Research suggests that an imbalance in the relative concentrations of ANG-1 and ANG-2 could be contributing to the uncontrolled, pathological patterns of angiogenesis that occur in most tumors. ANG-1's role in maintaining normal vasculature and its inhibitory effect on the leakage of cancer cells from the primary tumor. Blocking ANG2- TIE2 signaling in mice with a conditional loss of TIE1 function (gene knockouts of TIE1, TIE2 or ANG-1 are embryonically lethal) led to a pronounced anti-tumor effect, which was not repeated when VEGF was inhibited.
Sheridan C. Amgen's angiopoietin blocker fails in ovarian cancer[J]. 2015.