Immunotherapy, Targetted Therapy, Is there a Difference?
Targetted therapy means precisely what it says: there is a target and we have a medicine that works against that target. The target may be receptors that are present on the cancer cell, such as the estrogen receptor and Her-2 receptor on breast cancer cells. Or the target may be a receptor present on blood vessels supplying the cancer, such as VEGF or VEGFR. Using a VEGF inhibitor would hypothetically lead to less blood supplying the cancer. Other targets include mutations on cancer cells, such as EGFR, ALK and ROS-1 mutations found on lung cancer cells which make the cancer cells more sensitive to EGFR and ALK inhibitors, respectively. But sometimes, the presence of a mutation makes certain medicines not as effective, such as kras or nras mutations present on colon cancer cells make them less sensitive to EGFR inhibitors. Then there are multi-targetted drugs that work against many targets at the same time. Targetted therapy is a rapidly expanding field as scientists find more and more targets.
Imuunotherapy can mean many things. The recent "hot" drugs are called immune checkpoint inhibitors. In the human body, T-cells are activated by the cancer cell. These activated T-cells circulate, locate the cancer cells and attack the cancer cells. However, when PD-1 on the activated T-cell binds with the PD-L1 on the cancer cell, the T-cell becomes inactivated. Immune checkpoint inhibitors block the PD-L1 on the cancer cell, so the T-cell remains activated.