at alphamab oncology, we have developed the proprietary platform cram (charge repulsion induced antibody mixture) to produce two or more antibodies using one cell line with single cmc process, which reduces the cost and time as compared to the other manufacturing processes.
co-expression of the antibody mixture in a single cell line is key to reducing complexity during development and manufacturing of antibody combo. however, co-transfection of multiple light and heavy chains into cells often leads to production of mismatched, heterodimeric by-products that are inactive. therefore, the development of co-expression systems that robustly and efficiently produce highly active antibody mixtures is a critical step.
in the cram platform, we modified the ch3 domain interface of the fc region by changing several charge pairs to create electrostatic interactions favoring fc homodimer formation and preventing fc heterodimer formation. when co-expressed, these modified antibodies with altered charge polarity across the fc dimer interface preferentially formed homodimers that fully preserved the functions of each component, while minimum heterodimers formed due to repulsive interactions*
the patents for our cram platform have been granted in the us, japan and china.
* yu j, wang x, xu t, et al. a rational approach to enhancing antibody fc homodimer formation for robust production of antibody mixture in a single cell line. journal of biological chemistry, 2017, 292(43):17885.