Bintrafusp alfa, a bifunctional fusion protein composed of the extracellular domain of the human TGF-β receptor II (TGF-βRII or TGF-β “trap”) fused via a flexible linker to the C-terminus of each heavy chain of an IgG1 antibody blocking programmed death ligand 1 (anti–PD-L1) (13), has demonstrated significant activity in preclinical studies and is in various stages of clinical development for several cancers (14). This evidence concerns the gene TGFB1 and cancer.