CTLA4 and neoplasm: In addition, Herrmann et al., using the CTLA-4 aptamer-STAT3-siRNA AsiC in CD4+ T regulatory cells, showed that knocking down STAT3 along with the blockade of CTLA-4 caused an increase of CD8+ T effector cell response (and therefore increasing the impact of T lymphocytes against tumor cells) in an in vivo model [105].