CD4 and neoplasm: Complementing this preclinical trial, a phase 1b clinical trial revealed that combination therapy with IT T-VEC and an approved anti-PD-1 mAb (pembrolizumab) was effective in advanced melanoma patients: 82% of injected patients experienced >50% reductions in tumor volume without any dose-limiting toxicities, and this was accompanied by an increase in tumoral PD-L1 expression, CD4+ and CD8+ T cells, T cell PD-1 expression, and memory T cell density [147].