Nanoparticles can enhance precision and safety of tumor treatment
Researchers have developed a new nanoparticle that has the potential to make ultrasound cancer therapies both safer and more effective, and even prevent tumors from recurring. The study, which is detailed in the journal Nano Letters, seeks to enhance high-intensity focused ultrasound, which can potentially harm healthy tissues.
Oregon Health and Science University (OHSU) was the first hospital in Oregon to offer robotic-assisted high-intensity focused ultrasound for the treatment of prostate cancer. Scientists at OHSU's Knight Cancer Institute aimed to improve mechanical tumor ablation, a method that mechanically destroys solid tumors using energy without the use of surgery. The method has two major drawbacks: it typically requires a high level of energy, which also creates heat that can damage healthy tissue, and in certain situations, cancer cells can persist, leading to a potential return of the cancer. Co-lead author of the research, Michael Henderson, explained that they engineered nanoparticles, even smaller than a sheet of paper, to bring cancer treatment more effectively. The nanoparticles have small bubbles on their surface that burst when focused ultrasound is used on them, releasing energy to destroy tumors more specifically. They are also coated with a peptide that causes them to stick to tumors and penetrate cancer cells more efficiently.
To further enhance the therapy, the researchers attached a strong chemotherapy drug to the nanoparticle's peptide. Li Xiang, the other co-lead author, called the method a "one-two punch." The ultrasound destroys the tumor, and the drug assaults any cancer cells that may remain and lead to recurrence.
In preclinical studies using human melanoma models, the combination achieved more efficient tumor destruction and drug delivery compared to each treatment independently. Henderson added that nanoparticles had the potential to lower the energy requirement of ultrasound treatment up to 100-fold, enabling shorter ultrasound pulses to be used to break up tumors without overheating surrounding tissue.
When it was tested in mice with human melanoma tumors, the combined treatment using ultrasound and drug-loaded nanoparticles was far more effective than either of the treatments alone. Tumors vanished in some cases, with improved overall survival of over 60 days and no noticeable side effects.
This new treatment method can also be used in other diseases, such as infection or cardiovascular disease, where the combination of mechanical therapy and drug therapy can be beneficial. The study's senior author, Adem Yildirim, was interested in bringing this work into immunotherapy, with the vision of creating improved cancer treatment results and lower recurrence rates using focused ultrasound along with smart drug delivery.
Henderson pointed out that future combination therapies, such as immunotherapy and ultrasound, could exceed the benefit of each therapy by itself. The study is an important first step towards a new type of nanoparticle-based therapy that could boost the treatment of recalcitrant tumors.
