**1. Introduction**

[85] Walsh, N., Larkin, A., Kennedy, S., Connolly, L., Ballot, J., Ooi, W., Gullo, G., Crown, J., Clynes, M., and O'Driscoll, L. (2009). Expression of multidrug resistance markers ABCB1 (MDR-1/P-gp) and ABCC1 (MRP-1) in renal cell cacinoma. BMC Urology 9:6.

[86] Wang, Y., Kakinuma, N., Zhu, Y., and Kiyama, R. (2006). Nucleo-cytoplasmic shuttling of human Kank protein accompanies intracellular translocation of beta-catenin. J. Cell

[87] Wang, Y., Onishi, Y., Kakinuma, N., Roy, B.C., Aoyagi, T., and Kiyama, R. (2005). Alternative splicing of the human Kank gene produces two types of Kank protein.

[88] Xu, X., Patrakka, J., Sistani, L., Uhlen, M., Jalanko, H., Betsholtz, C., and Tryggvason, K. (2011). Expression of novel podocyte-associated proteins sult1b1 and ankrd25.

[89] Yamada, K., Hunter, D.G., Andrews, C., and Engle, E.C. (2005). A novel KIF21A mutation in a patient with congenital fibrosis of the extraocular muscles and Marcus

[90] Zhu, Y., Kakinuma, N., Wang, Y., and Kiyama, R. (2008). Kank proteins: a new family of ankyrin-repeat domain-containing proteins. Biochim. Biophys. Acta 1780 (2),

[91] Zhu, Y., Ogaeri, T., Suzuki, J.I., Dong, S.J., Aoyagi, T.I., Mizuki, K., Takasugi, M., Isobe, S.I., and Kiyama, R. (2011). Application of Fluolid-Orange-labeled probes for DNA

Gunn jaw-winking phenomenon. Arch. Ophthalmol. 123 (9), 1254-1259.

microarray and immunological assays. Biotechnol. Lett. 33, 1759-1766.

Biochem. Biophys. Res. Commun. 330 (4), 1247-1253.

Nephron. Exp. Nephrol. 117 (2), e39-46.

Sci. 119, 4002-4010.

30 Renal Tumor

128-133.

Sunitinib malate (Sutent, Pfizer inc., New York, NY) is an orally administered, multitargeted inhibitor of tyrosine kinases, including vascular endothelial growth factor (VEGF) receptor, platelet-derived growth factor (PDGF) receptor, stem cell factor receptor (KIT), fms-like ty‐ rosine kinase (FLT) -3, CSF-1R, and RET. Since the introduction of sunitinib for patients with advanced renal tumor [1], significant objective responses of sunitnib have been revealed [2-6]. In a randomized, multicenter, phase III trial enrolled 750 patients with previously-un‐ treated metastatic renal tumor to receive either sunitinib or interferon (IFN) -α, sunitinib was superior to IFN-α in the objective response rate (47% *vs* 12%), progression-free survival time (11.0 *vs* 5.0 months), and overall survival time (26.4 *vs* 21.8 months) [3, 4]. Also in a Jap‐ anese, multicenter, phase II trial enrolled 51 patients with first-line and pretreated metastatic clear-cell renal tumor to recieve sinitinib, significant responses of sunitinib have been report‐ ed that objective response rate was 52.9%, the median progression-free survival time was 12.2 and 10.6 months, and the median overall survival time was 33.1 and 32.5 months in first-line and pretreated patients, respectively [5, 6]. Sunitinib is approved worldwide for first-line treatment of advanced clear-cell renal tumor. However, approximately half of pa‐ tients with advanced renal tumor do not see clinical benefits from sunitinib treatment. A prognostic marker is needed for selecting patients who will benefit most from sunitinib.

It has been advocated that the necessity of determining molecular and clinical biomarkers that may predict efficacy of sunitinib. The identification of biomarkers to predict response is urgently needed. This chapter provides a brief overview of the signaling pathways of renal tumors and introduces biomarkers to predict response to sunitinib of clinical variables.

© 2013 Fujita et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Fujita et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
