pKDR/KDR ratio predicts response in a phase I/II pharmacodynamic study of erlotinib and bevacizumab for recurrent or metastatic head and neck cancer (HNC)

Abstract
6021 Background: EGFR activation up-regulates VEGF, which has been correlated with resistance to anti-EGFR agents. We previously reported early results (Vokes, JCO, 2005) of a phase I-II study of the EGFR inhibitor erlotinib (E) with the VEGF antibody bevacizumab (B) in recurrent or metastatic HNC. We now present results from the pharmacodynamic analysis as well as updated outcome data. Methods: Phase I/II trial of fixed dose erlotinib (E) 150 mg orally daily with escalation of bevacizumab (B) to a maximum of 15 mg/kg q 3 weeks and continued at 15 mg/kg in the phase II portion. Pts were randomized to receive the initial bevacizumab dose on either day 1 or 15. Paired biopsies were taken at baseline and after 2 weeks of treatment (after E alone or E+B) and analyzed by immunofluorescence and laser scanning analysis for target inhibition and apoptosis markers (VEGFR2/KDR, EGFR, CD31, and respective activated forms [pKDR, pEGFR]). Results: Paired biopsies were available from 20 patients. At baseline pKDR/KDR (ratio) correlated with clinical outcome and differed significantly between responses (CR>SD: pPD: pPD: p No significant financial relationships to disclose.

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