For example, researchers have used ultrasound-responsive nanovaccines and nano-discs vaccines combined with anti-PD-1 or anti-PD-L1 antibodies to significantly increase tumor-infiltrating CD8 + CTLs, natural killer (NK)1.1 cells, and CD8 + CTLs to Treg ratio, suppress tumor growth, and extend the survival time of mice bearing tumor [121]. This evidence concerns the gene PDCD1 and neoplasm.