How they work:
- Targeted therapies act on specific molecular targets that are associated with cancer, whereas most standard chemotherapies act on all rapidly dividing normal and cancerous cells.
- Targeted therapies are deliberately chosen or designed to interact with their target, whereas many standard chemotherapies were identified because they kill cells.
- Targeted therapies are often cytostatic (that is, they block tumor cell proliferation), whereas standard chemotherapy agents are cytotoxic (that is, they kill tumor cells).
Once hoped to be magic bullets for cancer. Not just yet.
Targeted therapies can have cancer cells develop resistance to them. Tumor cell receptors can mutate and no longer respond to the therapy. Tumor cells can find alternative pathways for growth which do not require the targeted pathway.
My analogy is this: Spray a bunch of Roundup on your weeds and you will kill 99 percent of them. When that one percent grows again, it doesn’t respond to the Roundup as it did the first spraying. This is resistance to a chemotherapy.