CD8A and neoplasm: However, two factors-amounts of high-quality neoantigen-reactive CD8+ T cells and a high tumor microbial diversity-determine long-term survival of a small subsets of PDAC patients.2,3 Although there is no experimental evidence showing causal association of pre-existing microbes with antitumor immunity in long-term PDAC survivors, existence of neoantigen molecular mimicry with microbial epitopes circumstantially supports the possibility that tumor-dwelling microbes can translocate from the gut and shape the TME favorable for antitumor immunity.