Although the tumor microenvironment of mCRPC has been shown to be enriched with TGFβ, T regulatory cells, and myeloid-derived suppressor cells that would suppress the anti-tumor immune response [7], the promising efficacy and safety data from part 1 of the phase 1 study with Xaluritamig monotherapy indicate that it is feasible to engage T cells in the immunosuppressive microenvironment of mCRPC with BiTE therapy. This evidence concerns the gene TGFB1 and neoplasm.