Collection of Tissue Samples for Study of Multidrug Resistance
Condition: Breast Carcinoma; Breast Cancer; Medullary Thyroid Carcinoma
MeSH terms: Carcinoma; Breast Neoplasms; Thyroid Neoplasms
Study type: Observational

Summary: 
      Background:

      Resistance to cancer chemotherapy develops in patients, rendering certain treatments
      ineffective. Despite much research, the prevailing cause of drug resistance is not known.

      One mechanism for drug resistance involves a protein called P-glycoprotein, or Pgp, which
      reduces the effectiveness of cancer treatments by "pumping" anti-cancer drugs out of tumor
      cells where they are supposed to work against the disease.

      Objectives:

      To identify and evaluate more thoroughly the roles of Pgp and other substances in mediating
      drug resistance.

      Eligibility:

      Patients enrolled in clinical trials of cancer therapies at the Children's Hospital of
      Pittsburgh; Cancer Centers of Carolinas; Arizona Clinical Research Center; University of
      Copenhagen; and Herlev Hospital, Copenhagen who have consented to the use of blood, tissue,
      or tumor samples for laboratory studies.

      Design:

      Blood, tumor, and tissue samples are collected from participants and sent to the NCI for
      various laboratory analyses.

      ...
    

Detailed description: 
      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.
    

Observational model: Cohort
Time perspective: Prospective
Keywords: Multidrug Resistance Molecular Target Analysis