Sabine Louët responds:

In researching the news story, I had several interviews with Huub Schellekens, who explained to me the key findings of his laboratory's research on Eprex. At no point during these interviews did he strongly underline the fact that there was such a level of uncertainty regarding the findings of his study. However, it is clear that the activity of a therapeutic protein is likely to depend on many factors; indeed, the news article pointed out this fact: “Not only could the immunogenic reaction be triggered by a change in formulation—as in the Eprex case—but also by variations in amino acid sequence, glycosylation or even by impurities cropping up during manufacturing or administration of the drug.” The adverse events associated with the manufacture, formulation and administration of Ortho Biotech's (a Johnson & Johnson affiliate) erythropoietin alpha (Eprex) exemplify the difficulties faced by companies that seek to manufacture and formulate generic biopharmaceuticals.