A genetically engineered cold sore virus could be effective against head and neck cancer, a small clinical trial suggests.
Scientists at the Institute of Cancer Research (ICR) and the Royal Marsden NHS Foundation Trust have completed a phase-I/II trial of the treatment involving 17 patients.
Participants received injections of the herpes simplex virus (called OncoVex) into their diseased lymph nodes.
Each patient received up to four doses, along with radiotherapy and chemotherapy.
Publishing their findings in the journal Clinical Cancer Research, the study authors revealed that 14 patients (82.3 per cent) showed signs of head and neck tumour shrinkage.
In 93 per cent of cases, subsequent surgery to remove the lymph nodes revealed that there were no traces of residual cancer in the nodes.
After a typical follow-up period of 29 months, 82.4 per cent of patients had not succumbed to cancer, and just two out of 13 patients who received a high dose of the modified virus suffered a relapse.
Principal investigator Dr Kevin Harrington, from the ICR and the Royal Marsden, said that the results compare 'very favourably', as up to 55 per cent of patients receiving chemotherapy and radiotherapy typically relapse within two years.
He noted: '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.'
The virus is thought to be effective against head and neck cancer because, unlike the unmodified version of the virus, it is only capable of multiplying inside cancer cells.
Upon injection into a patient, the virus bursts and kills tumour cells, as well as helping to stimulate their immune system to fight the disease.
Dr Alison Ross, senior science information officer at Cancer Research UK, told the BBC that the small study 'highlights the potential of using genetically modified viruses as a weapon to fight cancer'.