Questions and Answers About the 6C (Cooperative Colorectal Cancer Combination Chemotherapy Clinical) TrialNational Cancer Institute What is the 6C Trial? The 6C Trial is a study designed to evaluate the effectiveness of several different regimens of drugs as the initial therapy for patients with advanced colorectal cancer. This clinical trial will evaluate two new drugs, oxaliplatin and CPT-11, and two standard drugs already proven to be effective, 5-fluorouracil (5-FU) and leucovorin (citrovorum factor), in various combinations.  What is a clinical trial? A clinical trial is a study with people designed to show how a particular approach -- for instance, a promising treatment or a possible way to prevent cancer -- affects those who receive it. The study design is specified in a document called a protocol. Treatment clinical trials fall into three categories. Phase I trials test whether a new drug is safe and how the drug should be administered, how often, and in what dosage. Phase II trials assess how well the new drug works and generate additional information on safety and benefit. Phase III trials compare new drugs or combinations of drugs with the current standard. They usually involve many patients in different places. Why is NCI sponsoring this trial? The purpose of this trial is to determine the effectiveness of several different regimens of drugs for the initial treatment of patients with advanced colorectal cancer. Currently, the most widely used therapy in the United States for this form of cancer is the combination of 5-FU and leucovorin. Studies have suggested that two new drugs, oxaliplatin and CPT-11, are also effective. In some of these studies, different combinations of the standard and new drugs have shown improved response rates over 5-FU and leucovorin alone. This trial will sort out whether and which of these combinations are actually better than the standard treatment. Who can take part in the trial and how is it designed? The trial will enroll about 1,700 adults who have colorectal cancer that is either metastatic (spread to other parts of the body), locally advanced (spread to tissues near the colon), or recurrent (come back after surgery) and is not curable with surgery or radiation therapy. Patients who enroll will be divided randomly by computer -- much like the flip of a coin -- into six groups or "arms" in the first part of the trial: Part One Part Two If needed, the second part of the trial may evaluate the most effective regimens against each other. What specifically will researchers learn from this trial? Researchers will compare the different treatments to learn: 1) whether there are differences between the arms in time to tumor progression -- that is, the time during which the cancer does not grow; 2) which regimens are associated with longer survival; 3) how the side effects of the various treatments compare; and 4) how the different regimens affect quality of life. These are the principal objectives or "endpoints" of the trial, on which the researchers will collect data. Where will the trial take place? The trial will take place at hundreds of hospitals and cancer centers around the United States and in Canada. Any institution or physician who belongs to an NCI-sponsored Clinical Trials Cooperative Group can enroll patients. (Cooperative groups are networks of institutions and researchers who conduct studies jointly, using identical protocols and pooling their data.) To learn which centers are ready to enroll patients, patients and their physicians can check NCI's Web site for clinical trials, http://cancertrials.nci.nih.gov, or call the Cancer Information Service at 1-800-4-CANCER. When will the results be available? Results could be available in five years or less. However, the answer to this question depends on several factors, including how long it takes to enroll patients. NCI expects enrollment to take about three years. Up to a 12 month follow-up period is planned. What are 5-FU and leucovorin? The chemotherapy agent 5-FU, or 5-fluorouracil, has been the standard treatment for colorectal cancer for the past 30 years. It belongs to a class of drugs that interfere with DNA and RNA synthesis. Its more common side effects include diarrhea, heartburn, low white blood cell counts, and mouth sores. Approved by the FDA in 1962, it is now available from several different pharmaceutical companies. Leucovorin is used with 5-FU; it helps 5-FU work more effectively in specific treatment regimens. It has been available from various companies for many years and generally has no serious side effects. What is CPT-11 and what do we know about its benefits and risks? CPT-11, also known as Camptosar®, belongs to a class of anti-cancer drugs that keep cells from multiplying by blocking an enzyme called topoisomerase I. CPT-11 is approved in the United States and most other countries for the second-line therapy of metastatic colorectal cancer after failure of first-line 5-FU and leucovorin. Studies have shown that it shrinks tumors and may prolong survival when used alone and with other drugs. CPT-11's primary side effects include diarrhea and low white blood cell counts, as well as hair loss and weakness in some patients. There have also been infrequent reports of breathing difficulties in patients receiving CPT-11. CPT-11 is made by Pharmacia & Upjohn, Bridgewater, N.J., which is supplying the drug for this trial without charge. What is oxaliplatin? What is already known about its benefits and risks? Oxaliplatin is a platinum compound that binds to certain components of actively dividing cells, such as cancer cells, and kills them. In early trials, it has shrunk tumors in some patients with advanced colorectal cancer, both when used alone and in combination with other drugs. Oxaliplatin is approved for treating advanced colorectal cancer in France (where it is called Eloxatine®) and 14 other countries, where it is marketed by Sanofi-Synthelabo, but is still considered an investigational drug in the United States; i.e., it has not been approved by the Food and Drug Administration at this time. Oxaliplatin's side effects are like those of many chemotherapy agents; it causes some nausea and vomiting and diarrhea, and it can lower the number of white blood cells and platelets in a patient's blood. In a small percent of patients, the drug can also interfere with muscular coordination (ataxia) and may cause numbness in fingers and toes; these side effects disappear or subside in most patients after treatment is stopped. Oxaliplatin is under development by Sanofi-Synthelabo, a company with headquarters in Paris, France, and subsidiaries in New York, N.Y. and Malvern, Pa. A joint venture with Eli Lilly and Company for the further development and marketing of oxaliplatin in the U.S. was recently announced. Sanofi-Synthelabo is supplying the drug for this trial without charge.
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