On September 27, 2006, the U.S. Food and Drug Administration granted approval to panitumumab (Vectibix, Amgen, Inc) for the treatment of patients with EGFR-expressing, metastatic colorectal carcinoma with disease progression on or following fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens.
The approval is based on the results of a single, open-label, randomized, multinational study that enrolled 463 patients with metastatic colorectal cancer. Patients were randomized to either best supportive care (BSC) alone or BSC plus panitumumab, 6 mg/kg intravenously, every other week. All patients were required to have progressed following one or more chemotherapy regimens containing a fluoropyrimidine, irinotecan, and oxaliplatin. Confirmation of eligibility (disease progression following an adequate course of treatment) was verified for 75% of the patients based on review of source documents by an external committee masked to treatment assignment.
The progression and response evaluations were based upon review of radiographs and other source documents by the same independent review group. The mean PFS was 96 days for patients receiving panitumumab and 60 days for patients receiving BSC alone however, the median times to progression were similar (approximately 8 weeks.). There were 19 partial responses (8%) among the 231 patients randomized to panitumumab; the median response duration was 17 weeks. There was no difference in overall survival between the two study arms. Approximately 75% of patients in the BSC alone arm crossed over to receive panitumumab after determination of disease progression by the study investigator. The majority of patients’ tumors exhibited EGFR expression in ≥10% of tumor cells with no evidence of a correlation between either the proportion of cells expressing EGFR or the intensity of EGFR expression.
The most serious toxicities identified in clinical studies of panitumumab were pulmonary fibrosis, severe dermatologic toxicity complicated by infectious sequelae and septic death, infusion reactions, abdominal pain, hypomagnesemia, nausea, vomiting, and constipation. The most common adverse events were skin rash, hypomagnesemia, paronychia, fatigue, abdominal pain, nausea, and diarrhea.
Full prescribing information including clinical trial information, safety, dosing, drug-drug interaction and contraindications is available at in Drugs@FDA
Healthcare professionals should report all serious adverse events suspected to be associated with the use of any medicine and device to FDA’s MedWatch Reporting System by phone at 1-800-FDA-1088, by facsimile 1-800-FDA-0178, by mail, or by using the Form 3500