They labeled them candidate cells because no data have proven definitively the phenotypic relationship between progenitor and blood-derived endothelial outgrowth cells, Vroling said.
Their study included 23 patients with renal cell cancer and 19 patients with non-small cell lung cancer. The researchers also monitored plasma levels of VEGF. They assessed tumor response with computed tomography scans according to the RECIST criteria.
This is the first study to assess the kinetics of ccEPCs together with other circulating cells in the peripheral blood of patients with renal cell cancer during the first cycle of sunitinib treatment, Vroling said.
During a four-week on period of treatment with sunitinib, the ccEPC increases paralleled the rise in plasma VEGF levels; they decreased during the two-week off period, Vroling reports. Monocytes and hematopoietic progenitor cells (HPCs) demonstrated the opposite pattern, according to Vroling.
In a preliminary analysis, we found a significant difference in the change of ccEPC numbers and VEGF levels after two weeks of treatment between patients with clinical benefit and progressive disease, Vroling said. We also noted that an increase of ccEPCs was indicative of a longer progression-free survival in this small group of patients.
In the patients with non-small cell lung cancer treated with bevacizumab and erlotinib, ccEPC levels increased, while free plasma VEGF levels decreased. ccEPCs did not rise in a control group treated with erlotinib alone, Vroling said.
These data suggest that ccEPCs are increased in cancer patients in an anti-angiogenic, treatment-specific way, she said. Furthermore, this effect does not seem to be related to plasma VEGF levels.
In our study for the first time the behavior of two CD34bright cell populations, (CD45neg) candidate cEPCs and (CD45dim) HPCs were monitored and showed a different response of both ce
|Contact: Staci Vernick Goldberg|
American Association for Cancer Research