The Promise and Pitfalls of Phage Therapy: A Case Study

Tuesday - February 20 2024, 08:01 UTC - 9 months ago

Phage therapy, a treatment that uses viruses to target and kill specific strains of bacteria, has gained renewed interest in light of the antimicrobial crisis. While it has shown promise in some cases, a recent case study highlights potential challenges and limitations, including the possibility of antibodies affecting the effectiveness of the therapy and the lack of standardized regulation.

Lynn Cole had a blood infection she couldn’t shake. For years, she was in and out of the hospital. Each time antibiotics would force the infection to retreat. Each time it came roaring back.

In the summer of 2020, the bacteria flooding Cole’s bloodstream stopped responding to antibiotics. She was running out of time. Her doctors decided they had to try a different approach, and asked the US Food and Drug Administration to allow them to administer an experimental therapy, a virus known as a bacteriophage. Bacteriophages — or phages — are tiny viruses that infect and destroy bacteria.

What happened next? The details came out this week in a case study in mBio. The phages worked. Cole recovered with remarkable speed. But then the therapy failed. Cole’s case highlights the enormous promise and potential pitfalls of phage therapy.

Phage therapy has been around for more than a century, but it fell out of fashion throughout most of the world with the advent of antibiotics. The deepening antimicrobial crisis, however, has rekindled people’s interest and generated an enormous amount of excitement. Headlines have claimed that phages can "save the world" and that "one day, doctors might prescribe viruses instead of antibiotics." .

The excitement reached a fever pitch in recent years because of one particularly compelling story. In 2016, HIV researcher Tom Patterson picked up a deadly antibiotic-resistant infection in Egypt. His wife, infectious disease epidemiologist Steffanie Strathdee, helped hunt for the phage therapy that ultimately cured him. Strathdee gave a TED talk. She and Patterson wrote a book. She told her story in People magazine.

The potential of phage therapy was further demonstrated when Lynn Cole was successfully treated with phages. When Cole first received phage therapy, she had been dealing with a blood infection for nearly a month. Her doctors tried a variety of antibiotics with no effect. But 24 hours after they administered phage therapy, Cole’s infection was gone. She seemed cured.

About a month later, however, the infection returned. So the researchers found another phage that would work against the Enterococcus bacteria causing Cole’s infection, and began administering both phages. That seemed to do the trick.

For four months, Cole was infection-free. She left the hospital and went on vacation with her family. But then the infection returned. Cole was out of options. She entered hospice, and seven months later she died of pneumonia.

Van Tyne and her colleagues have spent the past couple of years trying to explain why their phages failed. They don’t yet have an answer, but they do have a hypothesis. A couple of weeks after Cole began receiving the second phage, she developed antibodies against both phages. "Possibly that played a role in limiting how well they were able to find their bacterial targets and kill them," says Madison Stellfox, a physician and postdoc in Van Tyne’s lab. She posits that perhaps the antibodies coated the phages so they couldn’t enter the bacteria. Or maybe they helped the body clear the phages faster, so they didn’t have time to work.

Cole isn’t the only patient Van Tyne and her colleagues at the University of Pittsburgh treated with phages. We know that the phages were able to reach their bacterial targets through the millions of phage particles they found in the patient’s blood.