Investigating the Immunogenic Potential of Variations in Host Cell Protein Levels in Clinical-Grade AAV8 Products

HCP impurities were of low complexity, but pronounced variations in their abundance were observed between lots. High HCP levels were not overtly immunogenic in vivo and in vitro. However, despite statistical limitations, they seemed to be associated with increased CRA. Thus, a negative effect of high HCP levels on retinal tolerability could not be ruled out.