Investigators confirmed that panitumumab, a monoclonal antibody developed by Amgen Inc and Abgenix Inc, reduced tumors in 9% of patients with advanced colon cancer who previously received no benefit from chemotherapy. Research from the Loma Linda University Cancer Institute showed that patients survived for an average of 37.6 weeks while in this trial. These results are similar to those of Erbitux, a product of ImClone Systems Inc and Bristol-Myers Squibb Co; however, Erbitux contains fragments of mouse proteins, whereas panitumumab is fully humanized. Panitumumab can also be administered less frequently than Erbitux and can be given safely weekly, biweekly, or every third week, with the most common side effect being a reversible skin rash. The drug also competes with "small-molecule" drugs Tarceva and Iressa, both of which target the epidermal growth factor receptor. According to Dr. David Parkinson of Amgen, a difference exists between antibodies and small molecules in terms of their biological impact, and researchers are just starting to understand how this will affect different patients. A late-stage colon cancer trial will take place later this year, and Amgen expects regulatory approval of panitumumab in 2006; this would be the first approved cancer drug for Amgen.
Ms. Farley is a freelance medical writer based in Wakefield, RI.