To assess the anti-tumor efficacy of anti-Dll4 and anti-Dll4/VEGF combination therapy, SCID mice were implanted with RP-R-01 or RP-R-02 ccRCC patient-derived xenograft tumors and treated with REGN1035 and/or sunitinib or ziv-aflibercept (Fig. 1A–C). Here, DLL4 is linked to nonpapillary renal cell carcinoma.