TGFB1 and glioblastoma: Given the scientific hypothesis of blocking the TGF-β signaling pathway and based on the observations of preclinical and clinical anti-tumor activity in patients with glioblastoma, a Phase 2 study was initiated to evaluate the anti-tumor activity, safety, pharmacokinetics, and biomarker activity of galunisertib in combination with lomustine in patients with recurrent glioblastoma [16].