Schematic shows the thumb-sized cold plasma patch, which has more than 200 hollow microneedles that can penetrate the skin and enter the tumor tissue. Photo by: UCLA Jonsson Comprehensive Cancer Center
Researchers have developed a patch that delivers both immune checkpoint inhibitors and cold plasma to melanoma tumours, designed to increase the efficacy of the immune response in treating the cancer. According to the researchers, the thumb-sized patch uses hollow microneedles to penetrate the skin and enter the tumour tissue. Cold plasma delivered through the microneedles generates reactive oxygen and nitrogen species that can destroy cancer cells. The destroyed cells then release tumour-specific antigens that stimulate an immune response. At the same time, the immune checkpoint inhibitors block the checkpoint proteins which would otherwise interfere with the immune system's targeting of the abnormal cancer cells. “Immunotherapy is one of the most groundbreaking advances in cancer treatment,” said study senior author Zhen Gu, PhD, professor of bioengineering at the UCLA Samueli School of Engineering and member of the Jonsson Cancer Center, in a press release. “Our lab has been working on engineering new ways to apply or deliver drugs to the diseased site that could help improve the effectiveness of cancer immunotherapy, and we found the patch to be a quite promising delivery system.” In a paper published in Proceedings of the National Academy of Sciences (Feb. 6, 2020), investigators detail how mouse models of melanoma, treated with the patch, experienced significantly inhibited tumour growth and extended survival. Some 57% of the mice in the treatment group were still alive at 60 days, while mice in other control groups had all died. Additionally, not only was the growth of the target tumour reduced, but growth of tumours that had spread to other parts of the animals' bodies was inhibited as well. The authors say this is the first study to show that cold plasma can effectively synergize with cancer immunotherapy. “This study represents an important milestone for the field of plasma medicine,” said co-senior author Richard Wirz, PhD, professor of mechanical and aerospace engineering at UCLA Samueli. “It demonstrates that the microneedle patch can realize the plasma delivery while also working with the drug to improve the effectiveness of cancer therapy.” “This treatment strategy can potentially go beyond cancer immunotherapy,” said Dr. Gu, who is also a member of the California NanoSystems Institute at UCLA. “Integrated with other treatments, this minimally invasive method can be extended to treat different cancer types and a variety of diseases.”