This is an open-label, multi-arm, multi-cohort, multi-center, Phase 1/2 study to determine the safety, tolerability, PK, efficacy and patient reported quality of life of JCAR017 in combination with various agents. The first combination, defined as Arm A, will evaluate JCAR017 in combination with durvalumab. Within each arm, cohorts and subcohorts will test different doses and schedules of the combination agent(s).