KDR and neoplasm: Although the mechanism why apatinib remains effective after bevacizumab failure is unclear, it may be associated with the different location of the VEGF signaling pathway where bevacizumab acts on VEGF-A antigen on the tumor cell membrane, whereas apatinib acts on VEGFR-2 in tumor cells (Grothey and Galanis, 2009; Ahir et al., 2020).