This drug that lights up cancer cells under infrared light is making tumor removal more precise for surgeons

“Our goal is really to get out all the cancer,” says Dr. Arvind Bakhru. In the operating room, the gynecologic oncologist relies on sight and feel to help identify the cancerous lesions he’ll remove. But at the Arizona Center for Cancer Care Gynecologic Oncology, where Bakhru practices, there has been another tool at his disposal for the past year.

Flicking on an infrared light at the end of his laparoscope—the thin surgical tube that helps surgeons see inside the body during minimally invasive procedures— cancerous lesions start to glow green.

“It’s a striking difference,” Bakhru says. This fluorescent glow allows surgeons to see exactly where lesions are located, making removal easier and more precise—all courtesy of a medication called Cytalux. It’s still relatively new, but the physicians using it and the company that produces it, On Target Laboratories, say it’s already having a big impact for some cancer patients.

What is Cytalux?

Cytalux—administered via IV up to nine hours before surgery for ovarian cancer and up to 24 hours before surgery for lung cancer—works by attaching molecules of highly fluorescent, but harmless, dye to receptors that bring folate into cells. Because folate, a nutrient found in leafy greens and citrus fruits, supports cell growth and division—and cancer cells are always growing and dividing—folate receptors are often over-expressed in tumors.

The result is that cancer cells shine brightly under infrared light, while other cells stay dim, helping surgeons remove cancerous masses while sparing healthy tissue.

The U.S. Food and Drug Administration first approved the medication in 2021 for use in ovarian cancer surgeries, following a successful clinical trial that saw Cytalux identify known cancerous lesions and, in over 30% of patients, additional lesions that hadn’t previously been detected. In 2022, it was also approved for lung cancer surgeries.

Since it became commercially available in September 2023, Cytalux has been used in over 1,000 surgeries for lung and ovarian cancers—most of which occurred just this year.

Bill Peters, CEO of On Target Laboratories, says there are many more potential use cases for Cytalux. “Because it has such an affinity for all different types of folate receptors—which unfortunately are represented by 85% of cancers—we are in the very early days of our ability to treat patients,” he says.

Making surgeries more precise

In lung cancer surgeries, Cytalux is a more precise alternative to dyes that can be applied to cancerous areas during the surgery itself. While these traditional dyes are effective at marking which areas need to be removed, it can be challenging for surgeons to avoid leakage and overlap when applying dye to multiple lesions in the same area.

Cytalux “gives the surgeon a lot of comfort,” says Ryan Levy, chief of thoracic surgery at the University of Pittsburgh Medical Center. It increases surgeons’ confidence that they’ve removed as much of the cancer hidden in the lobes of the lung as possible—while sparing the healthy tissue and lung function of their patients.

“To take a specimen out and then not be 100% sure that the lesions are in the specimen and then have to go back in and take out the rest of the lobe, that’s sort of the nightmare scenario,” Levy says.

Catching issues early

Beyond tissue-sparing surgeries, Levy says the drug is already playing an important role for patients who are referred to him with small, potentially cancerous, lesions on their lungs.

“The last thing a patient wants to be told is, ‘Oh, you have a five millimeter spot, and we’re not going to be able to find it, and you just have to wait until it gets bigger,’” Levy says. “Now we have a way of localizing stuff like that.”

Being able to find even the smallest spot of cancer is also pivotal in ovarian cancer surgery. Bakhru says patients with ovarian cancer tend to have vague symptoms—such as bloating, bladder issues, and “just not feeling quite right”—until the disease has progressed and the tumor is large. However, he notes that the past 15 to 20 years of research has pointed to removing even small, not yet symptomatic, lesions as being crucial for a good long-term prognosis.

For now, Cytalux is the only product of its kind available, and Peters says no other drugmakers have completed the clinical trials needed to apply for FDA approval. Bakhru sees it as “the lead example” of multiple potential products that will help surgeons identify and remove cancer with increased precision.

“I think it’s important for people to know that the quality of your surgery and the completeness of your surgery really matters in terms of survival and keeping that cancer from coming back,” Bakhru says.