A genetically engineered cold sore virus has been used to treat head and neck cancer patients in a Phase I/II clinical trial run by The Institute of Cancer Research (ICR) and The Royal Marsden NHS Foundation Trust.

The herpes simplex virus, known as OncoVEX and owned by BioVex Inc, had been modified so it multiplies inside cancer cells but not healthy cells. It bursts and kills tumour cells and, by expressing a human protein, it also helps stimulate patients' immune systems.

The virus was injected into 17 patients' cancer-affected lymph nodes in up to four doses, and the patients were also given radiotherapy and chemotherapy. Head and neck tumour shrinkage could be seen on scans for 14 patients (82.3%), while 93 per cent of patients had no trace of residual cancer in their lymph nodes during subsequent surgery to remove them. After an average follow-up time of 29 months (19 to 40 months), 82.4 per cent of patients had not succumbed to the disease. Only two of 13 patients given the virus treatment at a high dose relapsed.

"Around 35 to 55 per cent of patients given the standard chemotherapy and radiotherapy treatment typically relapse within two years, so these results compare very favourably," Principal Investigator Dr Kevin Harrington from the ICR and The Royal Marsden says. "This was a small study so the results should be interpreted with caution; however the very high rates of tumour response have led to the decision to take this drug into a large scale Phase III trial. This will be the first ever phase III trial combining virus therapy with curative chemoradiation."

Side-effects were generally mild to moderate, and most – except fever and fatigue - were thought to be due to the chemotherapy or radiotherapy. OncoVEX has previously shown promising results when administered on its own in early stage trials of patients with other cancer types, including a Phase II trial of metastaic melanoma patients.

"This trial showed for the first time that these oncolytic viruses can be safely used in combination with other cancer treatments given with the intention of curing patients," Dr Harrington says.

Around 650,000 people are diagnosed with squamous cell cancer of the head and neck each year worldwide, and around 350,000 die from the disease annually.

Source: The Institute of Cancer Research