- Substantial preclinical antitumor synergy supports the exploration of the combination of antiangiogenic compounds (including sunitinib and bevacizumab) plus ixabepilone. In Vivo, synergistic activity between ixabepilone and bevacizumab has been demonstrated using the 151-B human renal carcinoma xenograft model and this synergy compares favorably with other antiangiogenic inhibitors (i.e. sunitinib).