(630c) Modeling and Detection of T Cell Exhaustion Markers in a Novel High-Density Centrifugal Bioreactor System with Application in Cancer Immunotherapy Treatments

Cancer is one of the leading causes of death worldwide and furthermore, leads to high medical expenditures each year. As of today, there has yet to be a reliable cure that can eliminate the disease and most traditional treatments such as chemotherapy and radiation have harmful side effects. The need for alternatives has led to the rise of immunotherapy, which involves modifying a patient’s immune cells to target cancer cells for destruction. Immunotherapy allows for treatment of cancer with a good long-term prognosis and without the destruction of healthy tissue that occurs in chemotherapy. While immunotherapy is promising, it is not without high costs and significant cell manufacturing obstacles. For most immunotherapy treatments, immune cells must be expanded outside the body after modification using various bioreactor systems. Currently, the processes and systems utilized for cell expansion are costly and inefficient in use of medium. Additionally, in T-cell based treatments, an issue that often arises is the loss of cancer-killing ability during treatment after cell expansion, known as T cell exhaustion. Thus, there is a need for culture processes that are lower-cost, with higher efficiency in use of medium and better maintenance of the cells’ cancer-fighting function. Our research group has developed a high-density centrifugal bioreactor (CBR) that maintains suspensions based on a balance of forces in a chamber in which the cells are cultured, shown in Figure 1. Centrifugal force is applied to cells in an outward direction due to the motion of the rotating centrifuge, and fluid forces are applied in the inward direction due to drag and buoyant forces from the continuous flow of medium. The CBR can be used to culture cytotoxic T lymphocytes (CTLs) to high densities, as well as other mammalian cell lines. We developed an updated prototype version of the CBR, and the CTL growth process has been optimized with a kinetic growth model created for the system. More recently, the model is being modified to incorporate the influence of T cell exhaustion on growth kinetics of the effective CTL. Recent work is focused on expanding CTLs in static culture in conditions that have been shown in literature to lead to exhaustion pathways, including limited oxygen and glucose and increased lactate. Here we will report on initial efforts to establish these exhausted cells and confirm the presence of inhibitory receptors and cytokines associated with exhaustion. Initial exhaustion models will also be presented here, along with a comparison to results from large-scale cultures in the physical CBR system. The results of these models will be used to design a process control system and integrated sensors in the CBR that can detect indicators of T cell exhaustion pathways, such as limited oxygen and glucose, and prevent the cells from moving towards an exhaustion pathway. In summary, development of models to optimize the growth of cells in the CBR system, and eventually detect and prevent cell exhaustion from occurring, will allow for major improvements in the efficiency and availability of cancer immunotherapy.