We found that in mice bearing contralateral MEERvvS and MEERvvR, the Treg cells infiltrating the sensitive tumor are primed for fragility, harboring lower surface Nrp1 expression, lower TGFβ signatures (LAP-TGFβ, GARP, and CD103 surface expression), and a higher sensitivity to IFNγ via STAT1 signaling. This evidence concerns the gene TGFB1 and neoplasm.