Epoetins: differences and their relevance to immunogenicity

Area of Science:

• Biochemistry
• Immunology
• Pharmacology

Background:

• Recombinant human erythropoietin (epoetin) requires stabilization due to low therapeutic concentrations.
• Commercial epoetin formulations vary in stabilizers, impacting storage, handling, stability, and solubility.
• Differences in carbohydrate moieties also affect epoetin properties.

Purpose of the Study:

• To investigate the link between epoetin formulation changes and the incidence of pure red cell aplasia (PRCA).
• To determine if alterations in stabilizing agents contribute to increased immunogenicity and reduced protein stability.

Main Methods:

• Comparative analysis of epoetin alfa formulations, specifically Eprex before and after 1998.
• Examination of stabilizer composition, including human serum albumin (HSA), polysorbate 80, and glycine.
• Correlation of formulation changes with reported incidence of PRCA.

Main Results:

• A significant increase in PRCA cases was observed predominantly with the Eprex formulation after its 1998 European reformulation, which replaced HSA with polysorbate 80 and glycine.
• Conversely, HSA-containing epoetin alfa products and epoetin beta formulations showed consistently low PRCA incidence.
• The formulation change in Eprex appears linked to decreased protein stability and heightened immunogenicity.

Conclusions:

• The shift in Eprex formulation, specifically the removal of HSA, is strongly implicated as the cause for the observed surge in PRCA.
• Reduced protein stability and increased immunogenicity are likely consequences of the altered Eprex formulation.
• Stabilizer composition critically influences epoetin safety and efficacy, necessitating careful consideration in drug development and formulation.