By Indraneel Ghosh
Treating cancer is one of the biggest challenges faced by the healthcare industry today. Over the last few years, there has been rapid progress in the development of treatment methods used. Considering the speed at which new treatments are developing for the disease, it might be possible to develop a fool-proof way to treat cancers at any stage.
The cancer vaccine
Researchers at Stanford University were recently successful in treating ovarian cancer in mice using vaccines. Although devising a treatment for humans would take some time, the results of the technique used for the mice may help identify the processes that could help in creating the vaccine for the human cells.
When a person is infected by cancer, their immune system can recognise and target specific proteins present on the cancerous cells. However, as the immune system weakens, the body is unable to carry out the function. In fact, as cancer grows, it can trick the weak immune system into helping it to expand further. This proposed treatment taps into that weakened part of the immune response which can attack these cancer cells and destroy them.
The scientists noted that injecting two different immune-stimulating agents into the solid tumours helped remove all traces of cancer in the mice (not just the targeted tumour cell). They believe that this method of treatment can be extended for all kinds of cancer. If such a treatment is established, it could provide a rapid and affordable treatment for cancer. As of now, one of these agents has been approved for undergoing human trials and the other has been tested for use in several unrelated clinical trials.
How is it different from existing techniques?
The use of immunotherapy treatments like this is not new. Some immunotherapy approaches rely on stimulating the immune system. Other drugs target checkpoints which are responsible for weakening the immune cells. Certain other therapies, like Car-T cell therapy (for leukaemia and lymphoma), only work for specific cancers. In CAR-T cell therapy, the immune cells get removed from the patients healthy cells. They are then genetically engineered to target the tumour cells. What makes this vaccination-based treatment useful and unique is that it is both cheap and accessible. Other immunotherapies, which are in use today, are effective against only a specific class of cancer.
We cannot, however, celebrate just yet. Although the treatment has been wildly successful in the case of mice, the same may not apply to humans. This is because the same chemical may function in different ways in different organisms. The line of attack used in the case of mice may be useless when targeting a cancerous cell in humans.
Nanobots to treat cancer
One of the most important strategies used to treat any form of cancer is the Targeted Drug Delivery (TDD). In the process, a drug which had been designed to target the cancer cells is released into the body. One of the biggest challenges is to ensure that these drugs remain specific to the cancer cells and do not target other body cells. To work on providing an improved solution to this problem, biologists have designed ways to target a tumour by using nanorobots.
Nanobots have been used experimentally for treatment of various in several instances. In a major advancement, the scientists at Arizona State University and Nation Center of Nanoscience and Technology, of the Chinese Academy of Sciences, have programmed nanorobots to shrink tumours by cutting off their blood supply. The tumours in the human body use the blood from our blood vessels for growth. The blood vessels also provide the cancer cells a means for spreading across the body. The researchers at NCNST devised methods to cut off the blood supply to the tumours by inducing coagulation of blood with high therapeutic efficacy and safety profiles in many solid tumours which make use of DNA-based nanocarriers. These nanorobots must be programmed to transport molecules which are necessary to block the blood supply to a tumour. The blood supply acts as a mode of nutrition to a tumour. As the nutrient source is cut-off, the tumour shrinks in size.
The results of experimental testing
The nanobot is made up of a flat, rectangular DNA origami sheet, 90 nm by 60 nm in dimensions. A blood clotting enzyme called thrombin is attached to its surface. Thrombin can block the blood flow to a tumour, leading to its death. To perform their studies, scientists studied a well-known mouse tumour model.
First, four thrombin molecules were attached to a flat DNA scaffold. They were folded into a circle to form a hollow tube and then injected into the infected mouse. The key to ensuring that they attacked only the cancer cells was to include a special payload on its surface which would target a specific protein which is produced in high amounts in cancer-infected cells. Once these nanorobots bind to a tumour, it releases the thrombin enzyme and other drugs which are necessary to ease its action. Within two to three days, the tumour had shrunk without causing any damage to the host. It was also tested in case of a lung cancer model in a mouse, which follows a course of progression like lung cancer in humans, with success. Like the vaccination technique, the use of nanotechnology for treatment can be extended to various other fields.
One of the biggest concerns with these methods is their safety and compatibility in the case of a human subject. They have been proven to be compatible in case of other organisms like mice but havent yet been tested in humans. If proven to be successful in humans, they would completely revolutionise the treatment of cancers.
In cancer vaccines, we would have a weapon that can control any cancer at an affordable rate, without any major side-effects. In case we are using nanorobots to control cancer, we could choose the target cell with greater accuracy so that they could cause much greater damage to tumours. In due time, these methods can help treat cancer, providing relief to many people around the world.
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