Additional Study Information: The purpose of this study is to find out if the experimental combination of lenzilumab (an antibody that blocks the cytokine GM-CSF) and axicabtagene ciloleucel (which is identical to the FDA-approved CAR-T cell product YESCARTA) helps in protecting patients from side effects of axicabtagene ciloleucel. While axicabtagene ciloleucel has been approved by the FDA for use with your disease, there is a chance of developing neurologic side effects when it is given alone. The study will test if the addition of lenzilumab does or does not improve the safety of axicabtagene ciloleucel.Additionally, the study will test if lenzilumab helps improve the efficacy of CAR-T cells. Lenzilumab is not approved for use in any disease indication, but it has been studied in other clinical trials involving 114 patients.