VEGFA and small cell lung carcinoma: This functional change is the result of the downregulation of essential TJ proteins ZO-1, claudin-5, and occludin.12 The same group further characterized the role of secreted VEGF in compromising the BBB through similar mechanisms, and subsequent work has shown an ameliorating effect with VEGF inhibition via monoclonal antibody.13,14 The work by Li et al.15 in small cell lung cancer found that BrM is more common in patients with high levels of placental growth factor (PLGF).