Transmission Electron Micrograph of E. coli Cells Infected with Phages (Green Dots)
M. Mader/Department of Microbiology, Biozentrum/Science Photo Library
The innovative use of a bacteria-targeting virus has shown promise in destroying cancer cells in mice by harnessing immune responses previously built up through vaccination. In a groundbreaking study, mice immunized against malaria were treated with a harmless phage, a type of virus that specifically infects bacteria, which helped redirect their immune systems to target and eliminate tumors, achieving remarkable results in nearly 50% of the subjects.
Immunotherapy has revolutionized cancer treatment by leveraging the body’s immune system to fight malignancies. Nevertheless, many patients still find themselves without effective options due to the challenge of teaching the immune system to recognize tumors as threats.
Amin Hajitou, a researcher at Imperial College London, led a team that explored the potential of phages that specifically target Escherichia coli. By binding to these bacteria and inserting their genetic material, the phages commandeer the bacteria’s genetic machinery to produce thousands of new phages that effectively eradicate the bacteria.
The research team modified the phages to recognize and attach to proteins known as αvβ3 and αvβ5 integrins, which are prevalent in many tumor cells but rare in healthy ones. Additionally, they engineered the phages to carry instructions for producing malaria-specific antigens, which the immune system identifies as foreign. “Phages serve as targeted delivery vehicles,” explained Hajitou.
The experimental approach involved 60 mice with superficial cancerous tumors. Fifteen mice received the malaria vaccine, followed by a phage injection two weeks later, receiving a total of six injections in the next fortnight. Control groups included 15 mice with no treatment, 15 receiving only the malaria vaccine, and 15 receiving only the engineered phages.
The results were promising, with tumors vanishing in 44% of the treated mice, and these tumors did not reappear one year post-study. Moreover, treated mice exhibited extended lifespans compared to the control group, though no significant overall survival advantage was noted.
“When administered to mice systemically, these engineered viruses can selectively target and infect tumor cells,” noted David Withers from Oxford University. “This strategy enhances current tumor manipulation methods, such as oncolytic viruses that specifically destroy cancer cells. Direct injections into cancerous sites are limited and ineffective for metastatic disease.”
Adjustments to the phage’s instructions for antigen production could make this approach viable for humans vaccinated against infectious diseases like seasonal influenza and COVID-19. “Vaccines with stronger impacts than malaria should yield even greater efficacy,” said Hajitou. “This method takes advantage of pre-existing immune memory and is not limited to malaria.”
The research team is currently in discussions with the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) about assessing this innovative technique in early-stage human trials with hopes to commence as early as next year.
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Source: www.newscientist.com