This study will examine DNA from cancer patients previously treated with Gleevec to look for a variation (mutation) of the ABCG2 gene that may render the drug less effective in certain patients. Gleevec is used to treat chronic myeloid leukemia and gastrointestinal tumors. Although most patients respond to treatment, many with advanced disease develop resistance to the drug. It is thought that in some patients this resistance results from the action of a protein that causes Gleevec to be pumped out of the cells, reducing its usefulness. Patients enrolled in clinical trials of Gleevec at the National Cancer Institute and at other participating institutions are eligible for this study. DNA from patients' blood samples are analyzed for the ABCG2 gene and correlated with clinical data, such as the patient's age, race, disease state, weight, height, and body surface area. It will also look at the drug dose, how often the drug is given, the duration of treatment, side effects and other medications taken.

NCT00342056

Conditions

1. Cancer
2. Breast Cancer

Analysis of ABCG2 Genotype in Gleevec Treated Cancer Patients to Assess the Association of a Single Nucleotide Polymorphism (C421A) in ABCG2 and Response to Treatment. --- C421A ---

A single nucleotide polymorphism (C421A) has been identified in ABCG2 and has been shown in vitro to result in functional inactivation of this transporter protein. --- C421A ---