Results from a Phase III study of a new drug show promise for patients with colorectal cancer that has spread to other parts of the body, according to a study presented today during the 97th Annual Meeting of the American Association for Cancer Research.

Investigators have shown that panitumumab improves progression-free survival in patients with metastatic colorectal cancer (mCRC) who had failed standard chemotherapy. In the randomized trial of 463 patients, those who received panitumumab with best supportive care every two weeks (231 pts) showed a 46 percent decrease in the rate of tumor progression or death versus those who received only best supportive care (232 pts). At week 24, approximately four times as many pantimumab patients were alive and progression-free versus those on best-supportive care (18 percent versus five percent). Twice as many panitumumab patients were alive and progression-free at week 32 (10 percent versus four percent).

Study investigators also reported that panitumumab significantly improved disease control. In patients who responded, the median duration of response was 17 weeks. Extended follow-up also revealed that even after 32 weeks, a larger percentage of patients in the panitumumab with best supportive care group were alive without progression than in the group assigned to best supportive care alone.

“We are encouraged by these results, particularly that panitumumab was well-tolerated in patients with metastatic colorectal cancer, with very few major adverse reactions,” said Marc Peeters, M.D., Ph.D., coordinator of the Digestive Oncology Unit, from Ghent University Hospital in Belgium.

Recently, researchers have begun to focus their efforts on developing cancer therapies that are not only effective, but also are easier on the body than current therapies. Using newer therapies that are derived from human protein sequences, investigators are finding that the body is less likely to develop side effects from these drug,s such as allergic reactions.

Panitumumab is the first fully human monoclonal antibody that targets the epidermal growth factor receptor (EGFr), a protein that plays an important role in cancer cell signaling. EGFr activates when naturally occurring proteins in the body, such as epidermal growth factor (EGF), bind to it and trigger signals to encourage cell growth. Panitumumab binds to EGFr, preventing the natural protein from binding to it and interfering with the signals that would otherwise stimulate growth of the cancer cell and allow it to survive.

“Studies involving the use of panitumumab alone and in combination with other therapies for various cancers may confirm that the use of human monoclonal antibodies is a great step forward to effectively treat cancer,” said Dr. Peeters.

The most common side effect was rash, and other lesser side effects included fatigue, nausea and diarrhea. No anti-drug antibody formation was observed.

Abstract No. CP-1: A Phase 3, Multicenter, Randomized Controlled Trial (RCT) of Panitumumab Plus Best Supportive Care (BSC) vs. BSC Alone in Patients (pts) with Metastatic Colorectal Cancer (mCRC)