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FAQs - Fast Facts (Panitumumab)

Question: What is the action of panitumumab, what side effects may the patient experience, how is it given, is a test dose needed, and what is the focus of nursing care?

Answer: Panitumumab (Vectibix; Amgen, Thousand Oaks CA) is a fully humanized MAb active against EGFR. It was approved by the FDA on September 27, 2006, for treatment of metastatic CRC following progression on fluoropyrimidines, irinotecan, and oxaliplatin. The approval was based on statistically significant prolonged progression-free survival (96 vs 60 days) in patients receiving panitumumab compared with best supportive care.

Because panitumumab is fully humanized, hypersensitivity reaction (HSR) and infusion reaction are less likely to occur than with MAb’s that include some mouse antibody. Nonetheless, nurses need to monitor patients carefully during the first few infusions.

In the pivotal clinical trial, panitumumab was not given in combination with chemotherapy. Patients were required to have confirmed EGFR overexpression; because these are the only patients for whom a benefit was shown, confirmatory testing for EGFR overexpression is recommended before panitumumab therapy is initiated.

Adverse Events

Black box (severe or life-threatening) warnings about panitumumab include the following:

• Dermatologic side effects were reported in 89% of patients, and 12% of those toxicities were considered severe
• Severe infusion reactions or HSRs were reported in 1% of patients

Infusion reactions, including anaphylactic reaction, bronchospasm, fever, chills, and hypotension, were severe in approximately 1% of patients, but none were fatal. If a severe infusion reaction occurs, the infusion should be stopped. Depending on the severity and/or persistence of the reaction, panitumumab should be permanently discontinued (see Dose Modifications).

Skin-related toxicities, including skin rash, acneiform dermatitis, and paronychia, were reported in 90% of patients and were severe in 15%. Paronychia was reported in 25% of patients and was severe in 2%. Ocular toxicities were reported in 15% and included conjunctivitis, ocular hyperemia, increased tearing, and eye/eyelid irritation. Other common side effects include electrolyte disturbances (hypomagnesemia/hypocalcemia), diarrhea, constipation, nausea, abdominal pain and fatigue, pulmonary fibrosis, and potential fetal death. In cases of severe dermatologic or ocular toxicities, panitumumab should be withheld or discontinued and patients monitored for inflammatory or infectious sequelae (see Dose Modifications). Because sun exposure may exacerbate dermatologic reactions, patients should be counseled to use sunscreen and wear protective clothing.

Dosage and Administration

• Administer panitumumab 6 mg/kg over 60 minutes as an IV infusion (not as an IV push or bolus) every 14 days; administer doses > 1,000 mg over 90 minutes
• No test dose or titration is needed./li>
• Administer by infusion pump through either a peripheral or a central line, using a low–protein-binding 0.2- or 0.22-um inline filter
• Flush the line, before and after administration, with 0.9% sodium chloride injection to avoid mixing with other drug products or IV solutions
• Do not be mix with or administer as an infusion with other medicines, and do not add medications to solutions containing panitumumab

Dose Modifications

Infusion reactions

• Reduce infusion rate by 50% in patients experiencing a grade 1 or 2 (mild or moderate) infusion reaction for the duration of that infusion
• Immediately and permanently discontinue panitumumab infusion in patients experiencing grade 3 or 4 (severe) infusion reactions

Dermatologic toxicities

• Withhold panitumumab for dermatologic toxicities grade 3 or higher or considered intolerable. If toxicity does not improve to < grade 2 within 1 month, permanently discontinue panitumumab
• If dermatologic toxicity improves to < grade 2, and the patient is symptomatically improved after withholding no more than 2 doses of panitumumab, treatment may be resumed at 50% of the original dose
• If toxicities recur, permanently discontinue panitumumab
• If toxicities do not recur, subsequent doses of panitumumab may be increased by increments of 25% of the original dose until the recommended dose of 6 mg/kg is reached.

Nursing Interventions

• Observe patient carefully during the first several infusions for development of infusion reaction or HSR
• Monitor electrolytes during and for 8 weeks after completion of panitumumab therapy
• Patients need to be instructed on ocular and skin changes, and the importance of reporting dyspnea

1. Further information on panitumumab can be found in the full prescribing information at http://www.amgen.com/pdfs/products/vectibix_pi.pdf.
2. Reference: Vectibix prescribing information. Available at. Available at: http://www.amgen.com/pdfs/products/vectibix_pi.pdf Accessed December 5, 2006.

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This page was last modified on 4/4/2007, at 11:29:59 am ET.

Quick Facts

• Panitumumab is a fully humanized monoclonal antibody (MAb) active against the epidermal growth factor receptor (EGFR)
• Fully humanized MAb’s are less likely to cause infusion reactions, but the patients need to be monitored during the first several infusions
• Dermatologic side effects are the most common, reported in 89% of the patients receiving the drug