Additional Study Information: The main purpose of this research study is to determine if the experimental treatment, axicabtagene ciloleucel in combination with utomilumab, is safe and effective in treating individuals with Large B-cell Lymphoma. Axicabtagene ciloleucel is manufactured using your own blood cells. Utomilumab is a molecule (protein) which interacts with a specific region called 4-1BB on CAR T cells such as axicabtagene ciloleucel. Research suggests that this interaction may stimulate the CAR T cells to increase in number, become more active and stay alive longer, thus improving cancer fighting ability of CAR T cells. Approximately 48 subjects at approximately 8 clinics will participate in the study.