Importantly, the effectiveness of suppressing tumor growth and reducing immunosuppression with the ST bsAb was far greater than targeting S15 alone, targeting TGF‐β alone, and even a cocktail of both S and T mAbs, underscoring the importance of covalently linking the S15 and TGF‐β binding moieties, presumably due to greater accumulation of TGF‐β binding moieties within the tumor. Here, TGFB1 is linked to neoplasm.