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Panitumumab is a fully human EGFR antibody, the preferred first-line partner for chemotherapy in left-sided, RAS-normal bowel cancer after the PARADIGM trial.
Fully human IgG2 anti-EGFR; fewer infusion reactions than cetuximab and no ADCC. PARADIGM (2022) established superiority over bevacizumab in left-sided RAS wild-type disease; PRIME established it with FOLFOX. Partner of sotorasib in KRAS G12C mCRC (CodeBreaK 300, approved 2025). Same RAS-testing requirement and skin toxicity as cetuximab.
Backbone ribbon from PDB 5SX4. RCSB PDB 5SX4. The ribbon widens where the chain is folded into a regular pattern and narrows where it is a loose loop.
High-affinity EGFR blockade without effector function. Connects to EGFR.
1.Panitumumab binds EGFR on the tumour cell surface
Source: www.accessdata.fda.gov/drugsatfda_docs/label/2021/125147s210lbl.pdf. Doses are for orientation; the current label governs.
Given by infusion or injection in a clinic or hospital outpatient department, so it is a Part B drug: Medicare pays 80% after the Part B deductible and the patient owes 20% coinsurance, uncapped in Original Medicare unless a Medigap policy applies.
Covered under the medical benefit with prior authorisation confirming diagnosis, biomarker status and line of therapy; site-of-care policies may steer infusions away from hospital outpatient departments. RAS wild-type documentation required.
20% Part B coinsurance on a high-cost infusion adds up quickly: Medigap Plan G or N, Medicare Advantage maximum out-of-pocket, Medicaid dual eligibility, or a charity fund are the usual buffers.
Sources: Medicare.gov: Chemotherapy · Medicare.gov: Prescription drugs (outpatient, Part B). Not medical or financial advice; verify with your plan.
Sources: NICE TA439 · SMC advice: panitumumab. Funding decisions are indication-specific and change monthly; verify with NICE and your treating team.
Accelerated approval, refractory mCRC
EGFR-expressing metastatic colorectal carcinoma with progression on or following fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens
Accelerated approval on a surrogate endpoint, with a confirmatory trial required.
First-line with FOLFOX in RAS wild-type (PRIME)
EGFR-expressing metastatic colorectal carcinoma with progression on or following fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens
Confirmed: the accelerated approval of 2006 converted to traditional approval 7.7 years after it was granted.
With sotorasib for KRAS G12C mCRC (CodeBreaK 300)
| Region | Year | Indication |
|---|---|---|
| US | 2006 | EGFR-expressing mCRC after chemotherapy (later RAS wild-type) |
| US | 2014 | First-line RAS wild-type mCRC with FOLFOX |
| US | 2025 | KRAS G12C mCRC with sotorasib |
| EU | 2007 | Metastatic colorectal cancer; RAS wild-type from 2013 · Vectibix marketing authorisation issued 3 December 2007. |
| England (NICE) | 2017 | Previously untreated RAS wild-type metastatic colorectal cancer with FOLFOX or FOLFIRI · TA439 recommends panitumumab within its marketing authorisation subject to the patient access scheme. |
| Adverse event |
|---|
| Dermatologic toxicity (rash, paronychia) |
| Hypomagnesaemia |
| Diarrhoea |
Very common; boxed warning. Events listed without rates were not read from a primary source; see the label. Blank cells mean the figure was not sourced, not that it is zero.
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Patients with metastatic colorectal cancer carrying a KRAS G12C mutation (about 3-4% of cases) who have exhausted standard chemotherapy now have a targeted option that works far better than trifluridine-tipiracil or regorafenib. The higher sotorasib dose is clearly superior, and the EGFR antibody is essential because KRAS inhibition alone has little effect in bowel cancer. Responses are still modest and short-lived compared with EGFR or ALK inhibitors in lung cancer.
A UK-led trial that moved part of colon cancer chemotherapy in front of the operation, and showed that tumour regression grade after six weeks predicts recurrence, which is the basis for using the response itself to choose what follows.
The analysis that put 'left-sided, RAS and BRAF wild-type' into every guideline as the anti-EGFR population, and made an anatomical fact into a treatment-selection biomarker.
Extended RAS testing (KRAS and NRAS exons 2, 3 and 4) became the standard before any EGFR antibody, and about one in six patients who would previously have been treated is now spared a drug that would have made things worse.
It made acquired resistance a measurable, plasma-readable event, and it is the origin of anti-EGFR rechallenge strategies guided by ctDNA clearance of the resistant clone.
It reframed resistance as selection rather than mutation, which is why the field now asks how to suppress a pre-existing clone rather than how to prevent a new mutation, and why ctDNA is the natural monitoring tool.
Query for this drug: (TITLE:"Panitumumab" OR ABSTRACT:"Panitumumab" OR TITLE:"Vectibix" OR ABSTRACT:"Vectibix") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Panitumumab, not a curated reading list.
Shares Anti-EGFR antibody + chemotherapy in left-sided RAS/BRAF wild-type mCRC, Anti-EGFR rechallenge, CAIRO5, PRIME.
Shares A Rollover Study Evaluating Sotorasib With or Without Panitumumab in Participants With KRAS p.G12C Mutation, Study of Sotorasib, Panitumumab and FOLFIRI Versus FOLFIRI With or Without Bevacizumab-awwb in Treatment-naïve Participants With Metastatic Colorectal, Pre-operative Targeted Treatments in Molecularly Selected Resectable Colorectal Cancer (UNICORN), CodeBreaK 300.
Shares Anti-EGFR antibody + chemotherapy in left-sided RAS/BRAF wild-type mCRC, PRIME, Prognostic and predictive value of primary tumour side in patients with RAS wild-type metastatic colorectal cancer treated with chemotherapy and EGFR directed antibodies in six randomized trials, RAS wild-type (extended KRAS and NRAS testing).
Shares CHRONOS, Tempus xT CDx, PRIME, Panitumumab-FOLFOX4 treatment and RAS mutations in colorectal cancer (PRIME).
Shares A Phase 2 Study of VS-7375 in Patients With KRAS G12D-Mutated Colorectal Cancer, Testing Pump Chemotherapy in Addition to Standard of Care Chemotherapy Versus Standard of Care Chemotherapy Alone for Patients With Unresectable Colorectal Liver Metastases: The PUMP Trial, Anti-EGFR antibody + chemotherapy in left-sided RAS/BRAF wild-type mCRC, Anti-EGFR rechallenge.
Shares ValproIc Acid to Potentiate Anti-EGFR Treatment Efficacy and Prevent/Revert Resistance in Colorectal Cancer, Intermittent or Continuous Panitumumab Plus FOLFIRI for Left Sided RAS/B-RAF Wild-type Metastatic Colorectal Cancer, Anti-EGFR antibody + chemotherapy in left-sided RAS/BRAF wild-type mCRC, Systemic Oxaliplatin or Intra-arterial Chemotherapy Combined With LV5FU2 +/- Irinotecan and an Target Therapy in First Line Treatment of Metastatic Colorectal C.
Shares Anti-EGFR rechallenge, RAS wild-type (extended KRAS and NRAS testing), KRAS G12C-mutant colorectal cancer, EGFR.
Shares PRIME, PARADIGM, RAS wild-type (extended KRAS and NRAS testing), EGFR.