The in vivo xenograft experiments verified that ZF-598SKD significantly inhibits tumor growth of breast cancers with a long-term effect.255 Likewise, ATF-based SOX2 inhibition technology also shows impressive effect in growth suppression of SCC in lung and esophageal cancers.256 However, ZF-ATFs in most cases are delivered by virus, limiting its utility due to poor delivery efficiency and nonspecific nature of viral infections. This evidence concerns the gene SOX2 and esophageal cancer.