Fig. 7: Pladienolide B enhances the antitumor effect of αPDL1.

a Expression of PD-L1 in OVCAR8 and ID8 cells treated with different concentration of pladienolide B was detected by western blot. b Expression of PD-L1 in mice transplant tumor of vehicle group and pladienolide B group in Fig. 2c was analyzed by immunohistochemistry staining. c Schematic diagram of tumor allotransplantation and drug administration in mice. ID8 cells (2 × 10⁵/mouse) were subcutaneously injected into the left groin of C56BL/6 mice (6–8 weeks old). After three days, mice were randomized into treatment cohorts accordingly (n = 6 for each group) and given drug treatment: vehicle (10% DMSO in PBS and IgG isotype control), αPDL1 (200 µg/ mouse, every 3 days, 6 times), pladienolide B (0.5 mg/kg, every 3 days, 6 times) and αPDL1+pladienolide B. After the tumors were palpable, tumor volume was evaluated every 3 days. Drug administration was stopped at day 18 and tumors growth was kept to be observed for another 18 days. d Growth curve of tumor volume. e Image of transplantation tumors. f The proportion of CD8+ cells to CD3+ cells and the proportion of IFN-γ + CD8+ cells to CD8+ cells. p values were determined by One-Way ANOVA tests. *p < 0.05. **p < 0.01. ***p < 0.001. (All original blots images could be found in supplementary materials.).