In this blog post, we will look at the limitations of existing cancer treatments and explore the possibilities and future of new treatments using viruses.
Cancer and Health Issues in Modern Society
Cancer is one of the most serious diseases in modern society, with millions of people diagnosed with cancer each year worldwide. Cancer is the leading cause of death in South Korea, and its severity is increasing year by year. In particular, as lifestyle and environmental factors are known to have a significant impact on the development of cancer, many people are paying attention to cancer prevention. Smoking, excessive drinking, unbalanced diet, lack of exercise, chronic stress, and environmental factors such as air pollution are major factors that increase the risk of cancer.
In addition to regular health checkups, the following preventive measures are recommended for cancer prevention. Eating vegetables and fruits rich in antioxidants, quitting smoking, exercising regularly, and managing stress can reduce the risk of developing cancer. Improving these lifestyle habits not only helps prevent cancer but also improves overall health. However, because the causes of cancer are very complex and diverse, it is still a challenge to completely prevent certain cancers. This is why the development and improvement of cancer treatments is important.
Limitations of Existing Cancer Treatments and New Approaches
Existing cancer treatments are largely divided into surgery, radiation therapy, and chemotherapy (anticancer drugs). These treatments are effective in eliminating cancer cells or inhibiting their growth, but they can cause serious side effects to patients. Because radiation therapy and chemotherapy affect not only cancer cells but also normal cells, patients can experience various side effects such as hair loss, decreased immunity, fatigue, and digestive disorders. In particular, some cancer cells become resistant to anticancer drugs over time, making treatment more difficult. In addition, in the case of metastatic cancer, it is difficult to remove the cancer by surgery because it has spread to various organs and tissues, and complete treatment is often impossible.
For this reason, scientists are researching new treatment methods such as immunotherapy, gene therapy, and stem cell therapy to overcome the limitations of existing treatments. Immunotherapy, in particular, has been receiving a lot of attention recently as it activates the patient’s immune system to directly attack cancer cells. A representative example is immune checkpoint inhibitors, which help the immune system to more effectively eliminate cancer cells by blocking the mechanism by which cancer cells evade immune cells. CAR-T cell therapy is another emerging technology that involves manipulating a patient’s T cells to target and attack only cancer cells. These new treatments have the potential to be combined with existing chemotherapy or radiation therapy to maximize the effectiveness of cancer treatment.
New cancer treatments using viruses
Scientists have begun to look at viruses as a way to overcome the limitations of existing treatments and eliminate cancer cells more effectively. This is because viruses have the potential to selectively attack only cancer cells, excluding normal cells. Viruses have the characteristic of infiltrating host cells, replicating their genetic material, multiplying, and then destroying the host cells. Research is continuing to develop viruses that target only cancer cells by applying this.
If a promoter that recognizes a specific protein that exists only in cancer cells is inserted into a virus, the virus will not work in normal cells, but will only replicate and proliferate in cancer cells, destroying them. The “guided missile” virus created in this way can selectively attack cancer cells and can be used in two ways. The first method is to inject the virus through a blood vessel. The virus that circulates through the body through the blood vessel finds cancer cells, and when it encounters a cancer cell, it replicates within it and destroys the cancer cell. This method is effective even when the cancer has spread to multiple organs. The most commonly used virus for this method is the leo virus.
The second method is to directly inject the ‘guided missile’ virus into cancer cells. This method can quickly focus on specific cancer cells for treatment and is particularly effective in cases where the cancer has not metastasized. Manipulated vaccinia virus and adenovirus are mainly used, and these viruses multiply inside cancer cells and destroy them. In particular, adenovirus naturally destroys the HPV virus that causes cervical cancer, and some studies have reported that it is effective in eliminating cancers such as breast cancer, prostate cancer, and squamous cell carcinoma.
Challenges and the future of viral therapy
Although cancer treatment with viruses is attractive, there are still many challenges. First of all, the method of injecting the virus through the blood vessels may not allow the virus to reach all of the cancer cells due to interference from the immune system. On the other hand, the method of directly injecting the virus into the cancer cells can quickly eliminate cancer cells in a specific area, but may be limited in its effectiveness against cancer cells that have spread to other parts of the body. The current study also found that the virus was unable to spread properly inside cancer cells. Therefore, the effectiveness of the virus therapy will be maximized when used in combination with conventional radiation and chemotherapy.
In 2012, the British medical journal Nature Medicine published clinical results showing that anticancer treatment using vaccinia virus doubled the survival period of patients with terminal cancer. The Pexa-Vec used in this study is an anti-cancer drug that has been genetically engineered to make it only proliferate in cancer cells. The group of patients who received high doses survived for an average of 14.1 months, while the group who received low doses survived for only 6.7 months. This is an important case that suggests that virus-based anti-cancer treatment is indeed effective.
Viral-based cancer therapies are being further developed as research continues. The anti-cancer virus treatment called T-VEC (Talimogene laherparepvec) has already been approved by the FDA and is being used to treat melanoma (skin cancer), and it is expected to be applied to a wider range of cancer types in the future. Furthermore, scientists are also developing viruses that can control the microenvironment around cancer cells to inhibit their growth or activate immune cells around cancer cells.
The future of viral therapy and safety issues
The potential of a virus-based therapy is enormous, but it requires careful research and safety verification. Even if the virus is engineered to selectively attack cancer cells, there is a risk of unexpected mutations or immune responses. There is also a possibility that the virus could spread or mutate uncontrollably in the body. More clinical trials and long-term research are needed to address these issues.
Viral-based anticancer therapy is likely to become an important alternative for cancer treatment in the future. In particular, when personalized viral therapy becomes possible, personalized treatment can be provided for each patient’s cancer type and condition. Once this technology is commercialized and its safety is verified, the day when cancer can be completely conquered will come soon.
