Erbitux (Cetuximab): What It Is and What to Expect

This page is for people who have been offered Erbitux (cetuximab) for bowel cancer or head and neck cancer, and the people helping them. It explains what the drug does, what to check before the first dose, and which side effects to watch for.

Erbitux is the brand name. Cetuximab is the generic name. It is an antibody (a lab-made immune protein) that blocks EGFR, a receptor on the cell surface that tells cells to divide.

In bowel cancer this only works if the RAS genes in the tumor are unchanged. If the tumor carries a RAS mutation, the drug does not help. The label goes further. It says that in people with RAS mutations the drug gave no clinical benefit, only added toxicity. So the approved use is limited to KRAS wild-type (unchanged KRAS), EGFR-expressing bowel cancer that has spread, confirmed with an FDA-approved test. The label states plainly that cetuximab is not for RAS-mutant bowel cancer, and not for cases where the RAS result is unknown. Ask to see your own result before the first dose.

For squamous cell cancer of the head and neck there are three settings:

• With radiation, for disease that is locally or regionally advanced.
• With platinum chemotherapy and fluorouracil, as first treatment when the cancer has come back or spread.
• On its own, after platinum treatment has stopped working.

For bowel cancer that has spread and has unchanged KRAS, there are also three:

• With FOLFIRI as first treatment.
• With irinotecan when irinotecan-based chemotherapy has stopped working.
• On its own after both oxaliplatin- and irinotecan-based chemotherapy have failed, or when irinotecan cannot be tolerated.

A separate approval covers bowel cancer with a BRAF V600E mutation, given with encorafenib after earlier treatment.

Two things sit in the boxed warning, the most serious warning on the drug's label.

Infusion reactions. These occurred in 8.4% of 1,373 people across trials, and were severe in 2.2%. They can be fatal. About 90% of the severe ones came with the first infusion, the label says. They can happen during the drip or several hours after it. That is why an antihistamine is given first and why you are watched during the drip and for at least 1 hour afterwards. Speak up at once about flushing, hives, a tight throat, wheeze, dizziness, or a feeling that something is badly wrong.

Cardiopulmonary arrest. Sudden death has happened in people with head and neck cancer given cetuximab with radiation, or with platinum chemotherapy and fluorouracil. The label asks for magnesium, potassium and calcium to be watched during treatment and after it.

An acne-like rash on the face, scalp, chest and back is the signature effect. Skin dries and cracks. The skin around fingernails and toenails can become inflamed and infected. Broken skin can let serious infections in. The label says to limit sun exposure, so ask your team about covering up and sunscreen.

Ask your team before you put any acne product or other skin product on the rash.

Low magnesium occurred in 55% of 365 people in the trials the label cites, and was severe in 6% to 17%. It can start days to months after treatment begins. That is why the label asks for weekly checks during treatment and for at least 8 weeks after the last dose. Low calcium and potassium can come with it, so the label asks for all three to be checked. Ask your team which symptoms to report.

• What is my tumor's RAS result, and which test was used?
• Will I have cetuximab with radiation, with chemotherapy, or on its own?
• How often will my magnesium be checked?
• What should I put on my skin, and what should I avoid?
• Who do I call if a reaction starts after I get home?

• Call 911 or go to an emergency department if your throat tightens, you wheeze, your face or lips swell, or you feel suddenly and badly unwell after an infusion. Reactions can be fatal, and some begin after you have gone home. Chest pain, collapse or a pounding irregular heartbeat needs the same response, given the cardiac arrest warning on this label. Do not drive yourself.
• Call your care team right away, day or night, if the rash blisters, weeps or spreads over a wide area, or the skin beside a fingernail or toenail turns red, hot and swollen. The label lists serious skin infections, including cellulitis, abscess and sepsis, as possible effects.
• If you also get chemotherapy, call right away, day or night, for chills, a sore throat, mouth sores or burning when you urinate, even with a normal temperature. A temperature of 100.4°F (38°C) or higher needs the same call, since an infection on chemotherapy can become life-threatening.
• Call your care team right away if you get muscle cramps, twitching, odd heart flutters or unusual weakness. They may be linked to low magnesium. The label says low magnesium can start days to months after treatment begins.

https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8bc6397e-4bd8-4d37-a007-a327e4da34d9

https://www.cancer.gov/about-cancer/treatment/drugs/cetuximab