Panitumumab
Say it: pan-ih-TOO-moo-mab · Brand names: Vectibix
Panitumumab is a targeted antibody medicine that blocks a protein called EGFR that helps some colon cancers grow.
What it is
Some cancer cells use a protein called EGFR to get signals to grow. Panitumumab sticks to EGFR and blocks these signals. It only works when tests show the tumor does not have certain changes in the RAS genes.
Often used for
- colon and rectal cancer that has spread, without RAS gene changes
- colon cancer with a KRAS G12C gene change, together with a targeted pill
How you get it
You get panitumumab as an infusion into a vein at a clinic, and each infusion takes about 60 minutes. It is usually given once every 2 weeks, alone or with chemotherapy. Your schedule may be different.
Common side effects and what helps
- An acne like rash on the face, chest, and back. Use gentle, alcohol free lotion and sunscreen, and ask your team about creams.
- Dry, itchy, or cracked skin. Use thick, unscented moisturizer every day.
- Red, sore skin around the nails. Wear loose shoes and keep your hands and feet clean and dry.
- Feeling tired. Rest and short walks can help.
- Nausea or diarrhea. Eat small meals and drink fluids.
- Low magnesium in the blood, which can cause cramps. Your team will check your blood.
- Skin that burns easily in the sun. Wear a hat and sunscreen.
Call your care team right away if you have
- A rash that is painful, blistering, peeling, bleeding, or looks infected
- New or worse cough or shortness of breath
- Trouble breathing, chills, or swelling of the face during or after the infusion
- Eye pain, redness, or vision changes
- Muscle cramps, twitching, or very bad weakness
- Diarrhea that does not stop or makes you dizzy or dry
Before you start, tell your team
- If you have lung problems
- If you have eye problems or wear contact lenses
- If you are pregnant, may become pregnant, or are breastfeeding
- All the medicines, vitamins, and herbal products you take
Good to know
- This medicine can cause serious skin problems, which can lead to infections. Tell your team early about skin changes so they can treat them.
- You will have blood tests to check magnesium and other blood salts during and after treatment.
- Rarely, it can cause scarring in the lungs or eye problems.
- This medicine may harm an unborn baby. Ask your team about birth control during treatment and for 2 months after.
At home
- Limit time in the sun and wear sunscreen and a hat while on this medicine and for 2 months after.
- Use thick, unscented moisturizer on your skin every day.
Questions to ask
- What can I do to prevent or treat the rash?
- Has my tumor been tested for RAS changes?
- How often will you check my magnesium?
- How long will I get this medicine?
Part of these treatment plans
Side effect guides
- Fatigue (tiredness)
- Nausea and vomiting
- Diarrhea
- Skin rash (including EGFR-inhibitor rash)
- Hand-foot syndrome
Sources
Quick answers
- What is Panitumumab?
- Panitumumab is a targeted antibody medicine that blocks a protein called EGFR that helps some colon cancers grow. Brand names: Vectibix.
- What is Panitumumab used for?
- colon and rectal cancer that has spread, without RAS gene changes; colon cancer with a KRAS G12C gene change, together with a targeted pill.
- How is Panitumumab given?
- You get panitumumab as an infusion into a vein at a clinic, and each infusion takes about 60 minutes. It is usually given once every 2 weeks, alone or with chemotherapy. Your schedule may be different.
- What are the common side effects of Panitumumab?
- An acne like rash on the face, chest, and back. Dry, itchy, or cracked skin. Red, sore skin around the nails. Feeling tired. Nausea or diarrhea. Low magnesium in the blood, which can cause cramps. Skin that burns easily in the sun.
- When should I call my care team while taking Panitumumab?
- A rash that is painful, blistering, peeling, bleeding, or looks infected; New or worse cough or shortness of breath; Trouble breathing, chills, or swelling of the face during or after the infusion; Eye pain, redness, or vision changes; Muscle cramps, twitching, or very bad weakness; Diarrhea that does not stop or makes you dizzy or dry.
- Which chemotherapy plans include Panitumumab?
- FOLFIRI, FOLFOX.
Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.