Empirical Results Single Proteins

The theory was that the later genomic coamplification would produce a more sfable cell line if performed on cells with a single-site integration rather than those derived from multiple copies even if final protein expression levels were similar, our selected CHO line would possess between 10 and 20 copies of the DNA construct, whereas selecting and coamplifying cells with multiple initial copies would result in a cell line with an order of magnitude of more copies of the construct. This latter condition would increase the chance of unwanted mutation and instability in the cell line. Empirically, our hypothesis seems to have been bom out The CHO line used to produce rituximab and other amplified cell lines have few final copies and are highly stable, even in the absence of MTX. ... 

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