AN OVERVIEW OF IMMUNOTHERAPY FOR NON-SMALL LUNG CANCER
By Farhia Rashid
Non-small-cell lung carcinoma (NSCLC) is all epithelial lung cancer except small cell lung carcinoma. 85% of all lung cancers are NSCLC.
The treatments available to patients with NSCLC depend on a range of factors, including the size of the cancer, where it is, how advanced it is, and the patient’s overall health. The main treatments are surgery, radiotherapy, chemotherapy, and immunotherapy.
Immunotherapy is the use of drugs to stimulate a patient’s own immune system to recognise and destroy cancer cells.
In 1891, William B. Coley injected streptococcal organisms (bacteria) into a patient with terminal inoperable cancer. The theory behind this was that the bacterial infection produced with the injection would have the side effect of shrinking the tumour. This was successful, and for the next few decades, Coley injected hundreds of cancer patients with bacteria to induce an infection. The results were excellent, and Coley became the “father of immunotherapy”.
By the time most lung cancer patients become symptomatic and are diagnosed, their lung cancer has advanced to a late stage. At this point in the advancement of the disease, surgery, chemotherapy and radiotherapy are effective to a very limited extent. Therefore immunotherapy in lung cancer is being researched widely.
There are 3 main types of immunotherapy used for lung cancer: monoclonal antibodies, checkpoint inhibitors and vaccines.
Monoclonal antibodies are antibodies made in labs to treat cancer patients. One example is Naked Monoclonal Antibodies, which block proteins within tumours that help the cancer grow. There are also Conjugated Monoclonal Antibodies, which have chemotherapy or radiotherapy molecules attached to them; they attach directly to cancer cells so that the drugs have the biggest effect possible. Bispecific Monoclonal Antibodies bind to 2 proteins at once, such as one cancer cell and one lymphocyte, which assists the immune system to attack the cancer.
Checkpoints are the regulators of the immune system. The immune system has checkpoints in order to keep control and balance, and to ensure that it doesn’t attack the body’s own healthy cells and tissues. Tumours produce proteins (PD-L1) to turn on the checkpoints, which slows down the immune system to stop it from attacking the cancer. Checkpoint inhibitors block the checkpoints. Therefore they help the immune system find and attack cancer cells.
Examples of checkpoint inhibitors include atezolizumab (blocks PD-L1), permbrolizumab (blocks PD-1), and nivolumab (blocks PD-1). These drugs are delivered intravenously.
Vaccines can be used to treat lung cancer. A small amount of the patient’s own cancer cells, proteins, or pieces of proteins from cancer cells are injected into the body in order to restart the immune response. As of yet, preventative vaccines for lung cancer have not been developed and approved.
Immunotherapy is a revolutionary cancer treatment, and has the potential to be applied to a range of different cancers. There are a vast number of different kinds of immunotherapy treatments, each of which apply to different cases of cancer.