mAbs recycling - biologics 2

Question 1

what is mAbs recycling?

Answer 1

• Neonatal Fc Receptor (FcRn) mediates recycling of albumin and IgG.
• So called Brambell receptor or FcRn.
• Fc region binds to FcRn
• IgG binds at at acidic pH (endosomal, pH 6), low affinity at pH 7-7.4.
• IgG taken p by monocytes or endothelial cells through endocytic mechanisms
• IgG not bound will be sorted to lysosomes for degradation
• FcRn binding affinity is one of the CQAs
• Fv region may also bind to FcRn and alter interactions
• Antibody and antigen complexes are also recycled through FcRn pathway

Question 2

what is the glycosylation impact on mAbs PK?

Answer 2

• All IgGs (natural and recombinant) are glycosylated.
• Glycosylation is not required for an IgG antibody’s long half- life
• However for Fc fusion proteins, The shorter half-life of an Fc-fusion molecule in comparison to the whole IgG has been attributed to the lower binding affinity to FcRn, the glycan mediated disposition and the receptor (of fusion partner) mediated disposition

Question 3

what os the charge and PI impaact on mAbs PK?

Answer 3

• Changing the pI of mAbs is powerful way to improve KP.
• Charges variation can arise from manufacturing processes
• Charges differences may impact on both PK and PD

Question 4

what is the result of admin of therapeutic mAb?

Answer 4

may result in the formation of anti-drug antibody

Question 5

what does a anti-drug antibody do?

Answer 5

binds to the mAb to form a complex which impacts on the PK and safety of the mAbs

Question 6

what may happen during an ADA?

Answer 6

they may cause a hypersensitive response such as anaphlaxis and infusion reactions this may lead to acceleration of clearance of the drug

Question 7

how do mAbs bind?

Answer 7

very specific for the target antigen

binding to FcRn and recycling contribute to its half lif

Question 8

what is the PK/PD of a mAb?

Answer 8

PK is usually dependent on the biology of the target antigen

Question 9

what is the dose proportion for a mAb?

Answer 9

non linear PK at low doses

linear PK at high doses after a saturation of the target

Question 10

what is the distrubution of a mAb/

Answer 10

usually limited to blood and the interestial tissue

partionining from the blood to tissue is usually 5-15%

Question 11

how are mAbs metabolised/

Answer 11

usually catabolims by proteolytic degradation to produce amino acids

Question 12

how are mAbs excreted?

Answer 12

no renal clearance of the intact antibody

Question 13

what is the immunogenecity of a mAb?

Answer 13

formatiomn of ADA against mAb could occur
- this would impact on the PK and PD of the mAb
the reaction of animals cannot be used to compare against humasn

Question 14

what are the novel formats of mAbs?

Answer 14

• antibody fragments
• fusion protein
• antibody drug conjugates
• bispecific
• multispecific antibodies possessing multiple antigen binding sites

Question 15

what are novel formats more complex then mabs?

Answer 15

• different antigen binding domain in the same molecule
• different molecular domains linked through flexible linkers
• heterogenous product throught the conjugation, synthesis, physical and chemical attributes

Question 16

what are antibody fragments?

Answer 16

they skip the Fc part of the mAb
the most prominent type if the fragment antiboyd binding part
single domain antibodies - made flexible

Question 17

what are fusion proteins?

Answer 17

major class of new products
comprise of a protein, peptide or receptors exodomain fused to the Fc region of the mAb.
the Fc portion typically contains hinger region
the half life is extended

Question 18

what is a ADC?

Answer 18

mAb employed as drug delivery agent with chemotherapeutic drugs
cleavable link in either Lys or Cys residue allowing rhe release

Question 19

what is a multifunctional antibody?

Answer 19

bispecific or multispecific antibodies contain two or more viable domains with specific affinity to bind to different antigens

Question 20

what may cause aggregation of mAbs?

Answer 20

freezing or lyophilisation

Question 21

what is recombinant human insulin engineering?

Answer 21

• monomer 51 aa little protein structure
• exists naturally as a hexameric structure of 6 inuslin monmers
• hexamer adopts a structure of a globular protein
• two axial ZNn ions with 6 histidine side chains

Question 22

why do we use recombinant human insulin/

Answer 22

allows formulation to achieve fast acting and long acting insulin

Question 23

how would you change grom a hexamer to be able to use it?

Answer 23

• conversion to dimeric and monomeric
• faster acting on sub-cut admin
• rapid absorption
• rapid response

Question 24

why do we no use the insulin hexamer?

Answer 24

hexamer is not absorbed
only way to be absrorbed is as a dimer or a monomner.
you need to formulate it as a hexamer and then covert it
the faster acting you want the insulin - you need it to be a monomer

Question 25

how do you produce fully human recombinant antibodies?

Answer 25

• the mouse IgG gene is replaced with human transgenes to produce a transgenic mouse with human DNA
• mouse immunised to raise its immune response
• B cell selection to produce human antibodies with desired specificity
• antiboyd effection function longer circulation
• if the antibody doesnt match it will be destroyed

Question 26

what is the half life of fully human recombinant anitbodies?

Answer 26

14-21 days

Question 27

what are the pharmacokinetics of mAbs?

Answer 27

where there are relatively large loading doses and an i/v route of admin there will high a very high peak conc and then it will reach a trough level which needs to be monitored before the next dose

Question 28

what would happen if a patient had a reaction to the anti antibody drug?

Answer 28

if there not a flatline for the dosing of this then you would need to look into another antibody that would work.
if you are not already using a human antibody try and find one that is

Question 29

what is the purpose of Fc fragment engineering?

Answer 29

Fc engineering maintains interaction with immune system and binding site for antibody recyling FcRn to enable long circulation times but may not uyet be as long in practice

Question 30

what does a high Kd value mean?

Answer 30

this means it has a weak binding

Question 31

what is the relationship between binding and elimination?

Answer 31

the weaker the binding (higher Kd) the faster they will be eliminated