Within the durvalumab plus BCG arm (cohort 2a), treatment will begin at full-dose BCG. If the safety of durvalumab plus full-dose BCG (cohort 2a) is established, enrollment to durvalumab plus full-dose BCG will continue in Phase 2 of the study. If DLT criteria are exceeded with durvalumab plus full-dose BCG (cohort 2a), a one level dose reduction of BCG will be implemented. If DLT criteria are exceeded with durvalumab plus reduced-dose BCG (cohort 2a), the durvalumab plus reduced-dose BCG arm will not proceed to Phase 2 of the study. Similarly, if DLT criteria are exceeded within the durvalumab plus EBRT arm (cohort 2b), no radiation dose reductions are planned and the durvalumab plus EBRT arm will not proceed to Phase 2 of the study. Due to the prolonged half-life of antibody therapies, no dose adjustments are planned for durvalumab in any of the study arms.