Preservation of Bevacizumab Anti-VEGF Bioactivity and Monomeric Structure During Processing into a Sustained Release Bevacizumab Intravitreal Depot

Abstract

 

Purpose

 

To monitor the anti-VEGF bioactivity and bevacizumab monomer during processing into sustained release depots prepared for intravitreal injection in a rabbit model.

 

Methods

 

Bevacizumab was formulated as a solid dispersion for entrapment in a bioresorbable polyethylene glycol (PEG) matrix. The depot and entrapped drug was optimized for drug release rate and injectability using a fine gauge needle. The anti-VEGF bioactivity of the processed bevacizumab was assessed using an indirect bevacizumab (humanized anti-VEGF IgG1) ELISA kit available from Alpha Diagnostic International. The kit contains controls and the bioactivity is determined relative to a standard curve. The monomer content and high molecular weight species of bevacizumab was assessed by HPLC-SEC using methodology as described in the United States Pharmacopeia (final authorized version 1 dated July 25, 2014).

 

Results

 

Incorporation of the anti-VEGF antibody into sustained release bevacizumab PEG depots suitable for intravitreal injection (as shown in Figure One) requires optimization of hydrogel depot processing to maintain bioactivity and monomeric structure. The processed bevacizumab, as shown in Table One, conserved its monomeric structure to a high degree (>95%) and any high molecular weight species formed were identified only as dimer. The bevacizumab completely maintained its anti-VEGF bioactivity as determined by an ELISA test relative to the bevacizumab standards.

 

Conclusions

 

The anti-VEGF bioactivity of bevacizumab and its monomeric form was conserved through processing steps that are necessary to control particle size to ease injectability of the sustained release bevacizumab PEG intravitreal depot. Dissolution of the bevacizumab in its monomeric form demonstrating full anti-VEGF bioactivity was confirmed and this is critical during manufacture of efficacious sustained release bevacizumab intravitreal depots.