Further Phase 2 Data Confirm Panitumumab Single-Agent Antitumor Activity in Patients with Metastatic Colorectal Cancer
ORLANDO, Fla., May 17, 2005 (BUSINESS WIRE) -- Amgen Inc. (NASDAQ:AMGN), the world's largest
biotechnology company, and Abgenix, Inc. (NASDAQ:ABGX), a leading
antibody development company, today announced updated results from an
ongoing Phase 2 study of panitumumab, a fully human monoclonal
antibody directed against the epidermal growth factor receptor (EGFr).
The results demonstrate that panitumumab has antitumor activity when
administered as a single-agent treatment to patients with metastatic
colorectal cancer (mCRC) who have failed standard chemotherapy. An
independent central radiology review determined that treatment with
panitumumab resulted in a nine percent overall response rate and
median time to progression of 11.4 weeks. (Abstract #3520)
The data were presented today at the 41st Annual Meeting of the
American Society of Clinical Oncology (ASCO). Investigators reported
that patients with mCRC tumors expressing the EGFr protein who
received panitumumab monotherapy demonstrated a median survival time
of 37.6 weeks and a median duration of tumor response of 18.1 weeks.
Stabilization of disease was observed in 29 percent of patients
(n=43). Median progression-free survival time was 13.6 weeks.
"These data confirm previously reported safety and response
findings in patients with metastatic colorectal cancer who have
previously failed multiple lines of chemotherapy," said Imtiaz A.
Malik, M.D., professor of medicine, Loma Linda University Cancer
Institute, Loma Linda, Calif. and one of the study's lead
investigators. "Panitumumab's efficacy and safety data from Phase 1
and Phase 2 clinical trials to date suggest that panitumumab may
provide an additional avenue for oncologists to manage the disease."
Patients in the study (n=148) were previously treated with 5FU
(with or without leucovorin) and either irinotecan or oxaliplatin, or
both. Patients received 2.5 mg/kg of panitumumab by weekly one-hour
intravenous infusion without premedication. Tumor responses were
confirmed no less than four weeks after the initial response was
In this Phase 2 study, the most common side effect was skin
toxicity (95 percent, 7 percent grade 3). Other side effects
experienced by some patients were fatigue, nausea and mild diarrhea.
One infusion reaction (grade 3) was reported per investigator
assessment and the patient continued on full-dose panitumumab with
pre-medication. There were no instances of anaphylaxis observed. In
those patients tested who had a baseline and a post-baseline
assessment (n=107), no human antihuman antibodies (HAHAs) formation
Phase 1 Open-Label Dose Escalation Trial Suggests Panitumumab May
Provide for Flexible Dosing Schedules in Cancer Patients (Poster K4,
Additional data from a Phase 1 open-label dose escalation trial
were presented by Louis M. Weiner, M.D., chairman, department of
medical oncology, and vice president, translational research at Fox
Chase Cancer Center, Philadelphia, Pa. Exposure and tolerability
profiles were similar between weekly, every-other-week and
every-three-week dosing schedules.
"We are very encouraged by the safety profile at various doses of
this antibody in cancer patients and in different types of cancers. We
look forward to the continued evaluation of panitumumab, a promising
antibody cancer therapeutic," said Dr. Weiner.
Patients (n=96) were randomized to receive four infusions of
panitumumab at different dose levels and schedules ranging from 0.01
to 5.0 mg/kg once per week, 6.0 mg/kg once every two weeks or 9.0
mg/kg once every three weeks administered by intravenous infusion with
no premedication required.
For further information concerning ongoing clinical trials
involving panitumumab please visit, http://www.amgentrials.com/.
About Colorectal Cancer
Colorectal cancer is the third most common cancer diagnosed in men
and in women in the United States. The American Cancer Society
estimates that about 104,950 new cases of colon cancer (48,290 men and
56,660 women) and 40,340 new cases of rectal cancer (25,530 men and
16,810 women) will be diagnosed in 2005.
Co-developed by Amgen and Abgenix, panitumumab is an
investigational product in a novel class of targeted cancer treatments
called epidermal growth factor receptor (EGFr) inhibitors. Panitumumab
(formerly ABX-EGF) is the first fully human monoclonal antibody
directed against EGFr and is being evaluated as both a monotherapy and
in combination with other agents for the treatment of various types of
cancer, including colorectal, lung and kidney. Panitumumab was
generated with Abgenix's XenoMouse(R)(1) technology, which creates a
fully human monoclonal antibody that contains no murine (mouse)
protein. The fully human nature of panitumumab may result in a safety
profile with a low incidence of infusion reactions and antigenicity.
These are attributes currently being investigated in clinical trials.
Pivotal clinical studies evaluating panitumumab as a monotherapy in
colorectal cancer patients who have failed standard chemotherapy are
ongoing with an every-other-week dosing regimen.
About the Epidermal Growth Factor Receptor (EGFr)
Although EGFr normally helps regulate the growth of many different
cells in the body, EGFr can also stimulate cancer cells to grow. In
fact, many cancer cells actually require signals mediated by EGFr for
their survival. Residing on the surface of these tumor cells, EGFr is
activated when naturally occurring proteins in the body, epidermal
growth factor (EGF) or transforming growth factor alpha (TGFa), bind
to it. This binding changes the shape of EGFr, which, in turn,
triggers internal cellular signals that stimulate tumor cell growth.
Panitumumab binds to EGFr, preventing EGF and TGFa from binding to
the receptor and interfering with the signals that would otherwise
stimulate growth of the cancer cell and allow it to survive.
Amgen is a global biotechnology company that discovers, develops,
manufactures and markets important human therapeutics based on
advances in cellular and molecular biology.
Abgenix is a biopharmaceutical company focused on the discovery,
development and manufacturing of human therapeutic antibodies. The
company's antibody development platform includes a leading technology
and state-of-the-art manufacturing capabilities that enable the rapid
generation, selection and production of high affinity, fully human
antibody product candidates to a variety of disease targets. Abgenix
leverages its leadership position in human antibody technology to
build a diversified product portfolio through the establishment of
collaborations with multiple pharmaceutical and biotechnology
companies. For more information on Abgenix, visit the company's Web
site at www.abgenix.com.
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(1) XenoMouse(R) is a registered trademark of Xenotech, a
wholly-owned subsidiary of Abgenix, Inc.
SOURCE: Amgen Inc.
Trish Hawkins, 805-447-4587 (media)
Arvind Sood, 805-447-1060 (investors)
E. Blair Schoeb, 917-432-9275 (media & investors)