Name of the Trial
Phase II Study of Treatment Selection Based upon Tumor Thymidylate Synthase Expression in Previously Untreated Patients with Metastatic Colorectal Cancer (ECOG-E4203). See the protocol summary at http://cancer.gov/clinicaltrials/ECOG-E4203.

Principal Investigators
Dr. Neal J. Meropol and Dr. Jean Grem, Eastern Cooperative Oncology Group

Why This Trial Is Important
A number of treatments for metastatic colorectal cancer have been approved over the past few years, but doctors want to determine which treatments will work best in individual patients.

The drug fluorouracil (5-FU) is often used to treat colorectal cancer; however, previous clinical studies suggest that tumors with a high level of the protein thymidylate synthase (TS) are more likely to be resistant to 5-FU treatment.

In this trial, researchers will measure the level of TS in the tumors of patients with metastatic colorectal cancer. Patients whose tumors show a low level of TS will be treated with combination chemotherapy consisting of 5-FU, leucovorin calcium, and oxaliplatin (the so-called "FOLFOX" regimen) plus the monoclonal antibody bevacizumab. Patients whose tumors show a high level of TS will be treated either with the same drug combination plus bevacizumab or with an investigational combination of the drugs oxaliplatin and irinotecan plus bevacizumab. Researchers want to determine whether replacing 5-FU and leucovorin calcium with irinotecan will lead to better response rates and survival in these patients.

"As the array of treatments for metastatic colorectal cancer expands, it's important to match specific treatments with those patients who are most likely to benefit from them," said Dr. Meropol. "This is the first national study for patients with metastatic colorectal cancer to prospectively assign treatment based on the molecular characteristics of the tumor."

Who Can Join This Trial
Researchers will enroll 246 patients with metastatic or locally recurrent colorectal cancer. See the list of eligibility criteria at http://www.cancer.gov/clinicaltrials/ECOG-E4203. This clinical trial is eligible for special Medicare coverage.

Study Sites and Contact Information
Study sites in the United States are recruiting patients for this trial. See the list of study contacts at http://www.cancer.gov/clinicaltrials/ECOG-E4203 or call NCI's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237) for more information. The toll-free call is confidential.