A genetically modified version of the herpes virus has provided strong results against advanced cancers, according to the results of early clinical trials.
The researchers found that RP2 – a new version of the herpes simplex virus – showed signs of efficacy in a quarter of patients with a group of advanced cancers.
Patients in the trial had cancers including melanoma, esophagus, and head and neck and had exhausted other treatment options, including checkpoint inhibitor immunotherapy.
“Our study shows that the genetically modified cancer killer virus can inflict one or two strikes against tumors — destroying cancer cells directly from the inside while also invoking the immune system against them,” study leader Kevin Harrington, professor of cancer biological therapy at the Institute of Cancer Research, said in a statement. statement.
He stressed that it is rare to see such good response rates in early-stage clinical trials, whose primary goal is to test the safety of treatment, especially when it includes patients with very advanced cancers and current treatments have stopped working.
“The results of our preliminary trial suggest that a genetically modified form of the herpes virus could become a new treatment option for some patients with advanced cancers — including those who have not responded to other forms of immunotherapy,” Harrington said.
“I’m eager to see if we continue to see benefits as we treat increasing numbers of patients.”
The early results were presented at the 2022 European Society of Medical Oncology (ESMO) conference.
How it works?
The genetically modified herpes virus is designed to have a dual action against directly injected tumors.
Not only does it multiply inside cancer cells to blast them from the inside, but it also inhibits a specific protein – known as CTLA-4 – to throw the immune system into full swing and make it kill cancer cells more effectively.
Harrington’s team at the Institute of Cancer Research and the Royal Marsden NHS Foundation Trust evaluated the cancer-killing virus on its own in nine patients, and in combination with nivolumab immunotherapy in an initial 30 patients.
An ongoing Phase 1 trial, sponsored by the drug’s manufacturer Replimune, aims to test the safety and dosage of RP2, as well as its ability to shrink tumors.
Cancer free for 2 years
Three out of the nine patients treated with RP2 benefited from the treatment and saw their tumors shrink.
Someone saw his tumor disappear completely and remain cancer-free.
Krzysztof Wojkowski, a 39-year-old construction worker from west London, was diagnosed with a form of salivary gland cancer in 2017.
After several surgeries, he was told he had no treatment options left, before he had the chance to join the RP2 trial in 2020.
“It was my last lifeline. I had injections every two weeks for five weeks which completely killed my cancer.”
He has been cancer free for two years.
It is a true miracle, and there is no other word to describe it. I was able to work as a builder again and spend time with my family; There is nothing I cannot do.”
Seven out of 30 patients who received both RP2 and nivolumab immunotherapy also benefited from the treatment.
In this group, four out of nine patients with melanoma, two out of eight patients with uveal melanoma, and one in three patients with head and neck cancer saw their cancer growth stop or shrink.
Of the seven patients who received the combination and who saw a benefit, six patients remained progression-free at 14 months of age.
The positive effect of mild side effects
The researchers looked at patients’ biopsies before and after injecting the RP2 virus and found positive changes in the area just around the tumor.
The authors explained that the injections increased the number of immune cells in the area and “turned on” genes associated with the immune response that eliminates cancer cells.
The researchers found that most of the side effects of RP2 were mild, with the most common being fever, chills, and fatigue.
The team now hopes to continue exploring the potential of this strategy in a larger number of patients.
Viruses are one of humanity’s oldest enemies, as we’ve all seen during the pandemic. Professor Christian Helen, chief executive of the Institute of Cancer Research London, said: “But our new research suggests that we can exploit some of the advantages that cause them to defy enemies to infect and kill cancer cells.”
It’s a small study, but the initial results are promising. I very much hope to see patients continue to benefit as this research expands.”