Figure 6.

The antitumor activity of YPD-30 in vivo. (A) Chemical structure of YPD-30. (B) YPD-30 interrupts the hPD-1/hPD-L1 interaction as shown by the HTRF assay. (C) YPD-30 weakly activates T cells. The PBMC cells were treated with or without PHA (1 μg/mL) and PD-L1 (5 μg/mL). Then different concentrations of YPD-29B or YPD-30 were used to treat the cells for 72 h, and the IFN-γ in the supernatant was determined by ELISA (n = 3). Data are presented as mean ± SD, ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001 vs. the group only with PHA and PD-L1 (in black). (D) Diagram of double humanization mouse model. In this model, the expression of mouse PD-L1 in the mouse colon MC38 cancer cells is knocked out and then human PD-L1 is knocked in. In addition, the PD-1 protein in the tumor bearing mouse is humanized. (E) Images of the stripped tumor (n = 7). On Day 21, the mice were euthanized and the tumor tissue was excised and then photographed. (F) The growth curve of tumor volume (n = 7). The tumor volume is measured on Days 1, 3, 7, 9, 13, 16, 20. Quantitative data are presented as mean ± SD, ∗P < 0.05, ∗∗P < 0.01; ∗∗∗P < 0.001 vs. vehicle. (G) The inhibitory effect of YPD-30 on tumor weight (n = 7). Quantitative data was presented as mean ± SD, ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001 vs. vehicle. (H) The body weight of each group (n = 7). Mice weight was measured every day and the quantitative data are presented as mean ± SD.