CD4 and cancer: The structure and mutation spectrum were well-preserved in ALI PDOs derived from a wide range of cancer subtypes (including CRC, RCC, lung, or pancreatic cancers); numerous immune cell subsets were retained (CD4 T cells, CD8 T cells, B cells, NK cells, M2 macrophages, Tregs, and exhausted T cells); and T cell clonal diversity was also maintained.