OBJECTIVE: The anti-vascular endothelial growth factor (VEGF) antibody bevacizumab has received considerable attention as a first-line treatment of advanced colorectal cancers. Difficulties associated with effectively monitoring the activity of this drug have prompted us to seek a pharmacodynamic marker suitable for defining the optimum biological dose and schedule of bevacizumab administration against colon cancer in early clinical trials. METHODS: We evaluated inhibitory effects of bevacizumab on VEGF signaling and tumor growth in vitro and in vivo, and assessed phosphorylation of VEGF receptor 2 (VEGFR2) and downstream signaling in endothelial cells as pharmacodynamic markers using phospho-flow cytometry. We also validated markers in patients with metastatic colorectal cancer (mCRC) treated with bevacizumab-based chemotherapy. RESULTS: In in vitro studies, bevacizumab inhibited proliferation of human umbilical vein endothelial cells in association with reduced VEGF signaling. Notably, bevacizumab inhibited VEGF-induced phosphorylation of VEGFR-2, Akt, and extracellular signal-regulated kinase (ERK). In vivo, treatment with bevacizumab inhibited growth of xenografted tumors and attenuated VEGF-induced phosphorylation of Akt and ERK. The median percentages of VEGFR2 + pAkt + and VEGFR2 + pERK + cells, determined by phospho-flow cytometry, were approximately 3-fold higher in mCRC patients than in healthy controls. Bevacizumab treatment decreased VEGFR2 + pAkt + cells in 18 of 24 patients on day 3. CONCLUSION: Bevacizumab combined with chemotherapy decreased the number of VEGFR2 + pAkt + cells, reflecting impaired VEGFR2 signaling. Together, these data suggest that changes in the proportion of circulating VEGFR2 + pAkt + cells may be a potential pharmacodynamic marker of the efficacy of antiangiogenic agents, and could prove valuable in determining drug dosage and administration schedule.
OBJECTIVE: The anti-vascular endothelial growth factor (VEGF) antibody bevacizumab has received considerable attention as a first-line treatment of advanced colorectal cancers. Difficulties associated with effectively monitoring the activity of this drug have prompted us to seek a pharmacodynamic marker suitable for defining the optimum biological dose and schedule of bevacizumab administration against colon cancer in early clinical trials. METHODS: We evaluated inhibitory effects of bevacizumab on VEGF signaling and tumor growth in vitro and in vivo, and assessed phosphorylation of VEGF receptor 2 (VEGFR2) and downstream signaling in endothelial cells as pharmacodynamic markers using phospho-flow cytometry. We also validated markers in patients with metastatic colorectal cancer (mCRC) treated with bevacizumab-based chemotherapy. RESULTS: In in vitro studies, bevacizumab inhibited proliferation of human umbilical vein endothelial cells in association with reduced VEGF signaling. Notably, bevacizumab inhibited VEGF-induced phosphorylation of VEGFR-2, Akt, and extracellular signal-regulated kinase (ERK). In vivo, treatment with bevacizumab inhibited growth of xenografted tumors and attenuated VEGF-induced phosphorylation of Akt and ERK. The median percentages of VEGFR2 + pAkt + and VEGFR2 + pERK + cells, determined by phospho-flow cytometry, were approximately 3-fold higher in mCRC patients than in healthy controls. Bevacizumab treatment decreased VEGFR2 + pAkt + cells in 18 of 24 patients on day 3. CONCLUSION:Bevacizumab combined with chemotherapy decreased the number of VEGFR2 + pAkt + cells, reflecting impaired VEGFR2 signaling. Together, these data suggest that changes in the proportion of circulating VEGFR2 + pAkt + cells may be a potential pharmacodynamic marker of the efficacy of antiangiogenic agents, and could prove valuable in determining drug dosage and administration schedule.
Authors: Leonard B Saltz; Stephen Clarke; Eduardo Díaz-Rubio; Werner Scheithauer; Arie Figer; Ralph Wong; Sheryl Koski; Mikhail Lichinitser; Tsai-Shen Yang; Fernando Rivera; Felix Couture; Florin Sirzén; Jim Cassidy Journal: J Clin Oncol Date: 2008-04-20 Impact factor: 44.544
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Authors: Herbert Hurwitz; Louis Fehrenbacher; William Novotny; Thomas Cartwright; John Hainsworth; William Heim; Jordan Berlin; Ari Baron; Susan Griffing; Eric Holmgren; Napoleone Ferrara; Gwen Fyfe; Beth Rogers; Robert Ross; Fairooz Kabbinavar Journal: N Engl J Med Date: 2004-06-03 Impact factor: 91.245
Authors: M José Ortiz-Morales; Marta Toledano-Fonseca; Rafael Mena-Osuna; M Teresa Cano; Auxiliadora Gómez-España; Juan R De la Haba-Rodríguez; Antonio Rodríguez-Ariza; Enrique Aranda Journal: Cancers (Basel) Date: 2022-06-21 Impact factor: 6.575
Authors: J M Ou; Z Y Yu; M K Qiu; Y X Dai; Q Dong; J Shen; X F Wang; Y B Liu; Z W Quan; Z W Fei Journal: Eur J Histochem Date: 2014-03-17 Impact factor: 3.188