Researchers from the United Kingdom examined how a modified herpes simplex virus (HSV) may be useful to treat mesothelioma.
In this study, pleural mesothelioma patients were treated with an oncolytic virus. Modified herpesvirus HSV-1716 was used to treat tumor growth. Researchers found the therapy may be a safe option for patients with inoperable pleural mesothelioma.
What Is Oncolytic Herpesvirus Therapy?
Oncolytic herpesvirus therapy uses a modified herpes virus to attack cancer cells. This treatment involves injecting patients with HSV-1716, a modified form of the herpes simplex virus. HSV-1716 can infect and kill cancer cells but cannot survive in healthy cells.
HSV-1716 is an oncolytic virus. Oncolytic viruses specifically attack cancer cells, while leaving healthy cells intact. These viruses are a type of immunotherapy treatment. Immunotherapy works by stimulating a patient’s immune system to attack cancerous cells. Immunotherapy is a promising cancer treatment option, including for mesothelioma. It is minimally invasive and typically has fewer side effects than other treatments, including radiation.
This oncolytic virus treatment begins with modifying the chosen virus in a lab. In this case, researchers modified a herpes simplex virus. Patients are then injected with the HSV-1716 oncolytic virus cells. The virus then works by either:
- Infecting and killing cancer cells
- “Teaching” the patient’s immune system to recognize and attack cancer cells
Oncolytic virus treatment is often used in conjunction with more traditional treatments, such as chemotherapy.
UK Study Uses Herpesvirus Therapy to Treat Mesothelioma
Thirteen patients with non-resectable pleural mesothelioma were chosen for this study. Of this group, 11 had epithelial mesothelioma.
These patients all had an existing intrapleural catheter (IPC) due to pleural effusion or trapped lung. Any remaining pleural effusion liquid was drained prior to HSV-1716 treatment.
The patients were split into three cohorts. Each group received one, two or four doses of HSV-1716. The patients were divided as follows:
- One dose: three patients
- Two doses: three patients
- Four doses: seven patients
Several of these patients had received previous mesothelioma treatments, including chemotherapy.
Study Finds Positive Results Using Herpesvirus to Attack Cancer Cells
The study authors examined several factors to determine if HSV-1716 is effective in treating mesothelioma. They evaluated patients’ disease progression and immune responses.
Six patients achieved disease stability. This represents 46% of the total study cohort. Disease stability means there was no observed tumor progression during the post-treatment examination window. Two patients from each of the three dose groupings achieved stability.
Researchers also examined the patients’ immune responses. They found patients exhibited evidence the virus was able to encourage the immune system to attack cancer cells.
The authors also noted the treatment was “well-tolerated,” with minor recorded side effects. The most common side effects included:
- Fatigue/lethargy
- Fever
- Chest pain/discomfort
- Flu-like symptoms
- Cough
- Constipation
Other side effects were noted but did not occur in more than 15% of the treated patients.
What’s Next for Oncolytic Herpesvirus Therapy and Mesothelioma?
HSV-1716 is still undergoing research. It has been tested for other cancers besides mesothelioma. So far, published research indicates the virus is safe and potentially effective against:
- Glioma (a type of brain cancer)
- Oral squamous carcinoma (a type of mouth cancer)
- Melanoma
For patients with inoperable pleural mesothelioma tumors, HSV-1716 also appears to be a safe treatment option.
The study authors noted combining HSV-1716 oncolytic virus therapy with immune checkpoint inhibitors may also be worth investigating. Immune checkpoint inhibitors are another form of immunotherapy. Combining treatments is a common way to manage mesothelioma.
As immunotherapy research continues, researchers may be able to improve mesothelioma patient prognosis.
