What do you think of when you hear the word cancer? We hear the word everywhere, from medical dramas, to the news, biology classrooms, and more, but few people actually understand what cancer is, and even fewer people know that numerous recent studies have brought us closer to the ‘cure for cancer’ than ever before.
Your body is composed of trillions of cells. These cells undergo a growth, division and decay process called the cell cycle. This cell cycle is broken into different stages that occur in a specific order and are controlled by a number of environmental factors, chemical signals, and genes. As indicated by the National Cancer Institute, there are two main genes that control how cells grow and divide in the body: oncogenes and tumor suppressor genes. A good analogy to understand their functions is a car. Your cell growth is the acceleration of the car, your oncogenes are the gas pedal, and the tumor suppressor genes are the brakes. Now what would happen if the gas pedal gets pinned to the floor, and the brakes stop functioning altogether? Your car begins to accelerate out of control. In the same way, when either of these genes undergoes a mutation, and is unable to function properly, cell growth escalates without limit. Cancer occurs as a result of this uncontrolled cell growth.
There are two main branches of cancer: malignant and benign. Benign cancers are harmless, but malignant cancers are dangerous. Additionally, metastatic cancer is a type of malignant cancer that spreads throughout the body, making it even more life threatening.
Cancer cells hijack their environments to benefit them. They steal nutrients from surrounding cells, they deactivate cells whose purpose is to kill them, and they can even alter their own DNA to become resistant to treatments. This is what makes cancer so difficult to treat. Cancer has so many mechanisms of resistance, adaptation, and survival, all of which differ between types of cancer, and many of which we have yet to fully understand.
But that’s not stopping research scientists today.
According to the National Cancer Institute, three of the most notable developments in cancer treatment research in the last decade were CAR T cells, immune checkpoint inhibitors, and bispecific antibodies. All of these treatments fall under the larger umbrella of immunotherapy, which by definition translates to, “treatment or prevention of disease that involves the stimulation, enhancement, suppression, or desensitization of the immune system”. In other words, immunotherapy works by giving your immune system, the biological system in your body that prevents you from getting sick, an extra boost.
CAR T cells, or Chimeric Antigen Receptor T cells, are T cells that are genetically engineered to more efficiently target and attack cancer cells. T cells are a type of immune cell whose job is to attack and eliminate foreign invaders, or in the case of cancer, your body’s own cells which have become cancerous. The National Cancer Institute explains that the CAR T cell therapeutic approach involves the following steps:
- Scientists will extract the patient’s T cells from a blood sample.
- The T cells will be genetically engineered in the lab to be better at recognising and attacking cancerous cells based on what we know about the cancer’s mechanisms of resistance.
- Engineered T cells, or CAR T cells, are reinfused into the patient’s body near the site of the tumor.
T cells are one of the primary attackers of the immune system. While this is beneficial in combatting illness, it can also be dangerous. Without something to keep them in check, T cells have the potential to start attacking harmless body cells too. Therefore, evolution has made it so that T cells have receptors on their cell membrane (the outer layer of the cell), which act as an off switch. As reported by the National Cancer Institute, if these off switches are activated, then the T cell stops attacking and chills out. While this may prove useful in some situations, many cancers have developed the ability to act as immune checkpoints themselves and trigger the off switches on T cells themselves, allowing them to evade being attacked. Consequently, immune checkpoints present an obstacle in facilitating the effective T cell attack on cancerous cells. Therefore, Immune checkpoint inhibitors are emerging as a leading treatment approach. Immune checkpoint inhibitors block immune checkpoints from binding to their corresponding receptors on T cells, preventing any interaction with the T cell itself, and allowing the T cell to attack the cancer cells without restriction. The most common immune checkpoint inhibitors currently in circulation are Nivolumab and Ipilimumab.
According to the National Institute of Health, bispecific antibodies act as a microscopic velcro that directly attaches T cells and other immune cells to cancer cells, allowing for the immune cells to better recognise and eliminate cancer cells. Antibodies are a type of protein that are in the shape of a Y most of the time, the upper part of the Y being where the antibody attaches to a receptor on a cell. However, bispecific antibodies have a double Y shape, allowing them to attach to two different receptors, or two different cells, at the same time. Imagine the antibody as a puzzle piece. Different types of antibodies are different shaped puzzle pieces, and antibodies can only attach to receptors that fit with their puzzle piece. Scientists will engineer these bispecific antibodies so that one end is in the shape of a puzzle piece that fits with the receptor on the cancer cell, and the other side fits with the receptor on a T cell or other immune cell of their choosing.
Cancer’s insurmountable reputation has made it a leading role in several television dramas, stories, and news articles. Conventionally cancer treatments like radiation and chemotherapy treat cancer by basically bombing your body cells in hopes of killing the cancer, which is why they are so dangerous and make patients so ill. However, recent research studies that combine our surmounting knowledge in genetic engineering, immunology and cellular communication have led to several breakthrough treatments that act on each patient’s cancer on a specific and personalized level, leading to more effective outcomes with fewer unappealing ramifications.