What Is Cetuximab (Erbitux)? FDA Approval, Licensing and Reimbursement in Turkey

• FDA Approved: Yes (Initial Approval Date: February 12, 2004)
• Brand Name: Erbitux
• Active Ingredient: Cetuximab
• Route of Administration: Intravenous (IV)
• Class: Anti-EGFR monoclonal antibody
• Category: Targeted agent, biological response modifier
• Manufacturer: Bristol-Myers Squibb and ImClone/Eli Lilly
• Distribution in Turkey: Merck İlaç Ecza ve Kimya Tic. A.Ş.
• Approved Cancer Indications: RAS wild-type metastatic colorectal cancer, squamous cell carcinoma of the head and neck

What Is Erbitux, Containing Cetuximab?

Erbitux contains cetuximab, an anti-EGFR monoclonal antibody and targeted biological response modifier used to treat RAS wild-type metastatic colorectal cancer and squamous cell carcinoma of the head and neck. By binding to the epidermal growth factor receptor (EGFR) on the cell surface, it blocks growth and proliferation signals in cancer cells and activates the immune system against them, thereby inhibiting tumor growth and enhancing the antitumor immune response.

How Does It Work?

1. Cetuximab is a monoclonal antibody that works by binding to a protein called the epidermal growth factor receptor (EGFR). EGFR is present in excessive amounts in many cancers, particularly colorectal and head and neck cancer.
2. Cetuximab binds approximately 10 times more strongly than the normal cellular binding proteins (EGF and TGF-α) to EGFR. This strong binding stops EGFR activity and prevents cancer cell growth.
3. Cetuximab blocks EGFR homodimerization and heterodimerization, two different pairing processes that allow the receptor to send signals within the cell. This stops EGFR signaling that promotes cell growth and division.
4. Blocking the EGFR signaling pathway prevents signals required for cancer cells to grow, proliferate, metastasize (spread to other areas), and form new blood vessels (angiogenesis).
5. Cetuximab produces an antitumor effect by stimulating the immune system to attack cancer cells. This involves antibody-dependent cellular cytotoxicity and complement-mediated cell death as immune responses.

FDA (United States Food and Drug Administration) Approval History

• February 12, 2004: The FDA approved cetuximab (Erbitux) for metastatic colorectal cancer resistant to irinotecan or in patients intolerant of irinotecan.
• November 7, 2011: The FDA approved cetuximab for advanced head and neck cancer.
• July 6, 2012: The FDA approved cetuximab in combination with FOLFIRI (irinotecan, 5-fluorouracil, leucovorin) for first-line treatment of EGFR-expressing, KRAS mutation-negative (wild-type) metastatic colorectal cancer.

Licensing in Turkey

The conditions and therapeutic indications for which Erbitux is licensed in Turkey are listed as follows:

Therapeutic Indications:

For RAS wild-type metastatic colorectal cancer in patients with an ECOG performance score of 0-1 who have not previously received cetuximab or other anti-EGFR therapies, ERBITUX

• is indicated with only one of the FOLFOX or FOLFIRI combination chemotherapy regimens in the first or second line until progression. ERBITUX or another anti-EGFR therapy must not be used if progression occurs or the accompanying chemotherapy regimen is changed.

For patients with squamous cell carcinoma of the head and neck, ERBITUX is indicated:

• with radiation therapy for locally advanced disease in patients unable to receive cisplatin who have creatinine clearance below 55 mL/min and/or moderate-to-severe heart failure;
• with platinum-based chemotherapy in the first line for recurrent or metastatic non-nasopharyngeal squamous cell carcinoma of the head and neck in patients with an ECOG performance status of 0 or 1.

Treatment Duration: Cetuximab is generally continued until disease progression or unacceptable toxicity. Duration may vary according to the patient's response and tolerance.

What Is Cetuximab's Status on the List of Off-Label Drugs Usable Without Additional TİTCK Approval?

1. Nasopharyngeal Cancer: Suitable for use in the 2nd and subsequent lines.
2. Recurrent Metastatic Head and Neck Cancer (Non-Nasopharyngeal and Squamous Cell): For patients who did not receive cetuximab in the 1st line for recurrent head and neck cancer, use as one line of monotherapy or combination therapy in subsequent lines is appropriate.
3. Stage IV Cutaneous SCC (Squamous Cell Carcinoma): Suitable for use in the 2nd and subsequent lines.

Is Erbitux Reimbursed?

In Turkey, cetuximab (Erbitux) treatment is covered by the Social Security Institution (SGK) in the following situations:

• Metastatic Colorectal Cancer: In patients with RAS wild-type metastatic colorectal cancer, no prior anti-EGFR therapy, and an ECOG performance score of 0-1, use with FOLFOX or FOLFIRI combination chemotherapy may be considered for SGK reimbursement. Cetuximab or another anti-EGFR therapy is not reimbursed if progression occurs during treatment or the chemotherapy regimen is changed.

• Squamous Cell Carcinoma of the Head and Neck:

1. Locally Advanced Disease: Use with radiation therapy is reimbursed in patients unable to receive cisplatin who have creatinine clearance below 55 mL/min and/or moderate-to-severe heart failure.
2. Recurrent or Metastatic Disease: Cetuximab with first-line platinum-based chemotherapy is reimbursed in patients with an ECOG performance score of 0-1.

Price: As of December 2025, the retail prices of Erbitux vials are 9237.62 TL for 100 mg and 45668.18 TL for 500 mg. 

Mechanisms of Resistance

• Mutations in EGFR reduce cetuximab's ability to bind to EGFR, creating resistance to treatment.
• Reduced production of EGFR (decreased expression) reduces the drug's effect.
• TGF-α is produced in greater amounts, making EGFR harder to block.
• KRAS mutations generally occur at codons 12 and 13 and prevent the drug from working.
• BRAF and NRAS mutations cause cancer cells to develop resistance to cetuximab.
• Overproduction of the HER2 protein (gene amplification) results in drug resistance.
• Increased HER3 protein can also reduce cetuximab's effect.
• Activation of alternative signaling pathways such as PI3K/Akt and IGF-1R makes cancer cells more resistant to cetuximab.
• lncRNA MIR100HG and increased activity of genes such as its two embedded microRNAs (miR-100 and miR-125) activate the Wnt signaling pathway, a mechanism that produces drug resistance.

Absorption

Cetuximab is administered intravenously (IV).

Distribution

Its distribution in the body has not been well characterized.

Metabolism

There is insufficient information about cetuximab metabolism. Its half-life is 5-7 days.

Dosing Interval

1. The initial dose is 400 mg/m² IV over 120 minutes, followed by weekly doses of 250 mg/m² IV.
2. An alternative regimen is 500 mg/m² IV every 2 weeks. No initial loading dose is required with this regimen.

Drug Interactions

No drug interactions with cetuximab have been characterized.

Precautions

1. Cetuximab should be used cautiously in patients hypersensitive to mouse proteins or any of its components.
2. The level of EGFR expression does not accurately predict cetuximab's clinical activity. EGFR testing is therefore not required for clinical use of cetuximab.
3. Patients with metastatic colorectal cancer should undergo extended KRAS and NRAS testing. Only patients with wild-type (normal) KRAS and NRAS should receive cetuximab.
4. The development of skin toxicity is an indicator of cetuximab's clinical activity.
5. Use cautiously in patients with underlying interstitial lung disease (ILD), who have a higher risk of worsening ILD.
6. Patients developing a rash may receive topical antibiotics (clindamycin gel or erythromycin cream) or oral antibiotics (clindamycin, doxycycline, or minocycline). They should be advised to avoid sunlight exposure.
7. Approximately 90% of patients experience allergic reactions during the first infusion. Although preventive treatments such as antihistamines are used, some patients may also develop allergic reactions during subsequent infusions.
8. Electrolytes, particularly serum magnesium, should be closely monitored during cetuximab treatment. Hypomagnesemia has been observed with cetuximab.
9. Cetuximab is classified in pregnancy category C. It must not be used during pregnancy or breastfeeding.

 Adverse Effects

1. Infusion-Related Adverse Effects: Symptoms include fever, chills, hives, flushing, fatigue, headache, bronchospasm, shortness of breath, angioedema, and low blood pressure. They occur in 40-50% of patients. Severe reactions occur in fewer than 1%. Reactions are generally mild to moderate during the first infusion.
2.  Skin Toxicity: Skin toxicity may involve itching, dry skin, and a pustular or acneiform rash. It generally affects the face, neck, and upper torso. It improves during treatment and resolves when treatment stops.
3.  Pulmonary Toxicity: Pulmonary toxicity may develop as interstitial lung disease (ILD), presenting with increased cough, shortness of breath, and pulmonary infiltrates. It occurs in fewer than 1% of patients and is more common in those with underlying lung disease.
4.  Hypomagnesemia: Reduced serum magnesium levels (hypomagnesemia) have been observed.
5.  Asthenia and General Weakness: Approximately 50% of patients experience weakness and general malaise.
6.  Inflammation Around the Nails: Swelling and inflammation around the nails (paronychial inflammation), particularly on the fingers and toes, may occur with prolonged use.