PDCD1 and neoplasm: The results obtained with this biological assay, and for samples of the three tumor cell lines tested, confirmed those obtained in competition ELISA: vectorization of single-chain dimeric sdAb (scDimeric) gave the best PD1/PDL1 blocking activity among all PDL1 blockers assessed (Figure 2E) and without impairing virus replicative or oncolytic properties (Supplementary Figure S2A, C).