PDCD1 and neoplasm: However, studies in mouse models of colon or pancreatic tumor demonstrated that combining anti-PD-1 and anti-TGF-β therapies improved long-term survival and delayed tumor growth in the MC38 murine colon carcinoma model, while failing to do so in the CT26 colon carcinoma model and KPC1 pancreatic tumor model (Sow et al., 2019; Bertrand et al., 2021).