CTLA4 and neoplasm: Immune checkpoint molecules, which transduce co-inhibitory signals to immunocompetent cells, are one of the most important components that confer an immunosuppressive capacity in the TME.69 As outlined above, CTLA4 and PD-1 are typical immune checkpoint molecules that are intimately involved in the suppression of anti-tumour immunity.45 In a mouse model of PDAC, it was shown that combining PD-1 and CTLA4 antagonists with myeloid growth factor receptor CSF1R blockade, which inhibits signalling by the CSF1R, elicited tumour regression, even in large established tumours.