15632 Background: Sunitinib malate is an oral, multitargeted tyrosine kinase inhibitor of VEGFRs, PDGFRs, KIT, RET, and FLT3, approved multinationally for the treatment of advanced RCC and imatinib-resistant or -intolerant GIST. Angiogenesis and plasma VEGF correlate with poor outcomes in human urothelial carcinoma. We designed a preclinical study to examine the efficacy of sunitinib malate alone and in combination with cisplatin against human urothelial carcinoma in vitro and in a murine xenograft model. Methods: The IC50 for sunitinib malate and cisplatin was determined separately against two human urothelial carcinoma cell lines (TCC-SUP and 5637). Sunitinib malate and cisplatin were also applied concurrently to determine activity of the combination. Immunohistochemical staining was performed to detect expression of VEGFR2 on the cell lines, and to measure modulation of this pathway by sunitinib by measuring phosphorylated (p)VEGFR2. Anti-tumor activity of sunitinib malate alone and in combination with cisplatin was determined in a murine xenograft model bearing 5,637 cells. Results: Both human urothelial carcinoma cell lines were found to express VEGFR2. Sunitinib malate displayed significant activity against both urothelial carcinoma cell lines in vitro at low nanomolar concentrations. Furthermore, sunitinib malate in combination with cisplatin was synergistic in vitro. We observed primarily cytostatic activity for sunitinib malate at both 20 mg/kg and 40 mg/kg orally once daily against a murine xenograft model bearing subcutaneous 5,637 cell tumors during 4 weeks of treatment. Anti-tumor activity of sunitinib malate in combination with cisplatin and correlative studies are being evaluated in the murine xenograft model. Conclusion: Sunitinib malate has anti-tumor activity against human urothelial carcinoma as a single agent and is synergistic in combination with cisplatin in vitro. Sunitinib also has significant efficacy in a murine xenograft model of human urothelial carcinoma. These results warrant further exploration of sunitinib malate as a single agent and in combination with cisplatin chemotherapy in human urothelial carcinoma. No significant financial relationships to disclose.
Various Mechanisms Involve the Nuclear Factor (Erythroid-Derived 2)-Like (NRF2) to Achieve Cytoprotection in Long-Term Cisplatin-Treated Urothelial Carcinoma Cell Lines