Background: Vascular endothelial growth factor (VEGF) is involved in angiogenesis and has been found to be increased in a number of cancer types. Serum levels of VEGF have been evaluated in a variety of cancers using an assay which detects both of the VEGF-A isoforms known to be in circulation, specifically VEGF121 and VEGF165. We have developed an ELISA which specifically detects the VEGF165 isoform in serum or plasma samples and we have used this assay to assess the levels of VEGF165 in colon cancer, NSCLC and prostate cancer patients.

Methods: A total of 44 late stage colorectal and 46 prostate cancer serum samples were tested using the VEGF165 ELISA from Oncogene Science / Bayer Healthcare, Cambridge MA. In addition, 45 normal males and 45 normal female serum samples were analyzed for serum VEGF165 in order to determine a cutoff value for normal circulating levels. In addition, a group of 31 Non-Small Cell Lung Cancer (NSCLC) patients who received Nexavar were also analyzed for circulating VEGF165 levels.

Results: Serum VEGF165 levels from the 90 healthy male and female controls had a mean + SD of 144 + 121 pg/ml (range ND - 548 pg/ml). The upper limit of normal was defined as the mean + 2 SD of the normal range (387 pg/ml). Using this cutpoint, 6 of 90 control subjects (6.7 %) had elevated serum VEGF165 levels. A total of 7/44 (16%) of the colorectal cancer patient sera had elevated levels of VEGF165. For the prostate cancer samples, 2/46 (4.4%) showed an elevation for VEGF165. Results from the NSCLC patients receiving Nexavar showed that those NSCLC patients who had stable disease had a median level of VEGF165 of 68 pg/mL, while those patients that had progressive disease had a median level of VEGF165 of 227 pg/mL.

Conclusions: Serum VEGF165 levels were elevated in 16 % of colorectal cancer and in 4 % of prostate cancer patients compared to healthy control serum. In addition, VEGF165 may also be a useful test for anti-angiogenic therapies such as Nexavar. Serum VEGF165 level deserves further study to determine its predictive and prognostic biomarker potential in NSCLC, colorectal and prostate cancer patients.

98th AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA