Vessel Normalization (VN)

Vessel normalization (VN) is a hypothesized effect of anti-angiogenic therapy in which structurally abnormal, leaky tumor blood vessels are remodeled into a more mature, better-organized vasculature. In principle, this transiently improves blood flow and oxygen delivery to the tumor, reducing hypoxia and improving drug/immune cell penetration, before anti-angiogenic pressure eventually prunes vessels further. Whether — and to what extent — vessel normalization occurs varies by cancer type and treatment context, making it an important but not universal consideration when interpreting how anti-angiogenic drugs affect tumor oxygenation.