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Targeted therapy are drugs that target specific alterations in cancer. Cancer cells have specific changes in their DNA that give them the capacity to grow, divide and spread indefinitely. These genetic changes produce specific proteins that can be targeted using drugs.
Precision medicine is a growing field of Oncology which aims at understanding the above-mentioned changes that happen in cancer and use that information to target the cancer cells.
MECHANISM OF ACTION:
Targeted therapy can affect the cancer cell itself, the environment in which the cancer cell grows or the blood vessels that supply nutrients to these cancer cells. This can be in the form of small molecules that can easily enter the cells or as antibodies that are designed against specific antigens on the surface of the cancer cell.
The mechanisms by which targeted therapy work includes:
- Target specific proteins inside the cell and switch off its function
- Target the cancer microenvironment and make it less favorable for cancer growth
- Stimulate the immune system against cancer cells
- Carry toxins inside the cells and cause cell death
However, these drugs might not work if the tumor lacks the target at interest. Resistance to targeted therapy can develop over time. The adverse effect profile with targeted therapy varies with the drug used but is different from those seen with chemotherapy.
With time, the tumor might acquire a new mechanism to overcome the targeted drug used to kill it. The genetic alterations seen earlier can change with time when the cancer develops resistance to therapy. To understand the change a new genetic test might be done at the time of progression. There are specific drugs available for specific gene alterations seen after progression on a target drug eg.in lung cancer and CML.
The concept of one drug/ chemotherapy fits all has changed since the advent of targeted therapy. With more research and better understanding of these genetic alterations, targeted therapy might become the future of cancer therapy.
