A groundbreaking study has revealed how viruses that typically infect bacteria, known as phages, could be genetically modified to harness the body's existing vaccine immunity to combat cancer. Researchers at Imperial College London successfully demonstrated this method in mice, eradicating cancerous tumours in nearly half of the treated animals by redirecting their immune response built up from a malaria vaccine.
The study, led by Amin Hajitou, focused on a specific type of phage. This phage was engineered to recognise and bind to particular proteins, called αvβ3 and αvβ5 integrins, which are commonly found on the surface of many tumour cells but are largely absent from healthy ones. Crucially, the phage was also modified to deliver instructions for producing a malaria-specific antigen – a molecular signal that the immune system identifies as foreign. This effectively turned the phage into a targeted delivery vehicle, guiding the immune system's pre-existing memory towards the cancer.
To test their hypothesis, the team conducted experiments on 60 mice with cancerous tumours. Fifteen of these mice received a malaria vaccine, and two weeks later, were injected with the engineered phages over a fortnight. The results were significant: 44 per cent of the treated mice saw their tumours completely eradicated, with no recurrence observed a year later when the study concluded. Other treated mice also exhibited extended lifespans compared to control groups, which showed no survival benefit.
This approach addresses a key challenge in cancer treatment: helping the immune system to effectively recognise tumours as a target. While immunotherapies have revolutionised the treatment of some cancers, many patients still do not respond. David Withers from the University of Oxford highlighted the potential advantage of this new method, noting that these modified viruses can be administered systemically, reaching tumour cells throughout the body. This contrasts with some current approaches, such as oncolytic viruses, which often require direct injection into the cancer, limiting their application in cases of widespread metastatic disease.
A significant implication of this research is its potential adaptability. The researchers believe that by adjusting the phage's antigen-making instructions, the method could be made to work with immunity acquired from other common vaccines, such as those for seasonal flu or COVID-19. Hajitou suggested that "other vaccines, stronger than malaria, should work even better," emphasising that the principle relies on exploiting existing immune memory, rather than being specific to malaria.
Looking ahead, the research team is currently in discussions with the Medicines and Healthcare Products Regulatory Agency (MHRA) in the UK. They hope to assess this promising approach in an early-stage clinical trial involving human patients, with a potential start date as early as next year. Should these trials prove successful, it could pave the way for a novel and highly adaptable cancer treatment strategy.