TGFB1 and cancer: TGF-β inhibitors represent another class of novel therapies to prevent cancer bone metastases, as more than half of breast cancers display increased TGF-β activities.431 The inhibition of TGF-β has been found in preclinical research to suppress tumor growth and distant metastases, including those to bones, and is highly potent in triple-negative breast cancers.432 Many TGF-β antagonists, most of which remain at the preclinical stage, are currently under clinical development.