The von Hippel-Lindau gene mutation is associated with the good-prognosis profiling subtype of clear cell renal cell carcinoma

Abstract

4532 Background: The prevalence of von Hippel-Lindau (VHL) mutations in clear cell renal cell carcinoma (ccRCC) is about 30–50%. The association between VHL mutation and patient prognosis remains controversial, despite extensive in vitro research on its role in hypoxia response. We have previously reported a robust prognostic classification of ccRCC using gene expression profiling. In view of reports of activity of anti-angiogenesis agents, we studied the association of VHL mutation with tumor profiling subtypes, survival and other clinical parameters. Methods: All exons of the VHL gene in 88 ccRCC samples were sequenced. Expression profiling using oligonucleotide arrays (54,675 probe sets) was also performed, and the samples classified using hierarchical clustering. For identification of VHL mutation specific signatures, nearest shrunken centroids with internal validation was used with a 10% misclassification cutoff. Results: 35% of the samples had VHL mutations. Mutation status was not significantly associated with survival on univariate analysis (p = 0.54). Hierarchical clustering yielded two ccRCC subtypes with divergent clinical outcomes (HR = 4.13, p < 0.001). VHL mutations were significantly associated with the good-prognosis profiling subtype of ccRCC tumors (OR 3.3, p = 0.04), but no effect modification between VHL mutation and the prognostic subtypes was found (p=0.31). No standard clinical parameter was associated with VHL mutation. No significant association between VHL mutation and downstream hypoxia response gene expression, including VEGF (p = 0.14), PDGF (p = 0.5), TGF-A (p = 0.24) and GLUT1 (p = 0.45) was found. Conclusion: While VHL mutation is associated with a biologically distinct good-prognosis profiling tumor subtype, its lack of prognostic value on univariate analysis suggests an expanded study to evaluate effect modification. The absence of a specific gene classifier for VHL mutation and the lack of association between VHL gene mutation and known hypoxia response genes suggest that VHL mutations result in heterogenous tissue phenotypes. These results support molecular subtyping of ccRCC in laboratory and clinical studies; in particular, this may be critical for trials involving anti-angiogenesis agents. No significant financial relationships to disclose.