Selecting Clones from the SSI Pools with Similar Product Quality
for Later Stage Development
Although the materials from SSI pools have enabled the initiation of
clinical material production immediately against the backdrop of
pandemic outbreaks, clonal production cell lines are nevertheless
required for later-stage process development and the subsequent
greater-scale clinical and commercial manufacturing. With at least one
batch of clinical materials generated by the Gen1 GMP campaign, the
clonal production cell lines for the Gen2 GMP campaigns should
particularly focus on the proximity of the product quality profiles
along with the typical emphasis on productivity. For instance, there was
one COVID-19 mAb molecule, whose transfectant cell pools were cloned in
parallel with the Gen1 GMP production, to initiate the Gen2 development.
From the clone screening results, the top clone candidates displayed a
wide distribution of titer (Fig. 4A), as well as a broad kaleidoscope of
glycan profiles (Fig. 4B) and charge variant profiles (Fig. 4C). Such
observation of widespread variety should be largely attributed to the
diversity of the transfectant cells in the SSI pool, which provides
excellent flexibility and convenience for clone selection to match Gen1
materials. The candidates with both the closest product quality
attributes to the GMP materials and the higher titer were considered the
final clone candidates for the following Gen2 activities, to which the
process and assay used for Gen1 should be mostly applicable. With the
platform process, similar product quality was obtained between Gen1 and
Gen2 (Fig. 4D).