Virotherapy has proved to be a more effective treatment for colorectal cancer, considering that it successfully prevents the reoccurrence of the disease when used as therapy of choice. Oncolytic virotherapy is one of the current treatments being used in the treatment of colorectal cancer that is one of the commonly diagnosed cancers in contemporary times. According to Davis and Lahiri, 2015, colorectal cancer is ranked third among the most common types of cancers in the world, with men being more affected than women. It is approximated that about 55% of colorectal cancer cases come from developed countries where incidence cases vary depending on the geographical location. Mortality due to cancer remains high, and the use of new treatments such as virotherapy is a timely consideration at a time when the incidence and prevalence of cancer are on the rise. A combination of treatments is a chance to try and find a lasting solution to the resistance nature of colorectal cancer to certain cancer types. According to Tilgase et al., 2018, a combination of oncolytic virotherapy with other treatments has shown a successful remission of colorectal cancer and improved stability of the patient after the withdrawal of the therapy in a number of clinical trials.
A number of treatments are indicated for metastatic colorectal cancer, but the survival rate of patients has remained low; hence the need to seek more effective treatments for the disease. The in-vitro studies that have been carried out indicate that metastatic colorectal cancer patients are bound to benefit from therapies that combine both immunotherapy agents as well as oncolytic viruses. The mode of action of oncolytic viruses ranging from their entry mechanisms in cancer cells and the intercellular changes that occur make oncolytic viruses to be an effective treatment for various cancers where other therapies have failed. The selective nature of oncolytic viruses in the manner they destroy cancer cells and spare the health cells makes them a better choice in the development of new cancer therapies. Chemotherapy and radiation have failed in some metastatic colorectal cancer patients but use of virotherapy is a promising milestone in such patients.
Effective of Oncolytic Viruses in Treatment of Colorectal Cancer
Retrospective studies that have been carried out to determine the effectiveness of non-modified oncolytic viruses have shown an increased survival rate and a decreased mortality ratio determined to be between 4.39- to 6.57 fold. It was found out that the use of oncolytic viruses reduces the viability of the cells that were obtained from human samples. In the case of colorectal cancer, the oncolytic viruses are able to get deep to the perineural space to destroy the malignant tissues within a short time upon their administration. Positive effects have been identified in patients where immunotherapy has been combined with oncolytic viruses. According to Kurozumi et al., it was found out that the use of oncolytic viruses causes inflammatory responses in the body as well as cellular infiltration that are important responses that enhance the clearance of cancer cells.
The synergy of using immunotherapy and oncolytic viruses have been confirmed by the accelerated reduction of viability on cell lines of patients with colorectal cancer. According to Davis and Lahiri, 2015, oncolytic viruses have enhanced tropism that is associated with high selectivity in their action, making them effective in the treatment of deep malignant cells as the case with colorectal cancer. Upon getting to the tumour cells, the oncolytic viruses cause selective replication that facilitates the destruction of the cancerous cells. The action of oncolytic cells is greatly advanced compare to the therapeutic action of other therapies indicated for colorectal cancer. Most important about the oncolytic viruses is that they have improved protection compared with other conventional therapies indicated for the various types of cancers.
Virotherapy is a form of gene therapy that makes use of the agents available in nature to destroy malignant cells in cancer patients. Different oncolytic viruses have different mechanisms through which they destroy malignant cells; hence they are specific oncolytic viruses that have been indicated effective for colorectal cancer. A number of oncolytic viruses that have been tested so far have indicated to have a broad spectrum action in terms of their antitumor activity such that some of the oncolytic viruses that were initially indicated for specific cancers are being studied to identify how well they can be used in the treatment of other cancers. Non-human viruses are mostly preferred for oncotherapy due to their reduced risks in terms of safety issues of the viruses in the treatment of cancer
Davis, D., & Lahiri, S. (2015). Application of Oncolytic Viruses for Cure of Colorectal Cancer. Cancer Res J, 3(4), 76.
Kurozumi, K., Hardcastle, J., Thakur, R., Yang, M., Christoforidis, G., Fulci, G., … & Kaur, B. (2007). Effect of tumor microenvironment modulation on the efficacy of oncolytic virus therapy. Journal of the National Cancer Institute, 99(23), 1768-1781.
Tilgase, A., Olmane, E., Nazarovs, J., Brokāne, L., Erdmanis, R., Rasa, A., & Alberts, P. (2018). Multimodality Treatment of a Colorectal Cancer Stage IV Patient with FOLFOX-4, Bevacizumab, Rigvir Oncolytic Virus, and Surgery. Case reports in gastroenterology, 12(2), 457-465.