A further experiment where 15 mice previously cured of bilateral tumors were challenged with new tumor cells on the contralateral flank on day 108 demonstrated that these anti-tumor effects in combination with anti-PD1 are highly durable (Additional file 1: Figure S3A) and that due to the demonstrated protection of fourteen of the fifteen mice from re-challenge that effective memory immune responses had been induced. This evidence concerns the gene PDCD1 and neoplasm.