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Cytometry B Clin Cytom. 2006 May;70(3):107-14.

Pharmacodynamic monitoring of BAY 43-9006 (Sorafenib) in phase I clinical trials involving solid tumor and AML/MDS patients, using flow cytometry to monitor activation of the ERK pathway in peripheral blood cells.

Author information

1
Department of Pathology, Princess Margaret Hospital, Toronto, Ontario, Canada.

Abstract

BACKGROUND:

We previously reported a flow cytometry technique to monitor pharmacodynamic effects of the raf kinase inhibitor BAY 43-9006 based on the ability of phorbol ester (PMA) to phosphorylate extracellular-regulated kinase (ERK) in peripheral blood (Chow et al., Cytometry 2001;46:72-78). In this article, we describe its application to phase I trials of BAY 43-9006 in solid tumor and AML/MDS patients.

METHODS:

The previously described whole blood lysis method was used to monitor BAY 43-9006 effects on peripheral T-cells of solid tumor patients. A modified whole blood fixation protocol was developed for the AML/MDS trial, using the c-kit ligand stem cell factor (SCF) to activate ERK as an alternative to PMA, and incorporating immunophenotypic markers to identify leukemic blasts.

RESULTS:

At all dose levels of BAY 43-9006 used to treat solid tumor patients, ERK could be activated by PMA in peripheral T-cells and we were not able to show inhibition of raf kinase. A similar effect was seen in the lymphocytes of AML/MDS patients during treatment with BAY 43-9006. However, we found strong inhibition when ERK was activated via c-kit using SCF. Furthermore, normal donor CD34+ve stem cells were much more sensitive to BAY 43-9006 when ERK was activated by SCF, compared to PMA.

CONCLUSIONS:

These findings support the further development of flow cytometry applications to monitor signal transduction inhibitors during early phase clinical trials.

PMID:
16498671
DOI:
10.1002/cyto.b.20092
[Indexed for MEDLINE]
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