A novel fluorescent drug that makes nerve tissue glow during surgery has demonstrated safety and efficacy in its first human trial, offering surgeons a new tool to avoid accidental nerve damage during delicate procedures. The Phase 1-2 study, published in Nature Communications, tested bevonescein in 27 cancer patients undergoing head and neck surgeries.
Revolutionary Nerve Visualization Technology
Bevonescein represents a breakthrough in surgical imaging, combining a fluorescent molecule with a short chain of amino acids that selectively binds to nerve tissue. When exposed to specific light frequencies through specialized microscopes, the drug causes nerves to emit a distinctive greenish-yellow glow, making them visible as "wormlike yellowish-green structures that thread through the surrounding tissue."
"The way that I explain this drug to patients is that I think if we can help surgeons see things better, they can do faster, more efficient, safer surgery," said Dr. Ryan Orosco, an associate professor and otolaryngologist at the University of New Mexico School of Medicine who co-authored the study.
Clinical Trial Results and Patient Safety
The initial trial focused on patients undergoing neck dissections to remove lymph nodes, parotid surgery, or thyroid surgery—procedures where cranial nerves are particularly vulnerable. Patients received intravenous infusions of bevonescein prior to surgery, with the drug demonstrating favorable pharmacokinetics.
"We can image them five, six, seven, eight hours later, and it still stays bound to the nerves, but it flushes out of the body within 12 hours," Orosco explained. The drug is quickly cleared by the kidneys while maintaining its binding to nerve tissue throughout the surgical procedure.
The study confirmed that bevonescein was safe to use and highlighted longer stretches of nerves than would be visible to the naked eye, improving the odds of operating without causing injury.
Expanding Clinical Development
A larger Phase 3 study is currently underway across 10 sites, including UNM Hospital, with Orosco serving as the national principal investigator. This pivotal trial, expected to complete by summer, will assess whether use of the imaging agent meaningfully improves overall surgical outcomes—something the initial trial was not designed to determine.
The research team is also exploring practical implementation strategies, including testing specially modified headband-mounted magnifying loupes that surgeons already wear, rather than relying solely on bulky microscopes. "Testing those loupes in a spinoff trial is a critical and practical step toward real-world implementation," Orosco noted.
Scientific Foundation and Future Applications
The technology traces its origins to the laboratory of Dr. Quyen Nguyen at the University of California, San Diego, who collaborated with the late Nobel laureate Roger Tsien. Tsien won the Nobel Prize in 2008 for discovering green fluorescent protein, which enabled the development of methods to "tag" specific molecules and tissue types, including cancer cells.
If the Phase 3 trial demonstrates clear clinical benefit, bevonescein could receive FDA approval for head and neck surgery applications. However, the potential extends far beyond its initial indication.
"Once the FDA has approved it for a certain indication, then it'll be on the shelves," Orosco said. "Surgeons can also use it off-label for whatever they want. Then the big question is, how does that go? Who starts using it and in which types of surgeries?"
This development represents a significant advancement in surgical precision, potentially transforming how surgeons approach procedures throughout the body where nerve preservation is critical.
