Tumor hypoxia markers, such as HIF-1α or CAIX, can indirectly assess the effectiveness of anti-angiogenic treatments by monitoring the increased hypoxia that results from reduced tumor blood supply, while Tie2-expressing monocytes (TEMs), involved in tumor angiogenesis, can be used to reflect anti-angiogenic therapy effectiveness by monitoring the changes in their levels or activation status [110,111]. The gene discussed is TEK; the disease is neoplasm.