Prognostic significance of plasma vascular endothelial growth factor levels in patients with hormone-refractory prostate cancer treated on Cancer and Leukemia Group B 9480.

PURPOSE

Plasma vascular endothelial growth factor (VEGF) levels are significantly elevated in patients with hormone-refractory prostate cancer (HRPC) compared with patients with localized disease and have been associated with disease progression in other cancer patient populations. Therefore, we measured VEGF levels in plasma prospectively collected from patients enrolled in Cancer and Leukemia Group B 9480, an intergroup study of suramin in patients with HRPC, to determine whether these levels had prognostic significance.

EXPERIMENTAL DESIGN

Pretreatment plasma was collected from patients with HRPC enrolled in Cancer and Leukemia Group B 9480. In a subset of samples representative of the entire cohort, plasma VEGF levels were determined in duplicate using a Quantiglo chemiluminescent ELISA kit (R&D Systems, Minneapolis, MN). Statistical analyses were performed to determine the correlation between pretreatment plasma VEGF levels and time of overall survival. The proportional hazards model was used to assess the prognostic significance of various cut points in multivariate models.

RESULTS

Plasma VEGF levels in this population ranged from 4-885 pg/ml, with a median level of 83 pg/ml. As a continuous variable, plasma VEGF levels inversely correlated with survival time (P = 0.002). Using various exploratory cut points, plasma VEGF levels appeared to correlate with survival. In multivariate models in which other prognostic factors (serum prostate-specific antigen, alkaline phosphatase, evidence of measurable disease, and hemoglobin) were included, plasma VEGF levels were significant at various cut points tested.

CONCLUSION

Although these data are exploratory and need to be confirmed in an independent data set, they suggest that VEGF may have clinical significance in patients with HRPC.