A small clinical trial of a novel virus engineered to kill cancer cells while boosting the body’s immune response began this week. The hope is that the new therapy, which has been shown to shrink cancer cells in animals, will prove to be equally effective in humans. The virus, CF33-hNIS, also known as Vaxinia, was originally created by researchers at the City of Hope National Medical Center in California.

According to Gizmodo, it is now being jointly developed with the company Imugene Limited that gave the virus its name. Vaxinia is an oncolytic virus, meaning it prefers to target and infect cancer cells. Researchers have been looking into this mechanism to kill cancer cells for more than a century with limited success. Recent developments have led to designing a genetically modified virus that not only infects and damages cancer cells, but also makes these cells more identifiable to the immune system.

Researchers hope that this strategy will enhance the effects of other immunotherapy treatments, especially in attacking hard-to-target solid tumors. In preliminary laboratory and animal experiments, Vaxinia reduced the size of colon, lung, breast, ovarian and pancreatic tumors.

“Now is the time to further enhance the power of immunotherapy, and we believe that CF33-hNIS has the potential to improve our patients in their battle with cancer,” said Dr. Danang Li, principal investigator and assistant professor in the City of Hope’s Department of Medical Oncology & Therapeutics Research, in a news release.

The multicenter Phase 1 trial of the virus will start by delivering a low dose of CF33-hNIS to cancer patients with metastatic or advanced solid tumors who have had at least two other rounds of standard treatments. The study aims to recruit 100 patients across approximately 10 trial sites in the U.S. and Australia, according to the City of Hope.

Groups will receive Vaxinia alone or in combination with pembrolizumab, an immunotherapy drug, says Gizmodo. While Phase 1 trials are designed to study the safety and optimal dose of experimental treatments, the researchers will keep track of how the patients respond to the virus, and whether their cancers are progressing. They will also note the survival rate over the next few years. This data will determine the future of further clinical trials. The Phase 1 trial is expected to be completed by early 2025.

According to researchers, the genetically engineered virus is a unique way to fight cancer.

“Interestingly, the same characteristics that eventually make cancer cells resistant to chemotherapy and radiation actually enhance the success of oncolytic viruses, such as CF33-hNIS,” said Dr. Yuman Fong, the key developer of the genetically modified virus, and the Sangiacomo Family Chair in Surgical Oncology at City of Hope, headquartered in Duarte, Calif. “We are hoping to harness the promise of virology and immunology for the treatment of a wide variety of deadly cancers.”