Bevacizumab

Transcription of the VEGF protein is induced by 'hypoxia inducible factor' (HIF) in a hypoxic environment. When circulating VEGF binds to VEGF receptors (VEGFR-1 and VEGFR-2) located on endothelial cells, various downstream effects are initiated. It should be noted that VEGF also binds to the neuropilin co-receptors (NRP-1 and NRP-1), leading to enhanced signaling.

Cancer cells promote tumor angiogenesis by releasing VEGF, resulting in the creation of an immature and disorganized vascular network. The hypoxic microenvironment promoted by cancer cells favors the survival of more aggressive tumor cells, and gives rise to a challenging environment for immune cells to respond appropriately. As a result, VEGF has become a well-known target for anti-cancer drugs like bevacizumab. Bevacizumab is a mAb that exerts its effects by binding and inactivating serum VEGF. When bound to the mAb, VEGF is unable to interact with its cell surface receptors, and proangiogenic signalling is inhibited. This prevents formation of new blood vessels, decreases tumor vasculature, and reduces tumor blood supply.

There is also evidence to suggest that VEGF is upregulated in COVID-19 patients, hence, bevacizumab is being investigated for the treatment of associated complications. Higher levels of VEGF may contribute to pulmonary edema, leading to acute respiratory distress syndrome (ARDS) and acute lung injury (ALI). Researchers are hopeful that by inhibiting VEGF, bevacizumab may effectively treat ARDS and ALI - both common features of severe COVID-19 cases.