and how it is revolutionizing oncology
By Dr. A. Eli Gabayan
Chief of Medical Oncology at the Beverly Hills Cancer Center
Immunotherapy, the process of stimulating or tweaking the body immunity to fight cancer is changing the clinical practices in treating a variety of cancers. The concept of harnessing one’s immune system has brought about a paradigm shift in the approach of cancer treatment. Its potential in revolutionizing oncology is enormous and limitless.
Currently, immunotherapy is being increasingly applied in treating many acute and advanced stages of cancer. With FDA approvals in immunotherapy treatments and drugs for specific cancers lining up, a radical change in the cancer treatments is being observed. This clearly speaks how fast immunotherapy has been generating impact based on the positive responses from various cancer treatments. Immunotherapy treatments can also be applied in combination with chemotherapy or radiation.
What is cancer immunotherapy and how it is done?
Certain parts of the person’s immune system are used to fight cancer. Some types of immunotherapy are also known as biologic therapy or biotherapy. It can be either done by stimulating the person’s own body immunity system to make the cells work harder or by introducing man-made immune system proteins in the body.
Immunotherapy gives a targeted answer to cancer by virtue of its several important features.
• It enables the immune system of the body to recognize and target the specific cancer cells.
• Patients with specific types of cancer resistant to chemotherapy and radiation respond better with immunotherapy.
• Immunotherapy in a way trains the immune system of the body to identify and memorize the traits of cancer cells. In this way, it offers a great possibility of long-term cancer remission.
• Clinical studies on the overall cancer survival rate reveal that responses to immunotherapy are long lasting and continue even after the treatment is stopped.
• Immunotherapy does not cause common side effects often seen from chemotherapy or radiation therapy. Side effects related to stimulation of body immunity system cause mild inflammation, fever, headache and nausea. Some treatments may trigger autoimmune diseases which if uncontrolled can cause severe symptoms and even death.
Primary immunotherapy treatments currently being used:
• Monoclonal antibodies
These are specifically designed antibodies in the lab that can attack a specific antigen found in cancer cells. The US FDA has approved more than a dozen Monoclonal Antibodies to treat specific cancers. They work by either boosting the person’s immune response to cancer cells or may block the antigens in cancer cells and prevent its proliferation.
• Checkpoint Inhibitors
A person’s immune system fights the foreign cells, which are different from the normal cells through specific “checkpoints”. Checkpoints are nothing but molecules on specific immune cells that are required to be activated or deactivated to start an immune response. Checkpoint inhibitors are drugs that target these checkpoints and are showing promising results in treating melanoma, non-small cell lung cancer, Hodgkin Lymphoma and cancer of bladder, kidney, head and neck. Notable checkpoint inhibitor drugs are Pembrolizumab (Keytruda), Nivolumab (Opdivo), Atezolizumab (Tecentriq), Avelumab (Bavencio), Durvalumab (Imfinzi), Ipilimumab (Yervoy) etc.
• Cancer vaccines
Cancer vaccines are meant both for prevention and treatment. The vaccines for treatment are different from those used for prevention. Vaccines to prevent HPV (Human Papilloma Virus) and HBV infections are well known. Cancer treatment vaccines facilitate the immune system to attack the already existing cancer cells.
These vaccines are generally made from cancer cells, parts of cells or pure antigens. The patient’s immune cells may also be used at times to create the vaccine. Sipuleucel- T (Provenge) is the only cancer treatment vaccine approved in the US for treating advanced prostate cancer.
• CAR (Chimeric Antigen Receptor) T- Cell Therapy
The T-Cells, a type of white blood cells are removed from the patient’s body and tweaked in a lab to fight the cancer cells. These specially engineered cells are then infused back into the patient’s body. Currently, two CAR-T cell Therapies are approved by FDA – one for lymphoblastic leukemia and the other for specific types of large B-Cell Lymphoma (also one of the types of non-Hodgkin’s Lymphoma).
• Non-specific cancer immunotherapies and adjuvants
The adjuvants do not directly attack the cancer cells but stimulate the body immunity system to generate better immune response against the cancer cells. This is done by injecting cytokines (chemicals produced by some immune cells essential to maintain vitality of other immune cells) into the patient’s body. Sometimes these are combined with specific chemotherapy drugs but the side effects are more pronounced in combination therapy. These can be applied in treating certain types of Lymphoma, Leukemia, Melanoma and cancer of kidney.
Although cancer immunotherapy is still at the nascent stage, the success achieved so far assure an enhanced standard of care for patients with advanced stage of cancer extending their longevity.
Apart from all the promising features, immunotherapy cannot be applied to all cancer patients. The targeted nature of immunotherapy can also be an obstacle because all cancers may appear similar but in reality they are not. Moreover, the antigen expression in response to a specific monoclonal antibody may not be the same for all cancer patients and therefore the effectiveness may vary a lot. Another challenge can be the high cost of these treatments. Amidst the challenges, optimism rules which is reflected from the immense research support by leading authoritative bodies in cancer treatment.