Impact of CPPs on primary human NK cell CQAs during cell expansion - an experimental study using design of experiments.

Human natural killer (NK) cells represent a promising leukocyte population for use in immune cell therapies. Hematologic as well as solid tumors have been shown to respond to treatment with autologous or allogeneic NK cells. Providing NK cells in sufficient quantity and quality (i.e., efficacy, safety, identity, purity, and yield), remains a challenge. A deeper insight into the critical process parameters (CPP) and critical quality attributes (CQA) of primary NK cell culture is needed for the understanding and control of NK cell manufacturing. Due to the large number of potential CPP's, a design of experiments (DoE) approach was used for systematic planning and reduction of the number of experiments. Primary NK cells from two donors were cultivated under batch conditions and varying CPP's. A detailed analysis of the impact of the investigated CPP's was conducted, and the DoE based experimental setup allowed the interpretation of the influence of each selected process parameter as well as their combination on the relevant CQAs. Based on this data, a statistical model was formulated, which allows predictions of the maximal viable cell number. This approach allows for detailed insight into the CPP's and possible optimizations in the production of cell therapy products.