Biomedical Engineering Reference
In-Depth Information
FIGURE 7.3
Schematic for a four phosphospecific antibody panel designed to test multiple
potential signaling targets in AML patients. The assay has a modular design, and individual
pathways can be tested by the addition of appropriate stimulants or inhibitors, as indicated. (See
the color version of the figure in the Color Plates section.)
therefore important to extend the repertoire of flow cytometry applications to include
multiple signaling pathways. With the widespread availability of multilaser flow
cytometers and steady progress in reagent development, it is becoming feasible to
develop high-complexity protocols for pharmacodynamic monitoring in leukemia
patients. Figure 7.3 illustrates one that is currently being used in our own laboratory to
monitor a multikinase inhibitor ENMD2076, based on a combination of four
phosphospecific antibodies plus surface markers. The data shown in Figure 7.1
were produced using this protocol. Although for this particular drug the main interest
is in Flt-3 and c-Kit inhibition, as illustrated in the figure, the assay is sensitive to other
agents targeting a wide range of potential targets relevant to AML. It therefore has
considerable flexibility and can be rapidly redeployed to clinical trials involving other
signaling pathways, including PI3-kinase, Raf/MEK/ERK, and JAK/STAT.
7.2.4.4 Future Directions for Monitoring Signal Transduction Inhibitors in
Leukemia
This field is still evolving, and to some extent remains dependent on
progress introducing new and effective targeted agents to treat leukemia patients.
Future directions are likely to include the use of high-complexity flow cytometry
protocols first to select appropriate treatment, including the potential for combining
multiple targeted agents, and then to monitor effects during treatment (individualized
medicine). To move this into mainstream clinical practice, there is a need for
standardized reagents including reagent kits and eventually for automated sample
preparation and data analysis. Our results from the recent imatinib trial, where the
extent of pharmacodynamic effect was predictive of patient outcome, support the idea
that eventually these assays might be done in real time, with the drug dose being
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