Biological therapy refers to cancer treatments which exploit particular biological characteristics of cancers (biomarkers) in order to target them. Biological therapies can be either cytotoxic (killing cancer cells) or cytostatic (preventing cells from dividing). Because biological therapies are more specifically targeted to the cancer they often have significantly fewer side effects than standard chemotherapy treatments.
Like chemotherapy, biological therapy can be given orally or by injection. Common examples include hormone therapies such as Tamoxifen used to treat breast cancers which have a particular hormone receptor; monoclonal antibodies which can generate an immune response and/or destroy one or more of the driver proteins (called oncoproteins) which encourage cells to divide and survive; or receptor tyrosine kinase inhibitors (RTKIs) which can bind to such oncoproteins and “switch them off”. Biological therapies can be given by themselves or in combination with chemotherapy. They are often only suitable for certain subsets of patients whose cancers have the right biomarker.