indication

For the treatment of EGFR-expressing, metastatic colorectal carcinoma that is refractory to fluoropyrimidine-, oxaliplatin-, and irinotecan- containing chemotherapy regimens.

pharmacology

Panitumumab is a recombinant, human IgG2 kappa monoclonal antibody that binds specifically to the human Epidermal Growth Factor Receptor (EGFR). EGFR is a transmembrane glycoprotein that belongs to the subfamily of type I receptor tyrosine kinases. Although EGFR is expressed in normal cells, the overexpression of EGFR is detected in many human cancers, including those of the colon and rectum. Interaction of EGFR with its normal ligands causes phosphorylation and activation of a series of intracellular proteins that will in turn regulate the transcription of genes involved with cellular growth and survival, motility, and prolieration. Signal transduction through EGFR leads to the activation of the wild type KRAS gene, but the presence of an activating somatic mutation of the KRAS gene within a cancer cell can result in the dysregulation of signaling pathways and resistance to EGFR inhibitor therapy.

mechanism of action

Panitumumab binds specifically to EGFR on both normal and tumor cells, and competitively inhibits the binding of ligands for EGFR. Nonclinical studies show that binding of panitumumab to the EGFR prevents ligand-induced receptor autophosphorylation and activation of receptor-associated kinases, resulting in inhibition of cell growth, induction of apoptosis, decreased pro-inflammatory cytokine and vascular growth factor production, and internalization of the EGFR.

toxicity

Panitumumab was shown to cause skin, ocular and mucosal related toxicities in 90% of patients receiving panitumumab. Subsequent to the development of severe dermatologic toxicities, infectious complications, including sepsis, septic death, and abscesses requiring incisions and drainage, were reported.

half life

7.5 days (range: 4-11 days)