Protein Based Therapies

Major Protein-based therapeutic agents

1. Antibodies

2. Treatment agents

3. Vaccines

Protein-based therapeutic agents include

• peptide hormones

• monoclonal antibodies

• cytokines

• therapeutic enzymes

• blood factors

• vaccines

• peptide antibiotics

Protein-based antibodies

• monoclonal antibodies

• abciximab/Reopro

• adalimumab

• certolizumab pegol/Cimzia

Proteins as treatment agents

• IFN-alpha

• IL-2

• Insulin

Protein-based vaccines

• HBV

• HIV

• COVID-19

• alpha synuclein

• beta amyloid

History of protein-based therapy

• 18th century: albumin from egg white, blood serum albumin, fibrin, wheat gluten recognized

• protein: word propsoed in 1838 by Berzelius

1st protein therapeutic other than antibodies

• insulin

• purified from animal pancreases

• administered to diabetes mellitus patients in 1922

• 1970s: first recombinant protein therapeutic (humulin)

Development of recombinant DNA technology occured in

• 1970s

• PCR (1986)

Protein-based therapies in pharma industry

• new drug costs ~1 billion and takes 16 years to develop

Target of protein drug

• enzyme/ligand targeted: proteinase convert poly-protein into functional protein

• targeted-guide synthesis (TGS): peptide to inhibit ABeta aggregation

• mAb: specifically binding to protein

  • high affinity, high level of therapeutic result

• Vaccine (protein and peptides): generate antibody to bind the protein

Major factors affecting protein drugs

• immune system: antigenicity of the protein, activity of the immune system

  • low antigenicity desired to avoid elevated immune response against drug

• enzyme or substrate in the body (CYP 450)

• property of the protein (structures, folding, aggregations-solubility)

• bioavailability and affinity to the target (protein-protein interactions)

  • high affinity to target and low affinity to non-target desired

• modification of the protein (phosphorylation, glycosylation)

  • post-translational modification

• ADME

Pharmacological activity of protein drugs

1. replacing protein that is deficient or abnormal

   1. growth hormone

   2. cytokines

   3. neuro-growth factor (GCSF, BDNF)

2. Augmenting an existing pathway

   1. increase Wnt for neurogrowth

   2. reduce Abeta production

   3. decrease GSK-3beta

   4. reduce p-tau level

3. Provide novel function or activity

4. interfering with a molecule or organism

   1. blocking S protein binding to ACE-2 to prevent COVID-19 infection

5. Delivering other compounds or proteins, such as a radionuclide, cytotoxic drug, or effector proteins

   1. albumin as carrier

Molecular mechanism of function

1. specific noncovalent binders (antibodies)

2. proteins affecting covalent bonds (Enzymes)

3. others/carriers (human serum albumin)

Challenges of Protein-based therapies

1. safety: side effects due to therapeutic proteins could be divided into 2 large groups

   1. interactions with intended targets

   2. interactions with unintended targets (undesirable side effects)

2. immunogenicity: significant safety/efficacy issue

3. efficacy

4. quality: purity of protein therapeutic essential for safety

CAR-T

• chimeric-antigen receptor T-cells

• immunotherapy

• engineer host T cell to avoid host immune response/rejection

Proteins vs Small molecule drugs

• proteins serve highly specific and complex functions

• proteins are less likely to interfere with normal biological processes

• proteins are “natural” and often better tolerated/less likely to elicit immune response

• proteins are effective replacement therapy for certain genetic diseases

• protein-based clinical development and FDA approval faster than SMD

• better patent protection for proteins

• small-molecule drugs have “good geography” (can cross cell membranes) but limited function

• proteins have more diverse function but cannot get into cells (useless for intracellular targets)

Solution to overcome challenges of protein and small-molecule based drugs

• new class of drug

• synthetic biologics that combine bioavailability of small molecules with the functional diversity of proteins

• stapled peptides and RIPtides

Stapled Peptide

• synthetically locked (stapled) into alpha-helical shape with optimized cross-linking chemistry to mimic the structure found at the interface of many protein-protein interactions

• interaction domains of proteins, conformationally restrained in such a way that they still retain the active structure

• main body of protein replaced with hydrocarbon “staple” that keeps the interactive domain in the active conformation without substantially increasing its size

• taken up by cells via energy-dependent active transport process

• advantage: many proteins don’t have active sites

Functional Classification of Protein-based therapies

1. Group 1 : protein therapeutics with enzymatic or regulatory activity

2. Group 2: protein therapeutics with special targeting activity

3. Group 3: protein vaccines

4. Group 4: protein diagnostics

Group 1

• tenecteplase (recombinant protein)

• used in thrombolysis

Protein-based treatment for COVID-19

• peptide of ACE2: design peptide to block spike protein binding

• spike protein-based vaccine (recombinant protein or peptide)

• antibody therapy