Cancer immunotherapy has transformed the panorama of most cancer treatments, imparting hope to patients for whom conventional therapies like chemotherapy and radiation have proven insufficient. This modern-day approach utilizes the body’s own immune system to identify and destroy cancer cells, turning the immune system into a powerful ally against cancer.
Immunotherapy works by enhancing the immune response, removing the obstacles that allow cancer cells to avoid detection, or directly attacking the tumor microenvironment. Over the past decade, breakthroughs in this area have led to a new generation of precision medicine, enhancing survival rates for many types of cancer.
Immunity Fights Cancer
The immune system can be considered the body's defense mechanism. It recognizes and rejects anything that is harmful to the body, such as viruses, bacteria, and abnormal cells (including cancer). Normally, immune cells, especially T cells, search for invaders or damaged cells throughout the body.
Unfortunately, in many cases, cancer cells can evade the immune system. This is because cancer cells can disguise themselves or create an environment that is unfavourable to the immune system. This camouflage and ability to grow are factors that make cancer difficult to treat with traditional methods.
How Do Immune Therapies Work to Combat Cancer?
Cancer immunotherapy is designed to counter this strategy by enhancing the immune system's capacity to identify and attack cancerous tissues. There are a number of main immunotherapy strategies that have proven to be very effective:
1. Checkpoint Inhibitors
These work by inhibiting the proteins that suppress the ability of T cells to kill cancer cells. Cancer often exploits immune checkpoints such as PD-1 and CTLA-4 to prevent the activation of immune cells. Checkpoint inhibitors, such as nivolumab and pembrolizumab, are drugs that enable T cells to engage and kill tumor cells.
2. CAR-T Cell Therapy
In this advanced therapy, a person’s T cells are engineered in the laboratory to express chimeric antigen receptors (CARs) on their surface. These so-called CAR-T cells are designed to target specific molecules found on the surface of malignant cells and eliminate them. CAR-T cell therapy has shown extraordinary efficacy, especially with regard to blood cancers such as leukemia and lymphoma.
3. Cancer Vaccines
Cancer treatment vaccines are defined to activate specific or general immunity against tumor antigens. Cancer vaccines are designed to enhance the immune system's ability to identify and destroy tumors, similar to vaccines for viral infections like measles.
4. Monoclonal Antibodies
These are synthetic antibodies developed in the laboratory that attach to proteins on the surface of cancer cells, helping the immune system eliminate the targeted cancer cells. These antibodies can also be modified to carry therapeutic agents, delivering harmful substances to cancer cells while protecting healthy tissues.
The Promise and Perils of Cancer Immunotherapy
Cancer immunotherapy has had a profound effect on many types of cancer, especially melanoma, lung cancer, and hematological malignancies. For example, patients with advanced melanoma who once faced a dire prognosis are now experiencing prolonged relief due to immune checkpoint inhibitors.
However, the immune system is not without its challenges. Some patients do not respond to treatment, and immune suppression caused by some therapies can lead to serious side effects, including autoimmune diseases where the immune system attacks healthy tissue. Additionally, the high cost of immunotherapy presents accessibility issues for many patients.
Innovations, Challenges, and New Frontiers
As research continues, new strategies are emerging to improve and optimize patient safety in the delivery of cancer immunotherapy. To improve patient outcomes, immunotherapy is being developed in combination with chemotherapy, radiotherapy, and other treatment modalities. Moreover, future cancer treatments will be personalized, taking into account the specific genotype of each patient’s tumor.
On a broader note, after undergoing several changes and continuous evolution, it is evident that cancer treatment strategies have experienced a paradigm shift with the introduction of immunotherapy. It provides some patients—and maybe even most patients—with long-lasting effects, and in some cases, a cure. Though challenges remain, research and clinical advances suggest a future where the immune system will be the main arsenal in combating cancer.
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Authors
Ms. Akarsha Singh (Third Year B. Tech. Biotechnology), Mr. Amit Kumar Singh, and Dr. Latika Shendre* (Assistant Professor),
Microbial Diversity Research Center,
Dr. D. Y. Patil Biotechnology and Bioinformatics Institute,
Dr. D. Y. Patil Vidyapeeth,
Tathawade, Pune - 411033, Maharashtra, India.
Email: latika.shendre@dpu.edu.in