Along similar lines, the ability of RT to synergize with ICIs at the initiation of robust tumor‐targeting immune responses against experimental BC is inhibited by transforming growth factor beta (TGF‐β), which is released from the tumor stroma as an active molecule upon RT, and inhibin subunit beta A (INHBA), which recruits immunosuppressive cells including (but not limited to) CD4+CD25+FOXP3+ regulatory T (TREG) cells (De Martino et al, 2021) and bone marrow‐derived PD‐L1‐expressing myeloid cells (Niesel et al, 2021). Here, TGFB1 is linked to breast cancer.