Genetically engineered herpes virus can kill cancer cells by destroying and shrinking tumors
British researchers have developed a form of herpes simplex that can fight cancer in treatment-resistant patients, according to findings presented at the Congress of the European Society for Medical Oncology earlier this year. The virus is injected into the tumor, where it multiplies and bursts the cancer cells from within while supporting the body’s immune response.
Called RP2, the modified herpes virus blocks a protein that inhibits the immune response and “turns on” genes that trigger an immune response against cancer.
Side effects were mild, the researchers said, with the most common being chills, fatigue and fever. In a trial of 39 patients with cancers of the skin, esophagus, head and neck and other cancers who had not responded to other types of treatment, a quarter saw a response positive: their tumors stopped growing, shrank and, in one case, completely disappeared. This patient, who had a tumor on his salivary gland since 2017, has been cancer-free for two years.
“Our study shows that a genetically engineered, cancer-killing virus can deliver a punch against tumors – directly destroying cancer cells from the inside while calling on the immune system against them.“said Kevin Harrington, leader of the study, to Pharma Times.
He explained that it was rare to get such a distinct positive result from phase 1 clinical trials, which are conducted to assess the safety of a treatment rather than its effectiveness. The study was sponsored by Replimune, the maker of the drug nivolumab, which was used with the RP2 virus in 30 of the trial participants. Seven of 30 nivolumab plus RP2 recipients benefited from the treatment, and six of them maintained their improvement more than a year later.
Scientists at the Institute for Cancer Research in London aren’t the first to discover the potential of herpes viruses to fight cancer. A February article published in the journal Clinical Cancer Research showed a “experimental cancer-fighting herpes simplex virus called G207was effective in fighting the brain cancer glioblastoma by attacking and killing tumor cells.