On-treatment biopsy of one patient with heavily pretreated, PD-1 inhibitor refractory head and neck cancer in the highest dose cohort found that CD8 tumor infiltration increased and changed the immunophenotype from desert to inflamed, IFN-γ secretion driven by CD8+ T cells and HLA-I expression increased, and the frequency of E6 and E7 expressing cells was reduced significantly, all consistent with the proposed mechanism of action of SQZ-PBMC-HPV. Here, CD8A is linked to head and neck cancer.