Preclinical manufacture of an anti-HER2 scFv-PEG-DSPE, liposome-inserting conjugate. 1. Gram-scale production and purification

Biotechnol Prog. Jan-Feb 2005;21(1):205-20. doi: 10.1021/bp049840y.

Abstract

A GMP-compliant process is described for producing F5cys-PEG-lipid conjugate. This material fuses with preformed, drug-loaded liposomes, to form "immunoliposomes" that bind to HER2/neu overexpressing carcinomas, stimulates drug internalization, and ideally improves the encapsulated drug's therapeutic index. The soluble, single-chain, variable region antibody fragment, designated F5cys, was produced in E. coli strain RV308 using high-density cultures. Affinity adsorption onto horizontally tumbled Streamline rProtein-A resin robustly recovered F5cys from high-pressure-disrupted, whole-cell homogenates. Two product-related impurity classes were identified: F5cys with mid-sequence discontinuities and F5cys with remnants of a pelB leader peptide. Low-pressure cation exchange chromatography, conducted at elevated pH under reducing conditions, enriched target F5cys relative to these impurities and prepared a C-terminal cysteine for conjugation. Site-directed conjugation, conducted at pH 5.9 +/- 0.1 with reaction monitoring and cysteine quenching, yielded F5cys-MP-PEG(2000)-DSPE. Low-pressure size exclusion chromatography separated spontaneously formed, high-molecular-weight conjugate micelles from low-molecular-weight impurities. When formulated at 1-2 mg/mL in 10 mM trisodium citrate, 10% sucrose (w/v), at pH 6.4 (HCl), the conjugate was stable when stored below -70 degrees C. Six scale-up lots were compared. The largest 40-L culture produced enough F5cys to manufacture 2,085 mg of conjugate, enough to support planned preclinical and future clinical trials. The conjugate was 93% pure, as measured by polyacrylamide gel electrophoresis. Impurities were primarily identified as product-related. Residual endotoxin, rProtein A, and genomic DNA, were at acceptable levels. This study successfully addressed a necessary step in the scale-up of immunoliposome-encapsulated therapeutics.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Cell Division / physiology
  • Cells, Cultured
  • Electrophoresis, Polyacrylamide Gel
  • Escherichia coli / chemistry
  • Escherichia coli / cytology
  • Immunoglobulin Fragments / biosynthesis*
  • Immunoglobulin Fragments / isolation & purification*
  • Liposomes / isolation & purification*
  • Liposomes / metabolism*
  • Micelles
  • Molecular Conformation
  • Molecular Sequence Data
  • Phosphates / metabolism
  • Receptor, ErbB-2 / antagonists & inhibitors
  • Receptor, ErbB-2 / immunology
  • Time Factors

Substances

  • Immunoglobulin Fragments
  • Liposomes
  • Micelles
  • Phosphates
  • Receptor, ErbB-2