Genetically Modified Herpes Virus Shows Promise in Fighting Advanced Cancers

 

Herpes virus against cancer Image by Freepik

 Introduction:

In a groundbreaking phase I trial, a modified version of the herpes simplex virus, called RP2, has demonstrated remarkable potential in combating advanced cancers. Initial findings from the study indicate that RP2 displayed effectiveness in 25% of patients with various advanced cancer types, including skin, oesophageal, and head and neck cancer. 

These patients had exhausted other treatment options, including checkpoint inhibitor immunotherapy. The results, presented at the 2022 European Society for Medical Oncology Congress, suggest that cancer-killing viruses could offer hope to patients who have not responded to conventional immunotherapies.

Testing Safety and Dosage:

The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust conducted the trial, evaluating RP2's safety and dosage in a group of patients. The study involved administering the genetically engineered RP2 virus directly into tumors. RP2 acts on tumors through a dual mechanism: multiplying within cancer cells to burst them from within and inhibiting a protein called CTLA-4, which enhances the immune system's ability to kill cancer cells. Moreover, RP2 has been modified to produce molecules known as GM-CSF and GALV-GP-R, which further stimulate the immune system's response against cancer.

Positive Outcomes:

Out of the nine patients treated solely with RP2, three experienced tumor shrinkage. Notably, one patient with salivary gland cancer witnessed complete tumor disappearance and remains cancer-free 15 months after treatment initiation. The remaining two patients, one with oesophageal cancer and the other with uveal melanoma (a rare eye cancer that had spread to the liver), observed tumor shrinkage and maintained a positive response for 18 and 15 months, respectively. Among the 30 patients who received both RP2 and nivolumab, an immunotherapy, seven demonstrated treatment benefits.

Promising Combinations:

Within this group, four out of nine patients with melanoma skin cancer, two out of eight patients with uveal melanoma, and one out of three patients with head and neck cancer experienced halted or reduced cancer growth. Remarkably, six out of the seven patients who benefited from the combination therapy remained free of progression for 14 months.

Enhanced Anti-Cancer Immune Response:

Biopsies conducted before and after RP2 injections revealed positive changes in the tumor's immune microenvironment—the region surrounding the tumor. RP2 injections led to increased immune cell presence, particularly CD8+ T-cells, and activation of genes associated with the anti-cancer immune response.

Safety and Future Prospects:

RP2 treatment exhibited mild side effects, including fever, chills, and fatigue. However, none of these side effects required medical intervention. Moving forward, researchers plan to expand the study to include a larger cohort of patients to further explore the potential of RP2 as a treatment option for advanced cancers.

Conclusion:

The phase I trial results have demonstrated that genetically modified cancer-killing viruses, such as RP2, have the potential to deliver a dual impact on tumors—destroying cancer cells from within and activating the immune system against them. Despite the trial's primary focus on safety, the exceptional response rates observed in this early-stage study provide hope for patients with advanced cancers who have exhausted other treatment avenues. The future looks promising for the application of genetically engineered herpes viruses as a novel therapeutic approach, complementing existing immunotherapies and offering new possibilities for cancer treatment.

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