Biologics

Examples of biologic drugs

Proteins (mAbs), vaccines, oligonucleotides, polysaccharides

Size of mAbs and large proteins

150-300 kDa, or 10nm

Secondary non-responder refers to?

When a patient is given a product, with the treatment initially effective then failing

Biggest cause of loss of efficacy in biologics?

Immunogenicity creating antidrug antibodies 

What do single target mAbs do?

Block a single interaction with a ligand, like a receptor on a cell, target protein on a virus/bacteria, or proteins in plasma

What do antibody drug conjugate (ADCs) mAbs do?

They attach a small molecule anticancer drug/other drug agent to an antibody

What do multispecific mAbs do?

Can block and do other actions, like bridging immune/target cells, simultaneous inhibition of receptors/cytokines, or can target multiple immune checkpoints to enhance immune response

What are antibody effector functions?

The functions by which antibodies help destroy target cells via immune mediated functions

CDC

A type of antibody effector function

Uses classical pathway, invites macrophages

ADCC

A type of antibody effector function

Messes with Fcyr on NK cells 

ADCP

A type of antibody effector function

Messes with Fcyr on macrophages, incites phagocytosis

Nanobodies

Made from the fragments of camelid heavy chain only antibodies, have enhanced multi-target abilities and stability

What occurs during manufacturing a drug substance?

Developing host cells, producing protein, purifying protein drug substance, and freezing for storage 

What occurs during manufacturing a drug product?

Compounding solution, filtering bulk solution, filling vials, lyophilizing formulation, capping and inspecting

Why are non-invasive routes of delivery for biologics impossible?

High doses are needed, issues with oral, transdermal, and pulmonary environments

What is surface potential?

The electrical potential on the surface of a particle 

What is the stern layer?

A tightly bound layer of solvent and counter-ions on the solid surface of a particle

What do the presence of counter ions do to the stern layer?

Decreases electrical potential across the stern layer

What is zeta potential?

The electrical potential on the shear/slipping plane, basically the different between the sheer plane and the electrically neutral bulk medium

What does zeta potential indicate?

The magnitude of electrical repulsion between particles

Increasing electrolytes/salts in a solution does what to the zeta potential?

Decreases it, more at risk for aggregation

DLVO theory describes?

How Van Der Waals and double layer forces act together

Why is Gly and Pro found less in alpha helices?

Gly too flexible and Pro is too rigid 

Why do amino acids with side chains that can hydrogen bond destabilize alpha helices?

They can act as competitors of the main hydrogen bond donors and acceptors leading to instability

What is Flasp?

A rapid acting human insulin analog used to lower blood glucose

What makes Flasp fast acting compared to normal human insulin?

It is basically the same as human insulin except for a single substitution of proline by aspartic acid in position B28

What is the structure of an antibody?

150-180kDa, and a Y shape

Mostly made up of beta sheets organized into beta barrels

What isotype is most promising for CDC and ADCC?

IgG

What happens to IgG antibodies that interact with neonatal Fc receptors?

They have a much longer half life 

omab

Murine antibodies, 100% mouse protein

HAMAs?

Human anti-mouse antibodies, often had a neutralizing action leading to rapid murine antibody inactivation/affected PK

ximab

Chimeric antibodies, Fc portion of the antibody, the part that decides the function, was exchanged with human constant portion creating mAbs 

zumab

Humanized antibodies, 90% human 10% mouse, less immunogenic compared to chimeric

umab or numab

100% human mAbs

What does the nomenclature of a mAbs consist of?

A prefix, two substems, and a suffix

What is the prefix of a mAb mean?

Its random, makes a unique drug name

What does the substems of a mAb indicate?

Target (ci - cardiovascular, so - bone, tu - tumor, etc) and the source (o, xi, zu, nu)

What does the suffix of a mAb mean?

Its always “mab”

What are the suffixes for biosimilar mAbs?

Named as a reference drug followed by four random lowercase letters and are seperated from the reference name by a hyphen

𝑏𝑒𝑣𝑎𝑐𝑖𝑧𝑢𝑚𝑎𝑏−𝑎𝑤𝑤𝑏 example

What is Fc fusion?

A method of taking a Fc region of an antibody and fusing it to a biologically active protein or peptide

What is the point of Fc fusion?

To make a single protein with the desired properties, and cuts out post production conjugation 

How does fusing of proteins increase half life?

Increase the size slowing kidney filtration and interaction with FcRn

What is a polyclonal antibody?

A collection of IgG molecules that bind to various epitopes on a target antigen

What is an issues of polyclonal antibodies?

Has a higher likelihood of cross reactivity with similar antigens

What is a monoclonal antibody?

A single IgG that binds to a specific epitope on a target antigen, comes from a single B-cell parent clone

What makes up physical instability?

Conformational unfolding/misfolding, Colloidal aggregation/precipitation, and adsorption

What are the most common types of chemical instability?

Deamidation, oxidation, Asp isomerization and cross linking

What are the physical effects that can occur from chemical instability?

Can lead to addition of ionizable proton (added charge)

Affect hydrogen bonding

Can lead to conformational changes like aggregation

What are the biological effects of chemical instability?

May/ may not impact the activity of a protein, like asp isomerization in omalizumab leads to loss of binding

Increasing immunogenicity

What trends were discovered with deamidation?

Asn and Gln both at risk for deamidation, but Asn much more at risk

It is greatly influenced by pH

What are the major influences of oxidation?

H2O2 (hydrogen peroxide), metal ions, light