Adhesive patch delivers drug to tumour sites

The general approach to cancer treatment today is the use of systemic, or whole-body, therapies such as chemotherapy drugs. But the lack of specificity of anticancer drugs means they produce undesired side effects when systemically administered.

What's more, only a small portion of the drug reaches the tumour site itself, meaning the primary tumour is not treated as effectively as it should be.

Indeed, recent research in mice has found that only 0.7% of nanoparticles administered systemically actually found their way to the target tumour.

"This means that we are treating both the source of the cancer—the tumour—and the metastases resulting from that source, in a suboptimal manner," Artzi says. "That is what prompted us to think a little bit differently, to look at how we can leverage advancements in materials science, and in particular nanotechnology, to treat the primary tumour in a local and sustained manner."

The researchers have developed a triple-therapy hydrogel patch, which can be used to treat tumours locally. This is particularly effective as it can treat not only the tumour itself but any cells left at the site after surgery, preventing the cancer from recurring or metastasising in the future.

Firstly, the patch contains gold nanorods, which heat up when near-infrared radiation is applied to the local area. This is used to thermally ablate, or destroy, the tumour.

These nanorods are also equipped with a chemotherapy drug, which is released when they are heated, to target the tumour and its surrounding cells.

Finally, gold nanospheres that do not heat up in response to the near-infrared radiation are used to deliver RNA, or gene therapy to the site, in order to silence an important oncogene in colorectal cancer. Oncogenes are genes that can cause healthy cells to transform into tumour cells.

The researchers envision that a clinician could remove the tumour, and then apply the patch to the inner surface of the colon, to ensure that no cells that are likely to cause cancer recurrence remain at the site. As the patch degrades, it will gradually release the various therapies.

The patch can also serve as a neoadjuvant, a therapy designed to shrink tumours prior to their resection, Artzi says. When the researchers tested the treatment in mice, they found that in 40% of cases where the patch was not applied after tumour removal, the cancer returned.

But when the patch was applied after surgery, the treatment resulted in complete remission. Indeed, even when the tumour was not removed, the triple-combination therapy alone was enough to destroy it.

Unlike existing colorectal cancer surgery, this treatment can also be applied in a minimally invasive manner. In the next phase of their work, the researchers hope to move to experiments in larger models, in order to use colonoscopy equipment not only for cancer diagnosis but also to inject the patch to the site of a tumour, when detected.

"This administration modality would enable, at least in early-stage cancer patients, the avoidance of open field surgery and colon resection," Artzi says. "Local application of the triple therapy could thus improve patients' quality of life and therapeutic outcome."