Systematic anti-cancer therapies
Some hospitals have begun to conduct full genome scans of patients’ cancers to achieve a ‘genetic map’ 9 which means that instead of experimentation with different chemotherapy drugs (which are far more toxic than the specific inhibitors used for personalized medicine) in which the only way to check the effectiveness is to wait to examine the side effects and the change in size of the tumour, the gene mutation can be examined so that the correct specific therapeutic drugs can be given first time. These targeted therapy treatments mean that the patients can be prescribed a more effective drug to treat their lung cancer with fewer side effects that can be administered more easily. This improvement in cancer treatment is not just confined to lung cancer treatment as targeted therapy has been approved by the national cancer institute for treatment of over 30 different cancers 10 including breast cancer and prostate cancer which are the commonest cancers in women and men respectively.
Breast cancer
In 15-20% of breast cancers there is an overexpression of the HER2 gene. 11 This gene promotes growth and leads to a more aggressive cancer than its HER2-negative counterpart. To combat this scientists have created monoclonal antibodies which are complementary to the HER2 protein on the cancer cells, the most common of which is Trastuzumab (Herceptin). Monoclonal antibodies are manmade versions of antibodies in the blood which can be designed to attach to a specific target. Historically this was via the hybridoma method where an animal is injected with the desired antigen so that the humoral response takes place and plasma cells are produced on which carry the desired antibody to attach to the antigen. The problem with plasma cells is that they cannot divide by themselves and therefore can only produce a set amount of antibodies that are attached to their surface. In order to create monoclonal antibodies and produce a greater quantity of antibodies they are electrically fused with myeloma cells (cancer cells). These cells are then screened to see which ones are producing the correct antibody and are also rapidly dividing, the correct cells are called hybridoma cells and are then placed in an incubator to grow and divide until enough of the antibody is produced. 12 The invention of monoclonal antibodies has marked an advancement in targeted therapy as they can be specifically made to target certain antigens on the surface of cancerous cells. Currently, methods of developing monoclonal antibodies without using a host animal and instead using in vitro tissue-culture method are being explored. Presently, this method is more expensive, more complex and sometimes fails to produce the required 9 Sonett, J. Personalized medicine used for treatment of lung cancer at https://www.youtube.com/watch?v=1c9sKHtNuKQ. Consulted 23/08/23. 10 National cancer institute. List of targeted therapy drugs approved for specific types of cancer at https://www.cancer.gov/about-cancer/treatment/types/targeted- therapies#:~:text=Targeted%20therapy%20is%20a%20type,the%20foundation%20of%20precision%20medicine. Consulted 23/08/23. 11 Targeted drug therapy for breast cancer at https://www.cancer.org/cancer/types/breast-cancer/treatment/targeted-therapy-for-breast-cancer.html. Consulted 23/08/23. 12 See Nakamura, R. (1983) ‘Monoclonal antibodies: methods and clinical laboratory applications’, Clin Physiol Biochem 1(2-5): 160-172; National research council (US) committee on methods of producing monoclonal antibodies. (1999) Monoclonal Antibody Production. Washington (DC).
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