Panitumumab

What it is and how it works

Mechanism of Action The EGFR is a transmembrane glycoprotein that is a member of a subfamily of type I receptor tyrosine kinases, including EGFR, HER2, HER3, and HER4. EGFR is constitutively expressed in normal epithelial tissues, including the skin and hair follicle. EGFR is overexpressed in certain human cancers, including colon and rectum cancers. Interaction of EGFR with its normal ligands (e.g., EGF, transforming growth factor-alpha) leads to phosphorylation and activation of a series of intracellular proteins, which in turn regulate transcription of genes involved with cellular growth and survival, motility, and proliferation.

Mechanism class: HER1 Antagonists

Indications

Vectibix is an epidermal growth factor receptor (EGFR) antagonist indicated for the treatment of: Adult patients with wild-type RAS (defined as wild-type in both KRAS and NRAS as determined by an FDA-approved test) Metastatic Colorectal Cancer (mCRC)*: In combination with FOLFOX for first-line treatment. ( 1 , 14.2 ) As monotherapy following disease progression after prior treatment with fluoropyrimidine, oxaliplatin, and irinotecan-containing chemotherapy. ( 1 , 14.1 ) KRAS G12C-mutated Metastatic Colorectal Cancer (mCRC)* In combination with sotorasib, for the treatment of adult patients with KRAS G12C- mutated mCRC, as determined by an FDA-approved test, who have received prior treatment with fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy. *Limitations of Use: Vectibix is not indicated for the treatment of patients with RAS -mutant mCRC unless used in combination with sotorasib in KRAS G12C-mutated mCRC. Vectibix is not indicated for the treatment of patients with mCRC for whom RAS mutation status is unknown ( 1 , 2.1 , 5.2 , 12.1 , 14.3 ).

Dosage and administration (summary)

Wild-Type mCRC: Administer 6 mg/kg every 14 days as an intravenous infusion over 60 minutes (≤ 1000 mg) or 90 minutes (> 1000 mg). KRAS G12C -mutated mCRC: Administer 6 mg/kg every 14 days as an intravenous infusion over 60 minutes (≤ 1000 mg) or 90 minutes (> 1000 mg) in combination with sotorasib. Patient Selection RAS Wild-Type mCRC Prior to initiation of treatment with Vectibix as monotherapy, assess RAS mutational status in colorectal tumors and confirm the absence of a RAS mutation in exon 2 (codons 12 and 13), exon 3 (codons 59 and 61), and exon 4 (codons 117 and 146) of both KRAS and NRAS .

Contraindications

None. None

Warnings and precautions

Dermatologic and Soft Tissue Toxicity: Monitor for dermatologic and soft tissue toxicities. Reduce dose for recurrent Grade 3 toxicity and withhold or discontinue Vectibix for severe or life-threatening complications. Limit sun exposure. ( 2.3 , 5.1 , 5.7 ) Increased tumor progression, increased mortality, or lack of benefit in patients with RAS -mutant mCRC, receiving Vectibix monotherapy or in combination with oxaliplatin-based chemotherapy. ( 2.1 , 5.2 ) Electrolyte Depletion/Monitoring: Monitor electrolytes and institute appropriate treatment.

Pregnancy

Pregnancy Risk Summary Based on data from animal studies and its mechanism of action, Vectibix can cause fetal harm when administered to pregnant women . Limited available data on the use of Vectibix in pregnant women are not sufficient to inform a risk of adverse pregnancy-related outcomes.

Storage and supply

Store vials in the original carton under refrigeration at 2° to 8°C (36° to 46°F) until time of use. Protect from direct sunlight. Do not freeze or shake. Discard any unused portion remaining in the vial.

Source: Panitumumab (Vectibix) — US FDA prescribing information, 2026-06-23, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.