CD8A and melanoma: ,54 As PD-1 expression was significantly increased in the CD8+ T cells of both doses of ONCOS-212-treated tumor groups compared with the vehicle-treated group, the possibility that combination therapy with anti-PD-1 immunotherapeutic agents and ONCOS-212 may extend the benefits of anti-PD-1 therapy to a broader base of patients with melanoma warrants investigation.