Moreover, other tumor microenvironment factors may also limit PDAC immunity through the suppression of Th1 CD4+ T-cell responses and/or CD8+ cytotoxic T-cell responses, the recalibration of the milieu to favor tumor growth, and uniquely severe desmoplasia, which makes the TME fibrotic and creates physical barriers, making the delivery of cytotoxic chemotherapy or immune infiltration into the PDAC TME difficult. This evidence concerns the gene CD4 and neoplasm.