Trial Information

Multidrug Resistance Molecular Target Analysis of Human Samples Collected in Clinical Trials Performed Outside of the Intramural National Cancer Institute

Background:

Ultimately, patients who succumb to cancer do so because of drug resistance. Mechanisms of
drug resistance have been explored in the laboratory and in clinical samples for some time,
yet the prevailing cause of drug resistance, if indeed there is a single cause, is not
known. One mechanism of drug resistance is multidrug efflux, mediated by P-glycoprotein.
Other mechanisms have been proposed. Our laboratory has expertise in the analysis of drug
transporter expression and activity in clinical samples.

Objectives:

To determine expression of P-glycoprotein and other multidrug transporters thought to
mediate clinical drug resistance.

To evaluate inhibition of P-glycoprotein and other multidrug transporters through assessment
of efflux activity in cells obtained from patients enrolled on clinical trials at other
institutions.

To identify and evaluate mechanisms of drug resistance using molecular assays such as cDNA
array, real-time PCR analysis, and immunohistochemistry.

Eligibility:

Patients enrolled on clinical trials outside the NCI, and giving informed consent to the use
of blood, tissue, or tumor samples for evaluation of mechanisms of drug resistance or
evaluation of inhibition of multi-drug efflux.

Future collaborations for similar studies will be added via the protocol amendment
procedure; molecular studies other than ABC transporter assays will be added via the
protocol amendment procedure.

Design:

Human tumor biopsies or blood samples will be collected from cancer patients enrolled on
approved clinical trials, in accordance with the local protocol. These trials are being
conducted at outside institutions, and the samples will be sent to the NCI for
immunohistochemical analysis, cDNA array, PCR analysis, or for blood assays for detection of
P-glycoprotein inhibition.