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. Image: UCLA Jonsson Comprehensive Cancer Center
An interdisciplinary team of researchers at the UCLA Jonsson Comprehensive Cancer Center has developed a medicated patch that can deliver immune checkpoint inhibitors and cold plasma directly to tumors to help boost the immune response and kill cancer cells.
The thumb-sized patch has more than 200 hollow microneedles that can penetrate the skin and enter the tumor tissue. The cold plasma is delivered through the microneedles, destroying cancer cells, which facilitates the release of tumor-specific antigens and boosts the immune response. The immune checkpoint inhibitors — antibodies that block checkpoint proteins, which interfere with immune system function and prevent the immune system from destroying cancer cells — are also released from the sheath of microneedles to boost the T cell-mediated anti-cancer effects.
The UCLA researchers found that using the patch to deliver the two therapies to mice with melanoma enabled the immune system to better attack the cancer, significantly inhibiting the growth of the tumor and prolonging the survival of the mice. The team further found that the therapy not only inhibited the growth of the targeted tumor, but it also could inhibit the growth of tumors that had spread to other parts of the body.
“Immunotherapy is one of the most groundbreaking advances in cancer treatment,” says Zhen Gu, PhD, professor of bioengineering at the UCLA Samueli School of Engineering and a member of the UCLA Jonsson Comprehensive Cancer Center. “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.”
The study is also the first to demonstrate that cold plasma can be effective in synergizing cancer immunotherapy. Plasma, which is usually hot, is an ionized gas that comprises more than 99% of the universe. Cold plasma was generated by a small device operating at atmospheric pressure and room temperature; therefore, it could be applied directly to the body — internally or externally.
“This study represents an important milestone for the field of plasma medicine,” says Richard Wirz, PhD, professor of mechanical and aerospace engineering at the Samueli School. “It demonstrates that the microneedle patch can realize the plasma delivery, while also working with the drug to improve the effectiveness of cancer therapy.”
The team tested the cold plasma patch on mice with melanoma tumors. The mice that received the treatment showed an increased level of dendritic cells, which are a specific type of white blood cell that alert the immune system of a foreign invader and initiate a T-cell-mediated immune response. The group of mice also showed delayed tumor growth compared to the untreated group, and 57 percent were still alive at 60 days, while mice in other control groups had all died.
— Denise Heady
“Transdermal Cold Atmospheric Plasma-Mediated Immune Checkpoint Blockade Therapy,” Proceedings of the National Academy of Sciences, February 18, 2020
Zhen Gu, PhD
Richard Wirz, PhD