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FDA approves new colorectal cancer drug
Panitumumab showed effectiveness in slowing tumor growth and reducing tumor size.
The FDA approved panitumumab for the treatment of patients with colorectal cancer that has metastasized following standard chemotherapy.
Panitumumab (Vectibix, Amgen), a human monoclonal antibody that binds to epidermal growth factor receptors on some cancer cells, received an accelerated approval after showing effectiveness in slowing tumor growth, and in some cases, reducing tumor size.
In the United States, an estimated 150,000 new cases of colon cancer will be diagnosed and 55,000 deaths will occur from colon and rectal cancer in 2006. Approximately 70% of all colorectal carcinomas test positive for EGFR.
“Colorectal cancer is the third most common cancer and the third leading cause of cancer mortality in the United States,” said Steven Galson, MD, MPH, director of the FDA’s Center for Drug Evaluation and Research. “This approval adds a treatment option for patients with an advanced stage of a disease that can be life-threatening.”
Clinical trial results
The FDA approved panitumumab based on results from a randomized, controlled clinical trial of 463 patients with metastatic cancer of the colon and the rectum, who had undergone treatment with fluoropyrimidine, oxaliplatin (Eloxatin, Sanofi) and irinotecan (Camptosar, Pharmacia).
The mean time to disease progression or death in patients receiving panitumumab was 96 days vs. 60 days in patients receiving the best standard supportive care. In addition, 8% of the patients receiving panitumumab experienced a tumor shrinkage that in some cases exceeded 50% of the pretreatment tumor size. Both study groups showed similar overall survival.
Accelerated approval
Under the accelerated approval program, drugs for serious and life-threatening diseases can be made available earlier in the development process if a promising effect is observed. As part of the approval, Amgen committed to conducting a postmarketing trial to show whether the drug improves survival in patients with fewer prior chemotherapies.
The most serious adverse events included pulmonary fibrosis, severe skin rash complicated by infections, infusion reactions, abdominal pain, nausea, vomiting and constipation. The most common adverse events associated with the drug included skin rash, fatigue, abdominal pain, nausea and diarrhea.
Panitumumab is being evaluated in ongoing clinical trials as both a monotherapy and in combination with other agents for the treatment of various types of cancer.
Editor’s note: These results are not a major step forward since they are similar to what is already seen with cetuximab. – Joseph R. Bertino, MD