2.3 PARTICIPANT REGISTRATION AND STATUS UPDATE PROCEDURES Registration and status updates (e.g. when a participant is taken off protocol therapy and when a participant is taken off-study) will take place per CCR SOP ADCR-2, CCR Participant Registration & Status Updates found at: https://ccrod.cancer.gov/confluence/pages/viewpage.action?pageId=73203825. 2.3.1 Treatment Assignment Procedures  Cohorts Number Description 1 Previously untreated intermediate/high risk squamous cell carcinoma of the head and neck; T1-T4, N0-N3, M0 stage II, III or IV non-HPV associated squamous cell cancer that is surgically resectable  Arms Letter Description A M7824 (Days 1, 15) B M7824 + TriAd vaccine (ETBX-011, ETBX-051 and ETBX-061) (Days 1) C M7824 + TriAd vaccine (Days 1) + N-803 (Day 1) 25 Abbreviated Title: Neoadjuvant IO for HNSCC Version Date: August 31, 2022  Arm Assignment Cohort 1 will be sequentially assigned to arm A, B or C. Enrollment will begin with arm A.