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Get the most interesting and important stories from the 窪蹋勛圖厙 of 窪蹋勛圖厙.Antibiotics revolutionized medicine, but even these lifesaving medications have their limits. In two new studies involving 窪蹋勛圖厙 of 窪蹋勛圖厙 biologists, researchers show that an experimental technique using bacteria-killing viruses successfully treated two patients with deadly infections that were unresponsive to antibiotics. 泭
One case study is anecdotal. Its a one-off: We might have gotten lucky, said Graham Hatfull, the Eberly Family Professor of Biotechnology in the Kenneth P. Dietrich School of Arts and Sciences. With three documented successful cases,泭now we can start to look for consistencies and some sense that it may work for many more patients.
Bacteriophages, phages for short, kill bacteria by injecting their DNA into bacterial cells and turning their targets into phage factories. Harmless to humans, that ability has made phages a candidate for treating some otherwise intractable infections including those caused by Mycobacterium abscessus, a species of bacteria thats notoriously resistant to antibiotics and can be deadly to patients with cystic fibrosis or who are on drugs that suppress their immune systems.
Hatfull and his lab showed the techniques potential in 2019 in the first use of phages to treat a Mycobacterium infection and the first use of genetically engineered phages in such a treatment. Theyre now on a path toward helping more patients who have reached the limits of what established medicine can provide.
You have to have exhausted all of those options, from a regulatory point of view, before you can go to something truly experimental like phages, said Hatfull. These people dont have anybody else to go to. Its us or nothing.
A lifesaving transplant
In a , researchers report that the Hatfull Labs phage therapy was successful on another, much more common infection in patients with cystic fibrosis a disease that causes buildups of mucus in the lungs, among other catastrophic effects.
The success of the study shows that phage therapy may be useful for many more cystic fibrosis patients, potentially helping others who are stuck on transplant waitlists due to stubborn mycobacterial infections in the lungs.
But the treatments success was anything but certain. Performing phage therapy on a patient with a lung infection, rather than a skin infection like in the 2019 paper, brought with it a new set of challenges and questions.
If theres bacteria in the bloodstream, and you give a phage IV, youve got a pretty good chance that those two will find each other, Hatfull said. The lungs, however, are a complicated network of tubes where an infection can hide. Its just a big unknown, essentially.
Thats especially true in patients like Jarrod Johnson, at the center of the new paper. Johnsons泭infection persisted even after years of treatment with antibiotics. After phage therapy, however, he tested negative for the infection more than a dozen times, clearing the way for him to receive a lung transplant.
I am so grateful for the effort, persistence and creativity of all the people who were involved in my treatment, said Johnson. I thought I was going to die. They have literally saved my life.泭泭
The work was carried out by physicians at National Jewish Health in Denver, Colorado, and led by Jerry Nick, who sent samples to Hatfulls lab to seek phages that could tackle the infection.
Weve got a large collection of phages, and weve sequenced over 4,000 of their genomes, so we understand their genomic profiles and relationships in exquisite detail, Hatfull said. Plus, we have information about which bacteria are infected by which phages, which means that we can take intelligent guesses as to which are going to be the most useful types of phages to look for.
When they received the request, Hatfull and his lab were able to identify two phages that matched up with the strain of Mycobacterium abscessus in Johnsons lungs and genetically engineer them to be more effective at killing it.
As with any case study, its impossible to be sure that the patients recovery was a result of the treatment. But the evidence in this case is stronger than most, Hatfull said.
The patient has been followed incredibly carefully, clinically, for years, with multiple sequencing of strains and antibiotic profiles, he said. Especially convincing were molecular signals of parts of the bacterias cell wall in the patients urine a sign that the phages were killing the bacteria and doing their job.
From a cocktail to a straight shot
In the second of the two studies, , the Pitt team, along with colleagues at Harvard 窪蹋勛圖厙 led by Jessica Little, showed success in treating an immunocompromised patient with a mycobacterial skin infection.
The therapy seemed to really make a big difference when the antibiotics really hadnt done much for a long period of time, said Hatfull.
Its the first instance of phage therapy used to treat an infection by Mycobacterium chelonae a related, but different species from the bacteria previously treated with phages. And while the patients immune system seemed to mount an attack against the phage, it didnt stop the treatment from being effective.
Yet another novel aspect of the study was the phage the researchers used.
Researchers worry about the potential for bacteria to evolve resistance to viruses. Delivering a cocktail of multiple phages is how Hatfulls team previously attempted to avoid the problem: Barrage a bacterial infection with three kinds of viruses at the same time, and its less likely to be able to out-evolve them.
But when the team tested phages against this patients infection, only one turned out to be effective: Muddy, one of the three used in the 2019 study.
Thats all that we had we used all of the phages that were available, Hatfull said. We obviously ran the risk that we would see resistance and failure. But it was either that or do nothing.
The fact that the bacteria didnt evolve resistance to the single phage came as a surprise, and it also opens up new potential for treating patients, especially for those with a robust immune system.
Now we can contemplate giving them phage number one for a month. And then well stop. Then give them phage number two for a month and then stop, Hatfull said. Doing so would lessen the risk of the patients immune system attacking the phages.
Taken together, the two studies point toward a future for phage therapy for a broader array of Mycobacterium infections and new potential ways to maximize the therapys chance of success.
Opening the floodgates
Until today, it may have seemed to an outside observer that the labs clinical work started and ended with that 2019 breakthrough. The truth is just the opposite.
Thats when the floodgates opened, said , a research associate in Hatfulls lab. We started to get requests from around the world, and we still get them.
Dedrick coordinates the labs clinical side, handling the mountain of permits and other paperwork required to give patients around the world an experimental therapy. She and a team of three research technicians also screen samples of bacteria sent from those patients, test viruses against them to see if any may be effective and perform follow-up testing after the treatment.
It was a sudden shift for Dedrick, who up to that point in her career had focused on basic science. But she quickly embraced it. Theres nothing else for the clinicians to give them, and then we offer this little nugget of hope, she said. Just being able to offer that to a patient who has no other options, its really fulfilling.
Other members of the lab have also become an important part of the teams clinical work, including Research Instructor , who cultures and purifies the phages to a quantity and quality that they can be injected into patients. What was first a nerve-wracking process has through years of practice become a well-oiled machine that takes in samples from patients and sends out lifesaving therapies.
Viruses hiding in DNA
Experimental medicine, however, is just one component of the labs work. At the same time, the group is continuing basic research into what makes these viruses and bacteria tick, producing clues about ways to improve future treatments.
One target: the samples of Mycobacterium cells sent by more than 270 patients looking for treatment.
As well as having a really good and broad and diverse collection of phages, we now have a big, broad and diverse collection of clinical isolates of Mycobacterium abscessus and some related strains, Hatfull said. This is a huge resource for understanding basic biology.
In that library of samples, Hatfull and his lab have found a surprising new place to look for candidate phages to enlist in the fight against Mycobacterium infections: Hidden in the DNA of these bacteria are the full genetic material of phages that infected those cells in the past. Their existence is proof that the phage can infect those bacteria, and the lab is now able to use these blueprints to bring these viruses to life. The next step is to tweak their DNA so they can not only infect those Mycobacterium strains, but reliably kill them, too.
Were still working on how to engineer them and how to get them into a therapy, said Hatfull. We havent used any of them therapeutically yet, but I think were getting close.
And continuing research on which phages infect which Mycobacterium strains and why could impact treatments in the future. At the heart of that question is the potential to move beyond a time- and labor-intensive personalized medicine approach to a more generalized treatment that could help patients on a much broader scale.
The three-legged stool
The labs educational mission has forged ahead too, even during a pandemic. Since 2002, Hatfull has led a program that involves undergraduates in cutting-edge research. Now, this program is called the Howard Hughes Medical Institute Science Education Alliance-Phage Hunters Advancing Genomic and Evolutionary Science (HHMI SEA-PHAGES), and it gives students the chance to discover and name their own viruses. One such virus discovered through the program was Muddy, now used in around half of the labs therapies.
Hatfull refers to the three aims of his lab as a three-legged stool, with each leg research, education and clinical work enriching the others.
We have this constant, ongoing process of expanding the number of phages that we have available to us, he said. At the same time, 30 years of work on the genetics of phages allows them to effectively drink from the firehose of phages, organizing them in such a way that theyre ready for quick assessments when a mycobacterium sample arrives.
As for their clinical work, the lab expects to soon publish reports of more case studies, moving past proof of concept and developing a more robust body of knowledge about phage therapy for Mycobacterium infections the kind thats essential to lay the groundwork for a potential clinical trial where the therapy could be tested in a more rigorous way.
We need clinical trials, and we aren't going to get there until we have some information about each of these steps, said Dedrick.
Wherever the field goes next, its all but certain that the lab will be at the center of it.
When it comes to people who work on phages that could be used for mycobacterial diseases, we are it, basically, said Hatfull. You cant get this from any other lab in the world, I think its fair to say.
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Patrick Monahan, photos by Aimee Obidzinski