid cells

  -Target only cells that live as long as the individual (one individual, one generation)

  -Make up all approved gene therapy trails in humans
• Viral vectors and sizes:

  -Retroviral: 8000 base pairs (RNA)

  -Adenoviral 7500 base pairs (DNA)

  -Adeno-associated viral: 5000 base pairs (DNA)
• Name 5 types of non-viral vector delivery systems:

  -Naked DNA

  -Polymers/liposomes

  -Nanoparticles

  -Gene "gun"
• Gene therapy timeline:

  -Early 70s Theory of "gene surgery" proposed

  -1980s Advances in molecular biology techniques

  -1990 First human gene therapy trial

  -1998 First gene therapy death (Adenovirus)

  -2003 First gene therapy "gendicin" approved for clinical use in China (cancer) not licenced elsewhere

  -2013 No approved treatment in humans but many trials positive (e.g. haemophilia).

  -2017 FDA approves first cellular gene therapy to treat acute lymphoblastic leukaemia.
• Gene therapy successes:

  -Novartis received a FDA approval for spinal muscular atrophy (SMA) in under 2yr olds.

  -Uses an AAV9 viral vector, Zolgensma, delivers SMN protein into the motor neurons.

  -Zolgensma is injected into the patient's blood (IV injection), then the AAV9 virus can target neurons and deliver the SMN gene into the DNA inside these neurons.

  -$2.1M per treatment
• Setbacks in gene therapy:

  -Ornithine Transcarbamoylase deficiency

  -Jesse Gelsinger died due to extreme immune reaction to adenovirus vector resulting in multiple organ failure.

  -All trails stopped

  -Investigation found flaws in trail set up
• What is Casegevy used for?


  -Sickle cell disease

  -β-thalassaemia

  -Bone marrow stem cells from a patient have their faulty haemoglobin gene disabled by CRISPR in the lab

  -Edited cells infused back into patient and produce normal haemoglobin