Disulfide cross-linked Fab-aggregates: preparation and biodistribution

Area of Science:

• Biopharmaceutical Engineering
• Drug Delivery Systems
• Immunology

Background:

• Development of pharmaceutical carriers with prolonged circulation and reduced immunogenicity is crucial for effective drug delivery.
• Antibody fragments (Fab) offer potential for targeted therapies but often face rapid clearance.
• High-molecular-weight aggregates can alter pharmacokinetic properties.

Purpose of the Study:

• To prepare and characterize high-molecular-weight soluble aggregates of murine anti-cardiac myosin Fab fragments.
• To evaluate the circulation time and biodistribution of these aggregates as potential drug carriers.
• To assess the accumulation of aggregates in tumor xenografts and experimentally induced myocardial infarction models.

Main Methods:

• Preparation of Fab aggregates via thiolation and succinimidyl 3-(2-pyridyldithio)propionate modification.
• Radiolabeling of aggregates with Indium-111 (111In).
• Pharmacokinetic and biodistribution studies in normal mice, tumor-bearing nude mice, and rabbits with myocardial infarction.

Main Results:

• The prepared Fab aggregates exhibited prolonged circulation with a half-clearance time of approximately 3-5 hours.
• Aggregates demonstrated significant accumulation in human breast tumor implants and necrotic areas of infarcted myocardium.
• Similar accumulation ratios in tumors and infarcts suggest passive targeting due to impaired vasculature rather than specific interactions.

Conclusions:

• High-molecular-weight Fab aggregates can function as long-circulating pharmaceutical carriers.
• These carriers show potential for delivering drugs to sites with compromised and leaky vasculature, such as tumors and infarcted tissues.
• The observed accumulation is likely a result of prolonged circulation combined with impaired filtration in diseased tissues.