Scientists from Oregon State University in the US have developed a means to selectively introduce compounds into cancer cells so that they can be identified and malignant tissues removed in combination with phototherapy, and also killing remaining cancer cells once a tumor has been removed, preventing recurrence. Based on successful laboratory trials, this mix of surgery and non-toxic phototherapy has great potential for improving on existing chemotherapies and radiotherapies.

Although for many cancers surgery is the first choice treatment, it is not easy to remove most of the tumors, and residual cancer cells can eventually lead to relapse. The team were therefore exploring novel nanotechnology-based platforms to treat different cancers using intraoperative guidance with a real-time near infrared (NIR) fluorescence signal. As reported in the journal Nanoscale [Taratula et al. Nanoscale (2015) DOI: 10.1039/C4NR06050D], they devised a system for greater accuracy in the surgical removal of solid tumors and eradicating remaining cancer cells using the compound naphthalocyanine.

This derivative of phthalocyanine has unusual properties when exposed to near-infrared light, such as making cells glow – thus helping to guide surgeons to specific cells – and heating the cell to kill it off through mild heating and the development of reactive oxygen species. By adjusting the intensity of the light, the action of the compound can be controlled and optimized to kill only the tumor and cancer cells, and nothing else. It is hoped that this double attack from 'glowing' nanotechnology based on a single-agent-based nanomedicine platform capable of both NIR fluorescence imaging and combinatorial phototherapy could significantly improve the success of cancer surgeries.

However, while naphthalocyanine is commercially available, its potential clinical application is limited by low water solubility and aggregation, which reduces its ability to make cells glow and generate reactive oxygen species, as well as preventing it from finding its way through the circulatory system to reach specific cells. They overcame these obstacles through the use of a special water-soluble nanoparticle polymer called a dendrimer, which allows the compound to be concealed within a molecule that attaches to cancer cells.

Although the process has demonstrated in laboratory mice, the team will look to make improvements before testing on larger animals with malignant tumors. They also hope to explore the optimization of this nanomedicine platform by focusing on the performance of image-guided cancer surgery and intraoperative phototherapy and employing it with an imaging system specifically designed for real-time NIR imaging.