A comparative analysis of heterogeneity in commercially available recombinant factor VIII products

Advances in analytical technologies enable investigation of possible correlations between molecular structure, aggregation and subvisible particle content. Regulatory agencies place increasing attention on potential risks associated with protein aggregates in the micron range in biological therapeutics.

Assess the heterogeneity, high-molecular-weight protein (HMWP) species, subvisible particle content and posttranslational modifications in six commercially available recombinant FVIII (rFVIII) products.

Three B-domain-deleted (BDD) or B-domain truncated rFVIII products (turoctocog alfa, simoctocog alfa and moroctocog alfa) and three full-length rFVIII products (octocog alfa FS and two octocog alfa) were analysed. HMWP content, amount of micron range subvisible particles, tyrosine-1680 sulphation and N-glycan analysis were investigated.

The B-domain-modified products had more protein size homogeneity vs the full-length products. Size exclusion-high-performance liquid chromatography data indicated no association between B-domain structure and aggregate content or size of the products tested. The rFVIII products showed large variation in subvisible particle concentration, with turoctocog alfa and simoctocog alfa having the lowest numbers (1000-1600 and 1800-2400 particles/100 IU, respectively). Turoctocog alfa and simoctocog alfa displayed the most complete tyrosine sulphation (>99.5%).

Overall, there was no association between molecular structure (full-length B-domain, BDD or truncated) and subvisible particle or HMWP content. Dissimilarities may be related to production and product handling differences. In this study, turoctocog alfa, such as simoctocog alfa, had one of the lowest levels of subvisible particles and HMWP content, and high protein size homogeneity.