HUMAN CELLS FOR PROSTATE CANCER VACCINE THERAPY - THE IMPACT OF CENTRIFUGATION UPON KEY PRODUCT QUALITY ATTRIBUTES

Centrifugation is a unit operation used within a wide range of bioprocesses, including the production of a whole cell cancer vaccine to treat Hormone Refractory Prostate Cancer (HRPC) which has been tested in Phase II clinical trials. To quantify the effect of centrifugation-related stresses upon a whole cell vaccine population, a design of experiments (DOE) based investigation at micro-scale was implemented. Qualification of the cells may be by membrane integrity and by surface marker density as well as cytokines released and retained during bioprocessing. These and possibly other factors combine to affect the biopotency of the cells and their clinical efficacy. A range of processing factors that included relative centrifugal force, spin time and ambient cell holding time prior to processing were investigated, and their impact upon an array of cell quality attributes measured. A screening study indicated that both relative centrifugal force (RCF) and spin time were statistically significant factors with regards to the loss of cell membrane integrity. A range of two or more factor interactions were also suggested as having a significant negative impact upon the key cell quality attribute of membrane integrity, illustrating the power of multi-factorial experimental design. Data also indicated that loss of cell size was as the result of an increase within all three processing parameters, resulting in the emergence of a smaller, membrane-compromised cell population. Cell surface phenotype analysis by quantitative flow cytometry suggested no significant change in the surface staining profile for the range of product quality surface markers tested. The findings should allow for the creation of a design space for associated centrifugation operations, allowing an optimum processing window to be established. A UK Technology Strategy Board funded program in collaboration with LGC, Nottingham Trent University (bioinformation centre) and formerly with Onyvax