China’s modified virus therapy shows promise in last-stage cancer trials

A ground-breaking cancer therapy being tested in China is offering new hope for patients with advanced malignancies, particularly those who have exhausted conventional treatment options. The experimental treatment, HSV-1 VG161, utilises a genetically modified herpes simplex virus to target tumours directly while stimulating the immune system.

The therapy was recently tested in a Phase 1 clinical trial in China and has demonstrated potential in extending survival rates while minimising side effects.

The therapy, which uses an engineered herpes simplex virus, was approved for the next research stage last year under China’s emergency breakthrough protocol after early trial data based on 40 patients with liver cancer revealed a near-doubling in life expectancy, according to a report by SCMP.

Unlike current immunotherapies such as CAR-T cell therapy and PD-1 inhibitors, HSV-1 VG161 directly targets tumours using a modified virus.

Speaking on the mechanism of this therapy, Dr. Suman Karanth, Senior Consultant, Medical Oncology, Fortis Memorial Research Institute (Gurugram) said, “In CAR-T cell therapy, a patient’s T cells are genetically modified to express a chimeric antigen receptor (CAR) to recognise and attack cancer cells. PD-1 inhibitors, on the other hand, block the interaction between PD-1, a protein on T cells, and PD-L1, a protein on cancer cells, thereby enhancing the immune response.”

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She further added, “Both these therapies are administered intravenously, whereas HSV-1 VG161 is directly injected into the tumour, carrying multiple payloads including IL-12, IL-15 receptor units, and PD-L1 blocking peptides to overcome the immunosuppressive tumour environment. This leads to both direct tumour killing and activation of the body’s innate and adaptive immune systems.”

The preliminary trial results of HSV-1 VG161 have raised cautious optimism among oncologists. According to the data, patients who had exhausted prior immunotherapy options showed survival benefits ranging from an average of 9.4 months to 17.3 months.

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Discussing the implications of the findings, Dr. Karanth noted, “The trial data is promising, particularly because there is an unmet need to improve survival rates in patients who do not respond to checkpoint inhibitors. Currently, survival beyond five years for such patients is less than 20%.”

Despite the encouraging results, experts remain cautious, as the trial involved only 44 patients with advanced liver cancer. “By its direct administration into the tumor, this therapy helped reverse tumor resistance by stimulating immunity. However, we must wait for larger studies and trials across different cancer types to fully understand its potential,” Dr. Karanth emphasised.

With further research and larger clinical trials, HSV-1 VG161 could emerge as a ground-breaking advancement in oncology, providing new hope for patients with resistant forms of cancer.

According to a paper by researchers from the First Affiliated Hospital of Zhejiang University, the modified virus, known as VG161, was able to infiltrate and dismantle drug-resistant liver tumours in the patients while supercharging their immune defences.

A total of 40 patients with advanced liver cancer took part in the first clinical trial. All of them had reached a stage of drug resistance that left them with no available treatments, according to the 2024 study.

The patients were injected with the engineered oncolytic virus VG161, with the therapy targeted directly into the core of the liver tumours.

The researchers found that after receiving the oncolytic virus therapy, patients were able to continue receiving immunotherapy treatments, reporting significant survival benefits in patients who took first-line and second-line therapies after VG161.

According to the paper, four patients who were previously resistant to systemic therapies and were experiencing tumour progression appeared to display a reversal in their resistance after treatment with VG161.

The results suggested that the VG161 therapy stimulates anti-tumour immunity and is capable of transforming advanced liver cancer from “cold” to “hot”, the researchers said. Subgroup analyses suggested tweaks to the therapy could further prolong survival.

The study found that in its current form, VG161 effectively prolonged survival times from an average of 9.4 months to 17.3 months with only mild adverse effects, giving the patients time and opportunity for further treatment.