Photodynamic therapy (PDT), a long-standing cancer treatment, has shown promise in targeting tumors without harming healthy cells. However, its effectiveness has been limited by poor tissue penetration, prolonged sensitivity to light, and off-target toxicity. A study, published in Angewandte Chemie, introduces a potential solution: cyanine-carborane salts, a new class of compounds that improve PDT’s precision and safety.
Researchers from the University of California, Riverside (UCR) and Michigan State University (MSU) developed these salts to selectively accumulate in cancer cells and activate under near-infrared light. Once triggered, the compounds produce reactive oxygen molecules that break down tumor cells while minimizing damage to surrounding tissue. In laboratory tests on mice, this approach successfully eradicated metastatic breast cancer tumors.
One of the key improvements is the ability of these compounds to clear from the body quickly, avoiding prolonged light sensitivity, a major drawback of traditional PDT. According to Professor Vincent Lavallo, a UCR chemistry researcher and co-principal investigator, “The compounds target exactly where they’re needed and stay there, while the rest pass through.”
Unlike conventional PDT agents, which require costly targeting chemicals, cyanine-carborane salts exploit a natural vulnerability in cancer cells. Tumors overexpress certain proteins (OATPs) that readily absorb these compounds, enabling precise tumor targeting without additional modifications.
Another advantage is deeper tissue penetration. Traditional PDT is often limited to surface-level tumors due to its reliance on visible light. However, these new salts respond to near-infrared light, which can reach deeper into tissues. This could expand the use of PDT for treating cancers beyond the skin and bladder, such as breast and other internal tumors.
Given their success, researchers are now exploring ways to further enhance the therapy. Amir Roshanzadeh, a molecular biology graduate student at MSU and first author of the study, suggests that modifying the salts for activation by other energy sources could allow even greater penetration into the body. “Our work offers a targeted, safe, and cost-effective treatment for aggressive breast cancers with limited treatment options,” Roshanzadeh stated.
As research progresses, this development represents a significant step toward more precise and less toxic cancer treatments, potentially broadening the applications of PDT in oncology.
