**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.
December 30, 2005 at 12:54 am, john hayward md said:
where is the data.\? why is it so hard to find the data and not a press release?
December 30, 2005 at 7:08 pm, Nancy Roach said:
The only data publicly available is contained in the Amgen press release. Amgen is not required by law to release additional data at this point.
Data from trials is typically presented at major scientific meetings and in medical journal articles. If a drug is approved by the FDA, its label will also contain data from critical clinical trials. Once panitumamab data is presented publicly, C3 will post the information on this blog, so stay tuned.
There is extensive law around protection of trade secrets. [This site](http://www.canceractionnow.org/advocacy/disclosure.php) presents information and links on this topic. Please get in touch with me if you would like additional information.
Nancy Roach
President
C3: Colorectal Cancer Coalition
January 26, 2006 at 6:00 pm, Scott Eckels said:
Are there any estimates as to when Panitumumab might receive FDA approval? We’ve heard estimates from different oncologists ranging from 6-12 months to a few years.
Thank you.
Scott
May 29, 2006 at 2:19 pm, joy nixon said:
my son is in a clinical trial where panitumumab is being tested. He is not receiving the drug but is in a control group. We are wondering if the evidence is there to conclude that this drug is effective in cases where it has been used in conjunction with traditional therapies. I would appreciate a reply. Respectfully Joy A Nixon
May 29, 2006 at 10:09 pm, Kate Murphy said:
There are Phase II studies of panitumumab in combination with other drugs commonly used to treat metastatic colorectal cancer.
Joel Hecht and his colleagues reported results of a small Phase II trial combining panitumumab with irinotecan at the 2006 ASCO GI Symposium. His team studied both the IFL (irinotecan, bolus 5FU, and leucovorin) regimen in 19 patients and the FOLFIRI (leucovorin, continuous infusion 5FU, and leucovorin) regimen in 24 patients. None had had chemotherapy before.
There was activity with both regimens: 47% of the IFL group and 33% of the FOLFIRI group had responses to treatment with tumor shrinkage. 26% of the IFL group and 46% of the FOLFIRI group had stable disease. Median survival in the IFL group was 16.8 months. Median survival in the second FOLFIRI group could not be estimated at the time when the analysis was made since most patients were still alive.
Hecht found the amount of serious diarrhea with the older IFL (irinotecan, bolus 5FU, and leucovorin) regimen unacceptably high. It was lower in the FOLFIRI group. Almost all patients had some degree of rash.
Other Phase II trials studied the combination of panitumumab with oxaliplatin. Results of those trials have not yet been analyzed and published.
It is important to know that panitumumab has not yet been approved by the FDA and is only available through clinical trials at this time. Until the results of the current Phase III trial that is comparing standard treatment to standard treatment plus panitumumab are complete, we won’t know if it has an additional benefit for patients.
Your son’s participation in the clinical trial will help answer important questions. I’m glad he decided to take part in it. Thank him for me.