MKI67 and neoplasm: Notably, despite the Ki-67 levels in tumor tissues did not show any significant difference among combined treatment, anti-PD-1 or HSA-ATO NPs treatment alone, the number of TUNEL-positive cells in the tumors with combined treatment of ATO NPs and anti-PD-1 was much higher than that in the tumors with anti-PD-1 or HSA-ATO NPs treatment alone (Fig. 5f).