An agent targeted at the underlying molecular defect(s) of the cancer is used in treatment. This has the potential to be effective and less toxic.
There are 3 classes of targeted therapy for childhood cancer:
- Monoclonal antibodies
- Small molecule agents
- Nucleic acid based agents
Earliest targeted therapy
- Antibodies directed against cell surface markers of differentiation 20 (CD20), CD33, and CD52.
- present on lymphoma and leukemia cells
- CD20 is also present on normal lymphoid cells, targeting of this molecule affects overall immune function.
- Monoclonal antibody directed against the B-cell surface antigen CD20
- Treats autoimmune diseases (rheumatoid arthritis) and NHL (non-Hodgkin's lymphoma)
Epidermal growth factor receptor= EGFR (also called HER1).
- A tyrosine kinase EGFR
- present in multiple tumor types and contributes to cancer cell
- activated by binding of specific ligands and then triggers intracellular signaling which leads to cancer cell division and spread.
- This is the treatment target for
- monoclonal antibodies like cetuximab (Erbitux)
- small molecule inhibitors such as erlotinib (Tarceva), gefitinib (Iressa) in multiple tumor types.
Vascular endothelial growth factor = VEGF. A
- Signaling protein involved in angiogenesis
- Binds to tyrosine kinases (VEGF receptors) to initiate and promote angiogenesis.
- It is a target of treatment for the monoclonal antibody bevacizumab (Avastin)