Panitumumab (Specialist drug)

RAS wild-type metastatic colorectal cancer: 6 mg/kg every 14 days as monotherapy. Before starting monotherapy, assess RAS mutational status 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. KRAS G12C-mutated metastatic colorectal cancer: same 6 mg/kg every 14 days, in combination with sotorasib - confirm the KRAS G12C mutation with an approved test first, give the first sotorasib dose before the first panitumumab infusion, and refer to the sotorasib prescribing information for its dosing; if sotorasib is withheld or discontinued, withhold or discontinue panitumumab correspondingly. Appropriate medical resources for treating severe infusion reactions must be available during infusions. DOSE MODIFICATION for infusion reactions: reduce the infusion rate by 50% for a mild or moderate (Grade 1 or 2) reaction for the duration of that infusion; terminate the infusion for a severe reaction and, depending on severity and persistence, discontinue permanently. Dermatologic toxicity carries a boxed warning and has its own dose modification rules in the label (section 2.3), which were truncated in the retrieved text - check the full label. SOURCE CAVEAT: no UK SPC posology was retrieved for this drug - the dose above is taken from the US prescribing information for Vectibix (label date 2026-06-23) and must be verified against the current UK SPC before use.