CD274 and neoplasm: Detection of common immunosuppressive factors showed that PD-L1 levels were significantly higher after intratumoral injection of N. caninum compared with the tumor control group (t-test, t(8) = 24.17, P < 0.0001); VEGF-A (t-test, t(8) = 1.91, P = 0.083) and HIF-1α (t-test, t(8) = 2.22, P = 0.057) were elevated but not statistically significant.