HIF1A and neoplasm: The VHH212-encoding adenovirus designed in this study has been shown to have 3 levels of anti-tumor effects: (1) as a foreign body, the adenovirus vector activated the immune response of the tumor microenvironment; (2) intrabody VHH212 competitively inhibited HIF-1 pathways; and (3) its targeted HIF-1α enhanced the anti-tumor effects of gemcitabine.