LOS ANGELES - A phase III trial of 1,298 colorectal cancer patients has found that a combination of the drugs cetuximab (Erbitux) and irinotecan showed a significant improvement in progression-free survival over just irinotecan alone, according to an international team of researchers.
The Erbitux Plus Irinotecan in Colorectal Cancer (EPIC) study looked at survival in metastatic colorectal cancer patients who had already shown resistance to conventional therapies. The research was presented today at the 2007 Annual Meeting of the American Association for Cancer Research.
By the end of the study, a significantly larger number of patients who received the combination of cetuximab, an antibody against the epidermal growth factor and irinotecan, an enzyme-inhibiting cancer drug, survived without their cancers progressing further. The tumor response rate in this group was also significantly higher. The study was sponsored, in part, by Bristol-Myers Squibb and Merck KGaA.
"Patients who received both cetuximab and irinotecan experienced longer periods of time spent, on average, without further progression of the disease," said Alberto F. Sobrero, M.D., of the San Martino Hospital's Department of Medical Oncology in Genoa, Italy. "From a patient perspective, any improvement in progression-free survival, as well as tumor shrinkage, is worthwhile. These data confirm that, despite a moderate increase in side effects, cetuximab is a key therapeutic agent in the optimal treatment of advanced colorectal cancer."
The EPIC trial was designed to study the overall survival in patients treated with both cetuximab and irinotecan, with secondary objectives that include response rate and progression-free survival. Patients eligible in the trial had to have shown resistance to the drug oxaliplatin, a platinum-based therapy commonly used in the treatment of colorectal cancer.
The trial participants, enrolled from cancer centers across Europe, Australia and the United States, were primarily male (62.9%) and Caucasian (91.6 %), with a median age of 62. The patients were randomly placed in groups to receive irinotecan every three weeks or irinotecan plus cetuximab every three weeks, and were treated until their disease progressed.
Once the cancer progressed, the researchers stopped study treatment, and further treatment was at the discretion of the patient's physician. According to Sobrero, 16 percent of patients who received both medications responded to the treatment versus four percent of patients who received irinotecan alone.
Despite these positive findings, there was no difference in overall survival between the two arms in this study. Nearly half of the patients, who were initially treated with irinotecan only, were given cetuximab when their cancers progressed. Therefore, many patients in both arms actually received the same treatment, which the researchers say could explain the lack of difference in overall survival between the two arms.
The EPIC researchers reported a comparative increase in side effects for the patients who received the combination therapy, including fatigue, diarrhea and an acne-like rash previously associated with cetuximab.
The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, AACR is the world's oldest and largest professional organization dedicated to advancing cancer research. The membership includes more than 25,000 basic, translational, and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and more than 70 other countries.
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