Breast cancer: Biological therapy - trastuzumab and others

Biological therapy uses the body's own immune system to act on cancer cells - while leaving healthy cells unaffected. Theoretically this approach minimises side effects. Many of these treatments are still experimental. The idea is to use antibodies to attack cancer cells.

One such antibody is trastuzumab, which is a monoclonal (meaning single) antibody. An antibody is a protein made by the body's own immune system. Trastuzumab is believed to act in three ways to stop cancer cells from growing quickly and out of control:

• It sticks to special receptors on the cancer cells, stopping them from growing.
• It signals the body's own natural killer cells to attack the cancer cells.
• It can work with chemotherapy medications, stopping cancer cells damaged by chemo from repairing themselves.

However trastuzumab can work only if the woman carries the HER2 gene in those tumour cells. The NHS estimates that around 20% of women with breast cancer have tumours that will respond to trastuzumab, which has now been approved for NHS treatment for some people with early and advanced breast cancer. 

Other types of antibodies that are being researched to fight cancer include:

• Angiogenesis inhibitors. These antibodies prevent the growth of new blood vessels, cutting off the supply of oxygen and nutrients to cancer cells.
• Signal transduction inhibitors. These antibodies block signals inside the cancer cell that helps the cells divide, stopping the cancer from growing.

Side effects

Side effects can include allergic reactions, difficulty breathing, swelling, nausea, fever or chills, and dizziness or weakness. Talk to your doctor about the possible side effects to watch for.

Recognising a cancer emergency

Call your nurse or doctor or out of hours service if you have:

• A temperature greater than 38C (100F). If you experience any fever and chills, call your doctor immediately
• If you notice in your mouth new sores, patches, a swollen tongue or bleeding gums.
• If you experience a dry, burning, scratchy or ‘swollen’ throat.
• A cough that is new or persistent and produces mucus.
• Changes in bladder function, including increased frequency or urgency to go, burning during urination or blood in your urine.
• Changes in gastrointestinal function, including nausea, vomiting, constipation or diarrhoea that lasts longer than two or three days, heart burn or blood in your stools.