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Vectibix® (panitumumab) is indicated as a single agent for the treatment of EGFR-expressing, metastatic colorectal carcinoma (mCRC) with disease progression on or following fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens.
The effectiveness of Vectibix® as a single agent for the treatment of EGFR-expressing mCRC is based on progression-free survival. Currently, no data demonstrate an improvement in disease-related symptoms or increased survival with Vectibix®.
Important Safety Information including Boxed WARNINGS:
Safety data are available from 15 clinical trials in which 1467 patients received Vectibix®; of these, 1293 received Vectibix® monotherapy and 174 received Vectibix® in combination with chemotherapy.
WARNING: DERMATOLOGIC TOXICITY and INFUSION REACTIONS Infusion Reactions: Severe infusion reactions occurred in approximately 1% of patients. Severe infusion reactions included anaphylactic reactions, bronchospasm, and hypotension. Although not reported with Vectibix®, fatal infusion reactions have occurred with other monoclonal antibody products. Stop infusion if a severe infusion reaction occurs. Depending on the severity and/or persistence of the reaction, permanently discontinue Vectibix®.
Dermatologic Toxicity:Dermatologic toxicities occurred in 89% of patients and were severe (NCI-CTC grade 3 and higher) in 12% of patients receiving Vectibix® monotherapy. Withhold Vectibix for dermatologic toxicities that are grade 3 or higher or are considered intolerable. If toxicity does not improve to < grade 2 within 1 month, permanently discontinue Vectibix®. The clinical manifestations included, but were not limited to, dermatitis acneiform, pruritus, erythema, rash, skin exfoliation, paronychia, dry skin, and skin fissures. Subsequent to the development of severe dermatologic toxicities, infectious complications, including sepsis, septic death, and abscesses requiring incisions and drainage were reported.
In a single-arm study of 19 patients receiving Vectibix® in combination with IFL, the incidence of NCI-CTC grade 3-4 diarrhea was 58%; in addition, grade 5 diarrhea occurred in 1 patient. In a single-arm study of 24 patients receiving Vectibix® plus FOLFIRI, the incidence of NCI-CTC grade 3 diarrhea was 25%.
Pulmonary Fibrosis
Pulmonary fibrosis occurred in less than 1% (2/1467) of patients enrolled in clinical studies of Vectibix®. Of the 2 cases, 1 involved a patient with underlying idiopathic pulmonary fibrosis and resulted in death. The second patient had symptoms of pulmonary fibrosis, which was confirmed by CT. Additionally, a third patient died with bilateral pulmonary infiltrates of uncertain etiology with hypoxia. Following the initial fatality, patients with a history of interstitial pneumonitis, pulmonary fibrosis, evidence of interstitial pneumonitis, or pulmonary fibrosis were excluded from clinical studies. Therefore, the estimated risk in a general population that may include such patients is uncertain. Permanently discontinue Vectibix® therapy in patients developing interstitial lung disease, pneumonitis, or lung infiltrates.
Electrolyte Depletion/Monitoring
In the randomized, controlled clinical trial, median magnesium levels decreased by 0.1 mmol/L in the Vectibix® arm; hypomagnesemia (NCI-CTC grade 3 or 4) requiring oral or IV electrolyte repletion occurred in 2% of patients. Hypomagnesemia occurred 6 weeks or longer after the initiation of Vectibix®. In some patients, both hypomagnesemia and hypocalcemia occurred. Patients’ electrolytes should be periodically monitored during and for 8 weeks after the completion of Vectibix® therapy. Institute appropriate treatment, eg, oral or IV electrolyte repletion, as needed.
Photosensitivity
Exposure to sunlight can exacerbate dermatologic toxicity. It is recommended that patients wear sunscreen and hats and limit sun exposure while receiving Vectibix®.
Dermatologic, Mucosal, and Ocular Toxicity
Ocular toxicities occurred in 15% of patients and included, but were not limited to: conjunctivitis (4%), ocular hyperemia (3%), increased lacrimation (2%), and eye/eyelid irritation (1%). Stomatitis (7%) and oral mucositis (6%) were reported. One patient experienced an NCI-CTC grade 3 event of mucosal inflammation. The incidence of paronychia was 25% and was severe in 2% of patients. Nail disorders were observed in 9% of patients. .
Pregnancy Category C
Adequate contraception in both males and females must be used while receiving Vectibix® and for 6 months after the last dose of Vectibix® therapy.
Adverse Reactions
The most common adverse events of Vectibix® are skin rash with variable presentations, hypomagnesemia, paronychia, fatigue, abdominal pain, nausea, and diarrhea, including diarrhea resulting in dehydration. The most serious adverse events of Vectibix® are pulmonary fibrosis, severe dermatologic toxicity complicated by infectious sequelae and septic death, infusion reactions, abdominal pain, hypomagnesemia, nausea, vomiting, and constipation.
