The updated analysis showed that patients with measurable metastatic colorectal cancer which expressed the epidermal growth factor receptor (EGFr) experienced partial responses. Response rates were similar for patients treated with either two or three prior chemotherapy agents. The results confirm earlier interim findings from this study and were presented by the study's lead investigator, J. Randolph Hecht, M.D., Director of the Gastrointestinal (GI) Oncology Program at UCLA's Jonsson Comprehensive Cancer Center, in a poster presentation at the 40th American Society of Clinical Oncology (ASCO) Annual Meeting. (ASCO Abstract #3511)
"This is an exciting time in colorectal cancer research as we continue to see the development of new promising targeted therapies," said Hecht. "In this study, panitumumab showed durable responses and was well-tolerated in colorectal cancer patients. We are encouraged because we have not seen anaphylaxis in patients receiving panitumumab, and infusion reactions have been uncommon thus far."
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 intravenous infusion. Tumor responses were confirmed approximately four weeks after the initial response was observed.
"Response to panitumumab appears to be independent of prior treatment with oxaliplatin, indicating potential utility in refractory colorectal cancer patients," added Hecht.
Treatment with panitumumab resulted in a 10 percent overall response rate (15 partial, 0 complete) with a median duration of response of 5.2 months. Stabilization of disease was observed in 38 percent of patients (n=56). Median overall time to progression was two months and median overall survival was 7.9 months. Exploratory subgroup analyses comparing responses in patients who had received two prior chemotherapy agents (9/80) versus those who had received three prior agents (6/68), demonstrated similar efficacy (overall partial response rate of 11 percent versus 9 percent, respectively).
In this study, panitumumab was well-tolerated, with reversible skin rash as the most common side effect (95 percent, 3.4 percent grade 3). Other side effects experienced by some patients were fatigue, nausea and mild diarrhea. One patient had a grade 3 infusion-related reaction related to panitumumab. There were no instances of anaphylaxis. In those patients tested to date (n=110), no human antihuman antibodies (HAHAs) have been observed.
Further Analysis Suggests Panitumumab is Well-Tolerated in Advanced Non-Small Cell Lung Cancer
Data from Part 1 of a second Phase 2 study demonstrated that frontline therapy with panitumumab was generally well-tolerated in combination with paclitaxel and carboplatin in patients with advanced non-small cell lung cancer (NSCLC). The results were presented by Jeffrey Crawford, M.D., Professor of Medicine and Interim Chief of Medical Oncology at the Duke University Medical Center, in a poster at the 40th ASCO Annual Meeting. (ASCO Abstract #7083)
"We are encouraged by the safety profile of this antibody in lung cancer patients when given in combination with chemotherapy, which we believe reflects its fully human nature. We look forward to the results of the second part of this ongoing and now accrued study, which will evaluate the efficacy of panitumumab in combination with chemotherapy," said Crawford.
Nineteen patients were enrolled into three groups: those administered 1.0 mg/kg (n=6), 2.0 mg/kg (n=7), and 2.5 mg/kg (n=6) panitumumab weekly for three weeks, for up to six cycles. Five of 19 patients had objective responses (one complete, four partial). In this small study of 19 patients, the observed median time to progression was six months and the observed median overall survival was 17 months. The most common adverse event seen in this study was skin rash, but the incidence of grade 3 skin rash did not appear to increase with dose. Part 2 of this study (n=175) is designed to confirm these findings and compares time to progression for patients receiving panitumumab plus chemotherapy to that for patients receiving chemotherapy alone as frontline therapy for advanced NSCLC.
Co-developed by Amgen and Abgenix, panitumumab is an investigational product in a new class of targeted cancer treatments called epidermal growth factor receptor (EGFr) inhibitors. Panitumumab (formerly ABX-EGF), which was generated with XenoMouse(R)(1) technology, 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. Amgen initiated pivotal trials in the United States and Europe evaluating panitumumab as third-line monotherapy in colorectal cancer patients in January 2004.
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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Abgenix Forward Looking Statement
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(1) XenoMouse(R) is a registered trademark of Xenotech, a wholly
owned subsidiary of Abgenix, Inc.
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SOURCE: Amgen Inc. and Abgenix