Targeted therapy

There are «some of the differences within cancer cells that enable them to thrive. Targeted therapy refers to treatment with drugs that have been developed to “target” these differences within the cell. Unlike chemotherapy, targeted therapy drugs alter the inner workings of the cell focusing on the part of the cancer cell that makes it different from the normal (...). Because they leave the healthy cells alone the side effects of targeted therapies are different from standard chemotherapy treatments. Targeted therapy works by one of the following: arresting the development of new blood vessels that feed the cancer cell, triggering the immune system to attack the cancer cell, changing proteins within the cancer cell, blocking or turning off signals telling the cancer cell to grow or divide, or carrying toxins directly to the cancer cell [1].»

It is «a type of treatment that uses drugs or other substances to identify and attack specific types of cancer cells with less harm to normal cells. Some targeted therapies block the action of certain enzymes, proteins, or other molecules involved in the growth and spread of cancer cells. Other types of targeted therapies help the immune system kill cancer cells or deliver toxic substances directly to cancer cells and kill them. Targeted therapy may have fewer side effects than other types of cancer treatment. Most targeted therapies are either small molecule drugs or monoclonal antibodies [2].»

«Targeted cancer therapies are drugs or other substances that block the growth and spread of cancer by interfering with specific molecules ("molecular targets") that are involved in the growth, progression, and spread of cancer. (...). Many different targeted therapies have been approved for use in cancer treatment. These therapies include hormone therapies, signal transduction inhibitors, gene expression modulators, apoptosis inducers, angiogenesis inhibitors, immunotherapies, and toxin delivery molecules.

• Hormone therapies slow or stop the growth of hormone-sensitive tumors, which require certain hormones to grow. Hormone therapies act by preventing the body from producing the hormones or by interfering with the action of the hormones. Hormone therapies have been approved for both breast cancer and prostate cancer. 
• Signal transduction inhibitors block the activities of molecules that participate in signal transduction, the process by which a cell responds to signals from its environment. During this process, once a cell has received a specific signal, the signal is relayed within the cell through a series of biochemical reactions that ultimately produce the appropriate response(s). In some cancers, the malignant cells are stimulated to divide continuously without being prompted to do so by external growth factors. Signal transduction inhibitors interfere with this inappropriate signaling. 
• Gene expression modulators modify the function of proteins that play a role in controlling gene expression. 
• Apoptosis inducers cause cancer cells to undergo a process of controlled cell death called apoptosis. Apoptosis is one method the body uses to get rid of unneeded or abnormal cells, but cancer cells have strategies to avoid apoptosis. Apoptosis inducers can get around these strategies to cause the death of cancer cells. 
• Angiogenesis inhibitors block the growth of new blood vessels to tumors (a process called tumor angiogenesis). A blood supply is necessary for tumors to grow beyond a certain size because blood provides the oxygen and nutrients that tumors need for continued growth. Treatments that interfere with angiogenesis may block tumor growth. Some targeted therapies that inhibit angiogenesis interfere with the action of vascular endothelial growth factor (VEGF), a substance that stimulates new blood vessel formation. Other angiogenesis inhibitors target other molecules that stimulate new blood vessel growth. 
• Immunotherapies trigger the immune system to destroy cancer cells. Some immunotherapies are monoclonal antibodies that recognize specific molecules on the surface of cancer cells. Binding of the monoclonal antibody to the target molecule results in the immune destruction of cells that express that target molecule. Other monoclonal antibodies bind to certain immune cells to help these cells better kill cancer cells.
• Monoclonal antibodies that deliver toxic molecules can cause the death of cancer cells specifically. Once the antibody has bound to its target cell, the toxic molecule that is linked to the antibody — such as a radioactive substance or a poisonous chemical — is taken up by the cell, ultimately killing that cell. The toxin will not affect cells that lack the target for the antibody — i.e., the vast majority of cells in the body.

Cancer vaccines and gene therapy are sometimes considered targeted therapies because they interfere with the growth of specific cancer cells [3].»

Bibliographic references: 

[1] Cancer-champions.com. (n.d.). Chemotherapy, Immunotherapy, Targeted Therapy. What's the difference? | Cancer-Champions health-care consulting. [online] Available at: https://cancer-champions.com/chemotherapy-immunotherapy-targeted-therapy-whats-the-difference/ [Accessed 29 May 2019].

[2] National Cancer Institute. (n.d.). NCI Dictionary of Cancer Terms. [online] Available at: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/targeted-therapy [Accessed 29 May 2019].

[3] National Cancer Institute. (n.d.). Targeted Cancer Therapies. [online] Available at: https://www.cancer.gov/about-cancer/treatment/types/targeted-therapies/targeted-therapies-fact-sheet [Accessed 29 May 2019].