title: Modulation of antibody pharmacokinetics by chemical polysialylation.
abstract: Chemical coupling of a variety of polymers to therapeutic proteins has been studied as a way of improving their pharmacokinetics and pharmacodynamics in vivo. Conjugates have been shown to possess greater stability, lower immunogenicity, and a longer blood circulation time due to the chemicophysical properties of these hydrophilic long chain molecules. Naturally occurring colominic acid (polysialic acid, PSA) has been investigated as an alternative to synthetic polymers such as poly(ethylene glycol) (PEG) due to its lower toxicity and natural metabolism. Antibodies and their fragments are a good example of the types of proteins which benefit from pharmacokinetic engineering. Here, we chemically attached differing amounts and differing lengths of short (11 kDa) and longer (22 kDa) chain colominic acid molecules to the antitumor monoclonal antibody H17E2 Fab fragment. Different coupling ratios and lengths were seen to alter the electrophoretic mobility of the Fab fragment but have a minor effect on the antibody immunoreactivity toward the placental alkaline phosphatase (PLAP) antigen. Polysialylation generally increased Fab fragment blood half-life resulting in higher tumor uptake in a KB human tumor xenograft mouse model. One H17E2 Fab-PSA conjugate had over a 5-fold increase in blood exposure and over a 3-fold higher tumor uptake with only a marginal decrease in tumor/blood selectivity ratio compared to the unconjugated Fab. This conjugate also had a blood bioavailability approaching that of a whole immunoglobulin.
authors.affiliation: Division of Cell and Molecular Biology, Faculty of Natural Sciences, Imperial College London, Exhibition Road, London, SW7 2AZ, United Kingdom.
authors.forename: Antony
authors.initials: A
authors.lastname: Constantinou
authors.forename: Agamemnon A
authors.initials: AA
authors.lastname: Epenetos
authors.forename: Dale
authors.initials: D
authors.lastname: Hreczuk-Hirst
authors.forename: Sanjay
authors.initials: S
authors.lastname: Jain
authors.forename: Mahendra P
authors.initials: MP
authors.lastname: Deonarain
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry / Q000276:immunology; D000818:Animals; D000906:Antibodies / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D019540:Area Under Curve; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D007457:Iodine Radioisotopes; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009373:Neoplasms, Germ Cell and Embryonal / Q000737:chemistry / Q000276:immunology; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D012794:Sialic Acids / Q000737:chemistry* / Q000276:immunology / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: D000906:Antibodies; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D007457:Iodine Radioisotopes; D012794:Sialic Acids; C021319:polysialic acid; D000469:Alkaline Phosphatase