PDCD1 and neoplasm: Intra-tumoural injection of ICI-encoding OVs (ICI-OVs) resulted in significant reductions in tumour volume compared to untreated [46,71,72,79,80,81,82,83] and parental OV treated tumours [74,75,76,77,78,84,85,86,87,88], with ICI-OVs also significantly increasing OS compared to untreated [80,81,82,83,89,90] and parental OV treated tumours [75,77,79,84,86,87,88,91], demonstrating that OVs encoding for antibodies against CLTA-4, PD-1 and PD-L1 significantly increase the anti-tumour immune response.