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Targeted antibodies: how these drugs work
Monoclonal antibodies are lab-made proteins that latch onto one target on cancer cells or the blood vessels feeding them. They're given by IV, or for some, as a shot under the skin, usually every 1 to 3 weeks and often alongside chemo. Infusion reactions, like chills, fever, or flushing during the first infusion, are common to the whole group, so the first dose is usually given slowly with medicines beforehand. Beyond that, each antibody's side effects come from what it blocks.
ℹ️ General information to help you and your loved ones talk with your care team, not medical advice. Read our disclaimer.
On this page: HER2 antibodies · VEGF antibodies · EGFR antibodies · EGFR-MET bispecific antibodies
HER2 antibodies
Herceptin (trastuzumab) and Perjeta (pertuzumab) attach to different spots on HER2 and are often given together in HER2-positive breast cancer, before or after surgery and for metastatic disease. Their best-known risk is weakening of the heart's pumping, so heart scans are done before and during treatment.
VEGF antibodies
Avastin (bevacizumab) blocks VEGF, a signal tumors use to grow new blood vessels. It's used with chemo in colorectal, lung, and ovarian cancer. High blood pressure and protein in the urine are checked, and rare risks include bleeding, slow wound healing, and a tear in the bowel, so it's paused around surgery.
EGFR antibodies
Erbitux (cetuximab) and Vectibix (panitumumab) block EGFR in colorectal cancer that's RAS wild-type (no RAS mutation), usually for tumors on the left side of the colon. An acne-like rash is very common and can be a sign the drug is working. Low magnesium is also checked. Our RAS wild-type guide explains the testing.
EGFR-MET bispecific antibodies
Rybrevant (amivantamab) attaches to both EGFR and MET. It's used in EGFR-mutated lung cancer, including exon 20 insertions, and first-line with Lazcluze (lazertinib). Infusion reactions on the first day, rash, nail-fold soreness, and swelling are common. The label also flags blood clots early in treatment, so blood thinners may be given.
Side effect guides that may help
❓ Questions you and your loved ones can ask
- What is the goal of this treatment for me?
- How will we know if it's working?
- Which side effects should I call about right away, and what number do I call after hours?
- Which medicines, vitamins or supplements should I avoid?
- Will this affect my ability to work, drive, or care for my family?
- What will this cost me, and who can help me with coverage?
Written by the CSE Team from FDA labels and leading cancer centers. Not medical advice. · Last updated: October 15, 2026 · How we write
Sources
Last updated: October 15, 2026. We summarize these sources in our own words.