Monoclonal antibodies are lab-produced antibodies designed to bind to a specific target. In the context of immunotherapy, the target is typically specific to a type of cancer cell, or binds to an immune cell, such as a T-cell. Monoclonal antibodies must be highly specific to minimize unwanted effects on other cells and tissues in the body.
What are bispecific antibodies and how do they work?
Bispecific antibodies are an alternative option for the treatment of certain types of cancer. These therapies are composed of parts of two different monoclonal antibodies, allowing for dual specificity.
One part usually binds to a protein found on the surface of immune cells such as T-cells while the other part specifically binds to a protein found in excess on the surface of tumor cells. This ensures the direct connection of the T-cell to the cancer cell and is thought to enable T-cell activation, which results in cytotoxic activity directed to the cancer cell.
Other bispecific antibodies work through similarly innovative mechanisms, such as the stimulation of tumor cell clustering by simultaneously binding to tumor cells and special cells called fibroblasts.
Some bispecific antibodies simultaneously bind to lysosomal cells, which are known to break down cells and all types of biological molecules, and to tumor cells specifically directing lysosomal cells to the tumor.
They may also be used for more effective medical imaging of cancer cells.
Examples of bispecific antibodies
Bispecific antibodies being studied to treat cancer include AFM11, AFM13, AMG 330, AMG 420, APVO414, JNJ-61186372, RG7802, RG7828, Tb535H and XmAb14045.
Drawbacks of bispecific antibodies
Despite encouraging preclinical studies for new immunotherapeutic bispecific antibodies, toxicity and lack of significant tumor response have been common barriers. Modifying binding specificity and dosing will likely play a part in resolving these issues.
Bispecific antibodies have similar general side effects to that of monoclonal antibody therapies, and they tend to have fewer serious side effects than chemotherapy drugs. These typically include symptoms similar to an allergic reaction. Each individual therapy is associated with its own specific side effects, as different bispecific antibodies target particular cells and trigger distinct immune responses.
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