Posted by November 3rd, 2005
**Panitumumab** is a biologic agent with the potential to block *epidermal growth factor receptors (EGFr)* and reduce progression of colorectal cancer. Clinical trials of panitumumab, both alone and in combination with chemotherapy, have been closely watched by patients with colorectal cancer, some of whom are part of those trials.
This morning, November 3, 2005, a press release from [Amgen and Avgenix, Inc. announced](http://www.amgen.com/media/media_pr_detail.jsp?releaseID=777851) that clinical trials appeared to show that **panitumumab**, given alone, significantly improved progression-free survival time for patients with metastatic colorectal cancer. Patients in the trial had cancer that had spread beyond their colons (*metastasis*) and had already had their disease get worse on standard chemotherapy (*refractory*).
*Study Design* In the Phase III trial over 460 patients were randomized to receive either intravenous panitumumab every two weeks along with best supportive care or best supportive care alone. Supportive care included pain medications, radiation or surgery to relieve pain, blood transfusions, or other treatment designed to relieve symptoms. It did not include chemotherapy.
All patients in the study had previously been treated with both oxaliplatin (Eloxotin™) and irinotecan (Camptosar™) along with fluorouracil (5-FU) and had progressed on those treatments.
*Study results* Patients who received panitumumab had a 46% lower rate of tumor progression than those in the best supportive care arm, exceeding the trial design goal of at least a 33% lower progression-free survival rate. A secondary goal for objective response to the drug –reduction in tumor size –was also met. Overall survival will be analyzed in the future — 12 months after the time the last patient entered the study.
*Side effects* Despite the fact that no pre-medication was used to prevent them, reactions to the panitumumab infusion were limited and not severe. The most common side effect was an acne-like rash. Other less common side effects included fatigue, nausea, and mild diarrhea. The reseacher team did not find any formation of *human antihuman antibody (HAHA)* or anti-panitumumab antibodies.
*Panitumumab* (previously called ABX-EGF) is a fully-humanized monoclonal antibody that targets the *epidermal growth factor receptor (EGFr)*, blocking its activity. EGFr contributes to the growth of several cancers, including colorectal cancer. The fully-humanized agent eliminates mouse proteins present in other EGFr targeted therapies, hopefully reducing allergic reactions during its infusion into the body.
Previous Phase II results were presented as an [abstract](http://asco.org/ac/1,1003,_12-002643-00_18-0034-00_19-0030047,00.asp) at the 2005 annual meeting of the American Society of Clinical Oncology in Orlando.
Panitumumab is currently being evaluated in [clinical trials](http://www.amgentrials.com/general/search_results.htm?ExpressionSpec=panitumumab&search.x=0&search.y=0) both as a single agent (monotherapy) and in combination with chemotherapy in several clinical trials for colorectal and other cancers. Among them, the Phase III PACCE trial randomizes patients with newly diagnosed metastatic colorectal cancer to chemotherapy alone or chemotherapy with panitumumab.
Willard Dere, M.D., chief medical officer and senior vice president of Global Development at Amgen said in the [news release](http://www.amgen.com/media/media_pr_detail.jsp?releaseID=777851) of the clinical trial results,
Amgen is dedicated to developing safe and effective cancer therapies that significantly improve cancer patients’ outcomes, We are excited that panitumumab, our most advanced investigational cancer therapeutic, improved progression-free survival and response rate in metastatic colorectal cancer patients who had failed multiple prior chemotherapy regimens. These results will support a BLA submission, which we plan to initiate by the end of the year.