TLR4 and neoplasm: Thus, while the mouse model was critical to demonstrate a requirement for hexa-acylated LPS/TLR4 signalling in anti-tumour PD-1 responses, and the ability of orally administered hexa-acylated LPS to augment such responses, we complemented our metagenomic analyses of human anti-PD-1 responses with human macrophage experiments to explore the relative activating versus immunosilencing properties of hexa- and penta-acylated LPS in vitro.