A monoclonal antibody directed against latent human transforming growth factor (TGF)-beta 1 (TGFb1; TGF-b1), with potential antineoplastic activity. Upon administration, anti-latent TGFb1 monoclonal antibody SRK-181 specifically targets, binds to, and inhibits the activation of latent TGFb1 complexes, thereby preventing TGFb1-mediated signaling. This abrogates TGFb1-mediated immunosuppression, enhances anti-tumor immunity in the tumor microenvironment (TME) and promotes a cytotoxic T-lymphocyte (CTL)-mediated immune response against tumor cells leading to tumor cell death. This may lead to a reduction in TGFb1-dependent proliferation of cancer cells. The TGF-beta signaling pathway is often deregulated in tumors and plays a key role in the regulation of cell growth, differentiation, apoptosis, motility, invasion, and angiogenesis. It plays a key role in immunosuppression in the TME. TGFb1 is the predominant isoform in many tumors.