Activity

What is Oncolytic Virus?
Oncolytic Virus is a kind of tumor killing virus with replication ability, which can preferentially infect and kill tumor cells. It can replicate and then cleave tumor cells through different regulatory mechanisms, but does not affect the growth of normal cells. Oncolytic Virus releases tumor-specific antigens in the process of tumor cell lysis, and then activates the body-specific immune response.

Development of Oncolytic Virus
Oncolytic Virus was first reported in the world when it was found that a cervical cancer patient was infected with rabies virus and the tumor subsequently subsided. The earliest clinical use of Oncolytic Viruses can be traced back to the late 19th century, when a 42-year-old woman with leukemia suddenly recovered from her tumor after a suspected influenza virus infection. In 1912, Italian doctors reported a case of advanced cervical cancer in which a patient was apparently in remission after being vaccinated against rabies. Clinical research and treatment of Oncolytic Viruses experienced a brief upsurge in the 1950s and 1970s. However, due to the disadvantage that the efficacy of Oncolytic Viruses could not be sustained due to their easy clearance by the human immune system, they experienced a period of research downturn. By the 1990s, the technology of recombinant virus genome modification was gradually mature, greatly improving the efficacy and safety of Oncolytic Virus in tumor treatment, and a batch of anti-Oncolytic drugs were successively listed on the market. Subsequently, with the rapid development of virus genetic modification technology, Oncolytic therapy regained researchers’ attention.

Classification of Oncolytic Virus
At present, there are many types of Oncolytic Viruses applied in the clinical treatment of tumor, which can be roughly divided into two categories: one is non-gene editing virus, and most of them are naturally unedited viruses; The other is a virus that has been genetically modified to specifically package copies in tumor cells.
Mechanisms of action of Oncolytic Virus

Oncolytic Viruses are “live” drugs that can be programmed to kill tumors in a variety of ways, effectively avoiding drug resistance. At present, it is believed that there are three main mechanisms by which oncolytic viruses can kill tumors :(1) specific reproduction in tumor cells and direct lysis of cancer cells. Until about 2000, researchers thought this was the main way viruses killed tumors. (2) after 2000, researchers gradually discovered that the virus could induce the anti-tumor immune response of the whole body through a variety of ways to kill tumors. Therefore, Oncolytic therapy has been classified as a novel tumor immunotherapy drug from a pure tumor virus therapy, and the idea of gene modification has also changed. (3) in addition, it has been reported that some viruses can inhibit tumor angiogenesis by infecting tumor-related vascular endothelial cells, leading to tumor cell necrosis and indirectly killing tumor cells. In addition, Oncolytic Viruses can be modified in a variety of ways to synergistically kill tumor cells.

Research progress of Oncolytic Virus
The combination of Oncolytic Viruses and conventional cancer therapy has not only shown no significant negative effects, but also shown better efficacy. In 2017, a paper published in the journal Cell showed that when melanoma was treated with a combination of Oncolytic drugs, the tumor remission rate was as high as 62%, with 33% in complete remission. In 2001, Chinese researchers used prostate specific adenovirus CV706, combined with radiotherapy to treat prostate cancer mice, the therapeutic effect was significantly improved. During 2014 to 2016, a variety of Oncolytic Virus preparations entered clinical trials, which also reflects that Oncolytic Virus therapy is being more widely and in-depth research and development. In 2015, T-VEC became the first Oncovirus approved by FDA for the treatment of malignant melanoma, marking the maturity of Oncolytic therapy. Recent advances in genetic engineering have led to increased safety and efficacy of Oncolytic Viruses (OV), leading to increased interest in Oncolytic therapy (OVT). Tumor immunotherapy has become the backbone of the anti-tumor drug market. The global market size is expected to grow from 43 billion US dollars in 2016 to nearly 100 billion US dollars in 2022, accounting for more than half of the anti-tumor drug market, with an annual compound growth rate of 14.6%. Recently, there has been a breakthrough in the clinical trials of oncolytic combination therapy, and Oncolytic Virus may be another important breakthrough after checkpoint inhibitors.