Drug Delivery Platform Could Usher Phage Therapeutics to the Clinic

By Deborah Borfitz

September 16, 2025 | A biotech startup aims to revolutionize the use of phage therapeutics with a drug delivery platform enabling them to be used in real-world clinical settings. Paldara was founded after its young creator and CEO William Colton won his first pitch competition at Oklahoma State University (OSU) based on his studies using bacteriophages to combat antibiotic-resistant bacteria. 

The research-turned-business venture is focused on a three-part system to effectively deliver and protect bacteriophages, including a specialized hydrogel coating that can be applied to medical devices like urinary catheters to provide localized, controlled release of the bacteria-infecting viruses over an extended period, says the now-26-year-old Colton. Currently, many phage therapeutics are administered intravenously although the infections being treated are typically not systemic. 

Microencapsulation of the bacteriophages permits them to be released over seven to 14 days while supporting recovery and healing of surgical site infections, Colton says. The technique protects phages from the body’s immune system as well as extends their shelf life from hours to possibly a decade. 

The hydrogel is highly biocompatible and can therefore also be used topically to treat burn wounds, he adds. “We’ve tried to optimize this for real-world use scenarios ... to make sure that we can use this whole new arsenal of therapeutics that can help fight drug resistance.” 

Paldara’s platform incorporates a library of over 200 novel therapeutic bacteriophages chosen to combat “ESKAPE” pathogens, a group of six bacteria—Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.—known for their ability to escape the effects of antibiotics, says Colton. A seventh target, Escherichia coli, is also included due to its high prevalence and resistance issues. 

“We can modify the cocktail based on the use case, so we have different cocktails for catheter-associated UTIs [urinary tract infections] than for soft tissue infections,” Colton says. He likens the technology to “an Intel chip for the phage therapeutic pipeline,” helping to translate benchtop research into bedside treatments. 

To that end, the company is now partnered with the Mayo Clinic to advance and validate the technology for clinical use, he reports. The collaboration includes both animal and human studies, with a first-in-human clinical trial underway as soon as this December. 

“We’ve got a lot more work to do but once we save that first patient that’ll be everything,” says Colton. Since the journey is being undertaken with Mayo, it is “much more likely” that wish will become a reality. 

Lab Buildout

Colton says he fell into the phage therapy space while in a pre-med program involving a summer internship at Texas Medical Center after his senior year of high school. He was studying maxillofacial oral cancer under Simon Young, DDS, M.D., using “STING” (stimulator of interferon genes) hydrogels designed to deliver chemotherapeutics directly into head and neck tumors. 

The hydrogels, loaded with STING agonists, were typically systemically infused into patients, he says. This meant they came with off-target toxicity causing side effects such as nausea and hair loss that Young was working to circumvent.    

Colton’s role included doing tissue sampling and immunohistochemistry staining on preclinical mouse models, he adds. It was his first experience in a laboratory setting and sparked his interest in research. 

He arrived at OSU in pursuit of a microbiology degree and became one of the first three undergraduate students to join the lab of Matthew Cabeen, Ph.D., associate professor in the department of microbiology and molecular genetics, who had just joined the faculty. The Cabeen lab was studying biofilm formation, “one of the key mechanisms of drug resistance in bacteria,” Colton notes. 

The experience taught him how to build a lab and gave him the opportunity to run his own projects specific to P. aeruginosa. “I helped discover a gene called RecA and ... how it regulates biofilm, so that was my big step into research,” he says. 

All the while, Colton was nagged by the insidious problem of antibiotic resistance despite the massive investment of time and money devoted to finding a solution to this deceptively dangerous threat to public health. In trying to understand the biological challenges, he learned about bacteriophages—naturally-occurring viruses that control bacteria in the skin and gut microbiome as well as in the soil, marine environments, and wetlands. “Wherever there are bacteria, there are phages there regulating them.” 

Thus began his quest to make bacteriophages easier to use by clinical professionals like physicians and nurses. That meant reducing the side effects, and unnecessary burden on patients, much like the longstanding work in oncology to improve overall treatment success of chemotherapeutics.  

Gaining Traction

Paldara launched in May of 2019, during Colton’s sophomore year, and has been sustained thanks to the recognition and prize money associated with a series of pitch competitions where he was either the winner or a finalist. The initial competition at OSU was followed by others at Rice University, Princeton, and Arizona State University (ASU) while working towards his bachelor’s degree and subsequent master’s degree in microbiology. 

Colton opened his lab at OSU in 2020 with $21,000 in pitch competition winnings and $100,000 in financial backing. Despite being shut down for a few months because of the pandemic, by December 2020 Paldara had developed its first minimum viable product against multidrug-resistant E. coli strains and K. pneumoniae, two of the leading causes of catheter-associated UTIs. 

Combating antimicrobial resistance is not just a scientific objective, says Colton, who lost two half-brothers to opioid addiction and his grandmother to a superbug after routine surgery. Overreliance on prescription drugs was the common thread. 

The opioid crisis and antibiotic resistance crisis have both been neglected, resulting in their being top killers of the American people in recent years, he says.  “I recognize the gaps within the healthcare system ... and it’s personal to me to make a difference.”  

He found a peer in Gina Suh, M.D., director of Mayo’s phage therapy program, who says Colton’s “vision and determination” has been inspiring. “It has been a privilege to collaborate with him and his team as they push the boundaries of what phage therapeutics can achieve.” 

Conventional therapies do not help all patients, she says, in explaining why she began giving phages a try. “At the Mayo Clinic, we have now treated nearly 20 patients with phage or phage-adjacent therapies under FDA Expanded Access, spanning a wide range of indications and bacterial pathogens. Each case underscores both the urgency of the antimicrobial resistance crisis and the hope offered by innovations like Paldara’s platform, which can help bring these therapies into real-world practice for the patients who need them most.”  

Colton says he reached out to Suh after applying for the MedTech Accelerator program of ASU and the Mayo Clinic and learning of her remarkable work. Suh ended up personally recommending him for the program, helping to make Paldara one of the 10 companies worldwide selected for the program last year. The accelerator is helping to advance its antimicrobial medical device coatings—what Colton calls “next-gen Neosporin”—with an immersive curriculum in healthcare entrepreneurship as well as mentoring, business development, and networking events.   

As part of the program, the technology is being evaluated for market fitness and clinical need as well as how Paldara’s technology can improve the safety of bacteriophage therapeutics, Colton says. The Mayo Clinic also decided to support further development of the platform through a formal know-how license with Suh and a sponsored research agreement with Robin Patel, M.D., chair of Mayo’s infectious disease division who conducts animal trials and preclinical studies. 

Few physicians have used phage therapeutics, so the real-world perspective of Dr. Suh has been “invaluable” in guiding development of applications for the technology and the how to have the fastest go-to-market impact, says Colton. Separately, Paldara is collaborating with the OSU College of Veterinary Medicine on preclinical studies of its phage drug delivery platform for surgical site infections.  

Foundational Elements

“Localization and stabilization are two of the key hurdles that phage therapeutics face in going into clinical practice,” say Colton, as he recited the foundations of the Paldara platform—microencapsulation, time-released hydrogel matrix, and cocktail of bacteriophages. “All three of those together, along with synergistic antibiotics and other synergistic biologics, create our complete platform.” 

The microencapsulation component essentially traps bacteriophages in a small sodium alginate sphere that is then treated and coated to accommodate delivery of the therapeutics to different sites of care with different pH levels to avoid off-target effects, he explains. This also controls the extended delivery process, which is based on the interaction between the microencapsulated beads. 

The secondary hydrogel matrix also allows for controlled and sustained delivery of a consistent concentration of phages to the site of care, he continues. Since it is biocompatible with the surrounding tissue, it enables rapid wound healing with less pus and exudate (weeping fluid) being produced.  

At the same time, that hydrogel matrix “prevents white blood cells and antibodies from invading and neutralizing the bacteriophage,” says Colton. “Bacteriophage don’t trigger a strong immune response for the most part, since they’re typically part of our microbiome, but we do have a lot of neutralizing antibody components within our blood and throughout our body that will actively eliminate bacteriophage because they’re ... not part of our natural tissue systems, so we have to protect them in order to use them as a therapeutic.” 

The hydrogel method is “synergistic and complementary, and the phages themselves can be alternated out based on the application,” Colton says. Depending on the indication, the Paldara team might blend hydrogels in different ratios to change the delivery response profile to speed up or slow down release and perhaps alter the coating process for the microencapsulation procedure. 

Other synergistic components can also be included, meaning the platform is not solely for the development of bacteriophage cocktails, says Colton. The additions might include β-lactams antibiotics known to work well alongside bacteriophages for more broad-spectrum coverage, or human-derived growth factors to help improve wound healing and prevent fibrotic development.  

Clinical Scenarios 

The intent is to optimize patient care, which is exemplified by the hydrogel matrix that is easy for healthcare professionals to use and implement in their day-to-day operations, Colton says. It is stored as a dry powder to which an ionic buffer is added to create the gel, usually within five to 10 minutes. “It can function as an antimicrobial lubricant for urinary catheters, you can use it as a topical salve for surgical site infections or for burn wounds, and from there you can just expand upon [the use cases].” Since it is injectable, the applications include post-operative joint infections. 

When phage therapy is contemplated for treating post-surgical infections, the process currently involves directly irrigating the wound with bacteriophages mixed into a saline solution. “The problem is once you close that wound up those phages are rapidly eliminated,” he says. “You don’t get the sustained delivery, so you’ve left behind bacteria that can colonize and establish an infection again.”  

The overall success rate of phage therapeutics is low, adds Colton, but “it depends on the patient use case.” In the U.S., phage therapy commonly involves Emergency Use Authorization or Expanded Access approval from the Food and Drug Administration as a last-resort option for patients already in critical condition with a drug-resistant infection. The strategy famously cured UCSD psychiatry professor Thomas Patterson a decade ago from a strain of A. baumannii after he teetered close to death. 

In his case, naval researchers were able to quickly match phages to his bacterial isolate and inject billions of them into his system, to get him off life support in under two weeks. But the almost infinite number of bacteriophages on earth complicates the business of precisely pairing them with the bacterial pathogens they will attack, and there is not yet a centralized, open-source phage bank to fully remedy the situation. 

Paldara looks to be part of the solution with its ready-to-use dry powder phage formulations. “We can load a large variety of stabilized phages within our hydrogel and then have it ready on the shelf as needed, instead of having to culture the phages [case by case],” Colton says. “It bridges a huge gap [since], originally, they couldn’t be stored at room temperature.” 

Phage cocktail formulations, rather than single phages, are now the treatment norm to combat bacterial resistance, he says, noting that a new antibiotic class hasn’t come to market for 30 years. The beauty of phage therapeutics is that “each phage functions as its own antibiotic,” so bacterial populations don’t form resistance against all phages. “We can knock them out the first time.”  

Moving forward, the company hopes to aid in the mission of the Center for the Strategic National Stockpile with phage therapeutics that are ready to use in a matter of seconds, says Colton. There is always federal-level interest in disease prevention, and with the ongoing armed conflicts destabilizing healthcare systems in Gaza, Ukraine, and Eastern Europe, diseases not normally seen in the U.S. are only one flight away. If refugees start arriving with drug-resistant tuberculosis, polio, and typhoid fever, it could have potentially devastating consequences for the public health system. 

More than anything else, Colton wants everyone to know about the perils posed by antibiotic resistance and that scientists like him are spending their careers trying to develop new and better therapeutics. “Believe in them,” he implores, and give the stricken now and in the future a “fighting chance” of surviving.